I recently got a bench press question form a member. You know it's funny, I used to get more bench press questions than anything and after a while, I started getting more deadlift questions than anything. Which I liked until I almost have grown sick of talking about the deadlift so it's sort of a treat to get a bench press question again. The question was basically this:

Bench press - Flaring versus tucking the elbow: What exactly do people mean by this? It is confusing me, and I want to get the correct form. When I read 'Tuck Your Elbows in' I'm thinking moving the arms closer to Your body, like the close grip bench, but keeping the same grip width. Is this what it means?

After I answered the question, I figured that it is related to why a person can lift more on the flat bench press than on the incline press. So, I'll knock over two cans with one stone in this post. First to answer the basic question:

What does it mean to "flare your elbows" on bench press?

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When people say "flare the elbows" they mean that the elbows themselves are out away from the sides of the body. Obviously, in order to flare your elbows far out you would need to have a wider grip, and many bodybuilders, and some powerlifters adopt this elbows out position for the bench press, some so that the upper arms come close to being perpendicular to the body.

The reason bodybuilders do it is because it emphasizes the pectorals more, and they only do the bench press to grow their chest. Since both the upper and lower portions of the pectoralis major are very strong adductors of the shoulder, but especially the upper fibers, keeping the arms out brings to bear the pecs by calling on them to adduct the arms/shoulder joint more so than if the elbows were tucked in.

The Pectoralis Major

By the way, keep in mind that from a kinesiological perspective, when I say arms I am always referring to the upper arms. Otherwise I'd say 'forearms'. So having your "arms out" or your "elbows out" on bench press is the same thing. The reason people say "elbows out" is because when you say arms, people want to know 'which part' of the arm. So now you know that "arm' means upper arm. To help bring this home, the word "brachii" in biceps brachii means just arm. We use a similar convention for the legs, so that when we say leg we mean the upper leg or thigh, not the lower legs or shins/calves.

Okay, so keeping your arms out, away from your side, with the commensurate wider grip, emphasizes the chest more by calling on it's ability as an adductor, along with the anterior deltoids. So for bodybuilders, an arms out bench is done for the same reason as a dumbbell fly, except of course much more weight can be used in the bench press, and it also hits the triceps.

Some powerlifters use the elbow/arms out style with a wider grip simply because it decreases the distance the bar has to travel and for those with short arms who are suited to this style, it can be very successful.

Those are the reasons for the arms out style, but it is VERY stressful on the shoulder joint and is part of what gave the bench press a reputation as a shoulder killer…since so many people use the bodybuilder style of pressing.

The very opposite of that is having the elbows/arms tucked tight into the sides, which would of course mean you'd need to bring the grip in closer, maybe even closer than shoulder width. Having your arms tucked tight to your sides is a very uncomfortable way to bench and it is actually hard on the shoulders in it's own way. It also makes the pectorals less efficient since there is MORE shoulder extension but less adduction. The upper pecs are actually good extensors, but the lower fibers not so much and the deltoids have to do more than their fair share. The overall affect of this, without getting too complicated, is that an arms tucked tight in style means most will lift less weight and stress the shoulders.

It is quite normal for these dichotomies to be set up in strength training. If having your arms flared out bodybuilder style is incorrect and dangerous, then having your arms tucked tight into your sides must be correct, right? Wrong.

The more efficient and safest way to bench press, for most, is to have the arms come out from the body to just around 45 degrees or so..although it does not need to be perfect…whatever angle is most comfortable. So, if having your arms right against your sides is zero degrees, bringing them out about halfway between that and 90°, which would be at right angles to your torso, should be right. For most trainees this will mean a grip width of around shoulder-width, give or take.

When people say "tuck your elbows in" it is hard to be sure what they mean. Some people literally mean to tuck them in tight to your sides. But others may mean relative to having them flared out all the way. So that is an ambiguous cue, at best. The reasons for being able to lift more on the flat bench, as you shall see, is actually related to some of the points I made in this answer. To explore this, I'll go a bit more in-depth on some of the things I introduced above.

Why Can You Lift More on Flat Bench Press Than on Incline Bench Press?

The answer to this question, which I'm sure most bench press warriors have wondered about from time to time, is one of simple kinesiology and muscle recruitment. Although most people think of the bench press as a chest exercise, the movement is really one of the shoulder and the muscles involved are shoulder muscles. Yes, your pecs (pectoralis major) are shoulder muscles. As you move the weight upwards in the bench press, the triceps must extend the elbow, yet we can assume that the act of extending the elbow is pretty much the same in the flat and incline bench. So, something must change at the shoulder.

To figure out what is going on, the first thing to do is figure out what primary shoulder movements are taking place. Some of this depends on your technique and arm position when doing the bench press. Let's assume there are three positions in which you can place your arms: elbows out like a bodybuilder, elbows pinned to your sides, like a goofball, and elbows out around 45 degrees or so, like a sensible person. Here, we'll consider only arms out and arms at 45, as that is all we need to answer the question and because hardly anybody bench presses with their arms pinned to their torso, as it is uncomfortable to most of us.

Elbows Out Bodybuilder Style

If you have a "bodybuilder style" press, with a wider grip and the elbows flared outwards, the primary shoulder movement becomes horizontal adduction. Horizontal adduction is a movement of the humerus toward the midline of the body from a position of abduction (like a dumbbell fly). Of course, you could also introduce more flexion by not allowing the bar to go up in a straight line, but let us assume you lift the bar in a more or less fixed path. Now, the pectoralis major has two heads and therefore two "sets of fibers." The sternal head (lower fibers) and the clavicular head (upper fibers). Both parts are big-time horizontal adductors and so can produce a good amount of force during the "elbows out" bench press, which explains why bodybuilders do it, and during the chest fly, which is all about horizontal adduction. The anterior (front) deltoid is also, of course, a horizontal adductor. The elbows out style, as you may have heard, puts a lot of stress on the shoulder joint (some people talk about "middle fibers" but let's not over-complicate things).

During the flat bench press with the elbows out, you have all the fibers of the pecs and the anterior deltoids working to produce this horizontal adduction of the humerus. But what happens when you place the body on an incline, with your head higher than your torso? Well, instead of doing mostly horizontal adduction you do a combo of horizontal adduction and flexion (moving the humerus straight up in front of you). While the clavicular head (upper part) of the pectoralis major is active in shoulder flexion, acting to flex, horizontally adduct and medially rotate the joint, the lower sternal head does not have the exact same roles. Instead, it is more of an oblique adductor.

Okay, what the heck is the difference between horizontal adduction and oblique adduction? Think of horizontal adduction as moving your arm across your chest toward your opposite shoulder. Oblique adduction, on the other hand, is moving your arm across you body toward the opposite HIP. The reasons the lower fibers of the pecs act this way is because of the way they are attached to the humerus and their orientation. While the upper fibers are attached more to the front of the humerus the lower fibers are attached a little more to the rear of the bone. Plus, they attach a bit higher up. This makes them poor flexors and changes the way they act in adduction. As your arm is flexed in front of your body during the incline press, the sternal head starts to drop out of the picture, leaving you with only the anterior deltoids and upper fibers of the pecs. So essentially, the incline press leaves you with less muscle to work with and you have to rely more on your comparatively small anterior deltoids as you increase the incline.

Ah, but does this explain how the incline press builds the upper pecs more? Not really, you see, while the entire pectoral is maximally recruited during a flat bench press, during an incline press the lower pecs contribute less force, but this doesn't mean the upper pecs are recruited more, it simply means the entire muscle complex is at a disadvantage. The debate as to whether you can isolate and "build" the upper chest or lower chest may never be resolved, but simple observation seems to say that such isolation is folly. The pectoral fibers work together and, despite the slight differences that can explain the different lifting capacities during the flat and incline bench, their overall action is one of adduction and medial rotation. Medial rotation, by the way, is another way of saying internal rotation.

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by EricT

Force-velocity Relationship: A propery of skeletal muscle contraction in which the force capibiltiy of a given muscle contraction is dependent on the velocity of shortening of the muscle.

There are three primary characteristics which affect the force potential of human skeletal muscle: velocity, length, and time. For those engaged in the pursuit of maximal strength, the force-velocity relationship may be the most important mechanical characteristic of human skeletal muscle. It is also the characteristic that is least known and understood by strength trainees. It is especially problematic because of the relationship between most athletic endeavors and power. That is, most athletic pursuits require high power outputs rather than high total force outputs. Since most information on strength training concerns this end goal rather than training for maximal strength, the student of maximal strength is left with mixed and confusing information. Even so, it is important for everyone to know that up to a certain point in strength advancement, increases in absolute strength always correspond to a measurable increase in power.

Specifically, the force-velocity relationship means that as the velocity of shortening increases the force capability decreases. In other words, high velocity or "fast" movements correspond to low force output from the muscles and low velocity movements correspond to high force output from the muscles. The reverse, therefore, is also true, in that the force resisting the muscle (e.g. the weight of an object being lifted) dictates the velocity of muscle shortening. IN this way, high force movements (e.g. from lifting max loads) correspond with low velocity of muscle shortening and low force movements (e.g. lifting lighter loads) correspond with high velocity of shortening.

Of all the mechanical characteristics of muscle, the force-velocity relationship may the most important for strength trainees as it shows that the force of an active muscle is variable in all muscle actions, eccentric, isometric, and concentric) and completely dependent on the speed of movement, and therefore the relative weight of the load being lifted. curve” emerges. The following image is an idealized version of this curve for illustration purposes only.

by EricT

Every once in a while you will hear someone calling the squat a simultaneous lift. You'll even hear people calling the deadlift a sequential lift. What does this mean, and is it correct?

Well, these terms come from the description and measurement coordination of human movement, a branch of biomechanics called kinematics. Movements, in this context, are looked at in terms of the movement of body segments, and this means also the action of the body's joints. You may have never given it a second thought, but during some movements the joints act "all at once" or simultaneously and in others they act one after the other in a sequence. Most movements, however, are not really so black and white and fall in a continuum between the two. sometimes, for instance, a movement may look to be simultaneously, but upon close observation be sequential.

Notice that I used the word movements and not lifts. That is because high force activities such as strength training lifts tend to be simultaneous movements. The squat, the deadlift, and the overhead press are all simultaneous movements. They body must call upon many large muscle groups at once to produce such maximal forces.

Speedy but lower force movements, such as throwing a baseball, tend to be sequential. Although children may start out performing these movements in a more simultaneous way, using only the shoulder for instance, a highly skilled throwing action uses a sequential movement of the body's segments, and a sequential rotation of the hips and the trunk, which transfers to the upper body through the action of the shoulder and on to the ball. If you've ever seen someone 'throwing like a girl' you have witnessed a novice thrower who has made the throw a simultaneous movement. So, girls don't throw like girls! In reality, inexperienced girls or boys will display this same pattern.

In the squat and the deadlift, the knees and the hips both tend to extend at once. Tend, because not everyone is the same and some people display different movement patterns. You may see someone extending their knees first and then their hips, for instance. This is often true of the novice, which makes sense in terms of motor learning. But even some experienced lifters may use such a method. The question is, can they really produce the highest muscular force possible if the body's segments, and therefore it's largest muscles, are not used in a coordinated fashion? It is very hard to determine but it is safe to say, I think, that most of us must extend forcefully at all the involved joints in order to muster our highest force.

Strength training has much to do with intention. Always keep this in mind. What a maximal lift looks like, and what the lifter's intention was, are often two different things. This is why maximal lifts are often not the best ones to use for teaching examples. When many many different high force lifts are observed, we would never be able to view them as absolutely simultaneous. But if intentions were understood, then high force lifts would fall much closer to the simultaneous end of the continuum.

Olympic Lifts are Sequential

Olympic lifts are not simultaneous lifts although the initial powering up of the bar requires a strong simultaneous triple extension. In the case of the clean (and jerk) the bar must be transferred to the shoulders in the "catch" which is part of a sequence of movements that involves first getting the bar accelerating upwards then dropping down underneath and bringing the elbows beneath the bar. Then another extension is used to power the bar up in the press to overhead.

The snatch likewise requires a simultaneous triple extension but the momentum of the bar is transferred overhead in a sequential movement while the lifter drops down under the bar and subsequently returns to the upright position. In case you are confused, remember that the Olympic lifts are NOT high force movements, they are high power movements.

Watch closely the slow motion video of volleyball spikes below (you may want to mute your speakers). What do you think? Is the spike a simultaneous or sequential movement?

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by EricT

By Ground Up Strength

Many strength trainees, bodybuilders, and exercisers are told that there should be a certain ratio between the strength of their hamstring and quadriceps muscles. Called the H/Q ratio and reported to be anywhere from .50 to .75 with a normative value of .60, the strength ratio of this important agonist/antagonist pairing is considered essential to the stability of the knee joint and to prevent ACL and other injuries. It is also sometimes thought to be predictive of those at risk for hamstring strain.

Some strength and conditioning experts actually test the maximal strength of the quadriceps and hamstring muscles of their clients, using leg extensions and leg curls, respectively, believing that they should observe a certain ratio in maximum weight of each movement and that this relationship will tell them whether their clients are at risk for a knee injury. To calculate the hamstring-quadriceps strength ratio, the maximal knee extensor moment and the maximal knee flexor moment is tested at identical velocities (isokinetic), and the flexion result is divided by the extension result.

It is quite true that the functional relationships between an agonist muscle, like the quadriceps, and its antagonist muscle, the hamstrings are very important, the idea that testing the strength of each muscle for an ideal ratio is an accurate screen for injury potential is rather crude and simplistic.

In reality there is not one ratio for concentric hamstring and quadriceps torque ratios but a range of ratios depending on joint angle and speed of movement. These have been well studied, producing averages anywhere from 0.5 to 0.75. The mechanical advantage of a muscle tends to change with the joint angle which changes the angle of pull of the muscle. As the mechanical advantage of one muscle increases the mechanical advantage of the other muscle may decrease. Also, the speed of the movement changes the angle at which peak torque occurs. Therefore, although important considerations for screening, these agonist/antagonist muscle relationships certainly are not static entities.

Another problem is that conventional testing, as described above, involves testing the maximal strength of the quadriceps and hamstrings using the same concentric action. This may make no sense because these muscles do not function in terms of concentric-concentric actions but concentric-eccentric actions.

Another observation is that quadriceps weakness is a feature of ACL deficiency. When people with anterior knee pain are tested, weakened quadriceps with normal hamstring strength is often found. In other words, weak quadriceps are typical in those with ACL dysfunction but this does not mean that weak quadriceps are a cause of ACL problems.

See DEVELOPMENTS IN THE USE OF THE HAMSTRING/QUADRICEPS RATIO FOR THE ASSESSMENT OF MUSCLE BALANCE for an indepth review of this subject, including conventional viewpoints and new developments concerning joint angle and muscle action.

References

Coombs, Rosalind, and Gerard Garbutt. "DEVELOPMENTS IN THE USE OF THE HAMSTRING/ QUADRICEPS RATIO FOR THE ASSESSMENT OF MUSCLE BALANCE." Journal of Sports Science and Medicine 1 (2002): 56-62. <http://ww.jssm.org/vol1/n3/1/n3-1pdf.pdf>

Dvir, Zeevi. Isokinetics: Muscle Testing, Interpretation, and Clinical Applications. Edinburgh: Churchill Livingstone, 2004. Print.

Brown, Lee E. Isokinetics in Human Performance. Champaign, IL: Human Kinetics, 2000. Print.

Bennell, K., H. Wajswelner, P. Lew, A. Schall-Riaucour, S. Leslie, D. Plant, and J. Cirone. "Isokinetic Strength Testing Does Not Predict Hamstring Injury in Australian Rules Footballers." British Journal of Sports Medicine 32.4 (1998): 309-14.

by EricT

By Ground Up Strength

Directional terms are widespread in all references concerning human performance, including anatomy, kinesiology, sports medicine, athletic training; and strength and bodybuilding coaching. At first, these terms can be confusing to the student of strength training but they are easy to understand once the fundamentals are studied.

Why would you want to know these terms? Well, lets say you have injured your knee and are having pain on the "outside" part of the joint. To find out what kind of injury you may have suffered, you search for references for "pain on the outside of the knee." However, you find many different directional terms besides outside and inside. In fact, scholarly references may not use these terms at all. The correct terminology is lateral and medial. So which part of your knee has pain? That is where understanding anatomical direction terms comes in handy.

The first important thing to know is the reference position of the body that these terms are derived from. When you are standing straight with your feet pointing forward and together and your hands naturally at your sides, palms facing in, you are standing in the fundamental position. However, anatomists and kinesiologists do not use the fundamental position as a reference. They use the anatomic position. This position is exactly the same as the fundamental position except for one key difference: the palms or the hands are facing forward. The importance of this will become apparent later.

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The image below is a diagram of a human figure in the anatomic position. The labeled directional arrows are meant to give an idea of the fundamental direction terms.

Anatomic Directions

Take special note of the midline. The terms lateral and medial are used in relation to an imaginary line drawn vertically down the center of the body. This midline is also referred to the median or midsagittal plane.

The midsagittal plane is the plane of symmetry of the body, and divides it into equal left and right halves. As stated above this is synonymous with the median plane of the body. As you might find references to the sagittal plane a bit of extra explanation is required. In the figure below, the midsagittal or median plane is shown.

Alternative Names for the Midsagittal Plane

• Sagittal plane
• Median plane
• Anteroposterior plane
• XY plane (based on right-hand coordinate system)

Midsagittal Plane
Image by Edoarado via wikimedia commons

Technically, a sagittal plane is any plane that divides a symmetrical body into left and right halves. This plane, passing down through the body would be parallel to the sagittal suture of the skull, but not necessarily intersecting it. This type of plane could also be called an anteroposterior plane. Sometimes the term sagittal plane is used to refer to the median or midsagittal plane, but it is more conventional to refer to any plane parallel to the median plane, dividing the body into unequal left and right halves, as a parasagittal plane.

The median or midsagittal plane passes through the sagittal suture. When you perform a situp, bend over to touch your toes, do biceps curls, knee extensions or leg curls, you are performing work in this plane.

Anything away from this midline is lateral and anything toward this midline is medial. The tip of your nose is in the median line and your cheeks are lateral to your nose. Now, consider the position of the hands. Which part of the wrist is the medial part? That's right, its the part that is against the body in the anatomic position, or closest to the midline. Now look at the knees. Remember that hypothetical pain on the "outside" part of the knee? Well the outside part of the knee is the part away form the midline. So we are talking about the lateral knee.

Sometimes the terms inside and outside are used when referring to the wrist and the knee, as we have seen. Although these terms are used in this article to mean the same thing as the medial and lateral aspects of these joints, it is best to avoid these terms as different people will mean different aspects when using them. For some, for example, the "inside" of the wrist is the part that corresponds to the palm of the hand, while for others it is the side that is medial, as used here.

Chart of Anatomical Direction Terms, Definitions, and Examples

Anatomical Directions Also Refer to Motions

Although most of the examples given here are of structures and their position relative the anatomical position and to another structure, these directional terms also refer to motion that occurs relative to the anatomical position and to the median plane, or other planes, of the body.

However, the actual movements of joints have their own terms, also relative to the planes and anatomical position. Therefore, although you can move your wrist medially, this motion is usually referred to as adduction of the wrist. Adduction of the wrist is also called ulnar deviation or ulnar flexion, so as you can surmise, joint motions are just as confusing as muscle names, and perhaps more so. Therefore, the various terms of joint motion are beyond the scope of this reference.

Search for Other Terms and Definitions in Our Glossary

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by EricT

By Ground Up Strength

The various scientific names of the body's 600 to 650 or so muscles,¹ at first, appear to be a bewildering hodgepodge of Greek and Latin. You may think that anatomists were just picking mysterious words out of an ancient hat in order to confuse you. That is not true at all, however. Although in some cases the methods used to name muscles are not very effective, the names of muscles are based on a naming system and, believe it or not, there is order and logic in how the muscles are identified. The more you are exposed to the study of skeletal muscles, the more you will begin to recognize the underlying structure. Often, knowing the meaning of the words will help you understand what muscle is being referred to just by its name. Sometimes, though, even knowing the meanings of the words will not help and all you can do is memorize them.

Still, being familiar with the meanings and the underlying system of naming is better than relying on rote memorization alone, because even though you won't always be able to find a muscle by its name, you will at least know what muscles are NOT being referred to. Knowing the structure of muscle naming can also help you decipher the function, location, and other information about muscles form their names alone.

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Muscles May Be Named According to Any of These Characteristics

1. Where is the muscle located? This may refer to a body part, to the origin and insertion of a muscle.
2. What is its basic shape? What does it look like?
3. What is its function? Does it extend a joint or flex it?
4. How many origins does it have ("heads", parts or divisions)?
5. What is the muscle's origin and insertion?
6. What is the muscle orientation relative to the midline of the body? Or, in other words, what direction do the muscle's fibers run in? Are they straight (rectus), or perhaps oblique (slanted)?

Each of these basic characteristics are "coded" with root words used to form the larger name. Many times, as well, a muscles name must be based on its relationship to another similar or paired muscle. Let's look at some of the basic words used to describe muscles:

Words That Refer to Muscle Size

• Maximus: largest (gluteus maximus is the largest muscle of the buttock)
• Minimus: smallest (gluteus minimus is the smallest muscle of the buttock)
• Medius: intermediate in size, do not confuse with medialis (gluteus medius is the the intermediate sized muscle of the three buttock muscles)
• Major: larger (pectoralis major is the larger muscle of the chest)
• Minor: smaller (pectoralis minor is the smaller muscle of the chest)
• Brevis: shortest (peroneus or fibularis brevis is the shortest of the peroneal muscles)
• Longus: longest (peroneus or fibularis longus is the longest of the peroneal muscles)
• Vastus: great or huge (used for two muscles of the thigh: vastus lateralis and medialis)

Words that Refer to Muscle Shape

• Deltoid: triangular (e.g. deltoid muscle of the shoulder)
• Rhomboid: diamond shaped (e.g. rhomboideus minor and major muscles, collectively the "rhomboids")
• Quadratus: square or four-sided (e.g. quadratus lumborum or quadratus femoris)
• Trapezius: trapazoidal shaped (e.g. trapezius muscle)
• Serratus: serrated or saw-toothed (e.g. seratus anterior)
• Teres: round or cylindrical shaped (e.g. pronator teres)
• Platysma: flat (e.g. platysma muscle of neck)

Words that Refer to Body Parts or Regions (Location)

• Pectoral: chest (two muscles, pectoralis major and minor)
• Brachii: arm (biceps brachii)
• Carpus: wrist (flexor carpi radialis and ulnaris)
• Palmaris: palm of the hand (e.g. palmaris longus)
• Digiti: finger or toe, singular (extensor digiti minimi)
• Digitorum (finger or toes, plural (flexor digitorum profundus)
• Indicis: index finger (extensor indicis)
• Hallucis: great or big toe (abductor hallucis)
• Femoris: thigh (rectus femoris)
• Gluteus: gluteal or buttock region (three muscles, gluteus maximum, minimum, and medius)
• Tibialis: lower leg or shin bone (tibia) (tibialis anterior and posterior)
• Peroneus: fibula, sometimes fibularis is used (peroneus longus)
• Spina, Spinalis: spine (erector spinae, spinalis cervicis and capitis)
• Spinatus: spine of the scapula (infraspinatus and supraspinatus)
• Pollicis: thumb (adductor and opponens pollicis)
• Oculi: eye (orbicularis oculi)
• Oris: mouth (depressor anguli oris)
• Labii: Lips (levator labii superioris)
• Capitis: head (splenius capitis)
• Cervicis: neck (semispialis cervicis)
• Thoracis: thorax (spinalis thoracis)
• Abdominis: abdomen (rectus abdominus)
• Lumborum: lower back or lumbar (quadratus lumborum)
• Scapularis: scapula or shoulder blade (e.g. levator scapulae)
• Costals: ribs (intercostals or internal intercostal muscles meaning "muscles between the ribs")

Words that Refer To Relative Location

• Lateralis: located to the side or laterally (vastus lateralis)
• Medialis: located toward the middle or midline (vastus medialis)
• Anterior: toward the front or anterior surface (tibialis anterior or serratus anterior)
• Posterior: toward the rear or posterior surface (tibialis posterior)
• Superior or Superficialis: superficial or toward the surface (flexor digitorum superficialis and obliquus capitis superior)
• Inferior: underneath or away from the surface (Obliquus capitis inferior)
• Profundus: located deep (flexor digitorum profundus)
• Supra: above or over (supraspinatus)
• Infra: below or beneath (infraspinatus)
• Sub: below or under (subscapularis)
• Internal: inner (internal oblique)
• Inter: between (intercostals)
• Dorsi: of the back (latissimus dorsi)

Words that Refer to Muscle Fiber Direction

Note that some writers confound fiber direction terms with shape terms, so that rectus, which refers to fibers that run up and down, straight and parallel with the midline, are called "straight" muscles in terms of shape. However, fiber direction does not necessarily denote the overall profile of a muscle, only the orientation of the fibers.

• Rectus: straight, or "erect", specifically meaning parallel to the midline (rectus femoris meaning "straight muscle of the thigh")
• Transversus: transverse or perpendicular to the midline (transversus abdominis or transverse abdominis)
• Oblique: slanted or diagonal to the midline (external oblique)
• Orbicularis, Sphincter: a name given to ringlike muscles that encircle and orifice and that may form a constricting passage (lower esophageal sphincter and orbicularis oris and anal sphincter)

Words that Refer to Number of Origins or Heads

The suffix "-ceps" means heads. A head is a major division of a muscle that has its own tendon.

• Biceps: two heads (biceps brachii which means "two headed muscle of arm" and biceps femoris which means "two headed muscle of the thigh")
• Triceps three heads (triceps brachii which means "three headed muscle of arm")
• Quadriceps: four heads (quadriceps femoris which means "four headed muscle of the thigh", commonly called the quadriceps)

Words that Refer to Actions

Since the various muscle joint actions are so common, muscles that use action terms in their names usually also give other clues as to their appearance or location.

• Flexor: flexes joint, or brings two ends closer together, decreases joint angle (flexor carpi radialus)
• Extensor: extends joint or bring two ends further apart, increase joint angle (extensor carpi radialus)²
• Levator: elevates a structure or part (levator scapulae)
• Depressor: depresses a structure or part (depressor anguli oris)
• Adductor: adducts or moves a part toward the midline
• Abductor: abducts or moves a part away from the midline³
• Pronator: pronates or turns the hand or forearm downward or backward (pronator quadratus and pronator teres muscle)
• Supinator: supinates or turns the hand or forearm upward or forward (supinator muscle)⁴
• Rotator: rotates one structure relative to another (rotatores spinae)
• Opponens: Refers to thumb actions only and named for the action of opposition, which is when the tip of the thumb is brought into contact with other fingers (opponens pollicis)

Some special action words used for certain muscles:

• Sartorius Muscle: Derived from the muscles activity when crossing the legs and named after the Latin word for tailer, sartor. Tailors used to sit on the floor cross-legged to do their work, before sewing machines were invented. Other explanations are also put forth, such as the cross-legged pedaling action of old sewing machines, which enlarged the muscle in tailors, and the muscles location along the "inseam."
• Buccinator: Derived from the muscles action in compressing the cheeks, which occurs when pursing the lips and blowing forcefully, as when playing the trumpet. The word buccinator means "trumpet player" so the buccinator is the "trumpet player muscle."
• Risorius: Derived from this facial muscle's action in producing the facial expression associated with laughter, which is risor in Latin. The actual expression of the muscle is more appropriately described as a grimace. 2
• Masseter: Derived from the muscles major action in chewing, coming from the Greek masētēr, meaning "a chewer."

Words that Refer to Origins and Insertions

It is not necessary to name every possible origin and insertion for each muscle. Only a relatively few muscles are named by these terms. Below are some examples, giving the muscle name and the words for the individual attachments that form the name. The first part of the name always refers to the origin and the second part to the insertion, which are joined together to form a compound word.

• Sternocleidomastoid: Sterno and cleido for its origin, the sternum and clavicle; and mastoid for its insertion, the mastoid process.
• Brachioradialis: Brachio for its origin on the upper arm and radialis for its insertion on the radius of the forearm.
• Genioglossus: Genio for its origin on the chin or "geneion" and glossus for its insertion on the tongue (glossus).
• Sternohyoid: Sterno for its origin on the sternum and hyoid for its insertion at the hyoid bone.
• Coracobrachialis: Coraco for its origin on the corocoid process of the scapula and brachialis for its insertion on the humerus of the upper arm.

As can be seen by the various terms and methods used to name muscles, it is by far a perfect system. Unfortunately, throughout the many years spent describing and naming the body's muscles, anatomists failed to stick to one method. Although there is indeed structure, some parts of the structure is more scientific than others. For instance, there is nothing particularly scientific in calling a muscle "deltoid" because it is shaped like a triangle. Likewise, although a word like "femoris" would seem very precise, there are many muscles associated with the femoris, or "thigh bone" and therefore a name like "quadratus femoris" means only "a square-shaped muscle of the thigh bone," which still requires us to memorize the muscle rather than to be able to guess it's precise location and function by its name. This muscle, after all, could be located on the anterior or the posterior part of the thigh and could be a hip muscle or a knee muscle. Although gluteus maximus sounds sufficiently scientific to most laypeople, calling a muscle "a large buttock muscle" is hardly scientific.

It would seem, then, that those names giving location and action are best, and these would be termed physiological names. Well, for those studying only human anatomy and human muscles, this may be the case, but for comparative anatomy and to describe the same muscles in different animals, it is a mess, as not all muscles necessarily share the same exact function in all animals. As stated above, perhaps the best system is a morphological one, which uses the origin and insertion of a muscle for its name, at least for purposes of comparative anatomy. Still, for students of human kinesiology and physical training, comparative anatomy is, at best, a side-line. Therefore, more descriptive names are more useful and most of us should be thankful that the morphological system never really caught on, although anatomists may grapple with the incongruities.

There will always be some memorization involved in learning the names, functions, and locations of the muscles. There is just no way around it. Yes, you may know that the brachialis has something to do with the arm, because of the "brachi" in the word, but that's all you know. How is it different than the brachioradialis or the coracobrachialis?

After studying the terms above, you should start to see patterns emerging. As you move down the lists, you should start to recognize the terms previously encountered in the muscle examples given, so that, as you learn, the names start to make more and more sense. This is especially the case in the more descriptive names. Fortunately, the other, badly named muscles, such as the deltoid and trapezius muscles, are the more familiar muscles to laypeople, and most shouldn't have much trouble with these bad apples. Learn all the terms in this article, and even with no memorization of the individual muscles you will know a great deal more than most people about the muscles of your body.

Clearing Up Some Anatomical Confusion

As you read this article and study the lists, you may wonder about the terms arm, forearm, leg, and thigh. How are you supposed to know what arm means. Does he mean my upper arm or my lower arm (forearm)?

When it comes to anatomy, we rely on certain foregone assumptions. That is, anatomists rely on these assumptions while everyone else is confused by them. When this article refers to the "arm" as in "brachii" it means the upper part of the arm. Why? Because in anatomical terms arm means upper arm and forearm means lower arm. For the legs, it's the opposite. The word leg, in anatomical terms, means the lower leg and the word thigh means the upper leg. So your arm is actually only the portion of that appendage from your elbow to your shoulder and your leg is only the part of that appendage from your knee down.

Example of Specific Muscles and How They Were Named

The following is a list of specific muscle name explanations, with images, that should assist you in your study. When possible, further explanation to the relevant anatomy is given. These muscles are listed in no particular order, they are just examples!

Infraspinatus

The infraspinatus is named for its position relative to the spine of the scapula. "Spinatus" refers to the scapular spine and "infra" means that the muscle is situated below it.

The image above has the spine of the scapula labeled. I have also labeled the suprapinatus fossa, for reference. The scapular spine separates the infraspinatus and supraspinatus fossa on the posterior surface of the scapula. Note that the scapular spine ends on the acromion process, where the clavicle joins, forming the acromioclavicular joint. See that the muscles is situated "below" the spine.

Extensor Carpi Ulnaris

The extensor carpi ulnaris, as you should immediately know if you've been paying attention, is an extensor of the wrist (carpus).

The muscle inserts onto the ulna bone of the forearm. However, the name is not simply an indication of where the muscle inserts. It actually inserts onto the base of the fifth metacarpal (proximal part of the little finger). Instead, the "ulnaris" in the name describes it's relationship to the bone and it's role in movement. Here, we have an extensor of the wrist on the ulnar side which means it is an ulnar extensor of the wrist. Without opposition from other flexors and extensors on the radius, the extensor carpi ulnaris, together with the flexor carpi unlaris, would tend to cause wrist adduction or "ulnar flexion" rather than pure wrist extension. As it is, the muscle is active in both wrist extension and wrist adduction.

Coracobrachialis Muscle

This muscle arises from the coracoid process of the scapula, hence, coroco- refers to this origin. As you may note above, the term brachii refers to the upper arm or humerus bone and this muscle inserts onto the humerus, in the middle of the medial border of the shaft. This can be thought of as a muscle of the upper arm that arises from the coracoid process, and it's major actions are shoulder (arm) adduction and flexion.

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Unless otherwise noted, all images on this page used under license. Images by LifeART (and/or) MediClip image copyright 2010. Wolters Kluwer Health, Inc.- Lippincott Williams & Wilkins. All rights reserved. Images not for reuse.

by EricT

Center of Gravity (COG):The point on the body, acted upon by gravity, about which the body is in equilibrium. The point at which all of a system's mass is concentrated. The point at which the three midplanes (sagittal, frontal and transverse) of the body intersect. In an ideally aligned posture, it is considered to be slightly anterior to the first or second sacral segment. (Kendall)

by EricT

In the "flat back"¹ postural alignment, the cervical spine is slightly extended, the upper thoracic spine is in flexion, the lower thoracic straight, the lumber straight (flexed) and the pelvis is posteriorly tilted. 1

The normal lumber spine (lower back) has a slightly extended inward curve, called lordosis. In individuals with the flat back posture, the pelvis is tilted toward the rear and the lumber has lost this lordosis, causing it to be flat, which is actually a flexed position for this portion of the spine. People with flat back will tend to stand with their hip and knees hyper-extended and their head forward.

This deviation from ideal spinal alignment is marked by and sometimes called posterior pelvic tilt. This describes the backwards rotation of a the superior iliac spine (ASIS) in relation to the pubes of the pelvis. Laypeople can just think of this at the "top" of the pelvis tilting toward the rear.

Individuals who display this posture, besides having the appearance of a very flat back, will also show the appearance of a flat buttocks that is tucked under.

According to Kendall, et al. and commonly accepted, the one-joint hip flexors (iliopsoas) will tend to be long and weak; the hamstrings short and strong. The erector spinae will be elongated due to the loss of anterior curve but they will not necessarily be weak. The abdominal muscles may be strong. There has been little evaluation of these proposed relationships between muscle length and postural alignment and little agreement exists in the most current literature. 1

Flat Back Posture

One study found that, although hamstring stretching is commonly advised to correct the pelvic tilt and so the flattened lumbar position, there was no difference in the lumbar position and pelvic tilt of a hamstring stretching and control group, indicating no support for the relationship between hamstring length and flat back posture. Furthermore, according to the authors, another study found that hamstring length was negatively related to lumber curve. Hamstring stretching was found, however, to increase forward bending ROM. The author's incorrect method for using the straight leg raise test to assess hamstring length was called into question by one commenter and there are still many questions as to the actual relationship between hamstring length and flat back posture. 2

Conscious alterations in posture, mobility, and stability exercises are more likely to correct postural deviations and/or prevent future injury than stretching singles muscles. The flat back, of all the postural deviations, is considered the most likely to result in lower back injury. Decreased curvature of the spine is thought to increase risk by decreasing the normal shock absorbancy of the spine.

Flat Back Confusion

Flat back, as stated, refers to a postural deviation in which the lumbar has lost its normal curvature (lordosis). It is associated with a kyphotic position of the thoracic spine and a head forward position of the cervical spine. Flat should not be confused with neutral. A neutral position of the lumbar spine is one in which the spine retains its normal slight extension.

Strength trainees are often instructed to lift with a "flat back" when the instruction actually refers to a neutral back. This is when the pelvis is in a balanced "neutral" position without excessive posterior or anterior tilt, which entails a normal lordosis of the lumbar. See Ideal Postural Alignment (Normal Posture)

Keep in mind that dynamic functional activities and exercises move through the neutral position of the spine. Any rehabilitative program involving correction of excessive lumbar flexion (posterior pelvic tilt) should eventually progress to pain-free movement through the neutral position and beyond.

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by EricT

Anatomical Position: Position of the body standing upright (erect) with all the joints extended, arms at the side, the palms and feet facing forward, and the fingers and thumb extended. In kinesiology and biomechanics, all body locations, positions, and movements are described according to this position, even if the person is not in the anatomical position.

Anatomical Position of Body
Image by Osteomyoamare via Wikimedia

by EricT

by EricT

Active insufficiency occurs when a multi-joint muscle reaches a length (shortened) where it can no longer apply an effective force. To demonstrate active insufficiency one can fully flex (bend) the knee on one leg while simultaneously trying to bring that leg back to achieve full hip extension. Hip extension will be limited because the hamstrings are unable to shorten enough to produce a complete range of motion. Some will also notice a cramping in the hamstring muscles during this maneuver. Straightening the leg (extending the knee) should restore full range of hip extension motion and the difference will be significant.

by EricT

by EricT

By Eric Troy

I see this all the time. Should I just call this blog the "false dichotomy" blog? However, if there is one thing I hate more than people always preaching one of two extremes in strength training it's people teaching the deadlift that don't know what they are doing.

Verbal cues become mental cues. Mental cues slowly morph into mental imagery. Mental imagery becomes a visual mental schema of the lift. What am I saying in plain language here? I am saying that the words people use will eventually affect the way you "look" at an exercise with your mind's eye. It will 'become' that word. If I say "wet" to you then you visualize water. You don't think about the concept of "wetness" in some abstract way. Well, the same thing goes for most everything, whether you wish it or not.

Some of the most confusing bits of jargon in strength training are when people talk about lifts that are pulls versus lifts that are pushes. So squats are a push and deadlifts are a pull. This brouhaha gave rise to one of the worst "splits" known to strength training: The Push-Pull Routine. Leave it for bodybuilders, it's a dumb way to organize your training.

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The problem with this method of classification is that "instructors" take it too seriously and, in all earnestness, seek to qualify these words with confusing instructions to trainees. This most often happens with deadlifts when trainees are earnestly warned to not "pull" the bar but to "push" with their heels.

But, oh, wait. You not only have to push with your heels you have to drive the hips forward. See, it's a pull but it's better to push and then drive the hips because otherwise you won't get enough power and…deadlifts are not that complicated! You don't need a long string of cues to complete a deadlift. They aren't so technical. Just don't let the "pull" thing confuse you. It matters not whether the lift is a push or a pull. Your body doesn't care. Instead be aware of the actual movements taking place and the actual goal of the lift.

It's a pretty straight-forward goal. Lifting a barbell from the floor to your waist - all in one motion. Why complicate this with cool sounding jargon? Deadlifts are the coolest anyway. They deserve a class all their own. The Deadlift class. Let Olympic lifters have their "pulls".

The big movement with a capital M in deadlifting is hip extension. We also have knee extension and ankle extension. But the hip extension part is why deadlifts are called a "hip dominant" exercise. This movement is the bread and butter part of the lift.

Drive Your Heels Into the Floor

This is the most popular verbal instruction given to would-be deadlifters. They are told that the deadlift is a pull but that they shouldn't try to pull the bar they should instead focus on driving their heels into the floor and pushing. Pushing. So is it a pull or a push? Would you find this confusing? Well it's worse than confusing. Remember what I said before about imagery and all that. I just told you that the most important part of a deadlift is the hip extension. So what do you think happens when you "focus" on driving your heels into the floor and this becomes your primary goal in the deadlift? That's right, your schema for the lift fundamentally shifts. It becomes more a push with the legs rather than a violent extension of the hips.

The reason for this drive the heels instruction makes sense on paper. You push against the floor and your body extends. Well, sort of. Really what you are doing is trying to push down the floor. The body trying to extend is simply a counter to this. The primary goal is to move the bar from the floor to waist height. But we've just made our primary goal to push down on the floor. In fact, then we've made knee extension our primary goal and hip extension just an extraneous side-effect.

Since we are primarily focused on pushing the floor rather than lifting the bar we then have to divide our focus to the hips and to the back. Instead of doing one simple movement while keeping the torso relatively stable we have shifted our purposes. It is better to think of the deadlift as two stable points and one hinge.

Yes, it is important for the heels to be planted firmly and for the weight to be over the heel/midfoot rather than the toes, with the midfoot being what more experienced lifters will tend towards. But this is one of the stable points. The other stable point is the torso from the lumbar up. The fulcrum is the hips. So we plant the heels and lift the bar by violently driving our hips forward. By doing this we shift the focus of the movement onto the prime mover, the glutes. The glutes will then be valiantly assisted by it's hip extensor assistants, such as the hamstrings. The hamstrings still must take on a greater share before the bar passes the sticking point, which is commonly from mid-shin to just below the knees, but knowing what the muscles do is not necessarily the same as efficient mental cues. We want to emphasize the most powerful muscle group but what we really should think about is the movement.

When we try to push down on the floor with our legs, on the other hand, what is the prime mover? I'll give you a hint, it's the same as in the leg press. Yes, there is more than one prime mover in a complex movement involving more than one body segment but I am talking here about the focus of the "heel drive" cue, which is pushing on the floor. Yes, you got it. The prime mover is the quads. They are trying to extend the knees and therefore move the floor. The hamstrings are braking muscles. The floor "pushes back" with an equal force. The hamstrings are the counter for this force, trying to keep the knees from flexing once more.

There is a heavy weight hanging from your hands. What is the path of least resistance, then, if you try to push down the floor? Easy. Your hips shoot up as your legs extend. And the bar? It doesn't go much anywhere. In fact, I think that this instruction has resulted in many many trainees performing the deadlift as a sequential, rather than simultaneous, lift.

The Deadlift is a Simultaneous Lift: Results Versus Intentions

Beware of wolves in lab coats. I mean the kind of wolves that analyze really big guys doing really big deadlifts but have never ever actually lifted a heavy weight nor do they have any experience in instructing others on lifting heavy weights.

There has been at least one 'study' reporting that, after observing powerlifters in competition, that the deadlift should be viewed as a sequential movement. This is the height of ignorance as any decent trainer can tell you that if you try to do the deadlift as a series of movements rather than as one continuous lift, you are much more likely to fail. What these researchers saw were the superficial results of heavy lifts. You can analyze results but you cannot analyze intentions. The idea is that since it "looked" a certain way and the lifts were successful, then this must be the best way to go about performing the lift. When, in reality, lifters are often successful, if barely, even when looking like they are having a very difficult bowel movement rather than lifting a weight. There is always something to be said for sheer brute force and determination when speaking of maximal lifting. But this does not mean that what a lifter looks like when doing their best effort corresponds to how a lift should be classified.

Record breaking lifts sometimes appear to be sequential even though the lifter had every intention of moving the bar to the waist all in one go. Having said that, record breaking lifts just as often appear to be simultaneous. At least if you don't film them with a high-speed camera and play the lift back Hollywood style.

Despite this, many trainees end up performing the deadlift as a sequential movement even when lifting light weights. They are then told they are doing it wrong but given instructions that are just as likely to reinforce these tendencies..such as "drive the heels into the floor."

The hips shoot up first. This is because the lift has become "all quad". Then the lifter has run out of quads, as I say, and they have a hard time initiating a powerful hip drive to complete the lift. The load tends to transfer to the lumbar. So there are two choices. Finish the lift with mostly lower back or do a little "scoop" whereby you slightly bend the knees while leaning back so as to put the hips and knees in a better position for "pulling". What happens then is really a hitch as the bar is rested on the thighs and then inched up to complete the lift in any way possible.

Top Down Pulling

No, I am not talking about Romanian Deadlifts, which have been called Top Down Deadlifts by others. There is no such thing as a deadlift from the "top down". The Romanian is simply a "deadlift" initiated from the rack position and technically is is not a "dead lift". It's just a name for posterior chain assistance exercise. A very good one.

What I am talking about is what happens when the "pull" part of deadlifting goes to a trainees head. Earlier I was complaining of turning the deadlift into a push. Well turning it into a pull doesn't really help much either. It is quite instinctive for many trainees to want to simply pull the barbell off the floor. They reach down and simply start hauling on the bar and instead of trying to extend the hips against the weight of the bar they are doing "top down" pulling. They are initiating the lift at the shoulders instead of the hips…simply pulling up with their upper back.

What tends to happen is the bar does not move, the back begins to round, and the hips eventually move upwards without the bar moving. Then when the pull begins the load is placed entirely onto the back, which must move from flexion to extension to move the bar.

So we have two extremes. The deadlift as a push. Which doesn't work. And the deadlift as a pull. Which also doesn't work.

One Simple Thing: Straighten UP!

The solution, as should already be clear from the rest of this article, is to view the deadlift in terms of the primary movement that is happening and to be clear on the primary goal.

I really should not have to explain that pushing down the floor is not the same as lifting up a bar. So be clear that your goal is to lift the bar from the floor to the waist.

It should also be clear that your body, or I should say brain, does what it needs to get the job done. The part of your brain that hands out work assignments does not classify lifts as push versus pull. It simply fires the muscles that can best get the job done in a given situation. The best muscle(s) to get the deadlift done is the glutes and the hip extensors as a whole. The deadlift is a "hip dominant" exercise and is a movement centered on the posterior chain.

Once you get into the proper position your real job is to simply straighten up so as to move the bar to the waist. It's all in the hips and everything else is there for support. I feel so strongly about the hips, in fact, that my article on how to do a deadlift has the word hip or hips in it 31 times.

The Reality of Heavy Deadlifts

There are very few people, and none that I have personally encountered, that can perform a truly maximal deadlift with what looks like textbook form. The kind of thing that the armchair internet experts, who seem to come out in droves on Youtube for every video of a heavy lift, if it was witnessed, would almost certainly signal that the lift was not a true maximum attempt! There will be some rounding of the thoracic spine during any truly maximal deadlift and this rounding will also translate to at least a modicum of lumber rounding. Experienced lifters can control this and keep it from rounding to end range of motion. You'll never get it until you actually start lifting heavy.

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by EricT

By Ground Up Strength

Perhaps the biggest misunderstanding about how skeletal muscles function to produce the body's movements concerns their particular role. Most people think that a muscle performs ONE particular and very defined role and that they always perform this role. This is not how it works. Muscles must work together to produce different bodily movements and a particular muscle's role may change depending on the movement.

Synergy and Synergists

The most important aspect to understand about how muscles function to produce a joint movement is synergy. Synergy means that two or more things work together to produce a result that is greater than any of those things could do alone, so that the whole result is greater than the sum of the individual effects of the agents involved. Even the simplest joint movement requires muscles working together in this synergistic or cooperative fashion. When a group of muscles work together to optimally perform a given motor task this is known as a muscle synergy. These synergies are of utmost importance in biomechanical research and physiotherapy.2,3

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Usually, the muscles that are directly involved in producing a certain joint movement are called agonists and muscles that are indirectly involved, by some other role, are called synergists. However, even if a muscle adds directly to a joint's movement by adding it's own torque, it can still correctly be called a "synergist". Just as other muscles, such as stabilizers, neutralizers, and fixators, that help the movement by opposing unwanted movement or by helping to stabilize the joint are synergists. So, the word synergists is not a very useful word, in itself, when describing muscular roles since it is much too inclusive and the way it is used is contradictory to it's definition because it excludes muscles that could rightly be called synergists by their "synergistic" role in a joint movement. This happens when all the muscles involved in a movement besides the prime movers are termed synergists, as if the prime movers themselves are not synergists. These muscles, which contribute to a movement indirectly could more clearly be called supporters.

Students of strength training are always having great difficulty in distinguishing the difference between agonists, synergists, stabilizers, fixators, etc. The real reason for this confusion is that the word synergist is a silly word that is used in different ways by different texts. We'd do well to abandon it.

Although the word is not useful, it is largely used so we cannot simply ignore it even though we could easily side-step it by simply describing the different roles a muscle may take in helping to produce a movement. This would simply cause more confusion, not less, and it is not our place, here at GUS, to decide whether the term should be abandoned. It is used in two slightly different ways, depending on the precise definition of the word agonist:

• A synergist is an agonist that is not directly responsible for the movement of a joint but assists in some other fashion

• A synergist is another muscle, besides the agonist, that assists the movement of a joint indirectly

Do not be too surprised by this. As you study human movement you will find contradictions to be the rule. It is not always completely decided upon how terms should be used and, to be frank, many of the most popular usages are incorrect ones.

The first definition we can easily render incorrect, as will be seen, since it incorrectly uses the word agonist to include muscles that cannot be considered agonists. The second definition is better as it uses the word agonist correctly but it still uses the confusing word synergist, which we have to deal with. So, we will deal with it by accepting it but insisting upon using it properly. Therefore, we will say that a muscle that indirectly assists in producing a joint movement is the agonist's synergist. So from here on out, the term synergist will become agonist's synergist. Don't worry about the unwieldiness of this since, for the most part, we can simply avoid the word altogether as it adds little to any discussion of muscle actions.

While some muscles work together, in a concentric fashion, to produce a movement, others work in other ways to help cancel out other movement, such as the unwanted movement of another bone that the muscle attaches to, or by opposing movement that could occur in an undesired plane of motion. The movement produced is the net result of all the different forces produced by the muscles.

Agonist (Prime Mover)

As stated above, agonist muscles are muscles that are responsible for causing a certain joint motion. However, the term is often defined incorrectly to mean ALL the muscles that have a role in producing a movement. By this definition stabilizers, neutralizers, and fixators are also agonists. This is incorrect.

An agonist is a muscle that is capable of increasing torque in the direction of a limb's movement, and thus produce a concentric action. In other words, the muscle can produce a force that accelerates a limb around it's joint, in a certain direction. This does NOT mean that this direction is the only one the muscle can produce force in but only that it is capable of this and thus is directly involved in producing a certain movement, making it a prime mover. To keep it simple, then, an agonist is a muscle that causes rotational movement at a joint by producing torque. A movement can always have more than one agonist although a certain agonist may be capable of producing more torque than its partner. They are also sometimes called protagonists.

Agonist and Antagonist Relationship of Biceps and Triceps Muscle
Image by Davin via wikimedia

Many people refer to muscles having a redundant role in producing torque about a joint as being synergistic agonists but with one of these muscles being the prime mover. This is a silly and arbitrary distinction since there are many instances where a muscle with a redundant role can take over for a paralyzed one, making that muscle the "prime mover". Agonist and "prime mover" simply speaking, means the same thing and the terms are interchangeable. However, sometimes it is useful to refer to one muscle, usually a larger one that articulates at more than one joint, as the prime mover. In this way, the prime mover can be spoken of in relation to its fixators or supporters. This type of instance is very common in that certain terms only become useful in a specific context. The biceps brachii, which will be used as an example from here on, is often considered the prime mover in elbow flexion, although it is only one of several flexors of the elbow joint.

The brachialis, for instance, is another elbow flexor, located inferior to the biceps on the upper arm. Unlike the biceps, which inserts onto the radius, which is able to rotate, the brachialis inserts onto the ulna which cannot rotate. This, it can be said that the brachialis is the only pure flexor of the elbow joint whereas the larger biceps can also supinate the forearm.

When most people think of elbow flexion they
think of the more superficial biceps brachii.
But the brachialis is the only pure elbow flexor.

A muscle can only be referred to as an agonist in relation to a movement or another muscle. It is never proper to call any one muscle an agonist unless we are describing its role in a movement or we are referring to it in terms of a muscle on another side of the joint, known as an anatagonist. To say "the biceps is an agonist" is incorrect or at least incomplete (which comes down to the same thing). 1

The biceps brachii is an agonist for elbow flexion. It is assisted by the brachialis and the brachioradialis. These are the agonists of elbow flexion, all of which are capable of flexing the elbow joint to some extent.

Agonist's Synergists Roles: Stabilizer, Fixator and Neutralizer

Some muscles involved in a joint action do not directly contribute a torque force to the movmement but assist the movement in indirect ways. These roles that are commonly referred to as synergist muscles, as explained above, but that we are calling the agonist's synergists". These roles are many but some of the basic terms used to describe these muscles are stabilizer, neutralizer and fixator. However, the term stabilizer, for our purposes, means the same thing as fixator. The term stabilizer needs further clarification before we move on to the fixator.

Stabilizers and Stabilization

There is more than one way to categorize the functional role of muscles. It depends on perspective. When may look at the muscles in terms of their function is specific movements or we may look at them in terms of the entire body as a system, complete with many subsystems. The latter view is not what we are concerned with in this explanation but the when viewed this way muscles are classified according to their function rather than their role in a particular movement. The word stabilizer or stabilization has a much broader and complex definition.

This view sees the body as a system of motor (or mobilizer) and stabilizer muscles. This concept was first proposed by Rood and furthered by the work of Janda and Sahrmann as well as by Comerford and Mottram who proposed the concept of local and global stabilizers and global mobilizers. 4

Although, the concept of a stabilizing muscle can still be viewed in terms of a single movement in this system, certain muscles are considered to have the primary function of stabilizers in the body, being, by virtue of their position, shape, angle or structure, more suited to work as a stabilizer than as a mobilizer.

Although its complexities go way beyond the scope of this explanation (and the expertize of its author), this way of looking at the body is a valid and important one for the strength trainee. For instance, this view teaches us that the abdominal group of muscles, once primarily thought of as a muscle we perform situps with, is much more important as a major stabilizer of the spine. This lesson may lead us to train those muscles in a way that supports their function, thus making us stronger and more injury free. This, in fact, is one of the hallmarks of "functional" training, although the term has been much abused and overused.

The type of stabilizer we will discuss here, however, are fixators, which are active during one movement and at one joint. There are certain muscles that act primarily as stabilizes because of their angle of pull. An example of such muscles is a group of muscles known as the rotator cuff muscles of the shoulder girdle. This group comprises the supraspinatus, infraspinatus, teres minor and subscapularis. These muscles are mainly known as muscle of rotation for their contribution to external and internal rotation of the shoulder but they are actually much better suited for the primary role of stabilization and they are very important in stabilizing the humeral head in the glenoid fossa.

Fixator Muscle

A fixator is a stabilizer that acts to eliminate the unwanted movement of an agonist's, or prime mover's, origin.

Many muscles are attached to more than one bone. When this happens the muscles are said to be multiarticulate or multijoint muscles. When these muscles contract they tend to move both bones to which they are attached. This would, of course, make everyday movements quite impossible.

For instance, consider elbow flexion by the biceps brachii. When you do a curl, the biceps acts to flex the elbow. However, the biceps is attached at two places, proximally and distally. Its distal attachment, the insertion, is to the radius. It's the radius bone we want to move when we curl a dumbbell. One of its proximal attachments, though, the origin, is to the scapula. The scapula is one heck of a mobile bone. In fact, it has no real bony attachments of its own. When the biceps contracts it will tend to draw the radius and the scapula together. The movement of the scapula must be prevented. This is accomplished by fixators. Specifically, the trapezius and rhomboids work isometrically to keep the scapula from moving on the torso. 5

Neutralizer Muscle

Neutralizers, like fixators, act to prevent unwanted movement. But instead of acting to prevent the unwanted movement of a body part they act to pull against and cancel out an unwanted line of pull from the agonist or prime mover. Many muscles can produce a pulling force in more than one direction so that an undesired joint action may occur simultaneously with the desired on. Neutralizers prevent this.

For example, the biceps brachii can do more than flex the elbow. It can also supinate the forearm (twist the forearm so that the palm faces up). In order for bicips action to flex the elbow with the forearm also being supinated another muscle must cancel out the supination torque that the biceps also produces. The pronator teres, being the principal forearm pronator, is responsible for this.

Test the action of the pronator teres for yourself. You can easily palpate the pronator teres by flexing your elbow and making a fist as if you are holding a hammer (this is a "neutral" forearm position). The pronator teres will start to contract. You can feel it with your opposite fingers inside the middle of your forearm. Now, relax your forearm and bring your hand up toward the ceiling. You will feel the pronator teres relax and lengthen. At first it was contracting to provide a pronating force against the biceps supinating force while the elbow is flexed. When you supinated your forearm, it relaxed to allow this action to take place.

On the other hand, if forearm supination were desired without elbow flexion, the triceps would act isometrically to resist the flexion, making it a neutralizer.

Antagonist

An antagonist is a muscle that is capable of opposing the movement of a joint by producing torque that is opposite to a certain joint action. This is usually a muscle that is located on the opposite side of the joint from the agonist. The triceps, an extensor of the elbow joint, is the antagonist for elbow flexion, and it would also be correct to say that the tricep is an antagonist to the biceps, and vice versa.

In order for an agonist to shorten as it contracts the antagonist must relax and passively lengthen. This occurs through reciprocal inhibition, which is necessary for the designated joint movement to occur unimpeded. Reciprocal inhibition is a neural inhibition of the motor units of the antagonist muscle. When the agonist muscle contracts, this causes the antagonist muscle to stretch. Normally, this stretching would be followed by a stretch reflex which would make the muscle being stretched contract against the change in length. If this were allowed to happen unchecked then it would result in very jerky or oscillatory movement since the stretch reflex in the antagonists would elicit a new stretch reflex in the agonist, so on and so forth.¹ The inhibition of the alpha-motoneurons in the antagonist are brought about by **Ia-inhibitory interneurons of the spinal cord, which are excited by IA afferents in the agonist muscle. 6

However, antagonists are not always inactive or passive during agonist movements. Antagonists also produce eccentric actions in order to stabilize a limp or decelerate a movement at the end of a motion. For instance, during running the hip extensors are antagonists to the hip flexors, which act to bring the femur forward during the running stride. So, the hip extensor muscles must relax to some degree to allow this forward motion of the thigh to take place. However, the extensors must also act to arrest this forward motion at the top of the stride. So the antagonists both relax to allow the motion to happen and then contract to put the brakes on it. This makes for a very fine balance of activity between agonist and antagonist pairings. 7

Agonist Antagonist Coactivation or Co-contraction

When both the agonist and antagonist simultaneously contract this is called coactivation. It can be advantageous for coactivation to occur for several reasons. For instance, when movements require a sudden change in direction, when heavy loads are carried, and to make a joint stiffer and more difficult to destabilize.

The purported reason that co-contraction may occur during changes in direction is that modulating the level of activity in one set of muscles is more economical than alternately turning them on and off. For heavy loads, increased joint stiffness is desirably for lifting heavier loads and co-contraction of the core muscles of the torso routinely occurs during these activities. For fine motor activities of the fingers, as well, complex co-contraction activity is needed.

It should be noted that the word co-contraction is only used to describe the simultaneous activity of agonist/antagonist parings and should not be used to describe the simultaneous action of various agonist muscle groups.3,8

Spurt and Shunt Muscles

Muscles can also be described as being spurt or shunt muscles. These roles are largely unknown in the strength training world but are described in the orthopedic and physical therapy fields. Again, we will consider the elbow joint.

When a muscle acts on a bone it actually produces a force that, if one were to do a vector analysis, could be resolved into two component forces. These components are an angular component and a transarticular component. The angular component is actually the perpendicular or vertical component of the muscle's force. We normally call this the rotary component. If allowed to act alone this force would cause the bone to rotate around the joint. The rotary component is also known as a swing component.

The transarticular component is a parallel or horizontal component. It acts along the shaft of the bone and may produce a force that pulls the bone away from the joint or toward it, depending on the angle of the joint. This component, therefore, is also known as either a stabilizing component or a destabilizing component. When the component is stabilizing it is also known as a shunt component and shunt muscles are muscles that tend pull the bones of a joint together.

The Brachioradialis Muscle can
act as a shunt muscle due to it's position.

During elbow flexion, the angular component, the one that makes the radius move around the elbow joint, is the swing component. The brachioradialis is an example of a shunt muscle, which is able to provide a compressive force.

A certain muscle may exert a stronger spurt or shunt force. If the spurt force is stronger it is called a spurt muscle. If the shunt force is stronger it is called a shunt muscle. Which happens depends on the location of the muscle and whether the distal or proximal attachment is free to move. Generally, the distance of the origin and insertion of a muscle to the joint axis of rotation determines whether a muscle acts as a spurt or shunt muscle. When the distance of the insertion is greater than the distance of the origin, the muscle is considered a shunt muscle. when the origin is farther from the joint axis than insertion, the muscle is a spurt muscle. This is important because a shunt muscle may protect a joint from powerful distracting or compressive forces during certain movements. 9, 5, 10 A shunt muscle could be considered a stabilizer muscle as it help to stabilize a joint during movement.

You should be able to visualize, using the image of the brachioradialis above, how the insertion distance allows such a muscle to exert a shunt or stabilizing force on the bone and joint regardless of the joint angle. Imagine a dumbbell curl with the elbow flexed to greater than 90 degrees. The brachioradialis, like most of the elbow flexors, will pull the bone toward the elbow joint at this angle. However, imagine what would happen if the insertion were much closer to the elbow rather than all the way down at the end of the radius at the wrist.

As the angle of elbow flexion passes 90 degrees this same parallel pull is no longer pulling the bone toward the joint but is pulling the bone away from the joint, resulting in a translational or dislocating force. But since the insertion is so distant, at the wrist, the angle of elbow flexion does not affect the direction of the parallel component and it remains a shunt component, making the brachiradialis a shunt muscle, always able to exert a stabilizing force. See further explanations of this in the comments below this article.

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Unless otherwise noted, all images on this page used under license. Images by LifeART (and/or) MediClip image copyright 2010. Wolters Kluwer Health, Inc.- Lippincott Williams & Wilkins. All rights reserved. Images not for reuse.

by EricT

By Eric Troy, Ground Up Strength

The deltoid muscle is a large, triangular, course, and thick muscle which gives the shoulder it's shape and contour. Its name is often reported to have derived from the Greek letter Delta (Δ) but it actually derives from the Latin word deltoides which means "triangular in shape or form" and was taken from the shape of the letter delta and the word eidos (oid) meaning shape or form. The deltoid is the principal abductor of the arm at the glenohumeral (shoulder) joint and also flexes and extends the humerus. The deltoid is the largest and probably the most important muscle of the shoulder complex. 6, 5

The deltoid has three major parts: anterior, middle, and posterior, which, based on their origins can be considered the clavicular, acromial, and scapular divisions. These parts cover the upper (proximal) part of the humerus, converging to a thick tendon to insert on the lateral surface of the humerus bone. All three sections differ in structure and function but work in concert to produce important movements at the shoulder joint.

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It decreases stability, however, in the coronal plane where is tends to produce an upward shearing or traction effect on the head of the humerus, producing impingement on the acronium. The rotator cuff, namely the subscapularis, infraspinatus, and teres minor produce a synergistic downward pull to offset this upward translation of the humeral head. In other words, the rotator cuff muscles are very important to stabilize the humeral head when counterbalancing this pull by resisting the upward shearing of the deltoid. There are still many questions about the deltoid's role in dynamic stability versus it's role as a de-stabilizer and much of the data is conflicting. However, it is clear that the deltoid, acting alone, would be unable to function properly as a mover of the shoudler joint. The rotator cuff is the main means of holding the humeral head centered in the glenoid fossa during most daily functional movements and tasks of the shoulder. 1,2,3,5

The Glenohumeral (Shoulder) Joint

The deltoid is active during any lifting movement and contracts statically during most everyday tasks. As important as the muscle is, however, the importance of the smaller rotator cuff muscles, as mentioned above, must also be considered in it's actions, with the supraspinatus being important during abduction. However, the frequent claim of the supraspinatus being the primary adductor of the shoulder during the first 30 degrees, after which the deltoid takes over, has been questioned by several studies and EMG data. It is more likely that the suprispinatus and deltoid function synchronously although the suprispinatus, if maximally contracted, may be able to elevate the arm to the initial 30°. Although EMG data shows the activity of the deltoid and the supraspinatus progressively increasing of abduction motion, the supraspinatus is still usually reported as the "initiator" of abduction during normal tasks.²,3

Deltoid Muscle, Side View

The deltoid is activated for long periods of time during keyboard work and driving. If a keyboard or work surface is set too low or too high, this activation is increased. Driving with the hands on the top of the steering wheel primarily activates the anterior deltoid. Trigger points can develop from over-use through these mechanisms or through the abuse the muscle frequently receives in resistance training, as many bodybuilders and strength trainees dedicate entire workouts to the shoulder alone. Since the deltoid is also active during most other upper body movements during other workouts, over-use can easily produce TP's. The trigger points cause pain in the deltoid muscle itself which is felt as a deep pain the the shoulder.

Trigger points may also develop after direct impact trauma to the muscle during sports. The functional characteristics of the deltoid and the supraspinatus becomes much more complicated during sporting movements such as throwing or with sports requiring shoulder abduction and external rotation. The remainder of this article will cover the primary movements only as sport-specific functions are beyond its scope.

Deltoid Muscle: Origins, Insertions, and Actions

Origin:

• Anterior fibers: anterior and superior surfaces of outer third of clavicle and anterior acronium³
• Middle fibers: lateral margin of the acronium⁴
• Posterior fibers: inferior edge of almost the the scapular spine

Insertion: The anterior and posterior fiber portions converge into a thick tendon which inserts on the lateral surface of the humerus near its midpoint at the deltoid tuberosity. The middle portion, however, is multipennate and inserts via four to five intramuscular septa or tendinous expansions. 4, 2,5

Actions

The three portions of the deltoid can contract independently or together, depending on the action. The actions of the deltoid and its three parts will be considered first in terms of the primary actions of each group of fibers and then again by movement, together with synergists.

Notes on Deltoid Actions

• Contraction of the entire deltoid, with all its fibers, results in shoulder joint abduction but the middle fibers are usually considered to only be abductors. Some of these fibers are active in flexion, however. When the entire muscle contracts it can produce shoulder abduction to just beyond 90 degrees without scapular rotation, which must occur for full abduction to be possible.

• The lateral deltoid fibers have a multipennate arrangement which gives it greater strength over a short range of motion than the anterior and posterior fibers, which are fusiform, and are better suited to great speed over long ranges of motion.

• Contraction of the anterior fibers alone results in adduction, flexion, and internal rotation. Forward flexion and internal rotation of the humerus is carried out in conjunction with the pectoralis major.

• Contraction of the posterior fibers alone results in adduction, extension, and external rotation. Extension and external rotation of the humerus is carried out in conjunction with the lattisimus dorsi and teres major.

• The anterior and posterior portions can assist, by contracting together, with stabilization of the humerus by preventing the humeral head from leaving the plane of motion. (bibcite behnke)),5

• The deltoid, together with the supraspinatus, contracts when carrying heavy objects at the side to resist the strong downward pull. The deltoid is also contstantly active in positioning the hands for everyday manual tasks, by producing forward flexion of the humerus. 5

Deltoid Actions and Synergists

These are the primary shoulder movements that the deltoid is active in together with it's synergists.8 Please note that a synergist can have more than one type of role. For instance, some synergists may be stabilizers during a given action while others may have a redundant role or act as neutralizers.

Deltoid Trigger Points Causes and Symptoms

As stated above, trigger points can be activated in the deltoid by an impact trauma such as a direct blow or fall on the shoulder; or by over-use of the muscle. Also, any accident that traumatizes the deltoid muscle, such as reaching out to catch oneself during a fall, can activate trigger points. Unlike most other trigger points, however, deltoid trigger points do not refer pain to remote area. The pain tends to be concentrated in the immediate area of the TrP and occurs primarily during shoulder movements while not occurring often during rest. Continuous pain in the shoulder is more likely to come from some other underlying pathology or trigger points in other muscles that refer pain to the shoulder area. For instance, a continuous dull ache in the shoulder is more likely to trigger points in the rotator cuff muscles.

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When pain occurs in the shoulder joint during passive mobilization with scapula rotation and elevation, as opposed to active shoulder movements, this is more likely to indicate a sprain or subluxation of the acromioclavicular joint, the pain pattern of which mimics the pain pattern of anterior deltoid trigger points.

The pain from deltoid trigger points occurs deep in the deltoid and there may be difficulty in raising the arm or reaching back with the arm at shoulder level. Trigger points of the deltoid tend to occur in the anterior and posterior portions of the muscle although the posterior part rarely develops trigger points alone as the result of activity but rather develops them in association with TrP's in other muscles. Trigger points may sometimes develop in the middle portion of the muscle but how often this occurs, according to various texts, is unclear. Davies reports that the lateral deltoid is the portion where trigger points most often occur while Travell and Simons, and others reports that they are rare. However, when they do occur, the multipennate arrangement of these fibers means that the trigger points are likely to be sprinkled anywhere along lateral upper arm. Davies erroneously reports that the middle fibers are more likely to develop trigger points because this portion of the muscle is the "largest part of the muscle and works the hardest." 9,12,10,11

However, the front deltoid is much more likely to receive overload and trauma during everyday activities and during exercise and sports and there is no basis for claiming that the largest portion of a muscle is the most likely to be overworked. While the arrangement of the lateral deltoid's fibers give it the most strength over a short distance this is due to it's functional roles and not necessarily it's every-day workload. Reliable information on the frequency of middle fiber trigger points over anterior and posterior ones has been difficult to locate for the purposes of this article. Check for trigger points anywhere in the lateral upper arm if you experience deep pain in this area and suspect lateral deltoid trigger points.

Trigger Point Figure 1: Deltoid Muscle Trigger Points
Side View, Anterior and Posterior

Anterior Deltoid Trigger Points

When you have pain and difficulty while combing your hair, eating, or, in general, bringing your hand to your face this may be due trigger points in the anterior (front) deltoid. This part of the muscle is highly likely to receive a traumatic impact in many sports and can be suddenly overloaded by reaching out to catch a fall, such as when one stumbles on the stairs. Overuse occurs in the workplace when having to hold heavy tools or any job that requires frequent forward reaching. Exercise and sports activities that require a great deal of forward shoulder flexion such as swimming, skiing, and ball throwing may overload the muscle. And, as mentioned, shoulder abuse by improper emphasis of the shoulders in resistance training can strain and overload the muscle, setting up trigger points.

Anterior deltoid trigger points are usually located high in the front margin of the muscle, in front of the glenohumeral joint, or lower toward the midpoint. The referred pain pattern is in the area of the front shoulder surrounding the trigger point with some spillover pain further down the arm and posterior to the TP. See Trigger Point Figure 1 above for trigger point locations and Figure 2 below for pain patterns.

Trigger Point Figure 2: Anterior Deltoid Muscle Trigger Points
and Referred Pain Pattern

Posterior Deltoid Trigger Points

The posterior deltoid usually develops TrP's in conjuntion with other muscles such as the long head of the triceps, the latissimus dorsi, and the terses major. They may also be over-exerted, as by poling during skiing or other activities where the arm is frequently extended toward the back. TP's may also be activated by local intramuscular injection of irritable solutions such as B vitamins, penicillin or various vacines, after which the TP's are self-sustaining.

Trigger points in the posterior deltoid tend to be located on the lower posterior margin of the muscle and upward toward the midpoint. The pain is referred to the immediate surrounding area of the TP in the back of the shoulder with some spillover pain further down the arm and anterior to the TP.

Deltoid Trigger Point Self-Treatment

Don't try to use your hands to massage your own deltoids because it is too difficult a position to apply pressure and your hands will become exhausted and over-used. Instead, use a tennis or lacrosse ball against the wall. Place the ball against the trigger point area, lean into it, and roll the ball up and down over the area. It may help to place the ball in an old sock so that the end of the sock can be used as a handle. Also, smaller hard rubber bouncy balls can be used when you are ready to apply more precise pressure.

Alternatively a Knobble self massage tool or an Index Knobber can be used.

Trigger Point Figure 2: Anterior Deltoid Muscle Trigger Points
and Referred Pain Pattern

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by EricT

By Shanthi Johnson¹ and Krista Leck²

Abstract

Background:The study examined the effects of dietary fasting on physical balance among young healthy women.

Methods:This study undertaken involving 22 young healthy women (age = 22 ± 1.5) using a within subject counterbalanced 2-week crossover study design. Participants were asked to refrain from consuming any food or beverage for 12 hours prior to the fasting trial and to maintain their regular diet for the non-fasting trial. Measures included: a background questionnaire, 24-hour dietary recall, and functional reach and timed single-limb stances.

Results: Fasting resulted in significant declines in functional reach (p < 0.01), and ability to balance in a single limb stance with eyes open, on both the dominant and non-dominant legs (p < 0.01 and p < 0.01, respectively), and with eyes closed on the dominant leg (p < 0.01).

Conclusions: The findings have implications for athletic performance in younger individuals as well as emphasizing the need for health education for young women to avoid skipping meals.

Background: Importance of Balance

The importance of balance can be seen in every aspect of daily living: walking up stairs, bending over to tie shoes or standing still. While the human body must be able to adapt to its environment and movements in order to maintain this balance, the loss or impairment of balance influences quality of living, decreases athletic performance, and can lead to injury [1,2]. Balance refers to an individual's ability to maintain the body in mechanical equilibrium and relies on specific postural mechanisms and sensory inputs (e.g., visual, somatosensory, vestibular) the purpose of which is to promote an appropriate alignment of body posture to maintain an upright stance against the force of gravity [3,4]. The two main aspects of balance that have been critically assessed are static and dynamic balance. Static balance is balance while the body is at rest, while dynamic balance refers to the ability to maintain balance during movement [1,5-7].

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Balance is a complex and multifaceted fitness parameter and is assessed in a number of different ways. In young and old individuals, balance is generally assessed using functional performance tasks that evaluate everyday living skills (e.g., obstacle courses, timed up and go tests or functional reach tests) as well as more challenging situations (e.g., modifying a sensory input and the use of firm and compliant surfaces). Measures such as functional reach have also been used to quantify dynamic balance in all age groups [8]. Similarly, static balance can be assessed using a timed single limb stance procedure (e.g., eyes closed or open or a maximum timed duration), or by using a force plate to measure and quantify postural sway [9-12]. With minimal disturbances in balance, the ankle strategy is used to regain postural stability. However, as the difficulty increases, the ankle is no longer able to maintain control and the body shifts to using other postural mechanisms such as the hip strategy and/or upper limb movement [6]. Failure to recover balance through a combination of these mechanisms will ultimately result in a fall.

Studies suggest that there are many conditions or situations which can disrupt the control of balance. Age-related physiological changes, the presence of injury, disease, and medication, can alter the ability to maintain balance. Additionally, some research has reported sex differences in the ability to maintain balance [13,14]. This difference has been attributed to womens' lower centre of gravity, which in turn improves their ability to balance [13,14]. Research has also shown that physically active individuals have an increased balancing ability over sedentary individuals of a similar stature [15]. However, over the short-term, fatiguing exercise has been shown to reduce balance [16]. While physical activity and nutrition are important parts of overall health, limited research, to date, has examined the specific relationship between nutrition and balance. The few studies that do exist have used balance tests as a secondary measurement within an overall study of nutrition and performance among elite male athletes, and show that a decrease in dietary intake negatively affects one's ability to maintain balance [17-20].

Dietary Fasting

Fasting is a state of nutritional imbalance, which is generally characterized by an absence or interruption of caloric intake over a period of time [21]. Physiologically, the body shifts into a state of early fasting, also known as a post-absorptive state, 3 to 12 hours after eating. After 12 hours of fasting, the post-absorptive state shifts to that of a fasting state, which is characterized by hypoglycemia or low blood sugar levels and the associated increase in gluconeogenic activity, with amino acids being the primary source of substrate [21-23]. Although nutrition imbalance has not been identified as a direct risk factor related to falls, the symptoms of hypoglycemia include a lack of coordination, staggering gait, fatigue, disorientation, dizziness, and vertigo. These symptoms are well-known risk factors for impaired balance and falls in the elderly population [24-26]. It is not uncommon for younger and older individuals to practice partial fasting [27]. People may skip meals and not eat for extended periods of time due to a self-imposed weight loss strategy, delayed eating due to the administration of medication or medical testing (e.g., fasting blood tests), or because of adherence to religious practices. The interruption of caloric intake places additional stress on the body, and could undermine the body's ability to perform daily living tasks.

The potential implication of fasting on functional capacity has not been well examined. Studies investigating the effects of fasting on functional performance, as determined by various fitness indicators such as endurance and balance, have used a wide variety of fast durations, ranging from 14 hours to 3.5 days [19,20]. A limited number of studies show that fasting contributes to decreased endurance capacity and reaction time, as well as reduced static and dynamic balance performance, along with increased heart rate and blood lactate levels during exercise, all of which are detrimental to performance [17,18]. Studies have shown that the ability to maintain balance is affected after fatiguing exercise [16]. Researchers have found that compensatory mechanisms exist to help maintain balance and these mechanisms are more active after fatiguing exercise [1,19,20]. The majority of these studies, however, have involved functionally elite men such as athletes or soldiers [17-20]. None of the studies involved individuals from the general population or women. As indicated earlier sex differences in the ability to maintain balance have been reported [13,14]. In addition, young women are more likely to skip meals and not eat for extended periods of time due to a self-imposed weight loss strategy. Studies have examined the role of skipping breakfast on cognition but not physical function in general and balance in particular with young women [27]. Thus, the purpose of this study was to examine the effects of dietary fasting on physical balance among young women.

Methods

Participant selection and study design

A sample of 22 Caucasian women was recruited for this study. Given the lack of research in this area involving young healthy women, power analysis was not performed. Participants were included only if they had no health conditions that could be worsened by fasting or that could affect their ability to balance (diabetes, recent/chronic head injuries and/or lower extremity disabilities, low blood pressure, vestibular and/or inner ear problems). Participant recruitment was completed through advertisement in the University bulletin after the study design and protocol were approved by the authors' institutional Research Ethics Board. The participants provided signed informed consent prior to participation.

The present study adopted a within subject counterbalanced crossover design, given the many advantages inherent in this design—all subjects served as their own controls and therefore reduced possible error variance, while reducing the needed sample size. Each participant was tested under fasting and non-fasting conditions, with half of the participants randomly assigned to start under the non-fasted condition and the remaining half completed the fasted trial first. The conditions were reversed during the second trial and the two trials were separated by a two week duration time span to avoid learning effects. All participants completed the same set of tests at each trial, in the same order. Standardized testing procedures and equipment were used throughout the study. The testing took place in the investigator's research laboratory. Snack bars and juice boxes were available for the participants to consume after study testing. No other incentives were provided to the participants.

Fasting and non-fasting protocol

Participants were provided with the fasting/non-fasting protocol prior to each test period. Thus, it was not possible to blind study participants to the testing condition. All laboratory tests took place between 9 and 11 am in order for all participants to avoid time of day variations. For the fasting trial, participants were asked to refrain from consuming food or beverages for a minimum of 12 hours prior to testing. Specifically, all participants were instructed to consume an evening meal before 8 pm prior to the day of testing and to refrain from any food or beverages until the time of testing in the laboratory. Fasting protocol was planned to mimic the scenario of skipping breakfast which is common among young women, or overnight fasting necessary for certain blood tests (e.g., fasting blood glucose). For non-fasting tests, participants were instructed to maintain normal eating habits on both the day prior to and the day of testing. In both test conditions, participants were asked to refrain from strenuous physical activity to minimize the role of carry-over effects such as fatigue, muscle damage, or physiological potentiation. Prior to each testing period, a pre-trial checklist was completed to provide information on each participant's past 24 hours of activity (e.g., timing of last meal, exercise performed, and injuries/health episodes since the previous contact).

Measures

The measures included: a background questionnaire, nutritional intake, balance tests, and a pre-trial checklist.

Background questionnaire

This questionnaire was used to elicit information related to the participants' demographic characteristics (age, education, ethnicity, employment, and financial status) and health status (perceived health, tobacco use, and physical activity level). The questionnaire was completed by the participants once, prior to the first testing period.

Nutritional intake

A 24-hour food recall was used to collect data on average caloric intake of the participants. The recalls were conducted by the student investigator trained in the protocol, using a standard form and adopting strategies to avoid recall bias by asking the participants to record food intake for 24 hours prior to the food recall interview [28]. Recalls were collected once during the study period and at mid-point between the two trials.

Physical testing

Physical testing included: 1) dynamic balance and 2) static balance. These measures were completed twice, once in the fasted condition and again in a non-fasted condition.
Dynamic balance

The functional reach (FR) test was used to assess dynamic balance [8]. For this test, the difference in centimetres between the participant's standing arm length and maximal forward reach was recorded. While standing with feet flat on the floor, the standing arm length was measured using a metric measuring tape fixed to the wall. Participants were then asked to reach as far forward as possible, without taking a step, without their heels leaving the ground or without losing balance. Three trials were performed with the farthest reach identified as the final score.

Static balance

The single limb stance was used to assess static balance [1]. This test can be performed in various time durations (e.g., 10, 25, 45 seconds or maximum time to exhaustion or termination) as well as with and without the use of a force platform. In the present study, the test was conducted on the gym floor and the maximum duration the participant could maintain a single limb stance was recorded in seconds on both the dominant and non-dominant legs, as well as in eyes open and eyes closed conditions [29], to avoid ceiling effect, given the involvement of healthy young women in this study. The dominant leg was determined by assessing which foot took the first step when participants were asked to initiate gait. Participants stood on the dominant leg, raising their non-dominant leg to a 90 degree angle at the hip and the knee joints while keeping their hands down by their sides. In this study, the test was terminated if the participant voluntarily asked to stop for any reason (e.g., sore leg), if the knee dropped below 90 degrees, if one placed the foot on the floor, or began to use arms to maintain balance. The reasons for the termination of the test were recorded for each of the four static balance testing conditions. The same set of termination criteria were used in both the fasting and non-fasting trials. Trials were conducted using the same protocol for both legs and under both conditions—eyes open and eyes closed. A practice trial was provided to each participant to ensure proper form was used during the actual trial. One test trial was completed for each condition to prevent fatigue and practice effects.

Pre-trial checklist

During each test session, participants completed a pre-trial checklist. This checklist gathered information related to fasting duration, level of physical activity prior to testing, and any change in health since recruitment or first testing.

Data analysis

Data from the two trials were numerically coded and entered into a Statistical Package for the Social Science database [30] for analyses. Descriptive statistics (means and frequencies) were used to describe the demographic and health characteristics as well as balance measures. Subsequently, paired t-test was conducted to examine the changes in balance performance scores for the two trial conditions. Completed dietary recalls were entered into a dietary analysis program, Food Processor SQL [31], and were used to calculate an average nutrient intake for a 24-hour period. Similarly, foods consumed for breakfast (in the same 24-hour period) were analyzed using Food Processor SQL to calculate the average nutrient intake. Based on the difference of nutrient intake for the whole day versus breakfast, an average "caloric loss" for fasted trials was calculated. The significance level was set at (p ≤ 0.05) for all statistical procedures.

Results

A total of 22 female, Caucasian university students participated in this study without any attrition between trials. Descriptive statistics on the demographic characteristics and health status are presented in Table 1. The age of study participants ranged from 18 to 23 years with a mean of 21.8 years (SD = 1.5). Of the study participants, 95.4% rated their perceived health status as excellent to good and all the participants were non-smokers. Over 90% of the study participants consumed alcohol on a regular basis. The majority of the participants reported performing regular physical activity (90.9%) with a range of four to six days a week (63.6%) for a duration of 30 minutes or longer (90.9%) each time. The perceived health and physical activity status was self report and no definitions were provided. None of the participants reported any injuries or medical conditions that could affect their balance.

Table 1. Descriptive statistics on the demographic and health characteristics of the participants

Data from the pre-trial checklist showed that a minimum 12-hour fast was followed by the participants during the fasted trial, with a mean fast of 15 hours. As expected, there was a statistically significant difference in the time of last meal for the fasted and non-fasted trials (p = 0.011). The average daily caloric intake was 2062 kcals with 15.2% of these calories coming from protein, 60.2% from carbohydrates and 28% from fat. When analyzing the breakfast meal individually, the average total calories from breakfast alone was 465.8 kcals or 22.6% of the day's total calories. The breakfast meal consisted primarily of carbohydrate calories (74.6%) and interruption of the consumption of breakfast contributed to an average caloric deficit of 465.8 kcals during the fasted trial.

Table 2 presents the mean scores for each of the balance measures assessed, based on the trial condition (fasted or non-fasted). For the single limb stance test, there was a decrease in duration (seconds) of the participants' ability to maintain balance as the level of difficulty increased, from eyes open, dominant leg to eyes closed, non-dominant leg in both fasted and non-fasted trials, albeit the fasted trial had consistently lower scores compared to non-fasted trial. Similarly, for the functional reach test, the participants' score was lower in the fasted trial compared to non-fasted trial. Paired comparison t-test showed that fasting resulted in statistically significant declines in functional reach (p < 0.01), the ability to balance in a single limb stance with eyes open, on both the dominant and non-dominant leg (p < 0.01 for both) and with eyes closed trial on the dominant leg (p < 0.01) among healthy young adults. No statistically significant change was observed for the static balance test in the eyes closed condition on the non-dominant leg (p = 0.13).

Table 2. Comparison of scores of physical measures between non-fasted and fasted trials

Along with the decline in balance performance between trials, an increased postural response (e.g., stumble, use of arms, knee lowered) was recorded as the reason for test termination as the degree of difficulty progressed in the single limb stance (from eyes open dominant leg to eyes closed non-dominant leg) and from the non-fasted to fasted trial (see Table 3). Specifically, in non-fasted conditions, the frequency of stumbling as the reason for termination increased with the increase in the level of difficulty in the four trials (from eyes open, dominant leg trial to the eyes closed non-dominant leg trial). However, under fasted conditions, participants showed an increase in postural responses, mainly stumbling, leading to termination in both the eyes open and closed conditions in the dominant leg but the trend was not true for non-dominant leg. In each of the trials, those in the fasted condition reported higher frequency of stumble compared to those in non-fasted condition except for the trial with the highest level of difficulty (eyes closed, non-dominant leg) in which the scores in seconds were similar (as shown in Table 2).

Table 3. Reasons for Termination of Single Limb Balance Trial (Percentage reporting Postural Response)

Discussion

The present study provided insights into the relationship between dietary fasting on static and dynamic balance. Specifically, in a sample of physically active and healthy young women, dietary fasting of a 12-hour period affected the individuals' ability to maintain dynamic and static balance as measured using the functional reach and single limb stance tests, respectively. As indicated earlier, there is a paucity of research examining this issue among young women who are more likely to skip meals and not eat for extended periods of time to lose weight. No other study was found in the literature which examined static and dynamic balance in fasting condition in women, although decline in balance has been reported in studies which involved functionally elite men such as athletes or soldiers [17-20].

In addition to the decreased duration of balance ability between fasted and non-fasted trials, increased postural control mechanism responses were noted which resulted in the termination of the test. In the present study, at the easier stages of the single limb stance test (eyes open), the majority of the participants stopped due to sore leg. However, as the difficulty increased (eyes closed) more of the body was required to maintain postural control resulting in more stumbling and use of arms to aid balance. Under fasting conditions, during both the eyes open and eyes closed trials, the majority of the stances were terminated due to a stumble. This is consistent with previous studies which suggest that individuals use various postural strategies for the maintenance of balance after fatiguing exercise [1,19,20]. The fasting condition placed additional stress on the body's ability to balance and therefore, required a larger postural response in order to maintain balance.

In the present study, a minimum fasting duration of 12 hours was adopted. Although this is slightly lower than the range of 14 hours to 3.5 days of fasting duration reported in existing studies, it is similar to the standard fasting protocols required for certain blood tests and sufficiently long for the body to switch from a post-absorptive state into a fasting state [17-21]. By using a fast duration that mimicked a skipped breakfast scenario or fasting blood test, the study protocol reflected a common fasting situation in the general population. The results can therefore be applied to everyday situations, instead of what happens under extreme fasting situations (e.g., 3.5 days of fasting). In the present study, it was estimated that fasting could have contributed to a 465.8 kcals deficit or approximately 25% of daily intake when compared to the non-fasted condition. Although there are no comparable data, studies have used a standard breakfast of 595 kcals for male participants [17]. Further research is needed to examine the physiological mechanisms underlying the relationship between fasting and balance including the role of energy regulating hormones (insulin, leptin, adiponectin, ghrelin) as well as the resulting metabolic and biochemical changes (e.g., hypoglycemia). Association between nutrition and falls should be examined further in the population of older adults [26].

While the results of the present study have furthered our understanding of the relationship between dietary fasting and its effect on physical balance among healthy, young women, it is not without limitations. The study recruited participants through a non-random sampling approach. As such, self selection bias would be inherent in the sampling approach. Also, with the lack of research in this area, it was not possible to calculate an appropriate sample size. However, based on the changes observed in the present study in the functional reach test, which is an indicator of dynamic balance, it can be estimated that 20 participants are required for each group to study whether there is a gender difference in the observed effects of fasting. Additionally, it was not possible to gather dietary data in fasting and non-fasting states. Future studies should calculate the actual caloric deficit between the two conditions.

The present study also had several strengths. The use of a within subject counterbalanced crossover design was a major strength of this study. This set-up allowed many advantages; all participants performed the tests in fasted and non-fasted conditions, served as their own controls and therefore reduced possible error variance, while reducing the needed sample size. This is the first study to date that has examined the relationship between dietary fasting and physical balance as its primary focus within the general population, with the use of a common fasting duration (e.g., skipping breakfast). Standardized testing procedures and protocols were used to minimize variance errors and ensure reproducible data.

The findings raise issues to be addressed in future research. For example, while a small decline in balance may not translate into difficulties in performing activities of daily living in younger individuals or have serious clinical significance in the day to day functioning given the higher levels of functional threshold in young individuals, these small changes in balance may affect athletic performance if the young women are also actively competing in sport in which balance is integral to performance (gymnastics, skating). Also, changes in balance could limit elderly individuals from performing basic activities as well as predispose them to high risk for falls. Future studies are needed to test the sport performance and fall risk prepositions. Falling is a complex problem influenced by a multiplicity of risk factors, yet the inability to maintain balance (i.e., postural instability) is one of the best predictors of falls among the elderly individuals [24,32]. Given the high incidence of falls and the debilitating consequences such as hip fracture among the older population [25], future studies are needed to demonstrate the effects of aging on the relationship between fasting and balance. In these studies, the appropriateness of measure such as a single limb stance with increasingly difficulty conditions (eyes closed) for frail older adults and the related safety concerns should be considered.

Competing interests

The authors declare that they have no competing interests.
Authors' contributions

CSJ contributed to the conceptualization and design, as well as to the analysis, interpretation and writing of the article. KRL contributed to the conceptualization and design, data collection and analysis, and writing of the article. Both authors have read and approved the final manuscript.

Acknowledgements

Primary author acknowledges the financial support for the project by the Canadian Institutes of Health Research - New Investigator Award.

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© 2010 Johnson and Leck; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

by EricT

You may have heard trainers and coaches talk about movement amplitude. I often talk about amplitude as being one of those performance characteristics that determine the outcome of a training regimen and one of the factors indicating reductions or improvement in performance.

Amplitude is also part of the "law of repetitive motion" equation developed by Dr. Michael P. Leahy, who is the founder of Active Release Techniques (ART). This "law" is an equation describing the interaction between various parameters of human motion: I=NF/AR where:

I = Insult or injury to the tissues
N = Number of reps
F = Force (as a percentage of maximum strength)
A = Amplitude
R = Relaxation period (lets just say rest)¹

I doubt that Leahy was thinking of 400 pound back squats when he came up with that and I will not attest to it's right of title as "universal law" since it will break down depending on the type of movement (I'll get into that a bit later). For resistance training it also ignores interset rest which also greatly influences tissue recovery. Most trainees keep a fairly constant rate of repetition. That is the "rest between reps" is held fairly constant. Even small deviations in rate (or frequency) will tend to even out over time.

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The equation translates: Tissue injury or insult is equal to the number of reps times the force applied divided by amplitude times relaxation period. This means that the greater the reps and force the greater the insult to the tissues. The greater the amplitude and rest the lower the insult to the tissues. Most trainees will get most of that. Except for amplitude. What the heck is that?

You might know a physics definition or even several different ways of looking at wave amplitudes. The best way to describe what amplitude is, to me, is to invoke a guitar string. Think of the resting position of the string as the "zero point". Now you pluck the string by pulling on it a certain distance and letting go. The string vibrates back and forth in a wave. The peak of that wave goes back to the point which is the distance you originally pulled it, but never beyond that point. The distance between that peak and the original zero point is the amplitude. This is the most common and basic way (I think) of looking at amplitude.²

The definition of amplitude changes depending on the system (e.g. sound wave, spring, pendulum, etc.) and what to measure is a personal choice but usually the distance is measured from the middle to the extremes. And the unit of measurement could change depending on the conditions. This is important in human movement since some movements would be more correctly measured as an angle rather than a distance.

image via wikimedia

In the above image of a wave diagram γ is the amplitude. See that it fits, more or less, my description. By the way, λ is the wavelength. The important thing to see is that amplitude is basically a distance measurement. It is important not to take this thinking too far because if you try to relate human movement to wave amplitude things get messy. The time it takes for one repetition becomes a "period" and a repetition itself becomes a cycle. We don't want that although there are a number of "strength scientists" around who would have no problem applying this type of jargon to strength training.

So, amplitude is, for human movement, range of motion, change in position, or even displacement of the implement in a resistance exercise. All three could work. The important thing to know is that it is most useful to measure amplitude as the extent of movement or displacement from a mean to the extreme range of a repetitive movement. A little imagination and you'll see that this leaves a lot open for interpretation. It gets tricky and that is why such pat little equations, although superficially useful, can never be universally applied. There are different types of amplitude where movement is concerned.

There is "external amplitude" which is the range of movement of the entire body relative to some external benchmark such as the ground or an apparatus such as a gymnastic apparatus. Then there is "internal amplitude" which is the range of motion of individual body segments or joints or their movement relative to each other.1

A very typical scenario during the progression of the squat, whether back squat, front squat, etc. is that while the load on the bar increases relatively quickly for a period of time the amplitude decreases. Amplitude is a very easy concept to understand in this case. The mean is the upright, standing or ready position. The amplitude is the total distance the bar moves from that starting point. The deeper the squat the greater the amplitude. This is only external amplitude though and ignores the movement of individual joints and body segements. Which means that even if external amplitude remains apparently constant, the range of motion may be borrowed from inappropriate joints. So it not only matters "how deep" one goes, but what point is measured. Even a squat with good and constant amplitude could be very stressful to certain tissues. For instance, only the bar travel is measured, and the apparent depth is actually lumbar flexion rather than a deep "knee bend" using full range of motion in the hips, knees, and ankles. So amplitude is NOT just one measurement and what we measure matters.

Amplitude of course is not the only consideration. It's one among many..but this post is supposed to be about describing amplitude so I'll attempt to contain myself.

Since the distance the bar travels in our scenario does not remain constant (assuming internal amplitude does) the amplitude does not remain constant. Since amplitude is part of performance then performance does not remain constant. Simple but largely ignored by most trainers.

Applying the "law of repetitive motion" to this works fairly well as a general guideline as we can see that the force applied is going up and the amplitude is going down. So the tissue stress theoretcially goes up (again, internal amp being contstant) And despite the very large forces involved the law should predict that resistance training, when performed with full range of motion and sensible volume, is less injurious to tissues than acitivities such as running. It does not make sense, in fact, to group resistance training under the same "law" as high impact activities. Plyometrics, for instance can involve forces even greater than strength training. Even simple jumping movements, such as jumping jacks, can impart ground reaction forces (GRF's) of 3 to 5 times body weight.2 Depth jumps must surely impart the greatest GRF's of any plyometric drill. How does amplitude affect these forces?

Looking at the amplitude of a depth jump, however, would yield different conclusions. A depth jump is a plyometric exercise where the trainee stands on a box of certain height and performs a vertical jump with a controlled landing while flexing the hips, knees, and ankles but controlling the torso, followed by an immediate vertical jump from the floor as high as possible.

The height of the box would be one possible measure of amplitude. The distance the shoulders move may be another. A higher box during plyometric depth jump increases the load on the body (which is extreme to begin with) and thus the potential for injury. The extra force must be attenuated during landing by increasing the amplitude of flexion involved. This increase in amplitude would by no means lessen the injury impact to skeletal tissues. During a plyometric movement there is only a certain range of amplitude that is useful because to much amplitude increases the force the athlete must overcome in order to reverse the movement. Too much force and the amortization phase is increased which may defeat the purpose of the exercise since the phase between the eccentric and the concentric must be kept short to take advantage of the stretch-shortening cycle. Suddenly the law of repetitive motion isn't looking so good. All movement isn't the same. Human movement is too complex to apply a simple little equation to.

However, we can still say that the amplitude of joint movement must be kept high or maintained in order to 1.) perform the movement correctly and with skill and 2.) decrease the chances of injury. Knowing this we can also keep in mind a few other parameters which influence movement amplitude:

Mobility and Flexibility

Mobility must be constantly maintained to ensure that movements can be performed fluidly and with full range of motion of the various joints. While there is some question as to this, for resistance training it is probably useful to posses a degree of mobility that is slightly greater than that which is required by the movement or lift. In other words, what Bompa referred to as a "flexibility reserve".3 However, I emphasize the word "slight" here. There is no need for hyper-mobility and for most this takes the form of an over-indulgence in either flexibility training such as static stretching or the prolonged indulgence in various contortions that have no relation to human peformance such as in some yoga practices.

Time of Day

Range of motion can vary depending on the time of day. This is especially true of lumbar range of motion with this effect being more marked in flexion range of motion than extension. The lumbar flexion range of motion increases throughout the day from morning to afternoon.4 And, in general, most people are more flexibile in the afternoon than in the morning.

The most oft cited data are observations by Osolin in 1971 which reported that range of motion was lowest in the morning and greatest between 10 and 11 Am and 4 and 5 PM, however subsequent observations have amplitude being greatest at different periods and most tests were done on specific body regions. The peak "suppleness" of your lumbar region may occur at a different time of day than your hamstrings. It would be extremely difficult to find good data but it is safe to say that your range of motion will increase throughout the day and begin to dip again after about 4 PM, which some wiggles in between and that the stiffness we all feel in the morning is not just a feeling but indicates much less range of motion than occurs slowly throughout the rest of the day. Diurnal variations in movement amplitude lend credence to the advice that one should train always at the same time of day, when possible. And this of course would apply to training specifically for mobility as well.

Law of Repetitive Motion and Resistance Training

A number of writers have attempted to meld the law of repetitive motion with resistance training. What the law brings to the student of strength training is the understanding that training injuries are more likely to result from cumulative trauma brought about by high volume weight training with low amplitude. This is a valuable lesson since many trainers and trainees alike tend to assign heavy weight low volume resistance training to a higher risk category than high volume, moderate intensity training. While the acute risk of very heavy loads is greater the chronic risk of high volume training, as exemplified by the bodybuilding body part split, is much greater and most injuries are the result of chronic tissue overload.

However such a formula can be nothing more than a basic guideline when it comes to resistance training. Such a formula taken as "law" could lull a trainee into a false sense of security. It is much more applicable to continuous cyclic movements such as running than to the repetitive movements of resistance training. It is also important to realize that the bodies tissues do not only adapt to movement but also to static postures and positions held habitually for long periods of time.

Comments

by EricT

By Ground Up Strength

There is a big problem with information about the shoulder. It's not just one joint.

To be more precise, there is one joint that we call the "shoulder joint" but it doesn't act alone. Eric Beard will take us through a video ride to simplify these complex seeming details of the shoulder but I will begin with a bit of explanation first.

The shoulder joint itself is known as the glenohumeral joint. It is a multi-axial ball and socket enarthrodial joint. This joint is the articulation between the glenoid fossa of the scapula and the head of the humerus. This is the area that most people think of as the shoulder joint. The humerus is, however, one bone of the shoulder.

No complete movement of the glenohumeral joint can occur without accompanying movement of the shoulder girdle. The shoulder girdle involves two bones, the scapula and the clavicle and these bones tend to move as a unit. There is no bony link of the scapula to the rest of the skeleton. Since the humerus is articulated with the scapula there is therefore no bony link of the humerus to the axial skeleton.

The shoulder girdle is made up of three joints. The sternoclavicular (SC), acromioclavicular joint (AC), and the scapulothoracic joint. Sometimes movements of the shoulder girdle are confused with movements of the shoulder joint so the terminology can be confusing. See the table below to differentiate the movments terms between the shoulder joint and the shoulder girdle.

1. The sternoclavicular (SC) is a multiaxial arthrodial joint. As it's name implies this is the articulation of the clavicle and sternum.

2. The aromioclavicular joint (AC) is also an arthrodial joint and is the articulation of the clavicle with the acromium process of the scapula. This is the "top" of the shoulder and is the area that most people think of as the shoulder proper, as opposed to the shoulder joint.

3. The scapulothoracic joint is not really a true synovial joint. This is simply the scapula's relationship with the thorax. The scapula has no ligamentous support and it is only supported by it's muscles. It has no independant movement but it's movement occurs as a result of motion at the SC and AC joints. It may not be proper to think of the scapulothoracic as a joint but thinking of it this way, as part of the three joints of the shoulder girdle, helps us remember the primary importance of the scapula and it's muscles in all movement of the shoulder.

Together the shoulder joint (glenohumeral) and the shoulder girdle make up the shoulder complex. The movement and health of this complex must be considered together. The videos and the accompanying tables, therefore, are not just about the deltoids!

The rotator cuff is a very important group of muscles that are intrinsic to the glenohumeral joint: the subscapularis, infraspinatus, supraspinatus, and teres minor. These muscles are of primary importance in maintaining dynamic stability of the shoulder joint.

Pairing of Shoulder Joint Movements and Associated Shoulder Girdle Movements

* sometimes refered to as abduction
** sometimes refered to as adduction

Eric Beard, a great corrective exercise specialist out of Boston has agreed to make some videos exploring the shoulder complex. Actually, I asked him just to make a video demonstrating the movements and he instead has begun a series of seven videos on the shoulder complex, which he calls "short". Yep, GUS is not the only one with the motto "if it's worth doing it's worth overdoing". For more shoulder information you are going to want to check out Eric's site theAthleticShoulder.com

Here Eric starts with the movements of the shoulder joint, including flexion, extension, abduction, adduction, internal rotation (or medial rotation), external rotation (or lateral rotation) and horizontal adduction and abduction. These shoulder joint movements, he says, have a great deal of mobility but not much stability. This is one of the central features of the shoulder. It has such a wide range of motion in so many different planes and that comes with a price: reduced stability.

From there he shows us how to palpate the sernoclavicular joint. He explains that there should be some subtle movements of the sternoclavicular joint during various movements of the shoulder. For instance you should find some elevation and depression of the SC joint when your arm is abducting and adducting and some protraction and retraction of the joint during horizontal abduction and adduction of the shoulder joint. If there is not enough movement of the sternoclavicular the acromioclavicular joint, in Eric's words, gets beat up. You've probably heard of AC joint injuries as this is the most commonly separated joint of the shoulder complex.

The movements of the scapulothoracic joint comes next and you can see these movements in the table above. The pairings of the shoulder joint movements with the shoulder girdle movements are more specifically pairings of the shoulder joint with the scapulothoracic. Most of the time "the scapula" rather than the SC joint is refered to when discussing these movements but, even though it is not a "true" joint, as stated above, it is best to think of it in those terms.

This second video deals with the various ranges of motion of the shoulder complex. Eric begins by re-emphasizing the importance of sternoclavicular joint movement. Apparently this is an area that is often ignored.

Sternoclavicular Ranges of Motion

• Retraction (moving toward the body)
• Protraction (moving away from the body) - 15 to 30°
• Depression - 10°
• Elevation - 45°

*Posterior Rotation - 10 to 45°

The sternoclavicular does not move on it's own. The scapula must move to initiate movement at the SC.

Glenohumeral (Shoulder Joint) Ranges of Motion

• Flexion - 165 to 180°
• Extension - 35 to 60° (Eric notes that most do not have this range of motion in extension)
• Abduction - 180° (about one-third of this from the glenohumeral alone and two-third from the scapulothoracic joint)*
• External Rotation - 90°
• Internal Rotation - 70°**

* the movement of the scapulothoracic and the glenohumeral which occurs together is refered to as "scapulo-humeral rhythm". Remember that the clavicle must be moving as well.

** when checking for internal and external rotation of the shoulder note that you should be doing it passively. Notice while demonstrating internal rotation range of motion that Eric just lets his arm hang. He does not force it down further. So this is "passive" meaning that you are not actively trying to extend the range of motion through muscular force which would be "active"

Check back for more videos to come!

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by EricT

Normal Posture

In this postural alignment the neck is slightly extended, the upper back is in slight flexion, and the lower back is in slight extension.¹ The slightly extended inward curve of the neck (cervical spine) and lower back (lumbar spine) is referred to as lordotic. In this way a normal slightly arched position of the neck and lumbar in a position of lordosis. However, this term is generally meant to mean a hyper-extended or over-arched position.

The normal upper back or thoracic region (below the neck) is in a slightly flexed or "rounded" position.

In this alignment the abdominal and hip extensors and the lumbar and hip flexor muscles are in perfect opposition to one another. The former group tilting the pelvis posteriorly (to the back) and the latter tilting it anteriorly (to the the front) resulting in a neutral pelvic position.

Pelvic Inclination, Lumbar Lordosis, and Muscle Length

The information above is based on the widely accepted relationships presented by Kendall, et al. 1. However, the reliability of these relationships are currently in question and our understanding of the influence of pelvic inclination on lumbar lordosis is in flux.

It is generally accepted that the pelvic rotators, the abdominals and the erector spinae influence the lumbar curve and pelvic inclination in a standing position. The abdominal muscles tilt the pelvis posteriorly. When the pelvis is tilted to the rear, the degree of lumbar lordosis decreases. The erector spinae tilt the pelvis anteriorly. When the pelvis is tilted toward the front, the degree of lumbar lordosis increases. Therefore, it seems logical to assume also that the length of these sagital-plane pelvic rotators will influence the pelvic inclination and thus the degree of lumbar curvature.

Recent studies, however, have questioned these assumptions. To date, standing postural alignment has been used to make predictions about the performance and length of the abdominal and erector spinae muscles. This practice may be erroneous, as some studies have indicated that there is no relationship between these variables and that posture must be controlled by several complex factors.

Furthermore, Kendall and colleagues postulate a relationship between lumbar lordorsis, anterior pelvic tilt, and hip flexor (and low back) shortness. As well, there is a supposed relationship between hamstring tightness and posterior pelvic tilt. All these relationships give rise to various postural distortions. These relationships have been further used to assign muscle stretching techniques as a means to correct postural deviations.

As things stand all these assumptions may be seriously questioned. Ongoing studies are failing to support the relationships proposed by Kendall, et al. and the wisdom of predicting muscle length and performance from standing posture should be considered unproven. 3,4

1 iLiac crest 2 Ilium 3 Ala 4 Sacral promontory 5 SacroiLiac joint
6 Acetabelum 7 Obturator Foramen 8 Pubic symphysis 9 Pubic arch
10 Pelvic Brim
Image Source

by EricT

This Knees Over Toes thread contains information debunking the prevelant myth that the knees should never travel past the toes in a squat or lunge.

This excellent image courtesy of Artur Andrzej via wikimedia

• Link to excellent ACE article on the subject

• Other links to information from Tony Gentilcore, Diesel Crew, Mike Robertson and ExRx.

• The effect of this artificially curtailed movement of the knees on the hips and it's link to injury.

• A brief rant about "institutionalized" knowledge and the idea that certain certifying organizations are superior.

by EricT