Muscular Analysis of Weight Training Exercises

Question & Answer

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Target Muscle of Rollout

Can you tell me why Wheel Rollout shows hip flexor as its target muscle, whereas the Stability Ball Rollout suggested this movement should be for the Rectus Abdominis?

It is difficult to attribute one target muscle to these exercises, particularly the Stability Ball Rollout.

As mentioned, the abdominal muscles are exercised isometrically in both these movements since only a small degree of waist flexion occurs under resistance.

However, no appreciable hip flexion occurs in the Wheel Rollout whereas significant hip flexion occurs in the Kneeling Stability Ball Rollout. The Wheel Rollout has been classified as a hip flexor movement along with all the other hip flexor movements that also exercise the abdominals isometrically (eg: Leg Raise). It should be noted, all hip flexor exercises utilizing bilateral movement activate abdominal muscles isometrically, hence hip flexor classification of those exercises. Also see Lower Ab Myth.

To complicate matters, shoulder extension is predominate in both movements, so much that some may consider them akin to a pullover or straight arm pulldown exercise, however we believe most people performing the Stability Ball Rollout exercise intend to work the Abdominals, at least isometrically, so it has been classified as such for the Stability Ball Rollout since it could not be listed as a hip flexor movement.

We rarely classifying an isometric target muscle for a dynamic exercise but we have done so in the cases of the Deadlift and Stability Ball Rollout.


Pullover's Target Muscle

Barbell PulloverFirst of all i need to say to all of you big thanks for all the thing i lern from this amazin site. But (there's allways a but :) ) i have some problem of knowing something about the "pullover" exercise. I know that pullover is a exercise for the target muscle "Latissimus Dorsi" and so it say's in the site. When i look at pullover with, cable, Barbell and Lever. But when i look at pullover with Dumbbell i've paying attention that the target muscle is "Pectoralis Major (Sternal Head)". And i can't understand why, so i realy want you to tell me why, or that it's a mistake or something.

The pullover exercises both muscles. The chest is emphasized with the shoulders internally rotated (elbows out). This is the posture is assumed when grasping the dumbbell with both hands as with the Dumbbell Pullover. The clavicular pectoralis major has a more favorable line of pull in this posture. With the other apparatuses the shoulders are more in a neutral position where there is a more favorable pull with the lats.


Pullover Works Serratus Anterior?

I would appreciate your feedback about putting the serratus anterior muscles as primary muscles in the bent arm pullover part of the demo site as i think this is important, what do you think?

If you note the function of the serratus anterior, you will see these motions are virtually the opposite of the motion of the scapula during the concentric phase of the bent arm pullover. Contrary to what certain books suggest, the serratus anterior does not play an active role in this motion. I fact the Serratus Anterior is involved in the opposite movement, such as in the front raise. During the pullover, the serratus anterior could be activated if the shoulders are raise from the bench somewhat like at the end of a pushup. The Serratus Anterior is also known as the boxers muscle because of the movement during the end of a punch. The Serratus Anterior is also involved during overhead presses.

I can only speculate why this misconception came about. Older exercise guides (Pre-1970s) suggested performing pullovers while breathing deeply could expand the rib cage, particularly if performed in the teen years. The External Intercostals (involved in rib elevation) and the Internal Intercostals (involved in rib elevation during inhalation and rib depression during exhalation) are somewhat in proximity to the Serratus Anterior; but this is only my theory to explain a misguided idea.


Pull-ups with open centered bar

Can you tell me what are the differences between pull-ups performed with a standard chinning bar versus an open centered bar? By watching the animated gifs, I can't see any. Both exercises seem the same to me, however you suggest there are less muscles involved when performing pull-ups on an open centered bar. How so?

Most assisted pullup machines and some pull-up bars with an open centered design allow the head and body to travel straight up. A self-assisted pull-up or weighted pull-up is typically performed on a chinup bar in which the head travels behind the bar. Consequently the body is angled back at the top of standard chinning bar.

The differences between performing the movement on the two slightly different bars are very subtle. The body and head are more vertical when performing the movement on an open centered bar. In contrast, the spine is arched further back on a standard chinning bar so the head can clear the bar. Both movements involve shoulder adduction and scapula downward rotation. Due to the small difference of the angle of the torso, the movemenet performed on a standard chinning bar includes a small degree of of shoulder transverse extension and scapula adduction (retraction); hence the additional muscles involved. Incidentally, with the open centered bar, the clavicular head of the Pectoralis major is involved in shoulder adduction since the body is more vertical. This vertical posture is even more pronounced on the rear pull up. Granted these difference are difficult to see. You may more clearly see the differences between the Standard Pull-up and Rear Pull up. The Pull up on an open-centered bar is between these two extremes.


Chest Dip and Triceps Dip Differences

Weighted Chest DipI'm little curious to know what is the difference between the Chest Dip and the Triceps Dip? For Chest Dip we should bend forward more or so?

You should be able to see from the instructions the differences include the grip on the bar and the positioning of the arms and legs. On the Chest Dip, you place your hands diagonal on the bars to facilitate the elbows flaring outward, whereas on the Triceps Dip you have a more standard grip on the bar. On the Chest Dip you bend your hips and knees where as on the triceps dip your hips are straighter so your body will be more upright.


Pectoralis Major Adducts and Abducts

In shoulder articulations, pectoralis major (clavicular part) appears as a weak adductor as well as a weak abductor. How is this possible - that a muscle behaves in the same way in contrasting activities?

When the shoulder is externally rotated the clavicular pectoralis assists in abduction; particularly beyond where the arm is already abducted 90º. (Thompson & Floyd, Manual of Structural Kinesiology) This muscle is even more involved in abduction, or pushing an object overhead in an individual with a deep rib cage (barrel chest) and/or with their chest held high, as in the military press.

The clavicular pectoralis assist the sternal pectoralis in adduction particular when the shoulder is internally rotated (Above reference and Moore, Clinically Oriented Anatomy) where the arm is already adducted 90º. It is even more involve when the adduction is accompanied by slight horizontal flexion as with bending over slightly when performing the chest dip or standing cable fly.


Traps with Back or Shoulders?

I noticed that the middle and lower trapezius muscles are worked in back exercises, such as one arm dumbell rows, but that the upper traps are worked during deltoid exercises such as the military press. My question is when to do shrugs, with shoulders or with back. Is it okay to work the middle and lower traps with rowing exercises during my back workout, and then do shrugs to hit the upper traps during my shoulder workout, or should I keep lower, middle, and upper traps all together on one day?

Either way is acceptable. The upper trap is worked isometrically as a stabilizer on most front and side delt exercises. With a split program it is common to have movements that exercise muscles that have already been worked on another day. For example, many back and lat exercises involve the chest. The idea is to minimize overtraining those body parts that are prone to injury, like the lower back. Don't do squats on day and straight-leg deadlifts the next day, see Lower Back Recuperation.


Asymmetrical Chest

Since I have been weight training I have noticed my left pec is growing faster than my right. I have also noticed the right side of my coller bone is slightly higher than the left side. Do you think this could be the cause and if so do you have any ideas on targeting that muscle better.

Consult a physical therapist if you have had an old injury that has altered your range of motion, posture, or muscle function. They may prescribe specific stretches and exercises for postural muscles. Alternatively you may consider seeking a physiotherapist that practices ART (active release technique) or posturology.

Make certain your exercise form is close to symmetrical on your bench, incline and shoulder press. Have a few spotters look at your form for differences on each side. If there is a difference, use only the weight you can manage in symmetrical form, increasing only when you are able to manage near symmetrical form. You will need continuous feed back to correct your form at first. Incidentally, most studies have demonstrated that extra sets do not develop significant differences in muscular size or strength so an additional sets of the exercises you are currently performing will probably not be that effective.

Most people have subtle differences between their right and left sides. I have a similar chest asymmetry with the right scapula slightly anterior. In addition, I even have 2 abs on one side and 3 abs on my other side. Next time you see a bodybuilding publication take a close look at difference between these individuals right and left sides. Even those bodybuilders who are noted for their symmetry have differences. They just know how to hide it. If thinking about competing in bodybuilding, understand you will look more symmetrical in asymmetrical poses.

Also see Structual Symmetry.


Weight Training Exercise Utility Classification

Some execises are categorized as "Basic or Auxillary". Does that mean some authorities consider it basic, and others auxillary, or you can make it either one (depending on the way you do it)?

The latter. The classifications can be seen as a continuum. An exercise utility is also dependant upon the inclusion of other exercises. For example, an incline bench press is an auxiliary exercise in the context of a full body routine but a basic exercise in a split program. A step up is an auxiliary exercise when included with squats, but an auxiliary exercise if a leg extension is performed instead. You will find the definitions in the glossary eludes to relative characteristics.


Exercising Short Head of Hamstrings

Kneeling Leg CurlYour muscular analysis of the hamstrings says that the short head of the biceps femoris is involved in knee flexion but not hip extension. I am currently using straight leg deadlifts for my hamstrings since I lift at home and don't have access to a leg curl machine. Is it necessary to exercise the short head of the biceps femoris? Is there any way to do so without a leg curl machine?

You should be fine performing a straight leg deadlift instead of a leg curl for a month or so. You can however perform a leg curl like exercise on back with a exersice ball under your lower leg using you body weight. There are also lying or standing cable leg curls to consider. You get other ideas on our forum.


Target Muscle of Straight Leg Deadlift

Excellent Site! I had a quick question regarding the "Target Muscle" specified in the "Smith Straight Leg Deadlift." On your site you have two pages for the Smith Straight Leg Deadlift . . . one under Hamstrings, and the other for Erector Spinae. Which page is accurate for the "Target Muscle?" Both pages seem to contain the same information, with the Target and Synergist Muscle swapped. Also, the Smith Deadlift (or what appears to be the Romanian Deadlift) Muscle Target is the Erector Spinae and not the Hamstrings? Many thanks!

Most exercises work multiple muscles. The Straight-leg deadlift just happens to works both the low back and hamstrings about the same since torque forces occurs both through the spine and hip. People may report they fell fatigue (or soreness the day after) more in one or the other depending on what is likely 'weaker'. You will find other cases of this in other exercises.

Some may argue the deadlift (knees bending on descent) is a near total body exercise. You will also see the deadlift listed as a glute exercise (see link under comments) although most people never feel their glutes working partly because it is the most powerful muscle in the body and other muscles are working relatively so much more intensely, like the low back, although it acts as a stabilizer it is typically the muscle that most taxed. The hamstring's ability to work at the hip is severely hamstrung (pun intended) since the knees bend as the hips bend, although not as much as a squat but more than the Romanian Deadlift. On the Deadlift page, you can click on 'dynamic stabilzer' header just above hamstring to understand this concept more fully. Also notice the hips travel much lower on Deadlift as compared to the Romanian Deadlift.

Most classification system may not be perfect (most requiring notations and subnotations), but we can still use it as a tool for understanding general concepts as well as way to referencing large lists, such as exercises :-)


Dealift for Glutes -vs- Low Back?

DeadliftYou list two deadlifts (targeting Glutes and another targeting Erector Spinae) which are shown to be exactly the same, but each is missing the others muscle group. Any explanation on the difference?

Several exercises target one of two muscles depending on your perspective. Sometimes there may be subtle differences in execution and biomechanics as in the squat, the bodybuilding-style squat is more Quadriceps centric, whereas the Powerlifting-style squat emphasises the stonger Gluteus Maximus. See You can see on the exercise you cited, the Deadlift, the target muscle could either be considered a glute movement (where the greatest dynamic force is generated) or the low back exercise (where the greatest isometric force is generated). There are really no differences between the versions shown, only a difference on how the Deadlift could be classified.


New Kinesiology Terms

Where I can read scientific articles regarding the concept 'dynamic stabilizer'?

I coined the term 'dynamic stabilizer' many years ago to describe a biarticulate muscle that shortens at one joint and lengthens an adjacent joint so their is practically no net contraction of that muscle. At the time I could not find a term for a muscle with this characteristic even after consulting with professors of biomechanics.

The most cited example of this concept is the hamstrings stabilizing effects on the knee counteracting the powerful anterior dislocating effects of the quadriceps during closed chained pushing movements, such as with the squat and leg press. Hamstring weakness is of particular concern when there has been a compromise to the anterior cruciate ligament of the knee.

To fully understand this concept it helps to study how the force vectors act within the structures of the body. I remember seeing a vector diagrams of these of these counteracting forces in a biomechanics text book (Kreighbaum, E., Barthels, K.M., (1996). Biomechanics; A Qualitative Approach for Studying Human Movement, Allyn & Bacon, 4.) but to my understanding, it incorrectly illustrated the true location of the fulcrum and angle of pull of the quadriceps. I now exhibit a corrected diagram on the Angle of Pull page.

Actually on that diagram, I have used the corrected force vectors and added muscle's force vectors to understand a nearly opposite movement, open chain knee flexion, as in a lying leg curl. See how the tibialis anterior has the ability to activate the gastrocnemius as a synergist in knee flexion? And the Rectus Femoris has the potential to position the hip in a more favorable position for knee flexion, by decreasing active insufficiency of the hamstring. I call these sort of muscle 'antagonistic stabilizer', another term I have created because I found no better way to describe their action.

But if you only look at the force vectors within the purple rectangles only, how they were originally 'intended to be viewed in that textbook with its errors, you can use that part of the diagram to better understand how the hamstrings can counteract the dislocation forces of the quadriceps in a close chained leg press or squat movement.

As you have seen on ExRx.net, you can find other examples how other biarticulate muscles can be involved as dynamic stabilizers.


What exercises work the Sartorius?


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