Home Articles Bogus Biomechanics, Asinine Anatomy: Part II

Bogus Biomechanics, Asinine Anatomy: Part II

Written on January 29, 2008 at 10:15 am, by Eric Cressey

By Eric Cressey

Last month, I covered the five myths that you’re bound to come across in any gym during your time in the iron game. This month, five more!

Myth #6: Stance width dictates recruitment of the different muscles of the quadriceps during squats and leg presses.

Contrary to what the local self-proclaimed bodybuilding guru might have told you, this is false. Recruitment is more a function of squat depth than width. McCaw and Melrose (1999) demonstrated that although a wider stance will recruit more of the adductors and glutes, it doesn’t change the relative contributions of the four muscles of the quadriceps during a squat (1). In other words, the “feet together for the vastus lateralis” and “wide stance for the vastus medialis” concepts simply don’t hold water. The vastus medialis is better recruited with terminal knee extension and any movements that send the knee into valgus. Likewise, anecdotally, knee extension exercises from positions of great knee flexion (e.g. deep squats, lunges, and step-ups) preferentially recruit the vastus medialis. This could result from increased activity of the adductor magnus – which also works as a hip extensor – to assist in hip extension from the low position. Research has shown that because the vastus medialis oblique originates on the adductor magnus tendon, increasing adductor magnus activity will enhance vastus medialis recruitment. This is the premise behind many physical therapists recommending straight leg raises with the knee extended and femur adducted to strengthen the vastus medialis; unfortunately, this rehabilitation model isn’t functional at all, and therefore doesn’t have much value beyond the initial stages of rehabilitation.

The next time someone tells you that stance width is what determines quadriceps recruitment, ask him how we classify single leg movements, where there is no such thing as stance width!

Myth #7: The “core” consists of just the abs, and can best be trained with crunches.

This statement is accepted as gospel in most mainstream muscle magazines, but it’s actually way off the mark. The core actually encompasses far more musculature than the rectus abdominus alone; broadly speaking, it extends from the upper torso and neck to the knees, serving as the link between strength and power in the lower and upper body.

Clark (2001) put forth perhaps the best functional anatomy breakdown of the core when he divided it into the local (deep) and global (superficial, prominent) musculature (2). The local musculature – including most notably the transverse abdominus and multifidus – functions primarily to stabilize the spine. Much debate has arisen in the strength training and rehabilitation communities in regards to whether or not the local musculature warrants direct training in healthy individuals. Since it’s my article, I’m allowed to give my opinion: in healthy individuals, spinal stabilization occurs involuntarily, so direct training is unproductive, and potentially counterproductive, as McGill has pointed out (3). I’d also like to take this opportunity to say that I think it sucks that most canned tuna has soy hidden in it. Oh yeah, this is also a good spot for my prediction of a third Patriots Super Bowl win in four years.

Clark further divided the global musculature into the lateral, deep longitudinal, posterior oblique, and anterior oblique “subsystems.” All of these subsystems function as a cohesive unit during complex movements (2), but they warrant mention individually to understand how training can be targeted for improving function in one or more.

The lateral subsystem involves the interaction of the gluteus maximus, tensor fascia latae, adductors, and quadratus lumborum (think “inner and outer thighs and hips”). This subsystem plays an important role in stabilizing the body in the frontal plane during activities (especially single-leg work) involving the lower body (2).

The deep longitudinal subsystem most notably includes the erector spinae, biceps femoris, sacrotuberous ligament, and thoracolumbar fascia; this system is a crucial component of the powerful posterior chain that you’ve likely heard discussed by numerous strength coaches. Essentially, this subsystem’s primary function is to allow forces generated in the lower body to be carried up to the upper body (and vice versa, in less common occurrences) (2).

The posterior oblique subsystem also includes the gluteus maximus and thoracolumbar fascia, but this time in collaboration with the contralateral latissimus dorsi (2). You may have heard of the “serape effect,” which relates the gluteus maximus and latissimus dorsi during the gait cycle. Basically, both muscles are extensors; when the right arm is extending (thanks to the right lat) during gait, so is the left leg (thanks in part to the left gluteus maximus). By “posterior oblique,” we’re referring to the back and across nature of this muscular interaction. This subsystem also has implications in transverse plane stability (2).

The anterior oblique subsystem consists of the adductors, internal and external obliques, and external rotators of the hips: gluteus maximus, piriformis, obturator internus and externus, gemelli superior and inferior, quadratus femoris, long head of biceps femoris, posterior fibers of the gluteus medius, sartorius, and adductor complex (at certain degrees of hip flexion). Beyond its obvious role in producing rotational motion, this final system is an important part of transverse plane stabilization (2).

Myth #8: You can “isolate” muscles in a resistance training context.

True muscular isolation is only possible in fine movements like blinking and twitching. In more gross movements and those involving significant external loading, numerous muscles interact as prime movers, synergists, and stabilizers. While some single-joint exercises will allow you to focus more on one muscle than others in concentric, eccentric, and isometric actions, it’s simply impossible to truly isolate a muscle. In fact, the concept of isolated muscle action actually has dangerous implications, as elimination of important stabilizers would undoubtedly compromise exercise safety.

If you don’t believe me when I say that true isolation is impossible, you can continue to try to isolate your medial gastrocnemius while your bandana-sporting, belt wearing, pretty boy training partner screams in your ear about how badass you are. Meanwhile, those of us who know better will just keep to ourselves and do multi-joint exercises that allow for significant external loading, and we’ll see who makes better progress.

Myth #9: The secret to healthy shoulders is to have a big, strong chest, lats, delts, and “traps.”

I’ve heard this one on several occasions, and it never ceases to crack me up. These larger muscles are usually the problems, not the solutions! When you hammer your pecs, lats, anterior delts, and upper traps mercilessly and ignore their antagonists (external rotators, horizontal abductors, scapular retractors, and scapular depressors), unfavorable postures and movement patterns develop. Specifically, the humeri tend to assume an internally rotated resting position and the scapulae become elevated, winged and anteriorly tilted. These changes mechanically decrease the already-narrow subacromial space, increasing the likelihood that the tendons of the rotator cuff will become irritated when the arm is raised. When the rotator cuff is strong, it serves to depress the humeral head in the glenoid fossa so that this impingement doesn’t occur. If the SITS muscles (supraspinatus, infraspinatus, subscapularis, and teres minor) are weak relative to these larger muscles, the humeral head translates superiorly excessively; the pain is most prominent in bench pressing and overhead movements. Summarily, the secret to healthy shoulders is to train the antagonists to the “big dogs” in order to foster appropriate strength ratios and maintain ideal resting posture.

Myth #10: Calves won’t grow without calf raises.

In my experience, calf development is perhaps the single-most genetically influenced aspect of weight training. Some guys are born with high calves, and some have thick ankles attached to tree trunks. That’s not to say, however, that training and lifestyle factors can’t markedly improve the size of one’s calves. Yes, I said lifestyle factors! Take a look at any really fat person, and you’ll see a great set of calves. The soleus comprises roughly 2/3 of the lower leg musculature, and since it’s largely a postural muscle, it tends to hypertrophy in tubby people even if they don’t exercise. It may not seem fair to those of you who are putting in the time with hours upon hours of calf raises, but that’s life.

Speaking of calf raises, they aren’t the only way to train calves. The gastrocnemius works not only in plantarflexion, but also in knee flexion. As such, it gets hit hard with glute-ham raises and leg curls. Moreover, plantarflexion is trained heavily in a variety of more compound movements, including Olympic lifts, sprinting, sled dragging, and farmer’s walks (with accentuated pushoffs). Sometimes, ignoring the calf raises altogether and focusing on these compound movements is a great way to spark growth “by accident.” Or, they can serve as valuable adjuncts to your regimen of seated, standing, leg press, and donkey calf raises. Finally, the tibialis anterior (muscle on the front of the shin) can contribute to lower leg mass; dorsiflexion exercises and downhill running can be effective means of improving in this regard.

Conclusion

Hopefully, the past two articles have given you some intellectual firepower to call upon the next time you’re confronted with these myths. Then again, old myths die hard, so sometimes it’s better to just shake the “gurus” off and do your own thing.

References

1. McCaw ST, Melrose DR. Stance width and bar load effects on leg muscle activity during the parallel squat. Med Sci Sports Exerc 1999 Mar;31(3):428-36.

2. Clark, M. Performance Enhancement Specialist Online Manual. National Academy of Sports Medicine, 2001.

  • Eric

    What’s so bad about soy?


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