Exercise Analysis - Abdominal Crunches

In my opinion, reality television has missed a great opportunity. While it is true that a desert island, a house full of mixed martial artists and the corporate world (and the termination practices within) provide interesting environments in which to observe people, I would argue all pale in comparison to the typical resistance training facility. In fact, even after all these years, what I see when I people-watch in the weight room never ceases to amaze me!

A quick glance around a busy gym usually confirms that many iron pumpers’ exercise execution leaves a bit to be desired. This is not surprising if you consider that even some of the most experienced individuals adopt the wrong mindset when performing resistance exercise. Instead of training with weights, they employ any means available to accomplish the task at hand. This is akin to lifting, as opposed to training, and is contrary to achieving the stimulus required to force muscle to a higher level of development.

The most egregious errors I see in the weight room are associated with training that is high on just about every exercise enthusiast’s priority list. It is safe to say that regardless of whether improving form or function is your primary goal, everyone who visits the gym is interested in working their abdominal musculature. And while it is readily accepted that you cannot spot reduce this area, it’s also apparent that a well-developed rectus abdominis (the major muscle of the region) forms the visually impressive six-pack that will shine through once body fat is reduced. But that brings us back to the initial issue: If the exercises being performed don’t effectively stimulate the muscle, all bets are off.

Abdominal exercise errors are the worst because exercise execution isn’t even the primary problem. Instead, exercise selection is the major concern and it’s not uncommon for even savvy iron pumpers to perform “abdominal” movements that aren’t even characterized by shortening of the muscle group they are trying to target. Imagine doing squats in an attempt to work the muscles that curl the arm at the elbow! Crazy? Yeah, but that would be similar to what many abdominal exercisers wind up doing.

The rectus abdominis is a long, flat muscle that runs in front of the torso from rib cage to hip. Muscles create movement at the joints they cross and the rectus is no exception. Therefore, when this strap-like muscle develops sufficient tension in its contractile units to overcome any resistance to shortening that is present, it causes the spine to curl forward with motion occurring at the articulations formed between adjacent vertebrae. The C-shaped posture that is achieved (flexion) should be avoided at all costs when we are sitting, standing or performing other lifts because it is the neutral spine that establishes ideal postural conditions. The only time it is advisable to deviate from neutrality is when we are working the muscles that cause the spine to change its shape. In addition to the rectus, these include the internal and external obliques on the side and the erector spinae in the rear.

The rectus abdominis doesn’t cross the hips, so any movement of the thigh in relation to the hip does not require this muscle to change its length. This means that leg raises don’t work abs! You heard me right: Lifting your legs up while supporting yourself against a vertical pad or lying on a horizontal surface simply doesn’t cause the rectus to work, at least not as a prime mover. Granted, the muscle does prevent the hips from being drawn down as the players that do facilitate the motion (the hip flexors, which run from the hips to the thighs) do their job, but this isometric stabilization is certainly not the best way to target your abs.

The rectus abdominis can be trained as a prime mover by performing crunches. After assuming a supine body posture with the knees and hips bent at 90 degrees and the lower legs supported on a horizontal surface, crunches begin with the spine hyperextended so that the target muscle is stretched. This posture is characterized by exaggeration of the concave curve that is present in the spine’s lower section. From this position, tension is developed in the rectus to eliminate the curve before the actual crunch is initiated. This is called a posterior pelvic tilt because the abdominal contraction pulls the top of the hips toward the ribs, thereby rotating the pelvis to the rear. This rotation causes the spine to flatten and effectively fixes the hips, allowing them to act as an anchor when further rectus shortening curls the ribcage up toward them. Contrary to popular belief, having the ankles held down at this point is important because the hips can only provide a fixed origin from which the attached muscle can maximally shorten if they are not free to curl up. The only way to accomplish this stabilization is through the lower leg. Once full spinal flexion is achieved, the contracted position should be held momentarily to completely engage the target muscle before tension is reduced just enough to allow gravity to slowly pull the spine back to the starting posture.

This article was originally published in New Living Magazine, which can be accessed on-line at www.newliving.com.




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