Some good info right here,
GH Gut
By: Liquidanny
In recent years, a number of writers have observed that increasing numbers of world-class bodybuilders appear at contests with low body fat, etched abdominal muscles and protruding guts. We have named this phenomena "Protruding Gut Syndrome" or "PGS" for short. Most notable among its victims is none other than Mr. Olympia himself, Dorian Yates. One writer suggested that this was a side effect of Steroid use . Another, influential editor, states flatly that it is caused by the use of hGH or GH releasers. There is no research to support either explanation. Frankly, there is no proof that this protruding gut phenomena exists at all or that if it does it is anything new. Our eyes tell us that there is a problem that is manifest in some physique stars. The question is when did it first appear and is it restricted to Steroid and/or GH users.
It seems to me that in the 1950's, before Steroids , hGH or GH releasers, there were competitors that exhibited the same "problem". Moreover, the problem is not by any means limited to "ergogenic" drug users. An observant individual will notice it in thin individuals of every stripe who have never trained with weights or even exercised to any significant degree. If I'm correct, and I believe I am, the cause is failure to develop the set of muscles that are tasked with the role of holding the internal organs within the abdominopelvic cavity. This may be exacerbated somewhat in obese or formerly obese individuals by intra-visceral fat deposits, organ enlargement and prolapse of the abdominopelvic visceral sheath. Nevertheless, in most cases it is a lack of muscle development. These muscles have no significant visibility externally. In other words, they are not "show" muscles. Because they don't show directly, many never train them. Moreover, some who do train them don't realize that they are doing so or the benefit they derive from doing so. As an example, in a training course sold by Frank Zane many years ago, titled "How to Develop Championship Legs and a Small Waistline" he describes a technique called the "Stomach Vacuum". This is the kind of "exercise" that helps develop the muscles of which I speak. Arnold describes the same technique in his Encyclopedia of Modern Bodybuilding . It may not mean anything but neither Arnold nor Zane showed any evidence of protruding gut. By the way, before I go any further, it is worth pointing out that the most notable of these muscles are the internal obliques and the transverse abdominis but the Iliacus, Soleus and Intercostals are also involved. These muscles get a fair amount of stimulation from sit-ups but practically none from crunches. Over the past twenty years, the crunch has replaced the sit-up as the exercise of choice for developing the abdominals (technically rectus abdominis). This allows for another explanation of the increasing prevalence, if such exists, of PGS.
The lack of specific exercise for the gut retaining muscles is not the whole explanation for the phenomena. If it were, everyone who doesn't exercise would manifest the problem. As we can see by observing the public at large, this is not the case. However prevalent the problem, it is not universal among those who do not exercise. This suggests that while lack of the proper exercise may contribute to the problem, it is not the cause. Normally, the visceral sheath combined with the natural tonus of the retaining muscles is sufficient to maintain the organs within the Abdominopelvic cavity. Something must stretch the visceral wall and overcome the natural tonus of the retaining muscles, enter the big dinner, the TV and the soft couch. After eating the stomach and intestines are full of food and are, therefore, heavier and occupy more space then when empty. If the meal is particularly large they may require more space then can be provided in the un-distended space they have available to them. If one sits and the knees bend beyond 90 degrees, the space is further restricted. If the shoulders roll forward, as in relaxation, still further reduction of space is imposed by the pressure of the diaphragm in its downward excursion. Leaning forward, as some drivers do and as some chairs encourage one to do, allows gravity to force the viscera forward, placing increased pressure on the visceral wall. Watching television with the chin held on the hands also places the body in this position of increased pressure on the visceral wall.
For the body builder, or weight lifter, guzzling water or workout drinks and then squatting creates incredible inter-visceral force. In fact, almost any movement performed in a forward bent position and any movement performed wearing a lifting belt also increases the pressure to astronomical levels. In other words, there are a host of behaviors, some of them unique to weight trainers others not, that create the distention that precedes PGS. Add in the reduced natural tonus common to a more or less sedentary life style and we have all the explanation required.
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