explain
Mentzer confused theoretical, deductive reasoning with empirically derived facts. As far as I remember, he went from his premises to conclusions in a way that looked like "scientific reasoning", but he ignored the possibility that the premises could be wrong. Only empirical trials can tell the ultimate truth.
In medical science, you also see a lot of this. An example is the reasoning behind the use of antioxidants, such as vitamin E. In many types of disease, there is an etiology that involves oxidative stress (eg. in neurodegenerative diseases such as ALS or Parkinson's disease). Hence, the reasoning was that antioxidants should protect against these diseases.
Unfortunately, empirical studies have failed to show clear effects "in vivo". There are several "in vitro" studies that are promising, for vitamin E and plant-derived substances. However, in vivo, the evidence is sketchy. The point is, the premises may be wrong. It is not a logical necessity that taking antioxidants orally will benefit cells in the body that suffer from excessive oxidative stress, nor is it clear that oxidative stress in itself is causally related to the disease process.
If you read Mentzer, you'll se lot of similar error. If you want, I can find quotes and examples, but to me, the main error is his assumption that "one set to failure" is sufficient to induce optimal hypertrophy. This is starting to be disproved in trained subjects. It is also more complicated, as hypertrophy is not due to one single physiological process. For example, a recent finding is that training a muscle that is in a hypoxic/anoxic state, induces hypertrophy. Here is an example:
http://www.ncbi.nlm.nih.gov/pubmed/23166781This contradict Mentzer, in that metabolic stress is one mechanism by which hypertrophy is induced:
http://www.ncbi.nlm.nih.gov/pubmed/23338987. One rep to failure may not induce optimal metabolic stress. This may be complicated by whether there is constant tension, number of reps etc. And IF one trains with multiple sets, duration of pauses may influence growth.
To me, Mentzers premise appears to be that there is a single dimension, called "intensity", that can be called "the stimulus", and given that one reaches 100% intensity in the shortest possible time, optimal growth will be induced. This is clearly simplistic and not backed up by research, although it may be valid for beginning trainers.
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