DETERMINANTS OF THE MAGNITUDE OF TRAINING MEDIATED MUSCLE HYPERTROPHY

Abstract

<p>Chronic resistance training leads to muscle hypotrophy in a wide range of populations however most resistance training studies are relatively small in sample size</p> <p>Three studies were conducted to better understand the sources of this variability. The first study employed a unilateral resistance training model to test the effects of relative training load and volume on the magnitude of hypertrophy and strength gains. This study showed that high relative training loads were no better than low training loads at inducing muscle hypertrophy provided that each set was performed to the point of muscular exhaustion. In agreement with previous finding, strength gains were greatest with the highest loads.</p> <p>The next two studies attempted to correlate various putative regulators of muscle hypertrophy with the magnitude of hypertrophy after 16 weeks of training in 23 subjects. Study two showed no association between the acute responses of testosterone, GH or IGF-1 and muscle hypertrophy but did show associations with androgen receptor content and acute phosphorylation of p70S6K. This suggests that local rather than systemic processes are the most important regulators of muscle hypertrophy.</p> <p>The third study tested whether the acute post exercise protein synthetic response to a single bout of resistance exercise is related to the magnitude of hypertrophy following training in the same subjects. Although previous work has shown that acute post exercise protein synthetic response is qualitatively similar to the magnitude of hypertrophy after chronic training with similar manipulations in different subjects, we did not see any relationship.</p>