I am curious as to anyones thoughts on both the theory and the Time Under Tension per set parameter mentioned in the Greg Bradley-Popovich book Rational Strength Training: Principles & Casebook quoted below:
During the process of protein synthesis in any cell, energy is consumed in the form of adenosine triphosphate (ATP), the body's energy currency. Muscle contraction, like protein synthesis and the vast majority of other physiological processes, also consumes ATP. The moments of ATP shortage during protein synthesis (as a result of ATP being used for intense muscular contractions) are hypothesized to be of paramount importance. Supposedly, an unknown signal would report to the muscle cell nuclei ordering them to send more protein-building instructions back out into the cell. It is proposed that when a trained muscle attempts to "catch up" on its protein synthesis during rest, it inadvertently overshoots resulting in a supercompensation, or net increase, in the amount of muscle protein. The concept of this competition for energy, called the ATP Deficit Theory, is somewhat analogous to the glycogen supercompensation characteristic of trained muscles.
Evidently, to promote muscle hypertrophy, the activity must be demanding enough to produce this effect. Low intensity endurance training will not sufficiently deplete ATP stores available for protein synthesis. ATP can actually regenerate itself that quickly. Conversely, if the tension time of a set is too brief apparently under 45 seconds (although this is debatable) while implementing very heavy weights ATP is taken up quickly, but not in proportion to muscle fatigue; again resulting in lack of ATP store depletion allocated for protein synthesis. This may explain why power and Olympic lifters increase strength (via skill acquisition/adaptive coordination) without the characteristic hypertrophy of bodybuilders. Hence, in order to maximize muscle growth, it is best that sets last at least 45 seconds, but not so long (over 2 minutes) as to promote a high endurance capacity and potential overuse atrophy.
About the Author:
Dr. Greg Bradley-Popovich holds dual master's degrees in Exercise Physiology and Human Nutrition from West Virginia University as well as a doctorate in Physical Therapy from Creighton University. He is the Director of Clinical Research at Northwest Spine Management, Rehabilitation, and Sports Conditioning in Portland, Oregon.