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ABSTRACT
Schoenfeld, BJ. The mechanisms of muscle hypertrophy and their application to resistance training. J Strength Cond Res 24(10): 2857-2872, 2010-
The quest to increase lean body mass is widely pursued by those who lift weights. Research is lacking, however, as to the best approach for maximizing exercise-induced muscle growth. Bodybuilders generally train with moderate loads and fairly short rest intervals that induce high amounts of metabolic stress. Powerlifters, on the other hand, routinely train with high-intensity loads and lengthy rest periods between sets. Although both groups are known to display impressive muscularity, it is not clear which method is superior for hypertrophic gains. It has been shown that many factors mediate the hypertrophic process and that mechanical tension, muscle damage, and metabolic stress all can play a role in exercise-induced muscle growth. Therefore, the purpose of this paper is twofold: (a) to extensively review the literature as to the mechanisms of muscle hypertrophy and their application to exercise training and (b) to draw conclusions from the research as to the optimal protocol for maximizing muscle growth.
KEY WORDS muscle development, hypertrophic response, muscle growth, muscle tension, muscle damage, metabolic stress
INTRODUCTION
The quest to increase lean body mass is widely pursued by those who lift weights. Given the strong correlation between muscle cross-sectional area and muscular strength (111), increased muscle mass is a primary goal of athletes involved in strength and power sports such as football, rugby, and powerlifting. Muscle mass also is vital to the sport of bodybuilding, where competitors are judged on both the quantity and quality of dieir muscle development. On a more general level, muscle hypertrophy is also pursued by the many recreational lifters who aspire to develop meir physiques to the fullest. Therefore, the maximization of muscle mass has far reaching implications to a variety of populations associated with sports and health.
In untrained subjects, muscle hypertrophy is virtually nonexistent during the initial stages of resistance training, with the majority of strength gains resulting from neural adaptations (124). Within a couple of months of training, however, hypertrophy begins to become the dominant factor, with the upper extremities shown to hypertrophy before the lower extremities (124,177). Genetic background, age, gender, and other factors have been shown to mediate the...