The Role of Hormones in Exercise-Induced Muscle Hypertrophy

Abstract

Resistance exercise training leads to muscle hypertrophy; however the exact mechanisms involved in the hypertrophic process are still not fully understood to this day. Besides resistance training-induced mechanical stress, hormonal elevations triggered by resistance training seem to play important roles in the anabolic process via genomic and non-genomic activities. Nevertheless, studies with regard to the direct effects of resistance training-induced acute hormonal elevations on muscle growth led to contradictory findings. Indeed, several studies show direct correlations between acute hormonal elevations and muscle hypertrophy, while others deny such correlations. Even if direct effects of resistance training-induced acute elevations might not be the main driving factor for muscle hypertrophy, they are involved in many anabolic processes and therefore facilitate the hypertrophic mechanism. On the other hand, supraphysiological levels of hormones achieved via exogenous supplementation may create an anabolic and anti-catabolic environment leading to muscle hypertrophy going beyond the levels achievable with physiological hormonal levels.