Effects of oral creatine and resistance training on serum myostatin and GASP-1

Myostatin is a catabolic regulator of skeletal muscle mass. The purpose of this study was to determine the effect of resistance training for 8 weeks in conjunction with creatine supplementation on muscle strength, lean body mass, and serum levels of myostatin and growth and differentiation factor-associated serum protein-1 (GASP-1). In a double-blinded design 27 healthy male subjects (23.42 +/- 2.2 years) were assigned to control (CON), resistance training + placebo (RT+PL) and resistance training + creatine supplementation (RT+CR) groups. The protocol consisted of 3 days per week of training for 8 weeks, each session including three sets of 8-10 repetitions at 60-709 of 1 RM for whole-body exercise. Blood sampling muscular strength testing and body composition analysis (full body DEXA) were a performed at 0, 4th and 8th weeks. Myostatin and GASP-1 was measured. Resistance training caused significant decrease in serum levels of myostatin and increase in that of GASP-1. Creatine supplementation in conjunction with resistance training lead to greater decreases in serum myostatin (p < 0.05), but had not additional effect on GASP-1 (p > 0.05). The effects of resistance training on serum levels of myostatin and GASP-1, may explain the increased muscle mass that is amplified by creatine supplementation. (C) 2009 Elsevier Ireland Ltd. All rights reserved.