Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise in Young Men

Background: We aimed to determine the effect of resistance exercise intensity (% 1 repetition maximum- 1RM) and volume on muscle protein synthesis, anabolic signaling, and myogenic gene expression. Methodology/Principal Findings: Fifteen men (21 +/- 1 years; BMI = 24.1 +/- 0.8 kg/m(2)) performed 4 sets of unilateral leg extension exercise at different exercise loads and/or volumes: 90% of repetition maximum (1RM) until volitional failure (90FAIL), 30% 1RM work-matched to 90% FAIL (30WM), or 30% 1RM performed until volitional failure (30FAIL). Infusion of [ring-C-13(6)] phenylalanine with biopsies was used to measure rates of mixed (MIX), myofibrillar (MYO), and sarcoplasmic (SARC) protein synthesis at rest, and 4 h and 24 h after exercise. Exercise at 30WM induced a significant increase above rest in MIX (121%) and MYO (87%) protein synthesis at 4 h post-exercise and but at 24 h in the MIX only. The increase in the rate of protein synthesis in MIX and MYO at 4 h post-exercise with 90FAIL and 30FAIL was greater than 30WM, with no difference between these conditions; however, MYO remained elevated (199%) above rest at 24 h only in 30FAIL. There was a significant increase in Akt(Ser473) at 24h in all conditions (P = 0.023) and mTOR(Ser2448) phosphorylation at 4 h post-exercise (P = 0.025). Phosporylation of Erk1/2(Tyr202/204), p70S6K(Thr389), and 4E-BP1(Thr37/46) increased significantly (P<0.05) only in the 30FAIL condition at 4 h post-exercise, whereas, 4E-BP1(Thr37/46) phosphorylation was greater 24 h after exercise than at rest in both 90FAIL (237%) and 30FAIL (312%) conditions. Pax7 mRNA expression increased at 24 h post-exercise (P = 0.02) regardless of condition. The mRNA expression of MyoD and myogenin were consistently elevated in the 30FAIL condition. Conclusions/Significance: These results suggest that low-load high volume resistance exercise is more effective in inducing acute muscle anabolism than high-load low volume or work matched resistance exercise modes.