We reported, using a unilateral resistance training (RT) model, that training with high or low loads (mass per repetition) resulted in similar muscle hypertrophy and strength improvements in RT-naïve subjects. Here we aimed to determine whether the same was true in men with previous RT experience using a whole-body RT program and whether post-exercise systemic hormone concentrations were related to changes in hypertrophy and strength. Forty-nine resistance-trained men (mean ± SEM, 23 ± 1 y) performed 12 wk of whole-body RT. Subjects were randomly allocated into a higher-repetition (HR) group who lifted loads of ~30-50% of their maximal strength (1RM) for 20-25 repetitions/set (n=24) or a lower-repetition (LR) group (~75-90% 1RM, 8-12 repetitions/set, n=25), with all sets being performed to volitional failure. Skeletal muscle biopsies, strength testing, DXA scans, and acute changes in systemic hormone concentrations were examined pre- and post-training. In response to RT, 1RM strength increased for all exercises in both groups (p < 0.01), with only the change in bench press being significantly different between groups (HR: 9 ± 1 vs. LR: 14 ±1 kg, p = 0.012). Fat- and bone-free (lean) body mass, type I and type II muscle fibre cross sectional area increased following training (p < 0.01) with no significant differences between groups. No significant correlations between the acute post-exercise rise in any purported anabolic hormone and the change in strength or hypertrophy were found. In congruence with our previous work, acute post-exercise systemic hormonal rises are not related to or in any way indicative of RT-mediated gains in muscle mass or strength. Our data show that in resistance-trained individuals load, when exercises are performed to volitional failure, does not dictate hypertrophy or, for the most part, strength gains.
- growth hormone
- Copyright © 2016, Journal of Applied Physiology