Abstract

The purpose of our study was to compare the effects of 8-week progressive strength and power training regimens on strength gains and muscle plasticity [muscle fiber hypertrophy and phenotype shift, mammalian target of rapamycin (mTOR), regulatory-associated protein of mTOR (RAPTOR), rapamycin-insensitive companion of m-TOR (RICTOR), calcineurin and calcipressin gene expression]. Twenty-nine physically active subjects were divided into three groups: strength training (ST), power training (PT) and control (C). Squat 1 RM and muscle biopsies were obtained before and after the training period. Strength increased similarly for both ST and PT groups (P<0.001). Fiber types I, IIa and IIb presented hypertrophy main time effect (P<0.05). Only type IIb percentage decreased from pre- to post-test (main time effect, P<0.05). mTOR and RICTOR mRNA expression increased similarly from pre- to post-test (P<0.01). RAPTOR increased after training for both groups (P<0.0001), but to a greater extent in the ST (P<0.001) than in the PT group. 4EBP-1 decreased after training when the ST and PT groups were pooled (P<0.05). Calcineurin levels did not change after training, while calcipressin increased similarly from pre- to post-test (P<0.01). In conclusion, our data indicate that these training regimens produce similar performance improvements; however, there was a trend toward greater hypertrophy-related gene expression and muscle fiber hypertrophy in the ST group.