Lamas, L., Aoki, M. S., Ugrinowitsch, C., Campos, G. E. R., Regazzini, M., Moriscot, A. S., & Tricoli, V. (2010). Expression of genes related to muscle plasticity after strength and power training regimens. Scandinavian Journal of Medicine & Science in Sports, 20, 216225.

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This study compared the effects of eight weeks of 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]. Physically active subjects (N = 29) were divided into three groups: strength training, power training, and control. Squat 1 RM and muscle biopsies were obtained before and after the training period.

Strength increased similarly for the strength and power-training groups. Fiber types I, IIa, and IIb exhibited main time effects. Only type IIb decreased from pre- to post-test. mTOR and RICTOR mRNA expression increased similarly from pre- to post-test. RAPTOR increased after training for both groups, but to a greater extent in the strength-training than in the power-training group. 4EBP-1 decreased after training when the strength and power-training groups were pooled. Calcineurin levels did not change after training, while calcipressin increased similarly from pre- to post-test.

Implication. Strength and power training regimens produce similar performance improvements. Strength training stimulates greater hypertrophy in muscle fibers (although not necessarily significantly more).

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