Single muscle fibre contractile properties differ between body-builders, power athletes and control subjects

Meijer, JP, Jaspers, RT, Rittweger, J, Seynnes, OR, Kamandulis, S, Brazaitis, M, Skurvydas, A, Pisot, R, Simunic, B, Narici, MV and Degens, H (2015) Single muscle fibre contractile properties differ between body-builders, power athletes and control subjects. EXPERIMENTAL PHYSIOLOGY, 100. ISSN 0958-0670

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Abstract

We compared muscle fibre contractile properties of biopsies taken from m. vastus lateralis of 12 bodybuilders (BB; low- to moderate-intensity high-volume resistance training), 6 power athletes (PA; high-intensity low-volume combined with aerobic training) and 14 controls (C). Maximal isotonic contractions were performed in single muscle fibres, typed with SDS-PAGE. Fibre cross-sectional area (FCSA) was 67% and 88% (P<0.01) larger in BB than in PA and C, respectively, with no significant difference in FCSA between PA and C. Fibres of BB and PA developed a higher maximal isometric tension (32%, 50%, P < 0.01) than those of C. Specific tension (F0) of BB fibres was 62% and 41% lower than that of PA and C fibres (P < 0.05), respectively. Irrespective of fibre type, peak power (P) of PA fibres was 58% higher than that of BB fibres (P < 0.05), while BB fibres –despite considerable hypertrophy- had similar PP as C fibres. This work suggests that high-intensity low-volume resistance training with aerobic exercise improves PP, while low- to moderate-intensity high-volume resistance training does not affect PP and results in a reduction in F0. We postulate that the decrease in specific tension is caused by differences in myofibrillar density and/or post-translational modifications of contractile proteins.