Title

Relationships between maximal strength, muscle size, and myosin heavy chain isoform composition and voluntary postactivation potentiation

Document Type

Journal Article

Publisher

N R C Research Press

Place of Publication

Canada

School

School of Medical and Health Sciences

RAS ID

21105

Comments

Originally published as: Seitz, L. B., trajano, G. S., Haff, G., Dumke, C. C. L. S., Tufano, J. J. & Blaevich, A. J. (2016). Relationships between maximal strength, muscle size, and myosin heavy chain isoform composition and voluntary postactivation potentiation. Applied Physiology, Nutrition and Metabolism. 41(5). 491-497. Original article available here

Abstract

The purpose of this study was to examine the relationship between maximal voluntary postactivation potentiation (PAP) and maximal knee externsor torque, quadriceps cross-sectional area (CSA) and volume, and type II myosin heavy chain (MHC) isoform percentage in human skeletal muscle. Thirteen resistance-trained men completed a test protocol consisting of 2 isokinetic knee extensions at 180°·s–1 performed before and 1, 4, 7, and 10 min after the completion of 4 maximal knee extensions at 60°·s–1 (i.e., a conditioning activity (CA)). Magnetic resonance imaging and muscle microbiopsy procedures were completed on separate days to assess quadriceps CSA and volume and MHC isoform content. Maximal voluntary PAP response was assessed as the ratio of the highest knee extensor torques measured before and after CA. There were large to very large correlations between maximal voluntary PAP response and maximal knee extensor torque (r=0.62) and quadriceps CSA (r=0.68) and volume (r=0.63). Nonetheless, these correlations were not statistically significant after adjusting for the influence of type II MHC percentage using partial correlation analysis. By contrast, the strongest correlation was observed for type II MHC percentage (r=0.77), and this correlation remained significant after adjusting for the other variables. Maximal voluntary PAP response is strongly correlated with maximal knee externor torque and quadriceps CSA and volume, but is mostly clearly associated with the type II myosin isoform percentage in human skeletal muscle.

DOI

10.1139/apnm-2015-0403

Access Rights

Not open access

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