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Muscle Force per Cross-sectional Area is Inversely Related with Pennation Angle in Strength Trained Athletes

Ikegawa, Shigeki1; Funato, Kazuo2; Tsunoda, Naoya3; Kanehisa, Hiroaki4; Fukunaga, Tetsuo5; Kawakami, Yasuo5

Journal of Strength & Conditioning Research: January 2008 - Volume 22 - Issue 1 - pp 128-131
doi: 10.1519/JSC.0b013e31815f2fd3
Original Research

The present study aimed to examine the effect of pennation angle on the force per cross-sectional area for elbow extensor muscles in strength-trained athletes. A total of 52 male bodybuilders (n = 32) and Olympic weightlifters (n = 20) did maximal isometric elbow extension on an isokinetic dynamometer. Muscle cross-sectional area (CSA) and muscle-fiber pennation angle (PA) of the triceps brachii muscles were measured by ultrasonography. Bodybuilders had significantly greater isometric elbow extension force (F), CSA and PA than weightlifters. The ratio of force to CSA (F/CSA) of bodybuilders was significantly lower than that of weightlifters. A significant positive correlation was observed between CSA and PA in both groups (r = 0.832, P < 0.001, and r = 0.682, P < 0.001, for bodybuilders and weightlifters, respectively). The F/CSA was negatively correlated to PA both for bodybuilders (r = -0.408, P < 0.05) and weightlifters (r = -0.465, P < 0.05). Thus present study indicates that the larger pennation angle is associated with the lower force relative to muscle CSA in strength-trained athletes.

1Faculty of Human Health Science, Tokyo Metropolitan University, Tokyo, Japan; 2Japan Institute of Sports Science, Tokyo, Japan; 3Laboratory of Biodynamics and Human Performance, Kokushikan University, Tokyo, Japan; 4Department of Life Sciences, The University of Tokyo, Tokyo, Japan; 5Faculty of Sport Sciences, Waseda University, Saitama, Japan

Address correspondence to Shigeki Ikegawa, ikegawa@opal.famille.ne.jp.

© 2008 National Strength and Conditioning Association