Kawakami Y, Kanehisa H, Ikegawa S, Fukunaga T

Eur J Appl Physiol 1993;67(2):121-124

The purpose of this study was to investigate the force-producing characteristics of boys aged 13 years in relation to fatigue ofelbow flexor muscles. Maximal voluntary force in elbow flexion was measured before and after a muscle endurance test (MET)by using an isokinetic dynamometer isometrically, concentrically and eccentrically at three velocities, i.e. 0.21, 0.52, and 1.05rad.s-1. The MET consisted of maximal concentric and eccentric muscle actions performed alternately at 0.52 rad.s-1 for 50consecutive trials. Muscle cross-sectional area (CSA) of elbow flexor muscles (biceps brachii and brachialis) was measured by aB-mode ultrasound apparatus. Although eccentric force showed significantly higher values than concentric force during MET,there was no significant difference in the rate of decline in force between the two actions. There was no significant difference inthe rate of decline in force after MET for each velocity and muscle action. Isometric, concentric and eccentric force before METwas significantly related to muscle CSA whereas, after MET, concentric force significantly correlated with muscle CSA but therewas no significant correlation between muscle CSA and isometric or eccentric force. From our study, it is therefore suggestedthat in development to maturity, isometric, concentric and eccentric force decrease at the same rate with advancing muscle fatigue;however, there might be differences among muscle actions in factors affecting force development.