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Jpn J Biomechanics Sports Exercise 7(3):206-213, 2003

In vivo muscle fiber behavior of the triceps surae muscles during isokinetic concentric and eccentric plantar flexions

Kentaro CHINO1), Toshiaki ODA1), Toshiyuki KURIHARA1), Toshihiko NAGAYOSHI2), Hiroaki KANEHISA1), Senshi FUKASHIRO1), Tetsuo FUKUNAGA2), Yasuo KAWAKAMI2)

1) Department of Life Sciences (Sports Sciences), University of Tokyo,
2) School of Sport Sciences, Waseda University

Abstract

In the present study, muscle fiber behavior of the medial gastrocnemius (MG) and soleus (SOL) muscles during isokinetic concentric (CON) and eccentric (ECC) plantar flexions were directly measured in vivo. The subjects (n = 6 men) performed maximal voluntary plantar flexions on an isokinetic dynamometer at 60, 120, 180, 240deg/s, concentrically and eccentrically. With the use of ultrasonography, muscle fiber lengths and pennation angles were determined. From the time course of fiber length changes, muscle fiber shortening and lengthening velocities (Vfiber) were obtained. Considering the effects of pennation angle, muscle shortening and lengthening velocities were also calculated. Vfiber changed as a function of angular velocities [MG : 32 - 90mm/s (CON) and 37 - 97mm/s (ECC); SOL : 35 - 81mm/s (CON) and 37 - 84mm/s (ECC)]. However, relative changes of Vfiber were less than those of angular velocities. This result suggests that muscle fiber behavior does not always match joint movement due to muscle-tendon interaction. Vfiber of MG was larger than that of SOL for all test conditions, suggesting inter-muscle differences in muscle fiber behavior during isokinetic movements, but the differences were not evident at the muscle level.

Key Words: force‐velocity relationship, isokinetic movement, medial gastrocnemius muscle, soleus muscle, muscle‐tendon interaction

Submittted for Publication : June 3, 2003,

Accepted for Publication : September 5, 2003

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