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Jpn J Biomechanics Sports Exercise 11(1):9-24, 2007

Kinetics of the support leg during the side-jump for speed skaters

Jun YUDA1), Masahiro MURATA1), Kaoru YAMANOBE1), Kenji TAUCHI2), Toru AOYANAGI3)

1)Department of Sports Sciences, Japan Institute of Sports Sciences,
2)Faculty of Sport Sciences, Waseda University,
3)Nippon Sport Science University Women's Junior College

Abstract

The purpose of this study was to identify kinetic characteristics of the support leg due to fatigue during the side-jump test in speed skaters. Ten male skaters performed the 70-second-majdmal effort side-jump test on a tartan track in the laboratory ; two synchronized high-speed video cameras (250 fields/s) were used to record their performance using the DLT technique. Ground reaction forces (GRF) of the right leg were determined using the force platform (500Hz). The GRF and three-dimensional coordinates of the segment endpoints were collected over 70 seconds to calculate the right support leg kinetics during the first and second halves of the test, at 5 and 65 seconds, respectively, using an inverse dynamics approach. During the first half, the absolute work done by hip torque was significantly greater than those of the knee and ankle torques. This indicates that great energy exertion by the hip muscles is a characteristic of the side-jump. During the second half, there was decreased knee extension torque and power at approximately 80% stroke. Thus, minimizing the decrease in the torque and power under fatigue conditions would be an important factor for endurance training of the side-jump.

Key Words: speed skating, side-jump, three-dimensional motion analysis, joint torque, fatigue

Submittted for Publication : Jun 15, 2006,

Accepted for Publication : Oct 31, 2006

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