Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
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©Journal of Sports Science and Medicine (2009) 08, 548 - 552

Research article
Effects of Prolonged Tendon Vibration Stimulation on Eccentric and Concentric Maximal Torque and Emgs of the Knee Extensors
Yu Konishi1, , Junjiro Kubo2, Akinori Fukudome1
Author Information
1 Department of Physical Education, National Defence Academy, Kanagawa, Japan
2 Faculty of low, Heisei International University, Saitama, Japan

Yu Konishi
✉ Department of Physical Education, National Defence Academy, 1-10-20 Hashirimizu, Yokosuka City, Kanagawa, Japan 239-686
Email: yu57@nda.ac.jp
Publish Date
Received: 05-08-2009
Accepted: 15-09-2009
Published (online): 01-12-2009
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ABSTRACT

The purpose of present study was to compare the effect of Ia afferent attenuation on the activity of alpha motor neuron (MN) during concentric and eccentric action. Eight male subjects were enrolled in the present study. The experiments consisted of two sessions of MVC measurements, since all subjects performed both maximal concentric and eccentric action. EMG signals were simultaneously measured. To establish the baseline of strength, subjects were asked to perform MVC of knee extension in each session. After finishing the measurements, 20 min of vibration stimulation was applied. Immediately after finishing vibration stimulation, the MVC and AEMG were again measured. The means of MVC for concentric knee extension at pre and post- vibration stimulation were 192.2 ± 49.3 Nm and 162.3 ± 47.9 Nm, respectively. The means of MVC for eccentric knee extension at pre and post-vibration stimulation were 299.7 ± 77.0 Nm and 247.3 ± 88. 6 Nm, respectively. Two-factor repeated ANOVA detected significant differences in the MVC. Both main effects for pre-post condition (F(1,7)=, p = 0.0033) and action (F(1,7)=26.35, p = 0.0013) were noted. No interaction effect (action x condition) was noted. The means of AEMG (vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF)) at pre and post -vibration stimulation were decreased. Two-factor repeated ANOVA detected significant differences in AEMG (VM and VL). Both main effects for pre-post condition (VL;F(1,7)=7.27, p = 0.0308, VM; F(1,7)=9.55, p = 0.0175) and action (F(1,7)=12.40, p = 0.0097) were noted in the VL and the VM but not in the RF. Furthermore, significant interaction (action x condition) effect was noted in the VM (F(1,7)=7.03, p = 0.0328) but not in the VL. The MVC and the EMG activity of the VL in response to the prolonged vibration stimulation were significantly reduced in eccentric contraction over concentric contraction. These results represented that a deactivation effect on the alpha MN of the VL during eccentric action was greater than that of concentric action.

Key words: Concentric contraction, MVC, Vibration stimulation, QF


           Key Points
  • A deactivation effect on the alpha motor neuron of the vastus lateralis during eccentric action was greater than that of maximal concentric action.
 
 
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