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 (2022) 21, 487 - 492   DOI: https://doi.org/10.52082/jssm.2022.487

Research article
Passive Muscle Stiffness of Biceps Femoris is Acutely Reduced after Eccentric Knee Flexion
Lei Zhi1, Naokazu Miyamoto1,2, , Hisashi Naito1,3
Author Information
1 Graduate School of Health and Sports Science, Juntendo University, Inzai, Japan
2 Department of Sport Science and Research, Japan Institute of Sports Sciences, Tokyo, Japan
3 Institute of Health and Sport Science & Medicine, Juntendo University, Inzai, Japan

Naokazu Miyamoto
‚úČ Faculty of Health and Sports Science, Juntendo University 1-1 Hiraka-gakuendai, Inzai, Chiba 270-1695, Japan
Email: n-miyamoto@juntendo.ac.jp
Publish Date
Received: 27-07-2022
Accepted: 15-09-2022
Published (online): 01-12-2022
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ABSTRACT

Eccentric hamstring exercises reportedly prevent hamstring strain injury in the biceps femoris long head (BFlh). However, information on the favorable adaptive responses in the BFlh to eccentric hamstring exercises is limited. We aimed to examine the acute effect of maximal isokinetic eccentric knee flexion on passive BFlh stiffness as a potential risk factor for the hamstring strain injury using ultrasound shear wave elastography. Ten young participants randomly performed both tasks involving five consecutive repetitions of isokinetic concentric and eccentric knee flexion with maximal effort on different legs. Passive BFlh shear modulus was taken before and 30, 60, 90, and 120 s after each task. Passive BFlh shear modulus was significantly reduced at all time points after eccentric knee flexion, whereas there was no significant change in passive BFlh shear modulus after the concentric task. The present findings indicate that passive BFlh stiffness would reduce specifically after low-volume, slow-velocity eccentric knee flexion exercise. The findings may help provide practitioners with a basis to develop more effective exercise programs for preventing HSI.

Key words: Eccentric hamstring exercises, isokinetic knee flexion, ultrasound shear wave elastography, shear modulus


           Key Points
  • Passive muscle stiffness of the biceps femoris long head (BFlh) was directly assessed using ultrasound shear wave elastography.
  • Passive BFlh stiffness was reduced after five consecutive repetitions of eccentric knee flexion, but not concentric contractions.
  • The present findings may provide practitioners with a basis to develop more effective exercise programs for preventing HSI.
 
 
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