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Effect of knee extensor fatigue level and sex on bilateral jump-landing
  1. Byungjoo Noh1,
  2. Chang Hong Youm1,
  3. Myeounggon Lee1,
  4. Hwayoung Park2,
  5. Minji Son2,
  6. Jinhee Kim2
  1. 1Department of Health Care and Science, College of Health Sciences, Dong-A University, Saha-gu, Busan, South Korea
  2. 2Biomechanics Laboratory, College of Health Sciences, Dong-A University, Saha-gu, Busan, South Korea
  1. Correspondence to Dr Chang Hong Youm; chyoum{at}


Objective The purpose of this study was to determine the effect of fatigue level and sex on the range of motions of the lower extremities and impulses during the jump-landing phase after performing bilateral fatiguing tasks.

Methods In total, 41 healthy young adults volunteered for this study. Participants’ jump-landing trajectories were monitored using nine cameras, and ground reaction forces were measured using a force plate. Participants performed five maximal bilateral countermovement jumps as prefatiguing tasks. The fatiguing tasks consisted of maximal effort contractions of the knee extensor at 60°/s on a dynamometer until task failure, defined as the inability to reach 50% of the peak knee extension torque for three consecutive times. The post-task maximal bilateral jumps were immediately captured after the participants failed the fatiguing task. Participants were asked to perform this cycle again, performing the fatiguing contraction task until failure to reach 30% of the peak knee extension torque.

Results and conclusion It was found that the knee joint was more extended in the post-30% fatiguing task, which was due to the reduction of the flexion angle of the hip and knee joints in response to fatigue level. The impulses for both sexes were reduced at the severe fatigue level. Fatigability altered jump-landing kinematics, jump heights and impulses in response to fatigue level. The post-30% fatiguing task elicited more fatigue than the post-50% fatiguing task.

  • muscle fatigue
  • jump-landing
  • biomechanics
  • injury

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  • Contributors BN, CHY and ML were involved in the conception and design of the study and in the interpretation of data. BN was responsible for initial writing and drafting of the manuscript, which was reviewed by all authors. All authors approved the final version to be submitted.

  • Funding This work was supported by a Dong-A University research fund.

  • Competing interests None declared.

  • Patient and public involvement statement All participants participated voluntarily after reading all the details of the study and participants gave their informed consent.

  • Patient consent for publication Not required.

  • Ethics approval This study was approved by the Dong-A University Institutional Review Board, and was carried out in accordance with the Declaration of Helsinki and the ethical guidelines for human subjects of the Institutional Review Board of Dong-A University. After reading all the details of the study, participants gave their informed consent.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available in a public, open access repository. There are no data in this work. Data are available upon reasonable request. Data may be obtained from a third party and are not publicly available. No data are available. All data relevant to the study are included in the article or uploaded as supplementary information.

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