Reliability and fatigue characteristics of a standing hip isometric endurance protocol

Jessica A. Mutchler, Joshua T. Weinhandl, Matthew C. Hoch, Bonnie L. Van Lunen

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Muscle fatigue is a common consideration when evaluating and rehabilitating athletic injuries. The presence of muscular fatigue has been previously determined by quantifying median frequency (MF) through a power spectral analysis on EMG signals collected throughout an endurance task. Research has not yet determined if a prolonged isometric test in a standing position generates muscular fatigue of the hip. The purpose of this study was to determine the reliability and fatigue characteristics of a standing hip isometric endurance test. Twenty healthy participants completed one 60-s Maximum Voluntary Isometric Contraction of standing hip flexion, extension, adduction, and abduction. MF of the participants' dominant limb rectus femoris (RF), biceps femoris (BF), gluteus maximus (GMax), gluteus medius (GMed) and adductor longus (ADD) was determined via surface electromyography during two sessions, 30-min apart. Reliability values (ICC2,1) were moderate-to-excellent for all time intervals of each action (FlexionRF: >0.80; ExtensionBF: >0.89; ExtensionGMax: >0.60; AdductionADD: >0.78; AbductionGMed: >0.60) and MF significantly decreased over time for all actions. Results suggest the endurance test is a reliable technique to generate muscular fatigue for hip flexion, extension, adduction and abduction. It can be used as a time efficient fatigue protocol specific to the RF, BF, GMax, ADD and GMed.

Original languageEnglish
Pages (from-to)667-674
Number of pages8
JournalJournal of Electromyography and Kinesiology
Issue number4
StatePublished - Aug 1 2015

Bibliographical note

Funding Information:
The reliability of the MF values was supported by the results of the repeated measures ANOVA with no interactions found. Although a statistically significant difference was found between sessions one and two for Extension GMax , Adduction ADD and Abduction GMed , the mean difference was only −1.49 Hz (standard error (SE) = 0.5 Hz, 95% CI = −2.53 Hz to −0.44 Hz) for Extension GMax , −1.58 Hz (SE = 0.61 Hz, 95% CI = −2.85 Hz to −0.309 Hz) for Adduction ADD and −2.42 Hz (SE = 1.04 Hz, 95% CI = −4.6 Hz to −0.24 Hz) for Abduction GMed , with small-to-moderate effect sizes of 0.319, 0.263 and 0.186. Furthermore, the lack of significant differences in normalized torque between sessions lends support to the repeatability of the fatigue characteristics of the current protocol.

Publisher Copyright:
© 2015 Elsevier Ltd.

Copyright 2016 Elsevier B.V., All rights reserved.


  • Electromyography
  • Fatigue
  • Median frequency

ASJC Scopus subject areas

  • Neuroscience (miscellaneous)
  • Biophysics
  • Clinical Neurology


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