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Purpose <p>Central fatigue is defined as a progressive exercise-induced failure in the voluntary activation (VA) of the muscle. Muscle afferent III/IV neurons have been previously shown to be major contributors to central fatigue development by detecting increases in intramuscular metabolite accumulation. Yet, during high-intensity interval exercise (HIIE), few studies show consistent evidence of VA failure using the brief interpolated twitch technique (ITT). This study aimed to investigate whether sustained maximal voluntary isometric contractions (MVC) used in VA assessments will reveal pronounced VA failure following HIIE.</p> Methods <p>Ten young, recreationally active individuals (7&#xa0;M; 3 F) performed six sets of 30&#xa0;s all-out dorsiflexion contractions at an isokinetic velocity of 160°/s. Immediately after each HIIE set, VA was assessed during a 60&#xa0;s sustained MVC whereby 100&#xa0;Hz doublet interpolation was performed every 10&#xa0;s (ITT). There was a 2&#xa0;min rest between each HIIE set.</p> Results <p>%VA remained stable near 90% throughout the HIIE. No main effect of time was observed for %VA across the 60&#xa0;s MVCs (<i>p</i> = 0.48). Although a main effect of set was present (<i>p</i> = 0.009), reflecting small overall reductions in %VA across repeated HIIE bouts, post-hoc comparisons revealed no significant differences between baseline and post-set %VA at any time point during the 60&#xa0;s MVCs.</p> Conclusion <p>The human dorsiflexor muscles are exceptionally resilient to impairments in VA during metabolically-demanding HIIE.</p>

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Human dorsiflexor muscles are resilient against voluntary activation failure following high-intensity interval exercise

  • 期刊论文

  • 发表日期：

    2026年3月19日

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  • Alireza Vaziri,
  • Andrew J. Richards,
  • Rohin Malekzadeh,
  • Michael T. Paris,
  • Arthur J. Cheng

摘要

Purpose

Central fatigue is defined as a progressive exercise-induced failure in the voluntary activation (VA) of the muscle. Muscle afferent III/IV neurons have been previously shown to be major contributors to central fatigue development by detecting increases in intramuscular metabolite accumulation. Yet, during high-intensity interval exercise (HIIE), few studies show consistent evidence of VA failure using the brief interpolated twitch technique (ITT). This study aimed to investigate whether sustained maximal voluntary isometric contractions (MVC) used in VA assessments will reveal pronounced VA failure following HIIE.

Methods

Ten young, recreationally active individuals (7 M; 3 F) performed six sets of 30 s all-out dorsiflexion contractions at an isokinetic velocity of 160°/s. Immediately after each HIIE set, VA was assessed during a 60 s sustained MVC whereby 100 Hz doublet interpolation was performed every 10 s (ITT). There was a 2 min rest between each HIIE set.

Results

%VA remained stable near 90% throughout the HIIE. No main effect of time was observed for %VA across the 60 s MVCs (p = 0.48). Although a main effect of set was present (p = 0.009), reflecting small overall reductions in %VA across repeated HIIE bouts, post-hoc comparisons revealed no significant differences between baseline and post-set %VA at any time point during the 60 s MVCs.

Conclusion

The human dorsiflexor muscles are exceptionally resilient to impairments in VA during metabolically-demanding HIIE.