Acute responses to local tibialis anterior fatigue: Effects on dynamic balance and muscle mechanical properties.

Abstract

BackgroundLocal muscle fatigue can influence the neural functional mechanisms and intrinsic mechanical properties of the muscle. Considering the importance of the tibialis anterior (TA) muscle during walking and upright standing positions, the primary aim of this study is to understand how induced local muscle fatigue affects both dynamic balance and changes in muscle mechanical properties.MethodsThirty healthy participants (mean age: 21.83 ± 1.41 years) were included in the study. Muscle mechanical properties of the dominant TA were assessed using MyotonPro, and dynamic balance was evaluated bilaterally with the Modified Star Excursion Balance Test (mSEBT) before and after the fatigue protocol. The fatigue protocol was applied bilaterally to ankle dorsiflexor muscle muscles and consisted of repeated 30-s isometric dorsiflexion contractions followed by 15-s rest intervals, continued until participants reported a Borg Rating of Perceived Exertion score of 7 or higher.ResultFollowing the fatigue protocol, a significant improvement was observed in left mSEBT and right mSEBT scores (p < 0.05), except in the anterior direction, where no significant change was detected. Regarding muscle mechanical properties, stiffness decreased, but this change was not statistically significant (p = 0.06), whereas relaxation time and creep significantly increased (p < 0.05).ConclusionLocalized ankle dorsiflexor muscle fatigue acutely altered both dynamic balance and muscle mechanical properties. The apparent improvement in mSEBT scores likely reflects short-term neuromuscular compensation rather than genuine performance enhancement. Decreased stiffness and increased relaxation indicate transient adaptations in the muscle's passive behavior.