Publications

Background: Local 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.

Methods: Thirty 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.

Result: Following 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).

Conclusion: Localized 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.

Keywords: muscle fatigue, balance, postural control, muscle mechanical properties

In conclusion this study demonstrated that localized fatigue of the ankle dorsiflexor muscles acutely alters both dynamic balance performance and muscle mechanical properties. While postural stability appeared to improve immediately after fatigue, this effect may represents a short-term neuromuscular compensation rather than a genuine enhancement in balance performance. At the mechanical level, fatigue induced a tendency toward decreased stiffness and increased relaxation and creep, indicating a temporary loss of muscle tension and passive integrity. These findings suggest that, despite the apparent maintenance of functional balance, the muscle’s ability to resist external loading and maintain fine motor control may be transiently compromised following fatigue. From a functional perspective, these findings highlight the potential for functional balance tests such as the mSEBT to mask underlying changes in muscle mechanical properties following fatigue. Future studies should further explore the temporal persistence and clinical relevance of these compensatory and mechanical responses in both athletic and rehabilitation populations.