Fatigue-induced changes in static and dynamic balance control in athletes with chronic ankle instability: a systematic review.

BACKGROUND: Impaired balance control is considered as a key determinant of chronic ankle instability (CAI). Fatigue can exacerbate sensorimotor deficits in athletes with CAI. However, the effects of fatigue on static and dynamic balance control in athletes with CAI remain unclear. This systematic review aimed to synthesize the existing evidence regarding the effects of fatigue on static and dynamic balance control in athletes with CAI. METHODS: This review included experimental, quasi-experimental, and observational studies. PubMed, Scopus, Web of Science, the Cochrane Library, and Google Scholar were searched from their inception to November 2025. Methodological quality was independently assessed by two reviewers using the Mixed Methods Appraisal Tool (MMAT). Keywords such as "fatigue," "chronic ankle instability," and "balance control," along with their related terms, were used in the search strategy. Findings were synthesized qualitatively. RESULTS: Nine studies with high methodological quality (mean score: 4.11/5) were included in this review. Dynamic balance was assessed using the Star Excursion Balance Test (SEBT) in three studies, the modified SEBT in one study, the Y-Balance Test in three studies, and the unilateral landing tasks on a force platform in two studies. Static balance was assessed using the Romberg test in one study and the single-leg standing tasks on a force platform in two studies. This review consistently demonstrated the deleterious effects of different fatigue protocols on static and dynamic balance control in athletes with CAI, except for one study that the results showed no significant effect of fatigue on dynamic balance control. Moreover, two studies reported significantly poorer SEBT performance following fatigue in athletes with CAI compared to healthy controls. CONCLUSION: The findings suggest that fatigue can adversely affect both static and dynamic balance control in athletes with CAI. However, the extent to which CAI increases susceptibility to fatigue-related balance impairments remains unclear. Future research employing sport-specific fatigue protocols and sensitive balance measures while accounting for relevant participant characteristics may help clarify the effects of fatigue on balance performance in athletes with CAI and inform more targeted rehabilitation and injury-prevention strategies.