The effect of fatigue on kinetic and kinematic variables in individuals with flexible flatfoot during gait: a systematic review and meta-analysis.

backgroundFlexible flatfoot is a prevalent musculoskeletal deformity characterized by partial or complete loss of the medial longitudinal arch. It can modify lower-limb kinematic and kinetic parameters during walking. Fatigue may further impair gait patterns, potentially aggravating the deformity and increasing injury susceptibility. However, despite substantial research on fatigue and flatfoot separately, integrative evidence on fatigue-related gait biomechanics in individuals with flexible flatfoot remains limited.

methodsThis study was conducted as a systematic review and meta-analysis following PRISMA guidelines. A comprehensive literature search was conducted from January 2000 to August 2025 in databases including PubMed, Scopus, Web of Science, and Embase. The methodological quality of the included studies was assessed using the Newcastle-Ottawa checklist, and data extraction was independently performed by two reviewers. Statistical analyses were carried out using RevMan software version 5.4.1, and the I² test was used to assess data heterogeneity.

resultsA total of 14 studies were included. Meta-analysis results showed that fatigue had a significant effect on certain kinematic variables in individuals with flexible flatfoot. "Regarding kinematic outcomes, pooled analyses revealed that fatigue significantly affected several lower-limb joint angles. Specifically, significant reductions were observed in knee external rotation (SMD = - 0.79, 95% CI: -1.50 to - 0.08; p = 0.03) and ankle dorsiflexion (SMD = - 0.60, 95% CI: -0.97 to - 0.22; p = 0.002), while a borderline significant decrease was noted for knee internal rotation (SMD = - 0.48, 95% CI: -0.96 to - 0.00; p = 0.05). In contrast, changes in ankle inversion, ankle eversion, hip external rotation, and hip internal rotation were not statistically significant (p > 0.05). When all kinematic outcomes were pooled, fatigue was associated with an overall significant reduction in joint angles (SMD = - 0.40, 95% CI: -0.64 to - 0.17; p = 0.0008), with moderate heterogeneity across studies (I² = 44%). In contrast, The Meta-analysis of kinetic variables such as center of pressure (MD = 0.97, 95% CI: -0.92 to 2.87; p = 0.31; I² = 0%), peak pressure (MD = 1.19, 95% CI: -6.81 to 9.20; p = 0.77) and Peak force (MD = 0.07, 95% CI: -0.68 to 0.83; p = 0.85) showed no statistically significant differences before and after fatigue. However, some single studies reported significant changes in plantar pressure, joint moments, and ground reaction forces.

conclusionIn conclusion, fatigue appears to significantly disrupt gait kinematics in individuals with flexible flatfoot, potentially compromising postural stability and increasing the risk of musculoskeletal injury. While kinetic parameters remained largely unaffected in the meta-analysis, the findings underscore the importance of implementing targeted corrective interventions to mitigate the functional consequences of fatigue in this population.