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BACKGROUND: Flatfoot, characterized by a reduced medial longitudinal arch, alters lower-limb biomechanics and affects vertical ground reaction force (vGRF) during dynamic tasks like jumping. Kinesio taping (KT) is often used to support foot posture; however, its efficacy under high-load conditions-such as jumping, which increases arch stress, and fatigue, which reduces muscular support-remains unclear. METHODS: This double-blind randomized controlled trial included 46 physically active females with flexible flat feet (arch height ratio < 0.221), assigned to KT or sham groups. Participants performed countermovement jumps (CMJs) under fresh and fatigued conditions, with and without taping. Fatigue was induced via lateral hopping, and KT was applied to the foot arches and tibialis posterior. vGRF variables were assessed across all conditions and categorized into three functional domains: propulsion (eccentric and concentric peak force and power, amortization time and force, concentric rate of force development, and eccentric stiffness); flight (jump height and reactive strength index); and landing (landing stiffness and rate of force development). Navicular drop was also measured only under pre-fatigue conditions. RESULTS: Significant main effects of group, taping condition, and their interaction were observed for navicular drop, all with large effect sizes. KT reduced arch collapse by 17.8%, compared to 0.9% in the sham group. No significant effects of group or taping were found for vGRF variables. In contrast, fatigue significantly reduced jump height and increased force- and stiffness-related metrics across both groups (Benjamini-Hochberg adjusted p < 0.05), all with large effect sizes. CONCLUSIONS: KT applied to the foot arches and tibialis posterior had no effect on dynamic performance, and the static improvement did not reach clinical significance. In contrast, fatigue significantly reduced jump height and increased force- and stiffness-related parameters across both KT and sham groups, likely reflecting compensatory neuromechanical strategies in individuals with flexible flat feet. No taping effect was observed during CMJs performed under both non-fatigued and fatigued conditions. These findings suggest that KT offers limited functional benefit during dynamic tasks in this population. Future studies should investigate alternative taping techniques or adjunctive interventions that more effectively support performance under high-load or fatigued states in individuals with flexible flat feet. TRIAL REGISTRATION: https://irct.behdasht.gov.ir , IRCT20201128049511N4, registered on 11/28/2022.
Nickpey et al. (Mon,) studied this question.