Effects of metatarsal bar and heel lift on foot biomechanics during gait: implications for performance-related biomechanics.

[Purpose] This study investigated the biomechanical effects of metatarsal bars (MTB) and heel lifts (HL) on lower-limb kinematics and kinetics during gait. [Participants and Methods] Twenty healthy adults underwent three-dimensional gait analysis. Ankle dorsiflexion angle, internal plantarflexion moment, medial longitudinal arch (MLA) height, and gravity movement (GM) were evaluated at 0%, 12%, 31%, and 50% of the walking cycle (WC) and at peak stance. Data were analyzed using two-way repeated-measures ANOVA (condition × WC), followed by Holm-adjusted post-hoc comparisons. [Results] Compared with HL, MTB significantly increased ankle dorsiflexion and decreased MLA height at 31% and 50% WC. Conversely, HL significantly reduced the plantarflexion moment at 12% WC but increased it at 50% WC and peak stance. No significant differences were found in GM, though MTB tended to shift GM posteriorly and HL anteriorly during the latter half of the stance phase. [Conclusion] MTB and HL exhibit distinct phase-specific biomechanical strategies. MTB increases dorsiflexion and reduces MLA height during mid-to-late stance (31-50% WC), suggesting a shock absorption-oriented strategy. In contrast, HL modulates plantarflexion moments to facilitate forward progression. These findings emphasize selecting orthotic components based on specific biomechanical demands at different gait phases.