Influence of foot arch height on isokinetic knee muscle strength at varying angular velocities

Background The height of the foot arch is highly related to knee joint function. Knee joint strength is a significant contributing factor to knee joint injuries, while existing research has not yet clearly established the correlation between arch height and knee joint strength. Objective This study aims to investigate the influence of arch height on isokinetic knee muscle strength at varying angular velocities, thereby providing a potential scientific basis for the prevention and rehabilitation of associated conditions. Design Cross-sectional study. Participants Sixty healthy young adults (21, 22) years old were categorized into three groups based on arch classification (10 male and 10 female per group): low arch (LA; height 1.67 ± 0.075 m, weight 65.60 ± 13.11 kg), normal arch (NA; height 1.67 ± 0.084 m, weight 60.20 ± 9.22 kg), and high arch (HA; height 1.69 ± 0.080 m, weight 58.95 ± 6.60 kg). Methods Arch classification was determined via the arch index (AI) using a plantar pressure measurement analyzer. Knee flexor and extensor muscle strength were assessed at slow (60 °/s) and fast (180 °/s) velocities using the ISOMED2000 isokinetic muscle strength testing system. Isokinetic moment curves (IMC) from 10° to 90° were recorded and analyzed statistically. Results At 60 °/s, compared with NA, LA exhibited higher knee extension (55–83°) and flexion (73°–90°) moments, while flexion moments were lower in the 31–58°range ( P < 0.05). In contrast, HA exhibited lower knee extension (20°–66°) and flexion (43°–65°and 74°–86°) moments ( P < 0.05). At 180 °/s, both LA and HA groups had significantly lower knee extension (LA: 26°–90°; HA: 14°–90°) and flexion moments (LA: 10°–80°; HA: 10°–90°) compared with NA ( P < 0.05). Conclusion This study demonstrates that foot arch height is associated with knee muscle strength at varying angular velocities. LA individuals exhibited greater muscle strength in the posterior segments of the knee range at lower velocities, while those with abnormal arch heights (LA and HA) demonstrated weaker knee muscle strength at high velocities. These findings suggest that individuals with abnormal arch heights may benefit from incorporating targeted high-speed knee exercise training to enhance muscle performance and mitigate injury risk in competitive sports.