Characteristics of Lower Limb Dominant and Nondominant Joint Load Changes After Long-Distance Running in Young Male Runners Under OpenSim Environment

This study aims to investigate the characteristics of load changes in the hip, knee, and ankle joints of the dominant and non-dominant lower limbs of young male runners after long-distance running. Using the OpenSim public dataset (containing bilateral biomechanical data before and after long-distance running from 20 young male runners), personalized musculoskeletal models were established. Contact forces in three directions at lower limb joints during the running stance phase were calculated. Statistical analysis employed one-dimensional statistical parameter mapping (SPM1d) and two-factor repeated measures ANOVA (time × side). Results revealed significant time × side interaction effects (<i>p</i> < 0.05) for contact forces in the medial-lateral direction at the hip, the anterior-posterior direction at the knee, and all three directions at the ankle. Simple effects analysis showed that post-run medial-lateral hip forces significantly increased during the push-off phase, while anterior-posterior ankle forces significantly increased during the mid-to-late stance phase on both sides (d = 0.718-1.002). For the superior-inferior direction at the hip and knee, only main effects of time or side were present. Post-run joint contact forces significantly increased, with the dominant side consistently exceeding the non-dominant side across multiple stance and push-off phases (d = 0.58-1.6), indicating stable side-to-side differences. These findings indicate that long-distance running not only increases multi-joint loading in the lower limbs but also exacerbates asymmetry between the dominant and non-dominant sides during the initial stance and push-off phases. This redistribution of load, coupled with bilateral control imbalance, may further elevate the risk of injury.