Rearfoot striking is associated with lower modeled ACL loading during overground running: a musculoskeletal modeling study.

BACKGROUND: The purpose of this study was to examine knee ligament forces and conventional kinematic and kinetic variables across forefoot (FFS), midfoot (MFS), and rearfoot (RFS) strikes whilst controlling for running speed. METHODS: Twenty healthy male participants performed overground running at 4.3 ± 0.2 m/s in each of the strikes. Joint kinematics, moments, ground reaction forces (GRFs), and cruciate ligament forces were determined using musculoskeletal modeling. RESULTS: Results indicated that FFS exhibited significantly shorter contact times and smaller knee flexion angles compared to MFS and RFS (p < .05). Furthermore, FFS produced a higher peak vertical GRF than peaks observed in MFS and RFS (p < .05). Notably, ACL loading (both peak force and impulse) was significantly lower in RFS compared to FFS and MFS (p < .05), whereas PCL loading showed no significant differences across patterns. Additionally, vertical GRF demonstrated moderate-to-strong positive correlations with peak forces and impulses of the ACL (r = .558-.845, p < .01), whereas no significant correlations were found for the PCL. CONCLUSION: These findings suggest that the reduced ACL loading in RFS may be linked to its unique GRF profile. Conversely, higher ACL loads associated with FFS were observed under the tested straight-line running condition. Understanding these ligament mechanics could provide valuable insights for future research on injury-prevention strategies and rehabilitation protocols.