Lower Limb Muscle, Patellofemoral, And Tibial Compressive Forces Before And After A 5 km Run

Prolonged running may influence the risk of overuse injuries. Tibial loading is reduced while patellofemoral loading is increased following a 10 km run in high-level runners possibly due to decreased plantarflexor and increased quadriceps forces. Previous studies have not accounted for foot strike pattern variations which affect lower limb loading patterns. The effects of prolonged running on musculoskeletal loading for specific foot strike patterns (e.g., rearfoot strike) may provide insight into injury risk or rehabilitation programs in this group. PURPOSE: To investigate how a 5 km run influences lower limb muscle, patellofemoral, and tibial compressive forces in rearfoot strike runners. METHODS: An online published dataset of 20 male recreational rearfoot runners (average 30 km/week) was used. Runners completed a 5 K treadmill run at 80% of their maximum speed. Kinematic and kinetic data were collected during overground running, both before and after 5 K run. Patellofemoral compressive force (PCF), tibial compressive force (TCF), and lower limb muscle group forces (quadriceps, hamstrings, plantarflexors, and dorsiflexors) during the stance phase were calculated using a customized Matlab-OpenSim API. Paired t-tests were performed to compare aforementioned variables between pre and post 5 K run, and Cohen’s d effect sizes were calculated. RESULTS: The 5 K run led to increases in TCF but no changes in PCF (Table 1). The increase in TCF seems to be driven by a large increase in plantarflexor muscle force contribution despite a small reduction in dorsiflexor forces (Table 1). CONCLUSION: A 5 km run increases tibial compressive force but does not influence patellofemoral compressive force in recreational male runners. Thus, knee or tibial loading may be influenced differently by prolonged running at slightly below maximal running speeds. These findings may have implications for return-to-run programs depending on injury sites.