Effects of a 10-week footstrike transition programme on tibial stress fracture probability; a randomized controlled intervention using finite element and probabilistic modelling

Abstract

Introduction: The aim of this study was to undertake a randomized control trial examining the effects of a 10-week footstrike transition program on tibial stress fracture risk compared to control. Material and methods: Twenty habitual rearfoot strike runners were randomly assigned to either footstrike or control groups. The footstrike group undertook a graduated 10-week program which allowed them to convert their habitual rearfoot strike pattern, whereas the control group maintained normal training regime without any alterations to their strike pattern. Running biomechanics were collected using an eight-camera motion capture system and ground reaction forces using a force plate. Tibial strains were quantified using finite element modelling and stress fracture probability calculated via probabilistic modelling over 100 days of running. The primary outcome tibial stress fracture probability, and secondary outcomes running biomechanics, muscle forces, joint contact forces, and tibial strain indices; were measured at baseline and 10-weeks. Results: Intention-to-treat analyses revealed no significant alterations in the primary outcome (Footstrike: baseline = 12.82% & 10-weeks = 10.82%, Control: baseline = 15.43% & 10-weeks = 13.39%) between arms. However, alterations in the strike index (Footstrike: baseline = 21.79% & 10-weeks = 65.74%, Control: baseline = 13.61% & 10-weeks = 12.41%) and the loading rate (Footstrike: baseline = 165.85BW/s & 10-weeks = 100.01 BW/s, Control: baseline = 170.13 BW/s & 10-weeks = 197.87 BW/s) were significantly greater in the footstike group compared to control. Conclusion: This trial concludes that the footstrike intervention adopted in this study was not effective in mediating improvements tibial stress fracture risk, although future intervention trials could examine the efficacy of footstrike modification on other musculoskeletal injuries in runners.