Gait Retraining For Reduction Of Vertical Loading Rate Using Real-time Auditory Feedback Provided By Earphones

Running-related injuries (RRI) are common, with reported incidence and prevalence ranging from 19% to 92% depending on the population studied and the definition of RRI. Among various biomechanical risk factors implicated in RRI, a high level of vertical loading rate has been associated with patellofemoral pain, tibial stress fractures, and plantar fasciitis in runners. Recently, a gait retraining program using real-time visual feedback was found to reduce vertical loading rate as well as lower the risk of RRI in novice runners. PURPOSE: The purpose of this case study was to examine instantaneous vertical loading rate (IVLR) before and after a gait retraining program using real-time auditory feedback provided by earphones. METHODS: Two male novice runners (Runner A with the age of 23 and a body mass index (BMI) of 22.2; Runner B with the age of 26 and BMI of 27.5) were enrolled in this study. The primary outcome was the change in IVLR acquired at two different speeds, 8 km/hour (“slow”) and 12 km/hour (“fast”), after participating in eight sessions over two weeks of gait retraining for landing stiffness modulation. They were instructed to run at comfortable speeds on a treadmill identified during the initial visit. Auditory feedback was provided through the earphones to “run softer” if the IVLR was greater than 70 body weight (BW)/sec. The total running time was set to 15 minutes, with real-time auditory feedback provided at all times during the first four sessions, then progressively removed in the last four sessions. RESULTS: At 8 km/hour, the IVLR of Runner A decreased from 99.9 BW/sec to 32.3 BW/sec while that of Runner B from 63.7 BW/sec to 40.7 BW/sec after 2-week gait retraining. Likewise, at 12 km/hour, the IVLR of Runner A decreased from 113.8 BW/sec to 32.7 BW/sec while that of Runner B went from 98.7 BW/sec to 65.7 BW/sec. CONCLUSIONS: These results demonstrate that 2-week gait retraining using real-time auditory feedback provided by earphones can be useful in decreasing vertical loading rate in both slow and fast paces. These earphones may allow runners to not only reduce but also continue monitoring IVLR in natural training environments and potentially help prevent RRI. This research project was supported by a grant from the SME R&D project for the Start-up & Grow stage company, Ministry of SMEs and Startups (S3033204).