Runners’ individual learning responses to a biofeedback intervention to reduce tibial acceleration

Increased peak tibial acceleration has been related to tibial stress fractures. Reducing tibial acceleration could, therefore, help prevent injury. With the use of a single-subject analysis, it was aimed to give an insight into which individual gait strategies participants used and how quickly participants responded to a biofeedback intervention aimed to reduce tibial acceleration. First, a literature review was performed to identify gaps in the literature and inform primary research studies. Secondly, different methodological approaches were considered and a feedback system was developed based on exploratory studies focussing on the direct learning response, treadmill speed, target, and verbal instruction. A single-subject design was chosen and the minimal detectable difference was calculated to determine the minimum amount of change which was sufficiently greater than the measurement error and day-to-day variability in order to consider the measured change represented a genuine biomechanical difference. For the group, mean peak tibial acceleration significantly decreased by 26 per cent between the baseline measurements and the one-month follow-ups. Nine out of the eleven participants found a real decrease in mean peak tibial acceleration after a month. Participants needed one to six sessions to automatize running with reduced tibial acceleration. However, they were still able to reduce mean peak tibial acceleration after they automatized running. Further, participants found different shock-absorbing mechanisms comparing measurements taken directly after the intervention to after a month. This suggests participants did not learn a specific solution to be able to reduce tibial acceleration, but were able to switch in between shock-absorbing mechanisms. This programme of research showed the importance of a single-subject analysis in this area of research. Future directions could focus on in-field, individually tailored, gait retraining to improve the outcomes and be able to help reduce the prevalence of tibial stress fractures in runners.