Can biomechanical variables and asymmetry predict bone stress injuries in collegiate distance runners?

Runners are susceptible to bone stress injuries (BSI), due in part to cumulative loading, which is affected by force magnitude and frequency. We identified biomechanical variables that may predict BSI incidence by following 30 collegiate distance runners over three years. Athletes were classified as either uninjured (<i>n</i> = 8 male, 16 female) or injured (<i>n</i> = 3 male, 3 female) if they sustained a BSI. We measured ground reaction forces while athletes ran on a force-instrumented treadmill, and analysed step frequency (<i>f</i>_step), contact length (<i>L</i>_c), and bodyweight-normalised stance average vertical ground reaction force (<i>F</i>_avg) alongside asymmetry (expressed as symmetry index, SI). A secondary analysis examined inter-limb biomechanical changes in six runners prior to sustaining a BSI. We found an interaction between injury status, sex, and speed on <i>F</i>_avg values (<i>p</i> = 0.026). Forty-seven weeks prior to injury, <i>F</i>_avg values were greater in the unaffected leg than the affected leg (<i>p</i> = 0.022). In addition, female injured runners exhibited 1.62 percentage points greater <i>f</i>_step SI than uninjured females at 4.9 m/s (<i>p</i> = 0.030). Future research that incorporates more frequent data collection is needed to integrate biomechanical variables and physiological risk factors for injury prediction and prevention among collegiate distance runners.