The stability of step rate throughout a 3200 meter run

Step rate has been studied in controlled laboratory settings due to its association with biomechanical parameters related to running injuries. However, the stability of step rate in a run over ground when speed is not controlled remains unclear. In this observational cohort study, 30 subjects were asked to run 3200 meters (m) over ground at their self-selected pace during an Army Physical Fitness Test. Stationary cameras were placed along the paved course to capture step rate at 800 m, 1200 m, 1800 m, and 2200 m. For analysis of step rate at four different time points, a repeated measures analysis of variance (ANOVA) with a Bonferroni-Holm correction was utilized to determine statistical difference with a significance level set at p < 0.05 (95% confidence intervals). There was a statistically significant (p = 0.04) difference between step rate at two different time points; however, the mean group difference in step rate was approximately 1-2 steps per minute, which is not likely clinically meaningful. There was no difference in average weekly miles trained or performance time in those who demonstrated a change in step rate versus those who maintained a steady step rate. Clinicians and researchers may be able to expect step rate to be consistent from 800 m-2200 m during a 3200 m timed run regardless of the runner's training mileage or performance time. This may be valuable for observing over ground running characteristics when the full course of a run cannot be viewed as it could within a laboratory setting.