Ambulatory Monitoring of Injury Risk in Runners: The Effect of Sampling Frequency on Peak Tibial Acceleration and Impulse

Approximately 40% of runners experience a running-related injury (RRI) each year. RRIs predominantly affect the lower extremities, and are often attributed to the repeated impacts that occur while running. Peak tibial acceleration (PTA) has been used as an indirect measure of these impacts experienced during running, and has been linked to RRIs in the lower extremities. Widespread ambulatory monitoring of runners using reliable measurements of impacts could enhance our understanding of RRIs. However, previous research suggests that PTA might be sensitive to factors such as the sampling frequency of the measurement device. The impulse has been suggested as a more reliable, alternative measure. In the current study, we evaluated the effect of sampling frequency on the determined PTA and impulse values using data collected from a high-rate, custom inertial measurement unit (IMU) placed on the tibia of one runner. The results suggested that both PTA and impulse are underestimated at lower sampling frequencies, with impulse being less affected by sampling frequency than PTA. Furthermore, both PTA and impulse showed an increase in underestimation for higher running speeds. These findings underscore the need for additional research to ensure accurate interpretation of ambulatory movement data, thereby potentially enabling a more comprehensive understanding of RRIs.