Differences In Foot-strike Pattern In Relationship To Changes In Running Velocity

Abstract

Foot-strike patterns employed by runners have major implications on running economy and injury biomechanics. Although previous research has shown that as finish time decreases during a half marathon there is a general trend towards a mid-foot striking pattern and away from a rear-foot striking pattern, few studies have looked at the effect running velocity has on foot strike pattern in a controlled environment. PURPOSE: To quantify how a runner alters their foot-strike pattern across a range of velocities. METHODS: Fourteen recreational runners (23.1 ± 2.46 yr, 1.75 ± 0.08 m, 64.99 ± 9.80 kg) completed two testing sessions. The first session consisted of a timed one-mile run in order to attain maximum sustainable running velocity. On a separate day, subjects ran on an indoor treadmill at 100% - 60% of their maximum speed for two minutes at each 10% increment. A motion capture system (Qualisys, Goetenburg, Sweden), sampling at 240 Hz, was used to identify the participant’s foot-strike angle; and a with-in subjects ANOVA was conducted to determine if a difference was present in foot-strike angle between running velocities. RESULTS: The ANOVA results suggest that there was a significant difference among foot-strike angles (F(4,13)=5.72, p<.01). Further, the effect of velocity accounted for 31% (p2 =0.31) of the change seen in foot-strike angle. A Bonferroni post hoc test revealed a significant difference in foot-strike between the 100% trials and 70% trials (p=.04), as well as between the 90% and 70% trials (p<.01). CONCLUSIONS: The differences between 70% and higher velocity trials (90% and 100%) is attributed to participants shifting from a rear-foot to a mid-foot striking pattern as their velocity increased. However, no difference was seen between the 60% and higher velocity trials. This was attributed to the fact these velocities were slower than participant’s preferred running speed, resulting in an unorthodox gait pattern. Previous research has suggested that this transition in foot-strike pattern is done for runners to reduce the loading rates associated with higher running velocities. A better understanding of foot-strike pattern changes in regards to running velocity is important for training and injury prevention.