LANDING PATTERN AND VERTICAL LOADING RATES DURING SHOD AND BAREFOOT RUNNING IN HABITUAL SHOD RUNNERS

Abstract

There is evidence to support that habitual barefoot runners are able to disperse impact loading rates by landing pattern modification. However, case studies have been reported that barefoot running may cause stress fractures. It may be due to the immediate biomechanical response difference between habitual and novice barefoot runners. Therefore, purpose of this study was to examine the immediate effects of barefoot running in habitual shod runners. Thirty habitual shod runners were asked to run on an instrumented treadmill at 10km/hr in shod and barefoot. Vertical average (VALR) and instantaneous loading rates (VILR) were obtained by previously established methods. The landing pattern was presented as a ratio between number of footfall with heel-strike and the total step number. Twenty out of 30 participants demonstrated an automatic transition to a non-heel-strike landing. A mixed landing pattern was observed in 10 participants. Compared to shod running, both VALR and VILR significantly reduced during barefoot running (p<0.021). In the subgroup analysis, VALR for the shod condition was significantly higher than barefoot running, regardless of the state in the landing pattern transition. Furthermore, VALR for the non-heel-strike pattern during barefoot running was significantly lower than the condition of barefoot running with mixed landing pattern (mean difference=4.3; 95%CI 0.2-8.5). We observed the similar but marginal insignificant effect of footwear condition on VILR (p=0.066). Habitual shod runners presented lower loading rates during impact but their landing pattern transitions were not uniform. A kinetic evaluation after a transition program is thus recommended.