Ground reaction force differences between running shoes, racing flats, and distance spikes in runners.

Various shoes are worn by distance runners throughout a training season. This study measured the differences in ground reaction forces between running shoes, racing flats, and distance spikes in order to provide information about the potential effects of footwear on injury risk in highly competitive runners. Ten male and ten female intercollegiate distance runners ran across a force plate at 6.7 m·s(-1) (for males) and 5.7 m·s(-1) (for females) in each of the three types of shoes. To control for differences in foot strike, only subjects who exhibited a heel strike were included in the data analysis. Two repeated-measures ANOVAs with Tukey's post-hoc tests (p < 0.05) were used to detect differences in shoe types among males and females. For the males, loading rate, peak vertical impact force and peak braking forces were significantly greater in flats and spikes compared to running shoes. Vertical stiffness in spikes was also significantly greater than in running shoes. Females had significantly shorter stance times and greater maximum propulsion forces in racing flats compared to running shoes. Changing footwear between the shoes used in this study alters the loads placed on the body. Care should be taken as athletes enter different phases of training where different footwear is required. Injury risk may be increased since the body may not be accustomed to the differences in force, stance time, and vertical stiffness. Key pointsTo determine the differences in ground reaction forces between regular running shoes and competitive footwear, force plate data was obtained from 10 males (6.7 m·s(-1)) and 10 females (5.7 m·s(-1)) for each of three shoe types.Data from men and women were analyzed in two separate groups, and significant differences were found for various GRF components between the three types of shoes.The significant increases in GRF components in competitive footwear suggest that the body must deal with greater impact forces in these shoes than in running shoes at the same running speed.The results from this study warrant the recommendation that runners transition gradually from periods when most or all of their training is done in running shoes to more competitive seasons when more of their training is done in racing flats and spikes.