Differences In Reactive Strength Index Across Time After Wearing Minimalist Footwear

Transitioning from rigid, cushioned footwear to minimalist shoes can induce significant adaptations in the foot and lower leg musculature, potentially creating differences in athletic performance. Reactive strength index (RSI) is commonly used to evaluate performance in athletic movements such as hopping. PURPOSE: To evaluate the impact of minimalist footwear habituation on hopping performance. METHODS: 14 participants were fitted with minimalist footwear to wear for 8 weeks. To obtain RSI (Jump Height/Contact Time), hopping trials were conducted at day 0, day 7, day 14, day 28, and day 56, while wearing the minimalist shoes they were provided. A linear mixed effects model was fitted to account for participants variability, with RSI as the outcome variable, visit as the fixed effect, and participant as the random effect. RESULTS: Results revealed that the participants’ RSI values were significantly lower during their last visit compared to the baseline visit performance (p < .01). There was no significance between the first visit and any of the other visits, but the 3rd and 4th visit also showed a negative trend. CONCLUSION: Foot musculature adaptations to wearing minimalist footwear for 8 weeks could explain the RSI differences. The habituation period may have disrupted the participants’ foot musculature, increasing the medio-longitudinal arch’s ability to dissipate loads. A decrease in the rigidity in the foot could account for the decrease in performance shown in the results. Future studies will investigate whether these effects are exaggerated when analyzing a participant wearing the shoes for a longer period of time.