(4) EFFECTS OF MINIMALIST FOOTWEAR ON ANAEROBIC TESTING METRICS OF COLLEGIATE LACROSSE, ICE HOCKEY, AND VOLLEYBALL ATHLETES

Purpose: Minimalist footwear (MFW) is defined by thin and flexible shoes that allow for natural foot mechanics, such as toe splay, to occur. Much of the literature on the topic of MFW has focused on aerobic outcomes. The influence of MFW on aerobic outcomes is attributed to an increased strength of the intrinsic and extrinsic musculature of the foot, which improves running economy by reducing the average stride length and ground contact time. The present research focuses on anaerobic testing metrics commonly used in sports. The purpose was to compare the effects of MFW to conventional running shoes (RS) in terms of stability, change of direction, peak force, and time to peak force. Methods: Five club sports teams were recruited to participate (n_total = 59). These teams included: men’s lacrosse (n = 18), men’s ice hockey (n = 19), women’s ice hockey (n = 9), men’s volleyball (n = 9), and women’s beach volleyball (n = 4). A randomized cross-over design was used with the intervention condition implementing the HFS model of minimalist footwear (Xero Shoes, Broomfield, CO), and the control condition being standard running shoes with at least 4mm of heel-to-toe drop. The testing sessions were spaced out by one week. Each testing session consisted of a standardized warm-up, a Biodex stability assessment (BA), a pro agility test (PA), a modified T-test (MT), a vertical jump (VJ), and an explosive deadlift (DL) that was loaded with 1.0 times bodyweight for males and 0.8 times bodyweight for females. Statistical analysis was done using JASP. A paired samples T-test was used to compare the differences between the conditions. Effect size was determined by Cohen’s d for all normally distributed data and matched rank biserial correlation for any data that was not normally distributed. Results: For the BA assessment, different metrics were significant for each team and all the effect sizes were trivial, thus no clear pattern emerged. For the PA, the men’s hockey team did better on the first trial in RS (p = 0.028; ES = 0.547). Although, women’s hockey and men’s volleyball performed better in MFW (p = 0.033, ES = 0.858; p = 0.011, ES = 1.088), on the second trial and first trial respectively. For the MT, men’s hockey performed better in MFW on the first and second trials (p = 0.014, ES = 0.626; p < 0.001, ES = 1.194), respectively and women’s hockey performed better in MFW on the second trial (p = 0.021, ES = 0.960). For the VJ, MFW produced more force for 16/24 variables and had a quicker time to peak force in 14/24 variables. For the DL, MFW produced more force for 21/24 variables and had a quicker time to peak force for 22/24 variables. However, most of the variables for the VJ and DL were not significant. Conclusions: The present research indicates that wearing MFW acutely may provide no advantage to stability. Minimalist footwear may provide acute benefits to change of direction ability, improve time to peak force, and improve maximal force production. While many of the results were non-significant, there were some clear trends that emerged that may have practical meaningfulness. Practical Applications: In general, MFW may provide a slight advantage in terms of change of direction, time to peak force, and maximal force production, with no apparent advantage in stability. The effects of MFW were realized acutely, as no longitudinal intervention was used. strong>Acknowledgements: Minimalist footwear provided by Xero Shoes.