The effect of minimalist footwear on running economy following exercise-induced fatigue

Running economy (RE) is the oxygen utilization during a steady state submaximal running bout. The purpose of this study was two-fold: (a) to determine if running in minimalist footwear results in better RE (mL kg⁻¹ km⁻¹) compared to conventional footwear and to identify any relationships between RE and lower limb muscle activation; (b) to determine whether any changes in RE related to minimalist footwear are sustained following exercise-induced fatigue. In a fully randomized, counterbalanced fashion, ten well-trained male distance runners (age 29.0±7.5; BMI 38.6±6.5 kg m⁻²; 2max 61.6±7.3 mL min⁻¹ Kg⁻¹) completed a RE test pre- and post-fatigue on a motorized treadmill in both conditions using identical footwear (minimalist 178g; conventional 349g). The fatiguing protocol consisted of high-intensity interval training (7 X 1000-m at 94-97% VO₂max) on a 200-m, unbanked, Mondo surface, indoor running track. Cardiorespiratory, muscle activation, and kinematic parameters as well as, the rate of perceived exertion and blood lactate were measured throughout the experimental sessions. A significant main effect of footwear on running speed during intervals (p=0.041) was found. Participants ran faster during the minimalist compared to conventional footwear condition (3:24±0:44 vs. 3:30±0:47 (mm:ss), respectively). While fatigue was induced, no other effect of time or footwear on RE, muscle activation or stride frequency occurred. The results of this study suggest that the characteristics of the minimalist footwear did not differ enough from the conventional shoes to induce acute changes in metabolic, kinematic and muscle activation variables during the submaximal runs.