RESUMEN
OBJECTIVES: Ongoing debates about benefits and risks of barefoot- and minimally-shod running have, to date, revealed no conclusive findings for long-term effects on physical performance. The purpose of this study was to examine the effects of an 8-week transition to minimalist footwear (MFW) on running economy (RE). DESIGN: Randomised controlled trial. METHODS: Thirty-two male, habitually-shod runners were assigned randomly to an 8-week training intervention either in minimalist (=intervention group) or conventional running shoes (=control group). The intervention consisted of a gradual increase in use of the new footwear by 5% of the individual weekly distance. Before and after the intervention, a VO2max test was followed by a submaximal RE test at 70% and 80% of vVO2max in both shoe conditions 7days later. RE was measured at the submaximal tests and expressed as caloric unit cost (kcalkg-1km-1) and oxygen consumption (mlkg-1km-1). RESULTS: RE improved in the intervention group over time compared to the control group with small to moderate effect sizes (ES) in both shoe conditions: Effects on RE (kcalkg-1km-1) in conventional running shoes: ES vVO270%: 0.68 (95% CI: -0.14 to 1.51), ES vVO280%: 0.78 (95% CI: 0-1.56). In minimalist footwear: ES vVO270%: 0.3 (95% CI: -0.54 to 1.14), ES vVO280%: 0.42 (95% CI: -0.41 to 1.25). These effects were not statistically significant (p>0.05). The repeated-measures ANOVA also showed no group by time interactions for all submaximal RE testing conditions (p>0.05). CONCLUSIONS: Although not reaching statistical significance, training in MFW compared to CRS resulted in small to moderate improvements in RE.