Biomechanical Efficiency and Metabolic Economy: Vibram Five Fingers Versus Conventional Running Shoes
Minimalist running shoes like Vibram Five Fingers have flooded the market and shoe companies claim that they may improve biomechanical efficiency and metabolic economy when compared with conventional running shoes. PURPOSE: To test claims made by Vibram that running in their Five Finger (VS) shoes improves biomechanical efficiency and metabolic economy when compared to running in conventional shoes (CS). METHODS: Ten trained runners (18-35 yrs) completed a randomized, continuous treadmill running protocol in each footwear type. VO2 measurements were continuously collected during three submaximal stages. Each stage was five minutes in duration (6, 7.5 & 9 mi/hr) with three-minute walking recoveries between each stage in order to ensure steady state VO2. Saggital plane kinematic data were collected at 210 Hz using a highspeed video camera. Kinematic data were analyzed using KA PRO 7 kinematic analysis software. VO2 data from CS and VS shoe conditions were compared using repeated measures ANOVA. Differences between spatiotemporal and kinematic variables across conditions were analyzed using paired t-tests. RESULTS: The metabolic energy consumption (VO2) in VS was lower than in CS at 6 mph (33.3 vs. 33.8 ml•kg-1min-1), 7.5 mph (40.0 vs. 41.2 ml•kg-1min-1), and 9 mph (48.3 vs. 49.6 ml•kg-1min-1) but the results were not significant (p<0.93). Average delta efficiency in the VS condition was slightly higher (14.5%) than that of the CS (14.2%) condition but the difference was not significant (p<0.89). CONCLUSION: Results showed small, non-significant improvements in efficiency and economy in the VS shoe condition when compared with the CS condition. Results showed that only three out of ten subjects transitioned from RFS to non-RFS, and this stability in foot strike across conditions may explain the relatively small magnitude of improvement in efficiency and economy. Two out of three of minimalist-experienced subjects transitioned from RFS to non-RFS but only one out of four minimalist-inexperienced subjects transitioned. These results indicate that barefoot or minimalist training may be more critical than footwear choice in improving efficiency and economy in running.