The Influence of “Super-Shoes” and Foot Strike Pattern on Metabolic Cost and Joint Mechanics in Competitive Female Runners

Abstract

“Super-shoes” are designed to improve endurance running performance by reducing the metabolic demands of running. While the research on “super-shoes” is still developing and has mostly been studied in male runners, it is not clear how possible mediating factors, such as foot strike pattern, influence the metabolic cost and joint mechanics in competitive female runners. Purpose To assess the influence of “super-shoes” on metabolic cost and joint mechanics in competitive female runners, and to understand how foot strike pattern may influence the footwear effects. Methods Eighteen competitive female runners ran four 5-minute bouts on a force instrumented treadmill at 12.9 km·h-1 in: 1) Nike Vaporfly Next% 2TM (SUPER) and 2) Nike Pegasus 38TM (CON) in a randomized and mirrored order. Results Metabolic power was improved by 4.2% (p < 0.001; d = 0.43) and MTP negative work (p < 0.001; d = 1.22), ankle negative work (p = 0.001; d = 0.67), and ankle positive work (p < 0.001; d = 0.97) were all smaller when running in SUPER compared to CON. There was no correlation between foot strike pattern and the between-shoe (CON to SUPER) percent change for metabolic power (r = 0.093, p = 0.715). Conclusions Metabolic power improved by 4.2% in “super-shoes” (but only by ~3.2% if controlling for shoe mass differences) in this cohort of competitive female runners which is a smaller improvement than previously observed in men. The reduced mechanical demand at the MTP and ankle in “super-shoes” are consistent with previous literature and may explain or contribute to the metabolic improvements observed in “super-shoes”, however foot strike pattern was not a moderating factor for the metabolic improvements of “super-shoes”. Future studies should directly compare the metabolic response among different types of “super-shoes” between men and women.

Can the recent sex-specific evolutions in elite running performances be attributed to advanced footwear technology?

“…Specifically, Barnes and Kilding (37) reported running economy benefits of between 1.7% and 7.2% when highly trained runners used AFT, however differences between males and females were trivial to small across conditions. Most recently, Martinez and colleagues (38) reported metabolic power improvements of 4.2% and running economy improvements of 3.9% when trained female runners ran in AFT compared to control shoes, which is consistent with findings in males (15). Contrary to these initial findings, women have unique running injury profiles (39), specific running biomechanics (40), as well as unique energetics and fatigue dynamics during running when compared to men (41,42).…”

“…Notably, the only studies which have reported female-specific data regarding the influence of AFT on running economy indicate that there is no significant sex-based advantage ( 37 , 38 ). Specifically, Barnes and Kilding ( 37 ) reported running economy benefits of between 1.7% and 7.2% when highly trained runners used AFT, however differences between males and females were trivial to small across conditions.…”