Sex and Isolated Anthropometric Measures Do Not Explain Individual Differences in Responsiveness to Advanced Footwear...

Advanced footwear technology (AFT) has improved running economy in distance runners, yet individual responsiveness varies widely. Sex differences and anthropometric characteristics have been proposed as potential factors, but evidence remains limited. This study investigated whether sex-based differences exist in the response to running in an AFT shoe compared to a non-AFT control shoe. The response was measured by means of the change in energy cost (EC), ΔEC, and it was assessed whether isolated anthropometric characteristics could predict ΔEC in highly trained long-distance runners. Fifteen female and fifteen male runners completed treadmill running economy tests at 60%, 70%, and 80% of their VO_2peak speed in AFT and non-AFT shoes. Anthropometric measures investigated were height, body mass, foot length, femur and tibia length, and Achilles tendon length. Females showed significantly lower absolute EC than males across all speeds and shoe conditions (p < 0.05), but ΔEC did not differ between sexes (p = 0.5). Average individual ΔEC ranged from 1.1% to 6.4% in females and 0.2% to 8.7% in males. No anthropometric variable could significantly predict ΔEC in sex-stratified analyses. Highly trained runners exhibit large inter-individual variability in responsiveness to AFT shoes, but neither sex nor isolated anthropometric traits explained these differences in this study. These findings highlight the complexity of AFT individualization and suggest that personalization should not be based solely on sex or the anthropometric characteristics investigated in this study.