The Mediating Effect of Running Biomechanics, Anthropometrics, Muscle Architecture, and Comfort on Running Economy Across Different Shoes.

Advancements in shoe technology can improve running economy (RE). However, the effects of advanced footwear technology (AFT) have typically been investigated in one specific shoe brand and at relatively high speeds. Moreover, there is often considerable variability in the response to different running shoes. This study, therefore, investigated the effect of five different shoes (two with AFT, one standard shoe, one traditional racing flat, and participants' own shoes) on RE at a speed representative of recreational runners. Further, it also explored whether spatiotemporal running metrics, anthropometrics, muscle architecture, or comfort mediated the effect of shoes on RE. Forty-one (31 male) recreational runners ran at 10 km∙h^-1 in five different shoes while running biomechanics and gas exchange data were collected. Linear mixed models were used to compare RE across different shoes. Correlations were computed between the difference in RE and (difference in) spatiotemporal running metrics, anthropometrics, muscle architecture, or comfort to explore mediating effects. RE was significantly better in the AFT shoe one compared to other shoes by 2%-4%, with the enhancement relative to the other AFT being non-significant (2%). No spatiotemporal, anthropometric, muscle architectural, or comfort outcome was consistently significantly associated with relative RE. However, a longer contact time, shorter flight time, and higher duty factor showed consistent small-to-moderate non-significant associations with better relative RE. In conclusion, AFT technology can enhance RE at speeds typical for recreational runners, although with variable magnitude across different brands. Further, anthropometrics, spatiotemporal metrics, muscle architecture, nor comfort strongly influenced the effect of shoes on RE.