Human-in-the-loop optimized rocker profile of running shoes to enhance ankle work and running economy

Increasing the efficiency at which muscles generate mechanical power could improve running economy. A potential way to reduce muscle fiber shortening velocities and enhance energy storing of the Triceps Surae is changing their gear ratio at the ankle via optimization of shoe rollover profile. The aim of the current study was to individually optimize rollover profile of rocker shoes via human-in-the-loop optimization to maximize positive ankle work to redistribute joint work from the hip and knee to the ankle and improve running economy. A total of 10 runners ran on a treadmill with experimental rocker shoes in which apex position and angle were optimized using an evolution algorithm to maximize positive ankle work. We compared experimental shoes with optimal settings, standard settings, and control shoes in terms of biomechanics and running economy. Optimal apex parameters differed considerably between participants. The optimal condition resulted in higher positive ankle work and a higher proportional share of the ankle in the total positive lower limb work compared to the standard condition. A difference in running economy between these conditions was not found. Human-in-the-loop optimization can redistribute joint work from the hip and knee to the ankle by individually optimizing apex parameters. Although this did not improve running economy, the study showed that human-in-the-loop optimization could improve the effectiveness of footwear with respect to the selected optimization parameter on an individual level. Human-in-the-loop optimization is able to individually optimize apex position and apex angle of running shoes to enhance ankle work The increase in positive ankle work results in a redistribution of positive work generated around the lower limb joints from the hip and knee to the ankle The increase ankle work did not result in an increased running economy and therefore it should be further investigated which factors confound the theoretical benefit