Human running energetics: can ecological preferences inform assistive device design?

Jessica Selinger

Queen’s University, Canada

Humans have long been thought to have a unique and advantageous trait during running—the ability to consume a near-constant amount of energy per distance traveled, regardless of speed. It has been hypothesized that this allows speed to be adapted to particular task demands, with minimal energetic consequence. For example, in persistence hunting humans could select speeds to be least economical for their prey. However, recent work, by our group and others, has called this thinking into question. In this talk, I will first discuss how we combined free-living wearable data from thousands of recreational runners with experimental data to show that a runner’s preferred speed is largely unaffected by the distance they run and is consistent with the speed that minimizes the cost of transport (energy consumed per unit distance). Next, I will provide an example of how, even in the case of simple assistive device (a spring to assist swing), an understanding of energy optimal gait preferences can explain complex and unexpected interactions between the changing dynamics of the body and the adaptive strategies of the runner. Finally, I will end my talk by discussing gaps in our current understanding of running energetics, such as how or if training and fatigue can alter energy optimal preferences, and over what timescale.