AUTHOR=Pimentel Richard E. , Feldman Jordan N. , Lewek Michael D. , Franz Jason R. 

TITLE=Quantifying mechanical and metabolic interdependence between speed and propulsive force during walking

JOURNAL=Frontiers in Sports and Active Living

VOLUME=Volume 4 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/sports-and-active-living/articles/10.3389/fspor.2022.942498

DOI=10.3389/fspor.2022.942498

ISSN=2624-9367

ABSTRACT=Walking speed is a useful surrogate for health status across the population. Walking speed appears to be governed in part by interlimb coordination between propulsive (FP) and braking (FB) forces generated during step-to-step transitions and is simultaneously optimized to minimize metabolic cost. Of those forces, FP generated during push-off has received more significant attention as a contributor to walking performance. Our goal was to first establish empirical cause-effect relations between FP and walking speed and then to quantify their effects on metabolic cost in young adults. To specifically address the interdependence between these factors, we used a self-paced treadmill controller and real-time biofeedback to independently prescribe walking speed or FP across a range of condition intensities.  Walking with larger and smaller FP led to instinctively faster and slower walking speeds, respectively, with about 80% of variance explained between those outcomes. We also found that comparable changes in either FP or walking speed elicited predictable and relatively uniform changes in metabolic cost, each explaining about ~53% of the variance in net metabolic power and ~15% of the variance in cost of transport, respectively. These results provide empirical data in support of a cause-effect relation between FP and walking speed. Our findings build confidence that interventions designed to increase FP will translate to improved walking speed. Repeating this protocol in other populations may identify other relations that could inform the time course of gait decline due to age and disease.