Document Type
Journal Article
Publication Title
Scientific Reports
Volume
11
Issue
1
PubMed ID
34349146
Publisher
Nature
School
School of Medical and Health Sciences
RAS ID
38899
Funders
Natural Sciences and Engineering Research Council of Canada / University of Calgary Eyes High Doctoral Recruitment Scholarship / Biomedical Engineering Equiptment Grant
Abstract
During locomotion, humans sometimes entrain (i.e. synchronize) their steps to external oscillations: e.g. swaying bridges, tandem walking, bouncy harnesses, vibrating treadmills, exoskeletons. Previous studies have discussed the role of nonlinear oscillators (e.g. central pattern generators) in facilitating entrainment. However, the energetics of such interactions are unknown. Given substantial evidence that humans prioritize economy during locomotion, we tested whether reduced metabolic expenditure is associated with human entrainment to vertical force oscillations, where frequency and amplitude were prescribed via a custom mechatronics system during walking. Although metabolic cost was not significantly reduced during entrainment, individuals expended less energy when the oscillation forces did net positive work on the body and roughly selected phase relationships that maximize positive work. It is possible that individuals use mechanical cues to infer energy cost and inform effective gait strategies. If so, an accurate prediction may rely on the relative stability of interactions with the environment. Our results suggest that entrainment occurs over a wide range of oscillation parameters, though not as a direct priority for minimizing metabolic cost. Instead, entrainment may act to stabilize interactions with the environment, thus increasing predictability for the effective implementation of internal models that guide energy minimization.
DOI
10.1038/s41598-021-95047-x
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Comments
Schroeder, R. T., Croft, J. L., & Bertram, J. E. (2021). Evaluating the energetics of entrainment in a human–machine coupled oscillator system. Scientific Reports, 11, article 15804. https://doi.org/10.1038/s41598-021-95047-x