Why does the metabolic cost of walking increase on compliant substrates?

Grant, Barbara ORCID: 0000-0003-2771-7733, Charles, James ORCID: 0000-0001-8256-8035, Geraghty, Brendan ORCID: 0000-0003-0561-6667, Gardiner, James ORCID: 0000-0003-1902-3416, D'Aout, Kristiaan ORCID: 0000-0002-6043-7744, Falkingham, Peter L and Bates, Karl T ORCID: 0000-0002-0048-141X (2022) Why does the metabolic cost of walking increase on compliant substrates? JOURNAL OF THE ROYAL SOCIETY INTERFACE, 19 (196). 20220483-.

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Official URL: http://dx.doi.org/10.1098/rsif.2022.0483

Abstract

Walking on compliant substrates requires more energy than walking on hard substrates but the biomechanical factors that contribute to this increase are debated. Previous studies suggest various causative mechanical factors, including disruption to pendular energy recovery, increased muscle work, decreased muscle efficiency and increased gait variability. We test each of these hypotheses simultaneously by collecting a large kinematic and kinetic dataset of human walking on foams of differing thickness. This allowed us to systematically characterize changes in gait with substrate compliance, and, by combining data with mechanical substrate testing, drive the very first subject-specific computer simulations of human locomotion on compliant substrates to estimate the internal kinetic demands on the musculoskeletal system. Negative changes to pendular energy exchange or ankle mechanics are not supported by our analyses. Instead we find that the mechanistic causes of increased energetic costs on compliant substrates are more complex than captured by any single previous hypothesis. We present a model in which elevated activity and mechanical work by muscles crossing the hip and knee are required to support the changes in joint (greater excursion and maximum flexion) and spatio-temporal kinematics (longer stride lengths, stride times and stance times, and duty factors) on compliant substrates.

Item Type:	Article
Uncontrolled Keywords:	biomechanics, locomotion, energetics, musculoskeletal model, compliant substrate
Divisions:	Faculty of Health and Life Sciences Faculty of Health and Life Sciences > Institute of Life Courses and Medical Sciences
Depositing User:	Symplectic Admin
Date Deposited:	09 Nov 2022 10:21
Last Modified:	18 Jan 2023 19:43
DOI:	10.1098/rsif.2022.0483
Open Access URL:	https://doi.org/10.1098/rsif.2022.0483
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3166082