Metabolic cost and co-contraction during walking at different speeds in young and old adults

• Published in: Gait & posture Vol. 91; pp. 111 - 116
• Main Authors: Piche, Elodie, Chorin, Frédéric, Zory, Raphaël, Duarte Freitas, Patricia, Guerin, Olivier, Gerus, Pauline
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01.01.2022; Elsevier
• Subjects: Adult; Aged; Ageing; Biomechanical Phenomena; Co-contraction; Electromyography; EMG-driven model; Energy cost; Gait; Gait biomechanics; Humans; Knee; Knee Joint; Life Sciences; Middle Aged; Muscle, Skeletal; Walking; Young Adult; Co-contraction; Energy cost; Ageing; Gait biomechanics; EMG-driven model
• ISSN: 0966-6362; 1879-2219
• DOI: 10.1016/j.gaitpost.2021.10.014

•Metabolic cost of walking was higher in old adults.•Old adults co-contract their muscles around knee joint more compared to young adults.•Muscle co-contraction and metabolic cost were moderately related in older adults.•Co-contraction at the ankle joint was positively correlated with metabolic cost.•Co-contraction at the ankle joint was the main contributor to the metabolic cost. The net metabolic cost of walking (NCw) and the co-activation of leg muscles are both higher in old adults (OG) than in young adults (YG). Nevertheless, the relation between the two remains unresolved, mainly due to the controversial co-activation measurement method used in previous studies. To compare ankle and knee co-contraction (CCI), calculated using an EMG-driven method, between the groups and to examine their relationship with NCw. Nine young (YG = 25.2 +/- 3.3 years old) and nine older (OG = 68.7 +/5.9 years old) adults walked on a treadmill at five speeds (YG: 1; 1.2; 1.4; 1.6; 1.8 m/s; OG: 0.6; 0.8; 1; 1.2; 1.4 m/s) while electromyography (sEMG) and oxygen consumption were measured. CCI were calculated around the ankle and knee for different parts of the gait cycle (entire gait cycle 0–100 %, stance phase 0–60 %, swing phase 60–100 %). NCw was significantly higher (25 %, averaged over the walking speeds) in OG as were Knee_CCI, Knee_CCI_swing and Knee_CCI_stance. Multiple regression models in YG, OG and YG + OG highlighted Ankle_CCI as the main contributor in NCw (β = 0.08−0.188, p < 0.05) with a positive relation between the two variables. The present findings provide a better understanding of the association between muscle co-contraction and metabolic cost in older adults. It may help scientists and clinicians to further develop strategies aimed at neuromuscular rehabilitation as a means of improving mobility and independence among older adults.