Connecting the legs with a spring improves human running economy.
J Exp Biol
; 222(Pt 17)2019 09 03.
Article
em En
| MEDLINE
| ID: mdl-31395676
ABSTRACT
Human running is inefficient. For every 10 calories burned, less than 1 is needed to maintain a constant forward velocity - the remaining energy is, in a sense, wasted. The majority of this wasted energy is expended to support the bodyweight and redirect the center of mass during the stance phase of gait. An order of magnitude less energy is expended to brake and accelerate the swinging leg. Accordingly, most devices designed to increase running efficiency have targeted the costlier stance phase of gait. An alternative approach is seen in nature spring-like tissues in some animals and humans are believed to assist leg swing. While it has been assumed that such a spring simply offloads the muscles that swing the legs, thus saving energy, this mechanism has not been experimentally investigated. Here, we show that a spring, or 'exotendon', connecting the legs of a human reduces the energy required for running by 6.4±2.8%, and does so through a complex mechanism that produces savings beyond those associated with leg swing. The exotendon applies assistive forces to the swinging legs, increasing the energy optimal stride frequency. Runners then adopt this frequency, taking faster and shorter strides, and reduce the joint mechanical work to redirect their center of mass. Our study shows how a simple spring improves running economy through a complex interaction between the changing dynamics of the body and the adaptive strategies of the runner, highlighting the importance of considering each when designing systems that couple human and machine.
Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Corrida
/
Marcha
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Perna (Membro)
Tipo de estudo:
Clinical_trials
/
Health_economic_evaluation
Limite:
Adult
/
Female
/
Humans
/
Male
Idioma:
En
Revista:
J Exp Biol
Ano de publicação:
2019
Tipo de documento:
Article
País de afiliação:
Estados Unidos