Impulsive ankle push-off powers leg swing in human walking.

نویسندگان

  • Susanne W Lipfert
  • Michael Günther
  • Daniel Renjewski
  • Andre Seyfarth
چکیده

Rapid unloading and a peak in power output of the ankle joint have been widely observed during push-off in human walking. Model-based studies hypothesize that this push-off causes redirection of the body center of mass just before touch-down of the leading leg. Other research suggests that work done by the ankle extensors provides kinetic energy for the initiation of swing. Also, muscle work is suggested to power a catapult-like action in late stance of human walking. However, there is a lack of knowledge about the biomechanical process leading to this widely observed high power output of the ankle extensors. In our study, we use kinematic and dynamic data of human walking collected at speeds between 0.5 and 2.5 m s(-1) for a comprehensive analysis of push-off mechanics. We identify two distinct phases, which divide the push-off: first, starting with positive ankle power output, an alleviation phase, where the trailing leg is alleviated from supporting the body mass, and second, a launching phase, where stored energy in the ankle joint is released. Our results show a release of just a small part of the energy stored in the ankle joint during the alleviation phase. A larger impulse for the trailing leg than for the remaining body is observed during the launching phase. Here, the buckling knee joint inhibits transfer of power from the ankle to the remaining body. It appears that swing initiation profits from an impulsive ankle push-off resulting from a catapult without escapement.

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© 2013. Published by The Company of Biologists Ltd Impulsive ankle push-off powers leg swing in human walking Susanne W. Lipfert, Michael Günther, Daniel Renjewski, Andre Seyfarth Human Motion Engineering, 5021 SW Philomath Blvd, Corvallis, OR, 97333 USA Institut für Sportund Bewegungswissenschaft, Universität Stuttgart, Allmandring 28, D-70569 Stuttgart, Deutschland Institut für Sportwissensch...

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عنوان ژورنال:
  • The Journal of experimental biology

دوره 217 Pt 8  شماره 

صفحات  -

تاریخ انتشار 2014