Compliant ankle function results in landing-take off asymmetry in legged locomotion.
The spring loaded inverted pendulum (SLIP) model is widely used to predict and explain basic characteristics of human walking and running. Its periodic running solutions can be mirrored at the instant of the vertical orientation of the leg and thus are symmetric between landing and take-off. In contrast, human running shows asymmetries between touchdown and take-off (e.g. shorter brake than push duration, greater mean ground reaction force during braking phase). Yet it is not fully understood whether these asymmetries are caused by asymmetric muscle properties (e.g. velocity-dependent force generation) or the asymmetric lever arm system in the human leg. We extend the SLIP model by a foot segment and a compliant ankle joint. This represents the extended foot contact and the displacement of the center of pressure during contact. With this model we investigate to which extent the landing-take off asymmetry in legged locomotion is caused by this asymmetric lever arm system. We find similar landing-take off asymmetries as in human running suggesting that the asymmetric lever arm system contributes to the asymmetry.
Locomotion Laboratory Magdalenenstr. 27, 64289 Darmstadt, Germany. Electronic address: Maykranz@sport.tu-darmstadt.de.
Daniel
D
Maykranz
Locomotion Laboratory Magdalenenstr. 27, 64289 Darmstadt, Germany. Electronic address: seyfarth@sport.tu-darmstadt.de.
Andre
A
Seyfarth
D000843:Ankle Joint / Q000502:physiology*; D001696:Biomechanical Phenomena; D003187:Compliance; D006801:Humans; D007866:Leg / Q000502:physiology*; D008124:Locomotion / Q000502:physiology*; D008954:Models, Biological; D012420:Running / Q000502:physiology; D055815:Young Adult
Center of pressure; Force–length-relation; Spring loaded inverted pendulum