Neuromuscular changes for hopping on a range of damped surfaces


Humans hopping and running on elastic and damped surfaces maintain similar center-of-mass dynamics by adjusting stance leg mechanics. We tested the hypothesis that the leg transitions from acting like an energy-conserving spring on elastic surfaces to a power-producing actuator on damped surfaces during hopping due to changes in ankle mechanics. To test this hypothesis, we collected surface electromyography, video kinematics, and ground reaction force while eight male subjects (body mass: 76.2 +/- 1.7 kg) hopped in place on a range of damped surfaces. On the most damped surface, most of the mechanical work done by the leg appeared at the ankle (52%), whereas 23 and 25% appeared at the knee and hip, respectively. Hoppers extended all three joints during takeoff further than they flexed during landing and thereby did more net positive work on more heavily damped surfaces. Also, all three joints reached peak flexion sooner after touchdown on more heavily damped surfaces. Consequently, peak moment occurred during joint extension rather than at peak flexion as on elastic surfaces. These strategies caused the positive work during extension to exceed the negative work during flexion to a greater extent on more heavily damped surfaces. At the muscle level, surface EMG increased by 50-440% in ankle and knee extensors as surface damping increased to compensate for greater surface energy dissipation. Our findings, and those of previous studies of hopping on elastic surfaces, show that the ankle joint is the key determinant of both springlike and actuator-like leg mechanics during hopping in place.

Autor: Moritz CT, Greene SM, Farley CT

Organisation: Locomotion Laboratory, Department of Integrative Physiology, University of Colorado, Boulder, CO 80309-0354, USA.

Jahr: 2004

GID: 102

Erstellt am: 01.12.2007

Das Urteil unserer Kunden: Hervorragend


4,7 von 5 Sternen basierend auf 868 Bewertungen

TÜV zertifiziert

Wir sind vom TÜV zertifizierter Hersteller für Medizinprodukte.

Made in Germany

Die Entwicklung und Herstellung findet nur in Deutschland statt.

Bewährte Qualität

10 Jahre Servicegarantie & mehr als 35 Jahre Erfahrung im Firmenverbund.


Über 2000 wissenschaftliche Publikationen zu unseren Produkten.

Weltweit Tätig

Mit unseren Vertriebspartnern international tätig.

Fangen Sie an zu tippen, um die gesuchten Beiträge zu sehen.