Is elastic energy storage of quantitative relevance for the functional morphology of the human locomotor apparatus?
Elastic storage of energy in the vertebrate locomotor apparatus is supposed to be an important functional factor in cyclic and acyclic movements. In terms of physics, for humans a proof for the occurrence and quantitative relevance of this phenomenon in vivo and under physiological conditions has been missing until now. In addition to the large amount of plausible, but inconclusive information about elasticity in humans and animals, we describe a simple experiment to prove the existence of quantitatively relevant elastic energy storage in the human locomotor apparatus. Ten volunteers (5 female, 5 male) each assumed a relaxed, upright posture on a steel platform. After the release of a support, the volunteers and the platform fell for a defined distance of 33 mm. Loaded with the volunteers, the platform fell significantly (p < 0.001) faster than predicted by the laws of stiff body mechanics (50 vs. 82 ms). For a minimum time of 50 ms, the human locomotor apparatus is able to support an average external power output of more than 400 W by means of an energy transfer of more than 20 J. During the fall, no EMG activities of the ankle flexors could be recorded. We conclude that the acceleration of the platform fall is induced by elastic elements serving as energy sources. Elastic energy storage is of quantitative relevance for the functional morphology and biomechanics of the human locomotor apparatus.
Witte
H
H
Abteilung für Funktionelle Morphologie, Ruhr-Universität Bochum, Deutschland. Hartmut.Witte@rz.ruhr-uni-bochum.de
Recknagel
S
S
Rao
J G
JG
Wüthrich
M
M
Lesch
C
C
D000328:Adult; D000842:Ankle / Q000502:physiology; D001696:Biomechanical Phenomena; D004548:Elasticity; D004576:Electromyography; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009142:Musculoskeletal Physiological Phenomena