Reconstruction of the human gastrocnemius force-length curve in vivo: part 1-model-based validation of method.
The muscle fiber force-length relationship has been explained in terms of the cross-bridge theory at the sarcomere level. In vivo, for a physiologically realistic range of joint motion, and therefore range of muscle fiber lengths, only part of the force-length curve may be used; that is, the section of the force-length curve expressed can vary. The purpose of this study was to assess the accuracy of a method for determining the expressed section of the force-length curve for biarticular muscles. A muscle model was used to simulate the triceps surae muscle group. Three model formulations were used so that the gastrocnemius operated over different portions of the force-length curve: the ascending limb, the plateau region, and the descending limb. Joint moment data were generated for a range of joint configurations and from this simulated data the region of the force- length relationship that the gastrocnemius muscle operated over was successfully reconstructed using the algorithm of Herzog and ter Keurs (1988a). Further simulations showed that the correct region of the force-length curve was accurately reconstructed even in the presence of random and systematic noise generated to reflect the effects of sampling errors, and incomplete muscle activation.
Winter
Samantha L
SL
Department of Sport and Exercise Science, Aberystwyth University, UK.
Challis
John H
JH
D003198:Computer Simulation; D004548:Elasticity; D006801:Humans; D008954:Models, Biological; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D013314:Stress, Mechanical