%0 Journal Article
%T Contribution of non-extensor muscles of the leg to maximal-effort countermovement jumping
%A Akinori Nagano
%A Taku Komura
%A Shinsuke Yoshioka
%A Senshi Fukashiro
%J BioMedical Engineering OnLine
%D 2005
%I BioMed Central
%R 10.1186/1475-925x-4-52
%X A skeletal model that has nine rigid body segments and twenty degrees of freedom was developed. Two sets of muscle models were attached to this skeletal model: all (most of) major muscles in the leg ("All Muscles" model) and major extensor muscles in the leg (i.e., muscles whose primary function is leg extension; "Extensors Only" model). Neural activation input signal was represented by a series of step functions with a step duration of 0.05 s. Simulations were started from an identical upright standing posture. The optimal pattern of the activation input signal was searched through extensive random-search numerical optimization with a goal of maximizing the height reached by the mass centre of the body after jumping up.The simulated kinematics was almost two-dimensional, suggesting the validity of two-dimensional analyses when evaluating net mechanical outputs around the joints using inverse dynamics. A greater jumping height was obtained for the "All Muscles" model (0.386 m) than for the "Extensors Only" model (0.301 m). For the "All Muscles" model, flexor muscles developed force in the beginning of the countermovement. For the "All Muscles" model, the sum of the work outputs from non-extensor muscles was 47.0 J, which was 13% of the total amount (359.9 J). The quantitative distribution of the work outputs from individual muscles was markedly different between these two models.It was suggested that the contribution of non-extensor muscles in maximal-effort countermovement jumping is substantial. The use of a computer simulation model that includes non-extensor muscles seems to be more desirable for the assessment of muscular outputs during jumping.Jumping motions have been investigated by many researchers in the field of biomechanics in an effort to understand the coordination of the human body during explosive activities. A maximal-effort jumping is a suitable subject for this purpose, as the objective of a maximal-effort jumping can be defined in a very straight
%U http://www.biomedical-engineering-online.com/content/4/1/52