The Effects of Muscle Strengthening on Neural Control, Muscle Forces, and Motion Mechanics in a Squat Jump

P. Prokopow (Japan)


Muscle strengthening, squat jump, simulation, neural control, motion mechanics


This study investigates the effects of muscle strengthening on neural control, muscle exertion patterns and motion mechanics in vertical squat jump. In the experiments sixteen major muscles were strengthened up to 20%. A forward dynamics computer simulation was used to evaluate quantitatively the effect of strengthening the muscles. The model of the neuromusculoskeletal system used in this study was three-dimensional and had 20 degrees-of-freedom. It included 26 Hill-type muscles connected in a series with tendons. The optimal neural control, which produced maximum height jump, was found through a numerical optimization method. It was found that: (i) the pattern of the kinematical changes depend on which muscles are strengthened, while the magnitude of the changes depends on how much muscles are strengthened. (ii) The adjustment in muscle coordination, in some cases, can be done without adjustment of neural control. (iii) The adjustment in neural control is done in an adaptive manner. (iv) Inter segmental coordination is altered more if only some muscles are strengthened, as opposed to when all muscles are strengthened together, then inter-segmental coordination changes only slightly. (v) The main effect of equally strengthening of all muscles is the increase of joint torque, which is proportional to the increase in muscle strength.

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