The effect of bilateral asymmetry of muscle strength on jumping height of the countermovement jump: a computer simulation study.

The purpose of the current study was to examine the effect of bilateral asymmetry of muscle strength on performance (maximal jumping height) of the countermovement jump. In experimental studies, it is impossible to control for muscle strength asymmetry, since it varies widely among individuals. In the current study, we used computer simulation. Two three-dimensional human lower limb neuromusculoskeletal models (model-symmetry and model-asymmetry) were developed. The total muscle strength of the two models was set to be identical. Bilateral muscle strength was set equal in the model-symmetry simulation, while the model-asymmetry simulation was set with a 10% bilateral strength asymmetry. The countermovement jumps were generated successfully, producing jumping heights of 0.416 m for model-symmetry and 0.419 m for model-asymmetry. The small difference in height (0.7%) indicates that bilateral asymmetry by itself does not have a significant effect on jumping performance. With model-asymmetry, the strong leg compensated for the muscle strength deficit of the weak leg by lateral movement of the body to distribute the load proportional to the muscle strength of each leg.