Abstract
The evaluation and training of muscle force is often limited to one side of the body, as seen in manual muscle testing and uniform movement devices. However, most physical movements result from the sophisticated coordination of the four limbs on both sides; and there is a view that it is necessary to take bilateral movement which involves the interaction between both limbs, into account during training. In this study, an exercise requiring unilateral muscle force control during lower limb movement was assigned to consolidate the direction of attention, and the change in mutual interference with the opposite side in response to a change in the control level was examined. The subjects were nine healthy adults. Muscle force control of the right knee extensor (100%Maximal Voluntary Contraction (MVC), 75%MVC, 50%MVC, and 25%MVC by isometric contraction) was demanded, and at the same time, the subject was asked to make a bilateral movement, in which the maximum isometric extension muscle force of the left knee, the contralateral side, was demanded. The maximum isometric muscle force of knee extension on the left side alone was measured. The control measure of right knee extension muscle force was conserved as an absolute requirement during measurement, and the directionality of attention was consolidated. The analytical subject of data was the change in maximum left knee extension muscle force during exertion for each movement exercise. The results showed the influence of control of the right knee extension muscle force on the maximum left knee muscle force to be a syntonic change in which the maximum left knee extension muscle force decreased as the control level of right knee extension muscle force decreased. We believe this to derive from following mechanisms: the segmentation of attention at the cognitive and psychological levels, which is a mechanism of bilateral deficit, is involved, and the demand of muscle force control on the lower limbs, which has a high innervation ratio, demanded more attention due to both the increased difficulty level of assignments and the need for improving movement accuracy.
