歩行の効率

抄録

The energy consumption and the mechanical efficiency of leg muscles during walking were calculated from gait measurement data and mathematical models. We hypothesized that the power consumed in a muscle can be presented by modifying Hill's equation, which is p=(f+a)(v+b). (p: power). First, gait trajectory and floor reaction force were measured with an automated system during level walking of normal men at fast, usual, slow and very slow speeds. The data were fed into a mathematical 7 links model to obtain the joint moments. Then the joint moment data were fed into another mathematical model to obtain force (f) and velocity (v) of 8 muscle groups of the lower limbs. The values of f_<max> and v_<max> in the same activation level were calculated to obtain a=0.15 f_<max> and b=0.15v_<max>. Finally, power consumption was calculated using Hill's equation. In the v<0 range, power was estimated with p=fb+av+ab because in this range muscles will not output any external power. The energy consumption per unit time was calculated by integrating p during one walking cycle and divided by the cycle time. The mathematically calculated energy consumption values had good agreement with the values obtained from O_2 consumption studies in the literature. The efficiency of each of the 8 muscle groups was constant with gait speed, which was +31% on average during v≧O phase. In v<0 phase, the efficiency was calculated to be -20% to -5900% depending on gait speed.