Power requirements and mechanical efficiency of treadmill walking.

The instantaneous energy levels of body segments are computed from kinematic measurements on a level treadmill at various speeds with freely chosen step rates and a constant speed with different imposed step rates. The changes in the energy levels of segments are combined to compute the average work rate required to accelerate the total body (positive internal work). This work is compared to total metabolic power consumption to obtain a minimal estimate of mechanical efficiency. The efficiency increases rapidly from 9”/, to 0.84 m/set to a maximum of 23% at 1.70 m/set. Thereafter, the efficiency slowly decmases with speed to 18% at 2.35 m/set. When different step rates are imposed at one constant speed, the average positive work rate remains constant. This work rate level is identical to that required for walking at the same speed with self-determined (free) step rate. Thus, maximum gross efficiency results at the free step rate.