Methods for studying energy costs and energy flow during human locomotion

Methods are described for studying the metabolic cost of increased and diminished gravitational work done by the human subject during normal locomotion at various speeds and slopes on the treadmill. It is shown that the energy expenditure is a linear function of the gravitational work and, as long as the gait is of a smooth andnatural character, appears to be dependent upon the true vertical lijtper step multiplied by the number of steps per minute. The true vertical lifr is defined as the lijt resulting f rom muscle action, as contrasted with components due to treadmill motion. Methods are also described for recording the vertical and translational motions of the torso during a single step, andfor analyzing the flow of mechanical energy into and out of the torso during each phase of the walking cycle. Implications for calculation of eficiency are briefly discussed