Mechanical energy changes during treadmill running.

The purpose of this study was to investigate mechanical energy changes during treadmill running, using two biomechanical models of the human body: the multi-segment model and the center of mass model. Two university distance runners ran at 3.33 and 2.67 m/s on the treadmill, while the right side was filmed by a 16-mm high-speed movie camera (100 fps). The instantaneous mechanical energies of the multi-segment model composed of 11 rigid segments (ME total) and those of the C.M. model (ME C.M.) were calculated for two strides for each trial. The following results were obtained: the trunk segment was the major contributor to the body energy variations, compared to the four limbs; internal kinetic energy, which was the difference between the energy amounts of the two models, was found to have a phase relationship directly opposite to those of the C.M. model. These findings were contrary to the previous studies on walking and were seen to be important characteristics of running energetics.