Reliability calculation the mechanical efficiency into Resultant Work Method in comparison with the common method during one running step

The common methods to evaluate mechanical efficiency include metabolic cost assessment and calculation of mechanical energy fluctuations. However, these methods are limited to aerobic activities as well as time consuming, and limit subject motions. The purpose of this study were 1) to present a new method in calculating mechanical efficiency by using resultant work approach and, 2) to assessed its reliability. 16 active, normal, healthy male students were selected in this study. Kinematics and kinetics variables, as well as, metabolic cost were recorded using cameras (JVC, 200 HZ), a force plate (Kistler, 1000 HZ) and K4b2 gas analysis device, respectively. Mechanical efficiency in the new approach was calculated dividing work on COM by the total mechanical energy. Work on COM was assessed using point-mass method, and the total mechanical energy was calculated by inverse dynamic approach. Pearson's correlation coefficient was used to test research hypothesis (p≤0.05). A significant correlation wasnt observed between mechanical efficiency in the common method and mechanical efficiency in the new method) r=0.31, p=0.26(. The finding indicats that calculated resultant work approach in one step of gait cannot be an indicator of mechanical efficiency.