The effectiveness index of mechanical energy utilization (EI) is defined by the following equation;
EI =
Performance and / or Effective energy (and / or Work)
Mechanical energy (and / or Work)
The generic definition of EI is useful for evaluating skilled motion in human movement from the viewpoint of effective usage of mechanical energy and/or work.
Certain correlations between EI and locomotion speed were observed in several locomotion studies using EI. If the EI has correlations with locomotion speed, however, interpretation of the EI is complicated. In the present study, EI was applied to the evaluation of walking and running motion in order to examine if EI correlates with locomotion speed.
Two subjects were asked to perform 15 walks and runs at several speed levels. The trials in each speed level were measured using an automatic coordinate acquisition system and a force platform. Then the EIs with several numerators representing performance and/or effective energy utilization were calculated. The numerators were PE (= 0.5 x body mass x (locomotion speed)2), PV (= body mass x locomotion speed), PD (= body mass x step length) and PDV (= body mass x step length x locomotion speed). WJP (absolute work in a cycle obtained based on joint torque power) was used as the denominators of EI.
The all EIs examined in this study have significant correlations with locomotion speed. In these cases, correlation coefficients as well as regression coefficients were different among subjects, movements and the numerators of EI. Based on these results, in order to appropriately examine EI of the target locomotion, firstly we need to confirm correlation between EI and the locomotion speed. Then, if EI correlates with locomotion speed, it may be necessary to consider the effect of locomotion speed in the interpretation of EI.
