Muscle performance evaluation using the discharge-load index: A pilot study

Abstract

[Aims] There are many measurement conditions for muscle strength evaluation using surface electromyogram (EMG) and it is relatively difficult to measure muscle strength stably depending on the settings. We have reported that a specific assessment is possible using the discharge-load index (DLI) that we devised. In this study, we confirmed the characteristics and accuracy of DLI and verified whether it could be applied to the evaluation of individual muscle strength exertion ability. [Methods] The DLI of rectus femoris muscle (RF) was measured in 27 healthy volunteers. EMG was carried out in each subject with a load of 1–3 kg. The changes in the volume of muscle discharge were evaluated as the rate of increase in muscle discharge. Before the experiment, the circumferences of the thigh and RF were measured. In addition, the exercise history and exercise habits of the subjects were investigated. [Results] There were no significant differences in DLI between the right and left sides and genders. DLI was not significantly correlated with the circumference of the thigh, but was significantly negatively correlated with that of RF. When results were classified by exercise history and exercise habits, past exercise history did not affect DLI, but DLIs were significantly lower in the group with current exercise habits. All subjects showed no significant changes in DLI with age. However, in the group without exercise habits, DLI increased with aging. On the other hand, the group with exercise habits had a low DLI even in old age. [Conclusions] DLI may be used to assess the ability of each individual to exert strength.