The proposal of the measurement method of the mental stress using the surface electromyogram

Abstract

The purpose of this study is to investigate the effect of the mental load on the muscle activity to develop the method to which the human's stress can be measured by using the electromyogram (EMG). EMG has been usually used as an index that evaluates the kinetic load of body. The evaluation index of mental load has been electrocardiogram, blood flow, and so on. Althouth, we found EMG's feature changes when a mental load is added to the body. We set a hypothesis that a mental load effects to muscular activity because a muscle works under the nerve center. We measured EMG of single moter unit of musculus biceps brachii according to two conditions:with mental load and without mental load. The launching interval of the single moter unit action potentials and the muscle fiber conduction velocity were obtained from the analysis of the EMG. Comparing the calculation results of two kinds of mental load condition, we found the difference to be in the calculation results between conditions of two mental loads. We confirmed EMG's feature of single moter unit has the possibility as stress evaluation index.