Muscle fatigue monitoring using a multifrequency bioimpedance technique

Abstract

The objective of this work is to measure the changes of electrical bioimpedance module and phase related to muscular fatigue. The results could also be interesting for medical diagnosis of leg oedema, related to heart diseases, or muscular lesions. With this purpose in mind we have done multifrequency bioimpedance measurements on volunteers to evaluate the change of the impedance due to some physical exercises with the leg and with the arm. In the case of the measures performed on the arm we have obtained an initial increase of the impedance module after the first three exercises. The change of the impedance module taken after the 5th exercise respect to the first measurement was significantly lower (p<0.05) at all frequencies. In the case of the measures performed on the leg we have obtained an increase of the impedance module after the first four exercises if compared with the module at rest. The measured module after the first exercise was significantly different respect to the module at rest (p<0.05) for frequencies lower than 50 kHz. Subsequently, making the measurement after the fifth exercise we have obtained a decrease of the impedance module, if it is compared with the previous measurement. The change of the module measured after the 6th exercise is greater than the system noise if compared with the 1st impedance measurement but this change is not significant, if compared to the first measurement, at all frequencies.