An alternative electrical impedance myography technique for assessment of local muscular fatigue

Abstract

Electrical impedance myography (EIM) is a technique that has been used to evaluate muscle contraction features, but its application to assess fatigue is not completely described yet. This work presents the comparison between the detection of muscle fatigue by the muscle force and its counterpart performed by bioelectrical impedance. The experimental protocol performed by five volunteers was consisted by isometric contractions of the elbow flexor complex (biceps brachii, brachialis, and brachioradialis muscles) at 30% of their maximum voluntary contraction (MVC) up to the exhaustion. Time series of muscle force and bioelectric impedance data were obtained for a sample period of 10 seconds. Bioelectric impedance data were acquired by using a bipolar bioelectric impedance spectroscopy method based on the current response to a voltage step excitation (BIS-STEP). The findings indicate that the used impedance measurement method was sensible enough to detect changes on the muscular bioelectrical impedance that were associated to fatigue, suggesting an early detection of fatigue by the bioelectric impedance data when compared with detection performed by force data.