Acute effects of eccentric exercise on the electrical properties and estimated body water compartments of exercised and non-exercised segments

Abstract We investigated the acute effects of eccentric exercise on the electrical properties and body water compartments of exercised and non-exercised segments using direct segmental multi-frequency bioelectrical impedance analysis (DSMF-BIA), a method that enables assessment of multiple body segments within a single acquisition. Additionally, we examined frequency-dependent changes in these electrical properties. Twenty-three healthy male participants performed unilateral eccentric dumbbell curls with their left arms. They completed five sets of 10 eccentric contractions using a dumbbell load corresponding to 50% of the maximal voluntary contraction force of the left elbow flexors, as determined during a familiarization session. DSMF-BIA parameters were measured before and immediately after exercise. In the exercised segment, exercise significantly altered impedance, resistance, reactance, phase angle, total body water, intracellular water, and extracellular water. Notably, the most pronounced changes in electrical properties occurred at 5 kHz. In the non-exercised segments, electrical properties at several frequencies and body water compartments changed significantly, whereas effect sizes remained uniformly trivial to small. These findings suggest that DSMF-BIA, within a single acquisition, has potential utility for evaluating marked local responses in exercised muscle while distinguishing them from the trivial variations in non-exercised segments.