We investigated the effect of muscle damage and inflammation on electrical resistance and the body composition assessment by using bioimpedance spectroscopy (BIS). Twenty-two subjects completed 30 repetitions of maximal eccentric contractions of the elbow flexors with one arm. Whole-body resistance of extracellular and intracellular components (Re and Ri, respectively) on the exercised and non-exercised sides were measured using BIS. Body composition was calculated from both sides of resistance at baseline and 96 h after exercise. Re decreased only on the exercised side at 96 h after exercise (P < 0.05). Fat-free and fat mass values estimated from resistance on the exercised side were altered by 3.1% and - 15.6%, respectively, at 96 h after exercise (P < 0.05); those estimated from the non-exercised side were unaltered. Eccentric exercise-induced muscle damage and inflammation reduce Re and induce non-negligible estimation error in the body composition assessment using BIS.
Keywords: Body composition; Electrical resistance; Inflammation; Muscle damage.