Circulating Concentration of Chemical Elements During Exercise-Induced Muscle Damage and the Repeated Bout Effect.

Abstract

The objective of the study was to evaluate the circulating levels of chemical elements after exercise-induced muscle damage (EIMD) followed by the repeated bout effect (RBE). Seven physically active subjects (26.5 ± 4.0years) performed two sessions of EIMD (5 sets of 20 drop jumps), the second session 14days after the first for RBE assessment. Blood collections, countermovement jump (CMJ), squat jump (SJ), and delayed-onset muscle soreness (DOMS) were performed before (Pre), after (Post), and 24, 48, and 72h after the exercise session. Creatine kinase (CK) was detected by biochemical analysis and the concentration of chemical elements by total reflection X-ray fluorescence (TXRF). Differences between time points and sessions were assessed with two-way ANOVA and the effect size (ES). EIMD induced a reduction in the CMJ at 24h (P < 0.05) and an increase in DOMS at 24h (P < 0.01) and 48h (P < 0.01), and CK at 72h (P < 0.05). RBE alleviated all symptoms of EIMD in the second session (P > 0.05). EIMD induced a large to very large ES for Zn reduction at 24h (- 1.37) and 72h (- 0.93) and Br (- 0.83) at 72h. RBE presented large to very large ES for the increase in P at 48h (0.92); Cl at 24h (1.04); K at 24h (0.91), 48h (1.10), and 72h (0.96); Ca at 72h (0.92); and Fe at 24h (0.85). RBE influenced the concentration of elements associated with fatigue (K, Ca, Cl), inflammatory response, and glucose metabolism (Zn).