Electrolyte Changes Related to Muscle Pain After Resistance Exercises

Abstract

Introduction Resistance exercises (RE) performed at high intensity cause an inflammatory response and electrolyte abnormalities in blood plasma. Objectives To study the plasma electrolyte changes resulting from a high-intensity session of RE in untrained volunteers, and to correlate these with delayed onset muscle soreness (DOMS). Methods Twenty volunteers, aged 26.9 (±4.4) years, underwent an RE session. The workout (leg extension, squat and leg press) consisted of four sets of 10 maximum repetitions. Electrolytes (Na+, K+, Ca2+ e Mg2+) were evaluated before the training (baseline), immediately (0 min), and 30 minutes after the RE. The DOMS was assessed 24 hours after the sessions. Results The Na+ increased immediately after the RE and returned to normal after 30 min (p<0.001). After 30 min, K+ increased compared to baseline levels and immediately after the RE (p<0.001). Ca2+ and Mg2+ levels did not change throughout the study. Changes in Na+ and K+ levels were correlated immediately (r=-0.511; p=0.021) and 30 min (r=-0.455; p=0.049) after RE. Plasma concentrations of Na+ 0 min were correlated (r=-0.520; p=0.018) with the DOMS. Conclusion High-intensity RE in untrained volunteers leads to changes in plasma concentrations of Na+ and K+. Na+ concentrations immediately after RE were related to DOMS; individuals that presented smaller alterations in this electrolyte reported more muscular pain. Level of evidence II; Diagnostic Studies - Development of diagnostic criteria on consecutive patients (with universally applied reference “gold” standard).