Acute Biochemical Muscle Damage Responses to a Single Session of Whole-Body Electromyostimulation.

Abstract

This study aimed to investigate the acute effects of whole-body electromyostimulation (WB-EMS) on markers of skeletal muscle damage, renal function, and metabolic stress in sedentary adults. Given increasing reports of severe muscle damage after a single WB-EMS session, this study examined the time course and magnitude of biochemical and urinary responses after such an event. Twenty-six participants were randomly assigned to a WB-EMS group or a control (exercise-only) group. While both groups completed the same physical exercise protocol, only the WB-EMS group received low-frequency electrical stimulation (40-50 Hz). Venous blood and urine samples were collected at baseline and at 24, 48, and 72 h postexercise. Key biomarkers were measured: creatine kinase, myoglobin, alanine and aspartate aminotransferases, urinary cystatin C, and urinary potassium. Ratings of perceived exertion were also recorded. Despite low perceived exertion (<13), WB-EMS induced statistically significant elevations in serum creatine kinase and myoglobin, peaking at 72 h (1784 U·L -1 and 180.6 ng·mL -1 , respectively), indicating pronounced biochemical skeletal muscle stress. No such changes were observed in the control group. Hepatic enzymes remained within clinical reference ranges, while urinary cystatin C and potassium did not indicate acute kidney impairment. A single WB-EMS session can elicit marked skeletal muscle damage in previously untrained individuals, even when perceived exertion is low. Although no acute renal dysfunction was observed and the present findings do not indicate a clinical diagnosis of exertional rhabdomyolysis, the magnitude of the biomarker response underscores the physiological strain imposed by initial WB-EMS exposure. Collectively, these findings highlight the importance of careful progression and individualized load management when implementing WB-EMS protocols, particularly in EMS-naive populations.