Acute effects of belt electrode-skeletal muscle electrical stimulation on microvascular responsiveness of the gastrocnemius muscle in healthy young men.

Purpose: Belt electrode-skeletal muscle electrical stimulation (B-SES) improves muscle strength, mass, and exercise tolerance. However, its effects on skeletal muscle microvascular responsiveness remain unclear. In this study, we investigated the acute effects of a single B-SES session on gastrocnemius microvascular responsiveness in healthy young men.

Methods: In this randomized crossover study, 12 healthy young men (mean age: 20.8 ± 1.0 years) underwent two 20-min conditions: electrical stimulation at the sensory threshold (Sham, n = 12) and at the maximum intensity not causing discomfort (B-SES, n = 12). Gastrocnemius metabolic rate (tissue oxygen saturation [StO] downslope) and microvascular reperfusion rate (StO upslope) were assessed using near-infrared spectroscopy and a vascular occlusion test.

Results: In the B-SES condition, the StO downslope significantly steepened (Pre: -0.15 ± 0.03 %·s, Post: -0.20 ± 0.03 %·s, p = 0.002). The StO upslope also significantly steepened (Pre: 1.58 ± 0.52 %·s, Post: 2.56 ± 0.71 %·s, p < 0.001). A significant negative correlation was observed between the StO downslope and StO upslope (r = -0.581, p = 0.047). No significant changes were observed in the Sham condition.

Conclusions: A single B-SES session applied to the lower extremity significantly increased gastrocnemius metabolic rate and was associated with enhanced microvascular reperfusion. These findings suggest B-SES may be a useful therapeutic approach to improving microvascular responsiveness, particularly in individuals with limited exercise capacity.