Effect of the Combination of Whole-Body Neuromuscular Electrical Stimulation and Voluntary Exercise on Metabolic Responses in Human

Abstract

Purpose: Since neuromuscular electrical stimulation (NMES) can recruit high-threshold motor units and enhance glucose metabolism, the combination of NMES and voluntary low-intensity exercise would induce both anerobic and aerobic energy consumptions and this type of exercise could be more efficient and effective than conventional exercise regimens. We aimed to investigate metabolic responses and muscle fatigue during whole body NMES (WB-NMES), voluntary exercise, and their combination.

Methods: The blood lactate concentration and maximal voluntary contraction were measured before and after specified exercises: WB-NMES (E), voluntary exercise (V), and their combination (VE), and expired gas was sampled during the exercises in thirteen healthy young men. Each exercise was conducted for 15 min and interval between exercise was > 48h.

Results: Energy expenditure and $\dot{\text{V}}{\text{O}}_2$ relative to the body mass during VE were significantly higher than during V and E (p < 0.05). The Respiratory gas exchange ratio (RER) during both E and VE was higher than during V (p < 0.05), and the blood lactate concentration after VE was significantly higher than after V and E (p < 0.05). Although $\dot{\text{V}}{\text{O}}_2$ relative to the body mass was 18.6 ± 3.1 ml/min/kg and the metabolic equivalent was 5.31 ± 0.89 Mets, the blood lactate concentration reached 7.5 ± 2.7 mmol/L after VE.

Conclusion: These results suggest that the combination of WB-NMES and voluntary exercise can enhance the metabolic response to a level equivalent to high intensity exercise under the net physiological burden of low-middle intensity exercises.

Keywords: electrical muscle stimulation; electrical myostimulation; high-intensity interval training; lactate; life-style-related diseases; sarcopenia.

FIGURE 1

Experimental protocols in this study.

FIGURE 2

Arm band, vest, and shorts for whole-body neuromuscular electrical stimulation (Left panel) and their inside electrode locations for each muscle group (Right panel).

FIGURE 3

Energy expenditure (Left upper panel), $\dot{\text{V}}{\text{O}}_2$ relative to the body mass (Right upper panel), and the respiratory gas exchange ratio (RER) (Bottom panel) during voluntary aerobic exercise (V), whole-body neuromuscular electrical stimulation (E), and their combination (VE). ^∗p < 0.05, ^∗∗p < 0.01.

FIGURE 4

Blood lactate concentration (Left panel) and maximal voluntary contraction (MVC) after the exercises normalized by that before exercises (Right panels) for voluntary aerobic exercise (V), whole-body neuromuscular electrical stimulation (E), and their combination (VE). ^∗p < 0.05, ^∗∗p < 0.01.