Background:
Electrical muscle stimulation (EMS) could additionally induce the involuntary contraction of muscle by electric stimulation in addition to voluntary muscle contraction during exercise. Furthermore, additional muscular contraction that occurred by EMS may affect the energy metabolism of muscle and can lead to increase an energy expenditure during exercise. Although, several studies have been evaluated that EMS has been proven to be effective in energy expenditure, it is still not certain whether application of EMS contributes the additional energy metabolism during the resistance exercise.

Method:
In our study, a total of 10 healthy young female (age: 23.0±3.6 years, body weight: 54.5±4.8 kg, BMI: 20.4±1.5 kg/m2) were recruited to identify the acute effects of EMS. All participants were randomly divided into two groups (weight-bearing exercise group, WB-G; EMS group, EMS-G), and performed the same exercise program that consisted of six weight-bearing exercise in both sessions. We set a wash-out period (at least 14 days) to avoid the physiological effect of exercise. To verify the acute effect of EMS, energy expenditure and heart rate were measured by gas-exchange analyzer (VO2 Master Pro, VO2 Master Health Sensor Inc, Vernon, Canada), and heart rate sensor (Polar H10 and OH1, Polar Electro Oy, Helsinki, Finland), also, blood lactate concentration was measured before and after the exercise.

Results:
The acute EMS training showed significantly higher energy expenditure than general weight-bearing exercise (WB-G: 72.1±10.3 kcal/session vs EMS-G: 87.0±17.0 kcal/session; p=0.018) and showed more use of anaerobic energy metabolism (Lactate: 1.8±2.1 mmol/L vs 4.4±2.6 mmol/L; p=0.005). During exercise, the heart rate was higher in EMS-G compared with the WB-G.

Conclusion:
The findings of this study suggest that the application of EMS contributes to higher energy expenditure and anaerobic energy metabolism during exercise. In addition, these metabolic benefits of EMS may affect the reduction of the weight and/or lipid biomarker with long-term exercise.