Physical training augmented with whole body electronic muscle stimulation favorably impacts cardiovascular biomarkers in healthy adults - A pilot randomized controlled trial.

Background: Physical activity is protective against cardiovascular disease (CVD) and favorably improves CVD risk profile. However, more than 25 % of American adults report no participation in physical activity. Whole body electronic muscle stimulation (WB-EMS) training is a novel FDA-cleared technology which offers a time-efficient and adaptable method for physical training by simultaneously stimulating the main muscle groups using percutaneous electrical impulse transmission. Studies have demonstrated increased muscle mass, reduced fat mass, and improved functional capacity in sedentary individuals after training with WB-EMS, but studies evaluating the role of WB-EMS training on CVD risk profile are lacking.

Methods: We performed a pilot randomized controlled trial in healthy adults randomized to physical training with versus without WB-EMS for one session of 20 min duration per week across 16-weeks. Study participants were asked to perform their usual activities but to abstain from any strength training during the study. During each training session, all study participants wore a specifically designed vest and arm and leg straps that were connected with electrical wires to the WB-EMS device (Miha Bodytec Gersthofen, Germany). Biphasic electrical stimulation was delivered through the vest and straps (4 s on, 4 s off) at a frequency that elicited a score of 5 or 6 on the Borg rating of perceived exertion scale from study participants when each of the following muscle groups was stimulated: thighs, buttocks, lower back, upper back, latissimus dorsi, abdomen, chest and arms. These frequencies were 'titrated' during the first 4 weeks and were then fixed at each muscle group for each participant. Individuals randomized to no WB-EMS wore the same equipment but received no electrical stimulation. Physical training sessions were provided by personal trainers certified for WB-EMS training and consisted of a fixed number of exercises and repetitions. We measured and compared several clinically important cardiovascular parameters at baseline and post-intervention.

Results: Seventy-eight participants were recruited between January 2021 and March 2022 with a mean age of 35.9 ± 11.2, 61.3 % females, median BMI 24.3 (21.8, 28.1); N = 46 were randomized to intervention group and N = 32 were randomized to the control group. Eighteen (23 %) participants dropped out of the trial, including 9 participants from the EMS arm (19.6 %), and 9 participants in control arm (28.1 %). There was no significant differences in the rate of dropping out of the WB-EMS and control groups (p = 0.27). Those in the intervention group compared to controls exhibited the following changes after 16-weeks of training: waist:hip ratio (∆ -0.03 ± 0.05, p = 0.01 vs. -0.01 ± 0.0, p = 0.1), peripheral endothelial function, measured using reactive hyperemia peripheral arterial tonometry (∆: 0.02 ± 0.1, p = 0.5 vs. -0.20 ± 0.3 p = 0.05), high-sensitivity C-reactive protein (∆: 0.06 ± 0.7, p = 0.3 vs. 0.20 ± 2.3 p = 0.02), total cholesterol (∆: -1.7 ± 25.1, p = 0.3 vs. 19.2 ± 26.5, p < 0.001), high density lipoprotein (∆: 2.02 ± 6.6, p = 0.2 vs. 3.6 ± 7.5 p = 0.01) and low density lipoprotein cholesterol (∆: 0.5 ± 26.7, p = 0.4 vs. 17.1 ± 23.2, p < 0.001).

Conclusion: Once weekly physical training with WB-EMS in healthy adults resulted in either improved or stable biomarkers of cardiovascular risk, which either remained stable or worsened in those undergoing conventional training alone. Thus WB-EMS may provide an effective and time-efficient form of physical training that may be considered in those unable or unwilling to perform exercise conventionally.