Obesity is a disease condition in which there is an abnormal or excessive buildup of body fat caused by an imbalance between energy intake and expenditure.¹ Obesity is a definite risk factor for a wide range of chronic diseases, including type 2 diabetes mellitus, cardiovascular disease, respiratory problems, and cancer.^2-4 Obesity, physical inactivity, and type 2 diabetes mellitus are three interconnected factors that affect global health. Lack of physical activity leads to a decrease in energy consumption.^2,3 Chronic inflammation is a significant factor in many diseases. This is especially evident in obesity, where the overall immune phenotype changes from an anti-inflammatory to an inflammatory state.^5,6 Whole-body electrical muscle stimulation (WB-EMS) training is a common method in sport and rehabilitation and is an appealing clinical application for subjects unable to perform regular exercise.⁷ This method targets larger muscle areas to produce simultaneous stimulation of all parts of the body. EMS causes non-selective activation of all muscle fibers in the electrical field and has been shown to improve muscle mass and function in athletes and healthy adults. WB-EMS also is a useful tool to enhance muscle strength outcome measurements in unconditioned subjects.⁸ We aimed to study how this kind of training affects cytokines that cause or stop inflammation in the long term.

Participants

This study comprised 30 healthy but inactive men (25 to 35 years old). Due to gender differences in immune system responses, only men were used in this research. All men had never experienced WB-EMS, had stable body weight (less than 5 kg change in the last 3 months), no medication, no chronic metabolic disease or cancer, no surgery in the last 2 months, and no general contraindications for physical activity. They provided written informed consent before participation. This study was performed in line with the principles of the Declaration of Helsinki and was approved by the Human Research Ethics Committee of the University of Isfahan (IR.UI.REC.1400.064).

EMS protocol

The WB-EMS device provides simultaneous stimulation of an area of 2,600 cm² over the legs, front and back of thighs, arms, hips, abdomen and chest, lower and upper back. Bipolar electric current with a frequency of 85 pulses per second, a duration of 350 millionths of a second for each pulse, and a flat waveform with increments of 0.4 second was applied alternately with 6 seconds of activity and 4 seconds of rest. In total, the training program included 20 WB-EMS sessions of three training sessions per week for 7 weeks. All the training sessions lasted 40 minutes. Between sessions, there was 1 day of rest for recovery and acclimatization.^9,10

Statistical analysis

Analysis of covariance for independent samples was used to compare the physiological characteristics and cytokine levels in the training and control groups, and all analyzes were performed using a significance level of <0.05.

The EMS training group showed significant decrease in total cholesterol, low-density lipoprotein (LDL) cholesterol, and very low-density lipoprotein (VLDL) cholesterol. The same group also had higher levels of high-density lipoprotein cholesterol, but the difference from the controls was not significant (Fig. 1).

Significant increase in IL-10 and interferon γ (IFN-γ) was observed in the EMS training group, as was a significant decrease in IL-17 (Fig. 2).

Our research focused on the enduring outcomes of EMS training, an issue that has received little attention in previous studies. We found that EMS training led to significant improvement in total cholesterol, LDL cholesterol, and VLDL cholesterol among participants. The EMS exercise training method uses low- and medium-frequency electrical currents to greatly enhance the body’s natural muscle contractions, resulting in greater work of the muscle fibers than with conventional training methods. EMS usually involves placement of electrodes on different parts of the body or muscles and to a device that causes the muscles to contract with electric shocks. This exercise method, which causes multiple muscle groups to contract simultaneously, increases basal metabolism and burns a larger number of calories than typical exercises, helping to hinder central obesity, maintain body mass index, and increase physical fitness.^11,12

Pervious research has shown different results for lipid profiles based on duration and intensity of EMS exercise. Studies shorter than 8 weeks usually did not produce a significant difference, while those lasting longer than 8 weeks reported a significant reduction in lipid profile.^13,14 These differences may be due to the general characteristics of the subjects; type, intensity, and duration of training; and other factors. In our study, we saw significant improvement in lipid levels, consistent with previous results.^12-14

Our study showed that EMS exercise significantly increases IFN-γ and IL-10, in line with Schwappacher et al.¹⁵ We also found that IL-17 was reduced by EMS training. Our study is one of the first to examine the effects of this type of exercise on inflammatory and anti-inflammatory factors.^16,17

IL-23 has a key role in the formation and survival of Th17 cells but also influences the destructiveness of Th17 cells through interactions with IL-17 and tumor necrosis factor-α. Here, IL-23 attaches to its receptor IL-23R, allowing influx of the IL-12Rβ1 subunit. This interaction leads to the activation of Janus kinase 2 (JAK2) and tyrosine kinase 2 (TYK2) and then signal transducer and activator of transcription 3 (STAT3) and STAT5. IL-23, like IL-22, can have a dual role, both causing and reducing inflammation.^18,19 EMS training, which uses fewer but longer muscle contractions than conventional resistance training, could explain the increases in these inflammatory and anti-inflammatory factors. This kind of exercise also triggers specific changes in the muscles by activating more numerous motor units.²⁰

The authors declare no conflict of interest.

This research was conducted with the help of University of Isfahan, and the authors thank and appreciate Life Sense Sports Club members.

Study concept and design: JR and SMM; acquisition of data: MRPS; analysis and interpretation of data: MRPS, JR, and MA; drafting of the manuscript: JR and MA; critical revision of the manuscript: MRPS, JR, SMM, and MA; statistical analysis: JR and MA; administrative, technical, or material support: JR; and study supervision: JR.