Neuromuscular electrical stimulation (NMES), or electrical muscle stimulation for short, uses electrical currents to contract muscles. The stimulation devices are easy to use and widely available on the market, according to Sudip Bajpeyi, Ph.D., a professor in the Department of Kinesiology at The University of Texas at El Paso, but he has often wondered, “Can these stimulators offer any benefits when used during resistance training? What does the research say?”

Well, the results are in — and they are promising. In a new meta-analysis study published this month in the European Journal of Applied Physiology, Bajpeyi found that using NMES while doing resistance training leads to greater muscle mass and strength compared to resistance training alone.

Bajpeyi and his team conducted the meta-analysis comprising more than a dozen studies that used NMES and reviewed their results.

“A meta-analysis provides more comprehensive evidence on studies that explore the same research question,” Bajpeyi explained. “This approach allows us to move beyond the limitations of individual studies and make more informed, evidence-based conclusions.”

Co-authors on the study are Gabriel Narvaez, a recently graduated master’s student in kinesiology, and Jehu N. Apaflo, a doctoral student in interdisciplinary health sciences.

The team specifically analyzed research that combined NMES with resistance training.

The analysis focused on studies where participants performed traditional resistance exercises, such as bench presses or squats, while using NMES devices. That’s when you do about eight to 12 repetitions of one weight training exercise, rest and repeat, Bajpeyi said.

The studies compared the results of participants using electrical stimulators while exercising to those who did the exercises with no electrical stimulation. Participants’ muscle mass and strength were assessed at the beginning and the end of each study. Training periods for participants ranged from two to 16 weeks, with longer durations yielding better results.

“Under normal conditions, the brain activates muscles by sending signals through the nervous system.” Bajpeyi said. “NMES mimics this process by delivering external electrical currents to the nerves, causing the muscles to contract, without input from the brain. Think of it as though your muscles are contracting involuntarily.”

Bajpeyi is the director of the Metabolic Nutrition and Exercise Research (MiNER) lab at UTEP, where his team studies how NMES or other interventions can improve physical and metabolic health.

Funded by the National Institute of Diabetes and Digestive and Kidney Diseases, part of the National Institutes of Health, Bajpeyi is currently investigating how NMES might help regulate blood glucose levels and reduce the risk for type 2 diabetes.

“Exercise is medicine, but not everyone is able or willing to engage in traditional exercise” he said. “NMES has great potential for improving metabolic health by building muscle mass, which can help the body process blood glucose more effectively.”

Bajpeyi said his NMES study results are forthcoming.