Wearable TENS device may zap away pain, fatigue due to long COVID

Daily transcutaneous electrical nerve stimulation (TENS) therapy using a wearable device holds promise in alleviating pain, fatigue, and gait alterations in individuals with long COVID, according to a pilot study.  

A total of 25 adults with long COVID were randomly assigned to receive TENS therapy at high dose (intervention n=12, mean age 51.0 years, 83.3 percent female, 50.0 percent White, mean BMI 27.8 kg/m²) or at low dose (placebo n=13, mean age 43.4 years, 69.2 percent female, 46.2 percent White, mean BMI 27.7 kg/m²). Compared with those in the placebo group, participants in the intervention group were more likely to have a cancer history (41.7 percent vs 0 percent; p=0.03) and osteoarthritis (33.3 percent vs 0 percent; p=0.01). [Sci Rep 2024;14:27224]

High-dose TENS was delivered using an FDA-cleared wearable device that was unilaterally attached around the participant’s upper calf. The device consists of a one-channel electrical stimulator that communicates with a smartphone application through Bluetooth. For the placebo group, an identical device that elicited 10% dose of TENS therapy was used. All participants were asked to use the device for 3–5 hours over 4 weeks.

After 4 weeks of treatment, participants in the intervention group had a significantly greater reduction in functional interference from pain, as measured using the Brief Pain Inventory, compared with those in the placebo group (mean difference, 2.61; p=0.008).

The intervention group also had marked improvements from baseline in walking ability, including stride time (4–8 percent, test condition dependent), cadence (4–10 percent, depending on condition), and double-support phase (12 percent in dual-task).

In the subgroup of participants meeting the 2010 American College of Rheumatology Fibromyalgia diagnostic criteria, high-dose TENS yielded significant improvements in the global fatigue index at week 4 from baseline (mean change, 6.08; p=0.005).

There were no discontinuations documented over the 4 weeks of intervention, despite six patients reporting mild fatigue, pain, and skin irritation. These issues were resolved with advice from the research team. Compliance resulted in a median of >3.5 therapy sessions per day and >26 days of device usage. The percentage of participants with high compliance to the intervention (≥21 of days used) was 100 percent in the intervention group and 81.8 percent in the placebo group.

“A key factor contributing to high compliance may be high acceptability and perceived benefit of the wearable TENS device,” with participants who received high-dose TENS reporting a slightly higher perceived benefit compared with those who received low-dose TENS (71.2 percent vs 61.4 percent), the researchers noted.

As a supportive intervention, TENS may alleviate pain by stimulating peripheral nerves and modulating central pain processing. The researchers explained that the stimulation reaches the central nervous system and leads to the activation of pain inhibitory interneurons in the dorsal horn (referred as “nerve gate”). [Curr Rheumatol Rep 2008;10:492-499; Pain Manag 2014;4:197-209; J Pain Res 2019;12:3185-3201]

Co-lead researcher Dr Bijan Nafaji from the Center for Advanced Surgical & Interventional Technology at UCLA Health in Los Angeles, California, US, believed that the success of the high-dose TENS intervention may be attributed to the high rate of daily device usage, with the wearable nature of the device

One factor in the study's success was likely the high rate of daily device usage, Najafi said. “This wearable TENS system offered immediate, on-demand relief from pain and fatigue, making it easy to integrate into daily activities.”

Nafaji pointed out that the device has the potential to address similar symptoms in people with other respiratory diseases, those who have experienced extended ICU stays and developed posthospitalization weaknesses, and conditions involving chronic fatigue and pain, such as fibromyalgia or chemotherapy-related side effects. “But further studies are needed to confirm these potential uses.”