Effects of Transcutaneous Electrical Nerve Stimulation (TENS) During Functional Activities or Exercise: A Systematic Review.

Background: TENS is a non-pharmacological adjunctive treatment commonly recommended for analgesic purposes, with widespread use and acceptance in clinical practice; however, its effects simultaneously with exercise are controversial, and there are gaps regarding its effectiveness and applicability, especially regarding the parameters and protocols used to treat pain. In view of this, the aim of this study was to systematically review the effects of TENS applied simultaneously with functional activities or exercises in the treatment of individuals with pain.

Method: A bibliographic search was performed in electronic databases, including EMBASE, PubMED, Scopus, Web of Science, PEDro, SPORTDiscus, and the grey literature. The search yielded a total of 634 articles, of which only six met the inclusion criteria and were analysed individually. Of the selected studies, four evaluated the simultaneous use of TENS in patients with chronic pain, one in patients with fatigue-induced injury, and one in healthy subjects.

Results: The articles selected for synthesis of the review were assessed using the RoB 2.0 risk of bias tool, which found that three of the included studies had a low risk of bias, while two studies were analysed as high risk and only one with some concern. It is concluded that the use of TENS in conjunction with functional activities and exercises may benefit people with pain.

Conclusion: The studies showed that the use of TENS with high frequency and intensity at the sensory threshold and applied simultaneously with exercise produced more significant analgesic effects, but new clinical trials with robust methodological designs should be carried out.