Transcutaneous electrical nerve stimulation reduces exercise-induced perceived pain and improves endurance exercise performance

Purpose Muscle pain is a natural consequence of intense and prolonged exercise and has been suggested to be a limiter of performance. Transcutaneous electrical nerve stimulation (TENS) and interferential current (IFC) have been shown to reduce both chronic and acute pain in a variety of conditions. This study sought to ascertain whether TENS and IFC could reduce exercise-induced pain (EIP) and whether this would affect exercise performance. It was hypothesised that TENS and IFC would reduce EIP and result in an improved exercise performance. Methods In two parts, 18 (Part I) and 22 (Part II) healthy male and female participants completed an isometric contraction of the dominant bicep until exhaustion (Part I) and a 16.1 km cycling time trial as quickly as they could (Part II) whilst receiving TENS, IFC, and a SHAM placebo in a repeated measures, randomised cross-over, and placebo-controlled design. Perceived EIP was recorded in both tasks using a validated subjective scale. Results In Part I, TENS significantly reduced perceived EIP (mean reduction of 12%) during the isometric contraction ( P = 0.006) and significantly improved participants’ time to exhaustion by a mean of 38% ( P = 0.02). In Part II, TENS significantly improved ( P = 0.003) participants’ time trial completion time (~2% improvement) through an increased mean power output. Conclusion These findings demonstrate that TENS can attenuate perceived EIP in a healthy population and that doing so significantly improves endurance performance in both submaximal isometric single limb exercise and whole-body dynamic exercise.