Ahead-of-Issue JCEWM. 2024, 1. 10.55566/JCEWM-D-24 Original Research Assessment of Transcutaneous Electrical Nerve Stimulation Efficacy in Pain Management and Muscle Recovery: A Controlled Clinical Trial for Exercise-Induced Muscle Fatigue. Adriana M Degani, PT MSc PhD 1 ; Hannah Stefanek, DPT 2 ; Josh Sparks, DPT 2 ; Patrícia Driusso PT MSc PhD 3 ; Alessander Danna-dos-Santos PT MSc PhD 1,2 , Daryl Lawson, PT DSc 1,2 1 Laboratory for Advancements in Rehabilitation Sciences (LARS), Department of Physical Therapy, Western Michigan University, Kalamazoo, MI, USA 2 Department of Physical Therapy, Western Michigan University, Kalamazoo, MI, USA 3 Women’s Health Research Laboratory, Department of Physical Therapy, Federal University of São Carlos, São Carlos, SP, Brazil Purpose: To investigate the efficacy of transcutaneous electrical nerve stimulation (TENS) on the duration and magnitude of muscle pain and fatigue following an exercise-induced fatigue protocol. Methods: Twenty-one participants were tested over three visits. Each visit consisted of an exercise- induced fatigue protocol to the quadriceps muscle followed by one of the three randomized inde- pendent treatments: no intervention (NoTENS), TENS on the fatigued quadriceps (TENSactive), and sham intervention with an inactive TENS (TENSinactive) on the fatigued quadriceps. The visual analog scale (VAS) for perceived muscle pain and fatigue levels was recorded before and after ex- ercise, immediately after the designated follow-up protocol, and 24 and 48 hours after the visit. Results: Post-exercise muscle pain and fatigue decreased immediately following active TENS ap- plication to the quadriceps; this decrease persisted 24 hours post-TENS application. Muscle pain and fatigue immediately after active TENS were significantly lower than NoTENS and TENSinac- tive treatments. The active TENS also showed significantly faster recovery compared to NoTENS and TENSinactive protocols. Conclusions: TENS application immediately after muscle fatigue following exercise was more ef- fective in decreasing muscle pain and muscle fatigue, and improving muscle recovery time com- pared to no TENS or sham TENS. These findings support the use of TENS as a non-invasive, non- pharmacological evidence-based protocol to manage muscle pain and fatigue after exercise, train- ing, and sports, resulting in reduced muscle pain and fatigue, and shortened muscle recovery time after strenuous exercise for athletes and non-athletes aged between 18 and 45 years old. Keywords: muscle fatigue; pain management; exercise-induced fatigue; TENS; transcutaneous elec- trical nerve stimulation 1. Introduction Skeletal muscle fatigue is defined as a decrease in the efficiency of muscle force pro- duction in response to comparable levels of contractile activity. The most common devel- opment mechanisms for muscle fatigue are associated with both metabolic responses to exercise and inflammatory responses elicited by the micro-structural damages imposed on the muscle cells and their connective strata. 1,2 As a result, a broad range of symptoms might emerge, such as varying levels of pain severity, decreased muscle strength and power, functional impairment, changes in joint mechanics, and changes in muscle recruit- ment patterns. 2,3 Multiple interventional protocols aiming to mitigate these fatiguing Corresponding Author: Adriana M Degani; adriana.degani@wmich.edu Western Michigan University Kalamazoo, MI, USA Copyright JCEWM 2024