Transcutaneous electrical nerve stimulation improves fatigue performance of the treated and contralateral knee extensors

• Published in: European journal of applied physiology 2019-12, Vol.119 (11-12), p.2745-2755
• Main Authors: Behm, D. G., Colwell, E. M., Power, G. M. J., Ahmadi, H., Behm, A. S. M., Bishop, A., Murph, C., Pike, J., McAssey, B., Fraser, K., Kearley, S., Ryan, M.
• Format: Article
• Language: English
• Subjects: Adult; Analgesia; Biomedical and Life Sciences; Biomedicine; Chronic pain; Electromyography - methods; Fatigue; Female; Human Physiology; Humans; Isometric; Isometric Contraction - physiology; Knee; Knee - physiopathology; Knee Joint - physiology; Leg; Male; Muscle contraction; Muscle Fatigue - physiology; Muscle Strength - physiology; Occupational Medicine/Industrial Medicine; Original Article; Pain; Pain perception; Quadriceps muscle; Quadriceps Muscle - physiology; Sports Medicine; Transcutaneous Electric Nerve Stimulation - methods; Transcutaneous electrical nerve stimulation-TENS; Young Adult
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-019-04253-z

Purpose Transcutaneous electrical nerve stimulation (TENS) can reduce acute and chronic pain. Unilateral fatigue can produce discomfort in the affected limb and force and activation deficits in contralateral non-exercised muscles. TENS-induced local pain analgesia effects on non-local fatigue performance are unknown. Hence, the aim of the study was to determine if TENS-induced pain suppression would augment force output during a fatiguing protocol in the treated and contralateral muscles. Methods Three experiments were integrated for this article. Following pre-tests, each experiment involved 20 min of TENS, sham, or a control condition on the dominant quadriceps. Then either the TENS-treated quadriceps (TENS_Treated) or the contralateral quadriceps (TENS_Contra) was tested. In a third experiment, the TENS and sham conditions involved two\; 100-s isometric maximal voluntary contractions (MVC) (30-s recovery) followed by testing of the contralateral quadriceps (TENS_Contra-Fatigue). Testing involved single knee extensors (KE) MVCs (pre- and post-test) and a post-test 30% MVC to task failure. Results The TENS-treated study induced greater ( p  = 0.03; 11.0%) time to KE (treated leg) failure versus control. The TENS_Contra-Fatigue induced significant ( p  = 0.04; 11.7%) and near-significant ( p  = 0.1; 7.1%) greater time to contralateral KE failure versus sham and control, respectively. There was a 14.5% ( p  = 0.02) higher fatigue index with the TENS (36.2 ± 10.1%) versus sham (31.6 ± 10.6%) conditions in the second fatigue intervention set (treated leg). There was no significant post-fatigue KE fatigue interaction with the TENS_Contra. Conclusions Unilateral TENS application to the dominant KE prolonged time to failure in the treated and contralateral KE suggesting a global pain modulatory response.