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Transcranial Direct Current Stimulation Accelerates The Onset of Exercise-Induced Hypoalgesia: A Randomized Controlled Study

  • Jana Borovskis
    Affiliations
    School of Health Sciences, Western Sydney University, NSW 2560, Australia

    Brain Stimulation and Rehabilitation (BrainStAR) Lab, Western Sydney University, NSW 2560, Australia
    Search for articles by this author
  • Rocco Cavaleri
    Affiliations
    School of Health Sciences, Western Sydney University, NSW 2560, Australia

    Brain Stimulation and Rehabilitation (BrainStAR) Lab, Western Sydney University, NSW 2560, Australia
    Search for articles by this author
  • Felicity Blackstock
    Affiliations
    School of Health Sciences, Western Sydney University, NSW 2560, Australia
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  • Simon J Summers
    Correspondence
    Address reprint requests to Simon J Summers, Western Sydney University, Brain Stimulation and Rehabilitation (BrainStAR) Lab, Locked Bag 1797, Penrith, NSW 2751, Australia.
    Affiliations
    School of Health Sciences, Western Sydney University, NSW 2560, Australia

    Brain Stimulation and Rehabilitation (BrainStAR) Lab, Western Sydney University, NSW 2560, Australia

    Discipline of Sport and Exercise Science, Faculty of Health, University of Canberra, ACT 2617, Australia

    Research School of Biology, Australian National University, ACT 2600, Australia
    Search for articles by this author
Published:September 11, 2020DOI:https://doi.org/10.1016/j.jpain.2020.08.004

      Highlights

      • Motor cortex Transcranial direct current stimulation (tDCS) accelerates the onset of exercise-induced hypoalgesia (EIH).
      • The effect of tDCS on EIH is not mediated by descending inhibitory pain mechanisms.
      • tDCS may be a promising adjunct treatment to exercise for pain management.

      Abstract

      Exercise-induced hypoalgesia (EIH) describes acute reductions in pain that occur following exercise. Current evidence suggests that the magnitude of EIH is small-to-moderate at best, warranting exploration of novel avenues to bolster these effects. Transcranial direct current stimulation (tDCS) has been shown to relieve pain and represents a promising intervention that may enhance EIH. This study aimed to determine whether anodal tDCS of the primary motor cortex (M1) can augment EIH in healthy individuals experiencing experimentally-induced musculoskeletal pain. Twenty-four healthy subjects attended 2 experimental sessions (“Day 0” and “Day 2”). On Day 0, subjects were injected with nerve growth factor into their right extensor carpi radialis brevis to induce persistent elbow pain. On Day 2, each subject received active or sham tDCS over M1 followed by an isometric grip exercise. Pain intensity, muscle soreness, sensitivity (pressure pain thresholds), and conditioned pain modulation were assessed prior to the nerve growth factor injection, on Day 2 before tDCS, immediately post-exercise, and 15 minutes post-exercise. Active tDCS expedited the onset of EIH, inducing immediate reductions in pain intensity that were not present until 15 minutes post-exercise in the sham group. However, active tDCS did not reduce muscle soreness or sensitivity when compared to sham tDCS.

      Perspective

      These findings suggest that active tDCS accelerates the onset of EIH in healthy individuals experiencing experimentally-induced pain. This may represent a promising means of enhancing adherence to exercise protocols. However, larger randomised controlled trials in persistent pain populations are required to confirm the clinical impact of these findings.

      Key Words

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