title: The effect of transcranial direct current stimulation of the motor cortex on exercise-induced pain.
abstract: OBJECTIVE
  Transcranial direct current stimulation (tDCS) provides a new exciting means to investigate the role of the brain during exercise. However, this technique is not widely used in exercise science, with little known regarding effective electrode montages. This study investigated whether tDCS of the motor cortex (M1) would elicit an analgesic response to exercise-induced pain (EIP).
  
  
  METHODS
  Nine participants completed a VO2max test and three time to exhaustion (TTE) tasks on separate days following either 10 min 2 mA tDCS of the M1, a sham or a control. Additionally, seven participants completed 3 cold pressor tests (CPT) following the same experimental conditions (tDCS, SHAM, CON). Using a well-established tDCS protocol, tDCS was delivered by placing the anodal electrode above the left M1 with the cathodal electrode above dorsolateral right prefrontal cortex. Gas exchange, blood lactate, EIP and ratings of perceived exertion (RPE) were monitored during the TTE test. Perceived pain was recorded during the CPT.
  
  
  RESULTS
  During the TTE, no significant differences in time to exhaustion, RPE or EIP were found between conditions. However, during the CPT, perceived pain was significantly (P < 0.05) reduced in the tDCS condition (7.4 ± 1.2) compared with both the CON (8.6 ± 1.0) and SHAM (8.4 ± 1.3) conditions.
  
  
  CONCLUSIONS
  These findings demonstrate that stimulation of the M1 using tDCS does not induce analgesia during exercise, suggesting that the processing of pain produced via classic measures of experimental pain (i.e., a CPT) is different to that of EIP. These results provide important methodological advancement in developing the use of tDCS in exercise.
authors.affiliation: Endurance Research Group, School of Sport and Exercise Sciences, Faculty of Science, University of Kent, Chatham Maritime, Kent, ME4 4AG, UK.
authors.forename: Luca
authors.initials: L
authors.lastname: Angius
authors.affiliation: Endurance Research Group, School of Sport and Exercise Sciences, Faculty of Science, University of Kent, Chatham Maritime, Kent, ME4 4AG, UK.
authors.forename: James G
authors.initials: JG
authors.lastname: Hopker
authors.affiliation: Endurance Research Group, School of Sport and Exercise Sciences, Faculty of Science, University of Kent, Chatham Maritime, Kent, ME4 4AG, UK.
authors.forename: Samuele M
authors.initials: SM
authors.lastname: Marcora
authors.affiliation: Endurance Research Group, School of Sport and Exercise Sciences, Faculty of Science, University of Kent, Chatham Maritime, Kent, ME4 4AG, UK. lex.mauger@gmail.com.
authors.forename: Alexis R
authors.initials: AR
authors.lastname: Mauger
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology*; D010146:Pain / Q000503:physiopathology*; D059408:Pain Management; D017288:Pain Threshold / Q000502:physiology*; D065908:Transcranial Direct Current Stimulation; D055815:Young Adult
keywords: Exercise; Fatigue; Pain perception; Performance; tDCS