title: Perceptual and cerebro-spinal responses to graded innocuous and noxious stimuli following aerobic exercise.
abstract: OBJECTIVE
  The aim of this study was to evaluate the effect of aerobic exercise on perceptual and cerebro-spinal responses to graded electrocutaneous stimuli.
  
  
  METHODS
  The design comprised 2 x 30 min of cycling exercise at 30% and 70% of peak oxygen consumption (VO2 peak) on separate occasions in a counter-balanced order in 10 healthy participants. Assessment of nociceptive withdrawal reflex threshold (NWR-T), pain threshold (PT), and somatosensory evoked potentials (SEPs) to graded electrocutaneous stimuli were performed before and after exercise. Perceptual magnitude ratings and SEPs were compared at 30%PT, 60%PT, 100%PT before (Pre), 5 min after (Post1), and 15 min after (Post2) aerobic exercise.
  
  
  RESULTS
  There was no difference in the NWR-T and the PT following exercise at 30% and 70% of VO2 peak. ANOVA for the perceptual response within pooled electrocutaneous stimuli show a significant main effect for time (F2,18=5.41, P=0.01) but no difference for exercise intensity (F1,9=0.02, P=0.88). Within-subject contrasts reveal trend differences between 30%PT and 100%PT for Pre-Post1 (P=0.09) and Pre-Post2 (P=0.02). ANOVA for the SEPs peak-to-peak signal amplitude (N1-P1) show significant main effect for time (F2,18=4.04, P=0.04) but no difference for exercise intensity (F1,9=1.83, P=0.21). Pairwise comparisons for time reveal differences between Pre-Post1 (P=0.06) and Pre-Post2 (P=0.01). There was a significant interaction for SEPs N1-P1 between exercise intensity and stimulus intensity (F2,18=3.56, P=0.05).
  
  
  CONCLUSIONS
  These results indicate that aerobic exercise did not increase the electrocutaneous threshold for pain and the NWR-T. Aerobic exercise attenuated perceptual responses to innocuous stimuli and SEPs N1-P1 response to noxious stimuli.
authors.affiliation: School of Biomedical Sciences, Charles Sturt University, Bathurst, Australia - pmicalos@csu.edu.au.
authors.forename: P S
authors.initials: PS
authors.lastname: Micalos
authors.forename: J
authors.initials: J
authors.lastname: Harris
authors.forename: E J
authors.initials: EJ
authors.lastname: Drinkwater
authors.forename: J
authors.initials: J
authors.lastname: Cannon
authors.forename: F E
authors.initials: FE
authors.lastname: Marino
mesh_terms: D004558:Electric Stimulation; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D015444:Exercise / Q000523:psychology*; D005080:Exercise Test; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D010146:Pain / Q000503:physiopathology* / Q000523:psychology; D010147:Pain Measurement / Q000379:methods*; D058748:Pain Perception; D017288:Pain Threshold / Q000523:psychology*; D055815:Young Adult