title: Intensity and duration threshold for aerobic exercise-induced analgesia to pressure pain.
abstract: OBJECTIVE
  To examine how exercise-induced analgesia is affected by the duration and intensity of aerobic exercise.
  
  
  METHODS
  Repeated-measures design.
  
  
  METHODS
  Exercise science laboratory.
  
  
  METHODS
  Convenience sample of 12 healthy male and female volunteers (mean age +/- standard deviation, 32+/-9 y).
  
  
  METHODS
  Pain ratings were assessed before and at 5 and 30 minutes after treadmill exercise of 10 minutes at 75% maximal oxygen uptake (Vo(2)max), 30 minutes at 50% Vo(2)max, and 30 minutes at 75% Vo(2)max (randomized order and no less than 48 h between each bout).
  
  
  METHODS
  Pain ratings were measured on a visual analog scale at 10-second intervals during a 2-minute pressure-pain stimulus to the nondominant index finger.
  
  
  RESULTS
  Pain ratings were significantly decreased (P<.05) from pre-exercise values 5 minutes after 30 minutes of exercise at 75% Vo(2)max but returned toward baseline by 30 minutes after exercise. There were no significant changes in pain ratings after 10 minutes of exercise or after exercise at 50% Vo(2)max.
  
  
  CONCLUSIONS
  There are thresholds for both the intensity (>50% Vo(2)max) and duration (>10 min) of exercise required to elicit exercise analgesia.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Veterans Affairs Medical Center and Medical College of Wisconsin, WI, USA. martin.hoffman@med.va.gov
authors.forename: Martin D
authors.initials: MD
authors.lastname: Hoffman
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Shepanski
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Ruble
authors.forename: Zoran
authors.initials: Z
authors.lastname: Valic
authors.forename: John B
authors.initials: JB
authors.lastname: Buckwalter
authors.forename: Philip S
authors.initials: PS
authors.lastname: Clifford
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010147:Pain Measurement; D017288:Pain Threshold; D011312:Pressure; D013997:Time Factors