title: Muscle Pain as a Regulator of Cycling Intensity: Effect of Caffeine Ingestion.
abstract: Caffeine ingestion improves endurance time trial performance. However, the ergogenic mechanism of action remains unresolved. One potential explanation for caffeine's performance-enhancing effect is an improvement in work for a given amount of muscle pain.
  
  
  OBJECTIVE
  To test this hypothesis, participants performed two studies in which they regulated exercise intensity based on feelings of muscle pain.
  
  
  METHODS
  Thirteen young men were asked to regulate exercise intensity based on feelings of "moderate" muscle pain (a "3" on a 0-10 pain scale). After three familiarization trials, either caffeine (∼ 5 mg · kg(-1) body weight) or placebo were administered before a moderate pain trial. Nine caffeine "responders" were retested and ask to regulate their exercise intensity at a "strong" pain level (a "5" on a 0-10 pain scale). A caffeine (∼ 5 mg · kg(-1) body weight) or placebo was again ingested before exercise.
  
  
  RESULTS
  Participants performed more work (P = 0.008) and covered more distance (P = 0.008) at a higher average power output (P = 0.009) and VO2 (P = 0.019), for an identical amount of "moderate" muscle pain in the caffeine condition. When exercising at a rating of a "5," caffeine did not increase total work, distance covered, or VO2 for an identical amount of "strong" pain in the nine caffeine "responders."
  
  
  CONCLUSIONS
  Our findings indicate caffeine increases work performed during exercise, eliciting a moderate amount of a pain. However, a threshold level of muscle pain may exist above which antagonism of adenosine receptors alone does not induce a hypoalgesic effect.
authors: Department of Health and Exercise Science, University of Oklahoma, Norman, OK.
authors: Alexander R
authors: AR
authors: Gonglach
authors: Carl J
authors: CJ
authors: Ade
authors: Michael G
authors: MG
authors: Bemben
authors: Rebecca D
authors: RD
authors: Larson
authors: Christopher D
authors: CD
authors: Black
mesh_terms: D000293:Adolescent; D000328:Adult; D001642:Bicycling / Q000502:physiology*; D002110:Caffeine / Q000008:administration & dosage*; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D063806:Myalgia / Q000503:physiopathology*; D010101:Oxygen Consumption; D058573:Performance-Enhancing Substances / Q000008:administration & dosage*; D010807:Physical Endurance / Q000187:drug effects / Q000502:physiology*; D055815:Young Adult
chemical_list: D058573:Performance-Enhancing Substances; D002110:Caffeine