Resumen de Muscle Pain as a Regulator of Cycling Intensity: Effect of Caffeine Ingestion.
Alexander R. Gonglach, Carl J. Ade, Michael G. Bemben, Rebecca D. Larson, Christopher D. Black
AB 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. Purpose: 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[middle dot]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[middle dot]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 V[spacing dot above]O2 (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 V[spacing dot above]O2 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
