title: Effect of caffeine intake on pain perception during high-intensity exercise.
abstract: Caffeine has been shown to reduce leg-muscle pain during submaximal cycle ergometry, as well as in response to eccentric exercise. However, less is known about its analgesic properties during non-steady-state, high-intensity exercise. The primary aim of this study was to examine the effect of 2 doses of caffeine on leg pain and rating of perceived exertion (RPE) during repeated bouts of high-intensity exercise. Fifteen active men (age 26.4 ± 3.9 yr) completed 2 bouts of 40 repetitions of "all-out" knee extension and flexion of the dominant leg at a contraction velocity equal to 180°/s. Before each trial, subjects abstained from caffeine intake and intense exercise for 48 hr. Over 3 days separated by 48 hr, subjects ingested 1 of 3 treatments (5 mg/kg or 2 mg/kg of anhydrous caffeine or placebo) in a randomized, single-blind, counterbalanced, crossover design. Leg-muscle pain and RPE were assessed during and after exercise using established categorical scales. Across all treatments, pain perception was significantly increased (p < .05) during exercise, as well as from Bout 1 to 2, yet there was no effect (p > .05) of caffeine on pain perception or RPE. Various measures of muscle function were improved (p < .05) with a 5-mg/kg caffeine dose vs. the other treatments. In the 5-mg/kg trial, it is plausible that subjects were able to perform better with similar levels of pain perception and exertion.
authors.affiliation: Dept. of Kinesiology, California State University-San Marcos, San Marcos, CA, USA.
authors.forename: Todd A
authors.initials: TA
authors.lastname: Astorino
authors.forename: Michael N
authors.initials: MN
authors.lastname: Terzi
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Roberson
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Burnett
mesh_terms: D000328:Adult; D002110:Caffeine / Q000008:administration & dosage* / Q000494:pharmacology; D000697:Central Nervous System Stimulants / Q000008:administration & dosage* / Q000494:pharmacology; D018592:Cross-Over Studies; D015444:Exercise / Q000502:physiology / Q000523:psychology*; D006801:Humans; D007866:Leg / Q000502:physiology; D008297:Male; D009132:Muscles / Q000502:physiology; D010147:Pain Measurement / Q000523:psychology; D058748:Pain Perception / Q000187:drug effects*; D005082:Physical Exertion / Q000187:drug effects / Q000502:physiology; D055815:Young Adult
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine