The effect of caffeine ingestion on 8 km run performance in a field setting.
The aim of this study was to assess the effect of caffeine ingestion on 8 km run performance using an ecologically valid test protocol. A randomized double-blind crossover study was conducted involving eight male distance runners. The participants ran an 8 km race 1 h after ingesting a placebo capsule, a caffeine capsule (3 mg x kg(-1) body mass) or no supplement. Heart rate was recorded at 5 s intervals throughout the race. Blood lactate concentration and ratings of perceived exertion were recorded after exercise. A repeated-measures analysis of variance (ANOVA) identified a significant treatment effect for 8 km performance time (P < 0.05); caffeine resulted in a mean improvement of 23.8 s (95% confidence interval [CI] = 13.1 to 34.5 s) in 8 km performance time (1.2% improvement, 95% CI = 0.7 to 1.8%). In addition, a two-way (time x condition) repeated-measures ANOVA identified a significantly higher blood lactate concentration 3 min after exercise during the caffeine trial (P < 0.05). We conclude that ingestion of 3 mg . kg(-1) body mass of caffeine can improve absolute 8 km run performance in an ecologically valid race setting.
Bridge
C A
CA
Sport and Exercise Research Group, Edge Hill College, Ormskirk, UK. bridge@edgehill.ac.uk
Jones
M A
MA
D000328:Adult; D015992:Body Mass Index; D002110:Caffeine / Q000008:administration & dosage*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007773:Lactates / Q000378:metabolism; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010807:Physical Endurance / Q000187:drug effects*; D005082:Physical Exertion; D011336:Probability; D012016:Reference Values; D012420:Running / Q000502:physiology*; D014142:Track and Field
D000697:Central Nervous System Stimulants; D007773:Lactates; D002110:Caffeine