title: The metabolic and performance effects of caffeine compared to coffee during endurance exercise.
abstract: There is consistent evidence supporting the ergogenic effects of caffeine for endurance based exercise. However, whether caffeine ingested through coffee has the same effects is still subject to debate. The primary aim of the study was to investigate the performance enhancing effects of caffeine and coffee using a time trial performance test, while also investigating the metabolic effects of caffeine and coffee. In a single-blind, crossover, randomised counter-balanced study design, eight trained male cyclists/triathletes (Mean ± SD: Age 41 ± 7 y, Height 1.80 ± 0.04 m, Weight 78.9 ± 4.1 kg, VO2 max 58 ± 3 ml • kg(-1) • min(-1)) completed 30 min of steady-state (SS) cycling at approximately 55% VO2max followed by a 45 min energy based target time trial (TT). One hour prior to exercise each athlete consumed drinks consisting of caffeine (5 mg CAF/kg BW), instant coffee (5 mg CAF/kg BW), instant decaffeinated coffee or placebo. The set workloads produced similar relative exercise intensities during the SS for all drinks, with no observed difference in carbohydrate or fat oxidation. Performance times during the TT were significantly faster (~5.0%) for both caffeine and coffee when compared to placebo and decaf (38.35 ± 1.53, 38.27 ± 1.80, 40.23 ± 1.98, 40.31 ± 1.22 min respectively, p<0.05). The significantly faster performance times were similar for both caffeine and coffee. Average power for caffeine and coffee during the TT was significantly greater when compared to placebo and decaf (294 ± 21 W, 291 ± 22 W, 277 ± 14 W, 276 ± 23 W respectively, p<0.05). No significant differences were observed between placebo and decaf during the TT. The present study illustrates that both caffeine (5 mg/kg/BW) and coffee (5 mg/kg/BW) consumed 1 h prior to exercise can improve endurance exercise performance.
authors.affiliation: Human Performance Laboratory, School of Sport and Exercise Science, University Of Birmingham, Birmingham, United Kingdom.
authors.forename: Adrian B
authors.initials: AB
authors.lastname: Hodgson
authors.forename: Rebecca K
authors.initials: RK
authors.lastname: Randell
authors.forename: Asker E
authors.initials: AE
authors.lastname: Jeukendrup
mesh_terms: D000328:Adult; D056352:Athletes; D054874:Athletic Performance; D001642:Bicycling; D001786:Blood Glucose; D002110:Caffeine / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D050260:Carbohydrate Metabolism / Q000187:drug effects; D003069:Coffee; D018592:Cross-Over Studies; D005227:Fatty Acids / Q000097:blood; D005990:Glycerol / Q000097:blood; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D050356:Lipid Metabolism / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D058573:Performance-Enhancing Substances / Q000494:pharmacology*; D010807:Physical Endurance / Q000187:drug effects*; D016037:Single-Blind Method
chemical_list: D001786:Blood Glucose; D003069:Coffee; D005227:Fatty Acids; D058573:Performance-Enhancing Substances; D019344:Lactic Acid; D002110:Caffeine; D005990:Glycerol