Caffeine, cycling performance, and exogenous CHO oxidation: a dose-response study.
OBJECTIVE
This study investigated the effects of a low and moderate caffeine dose on exogenous CHO oxidation and endurance-exercise performance.


METHODS
Nine trained and familiarized male cyclists (mean +/- SD: 29.4 +/- 4.5 yr, 81.3 +/- 10.8 kg body weight [BW], 183.8 +/- 8.2 cm, V O2peak = 61.7 +/- 4.8 mL.kg.min) undertook three trials, with training and high CHO diet being controlled. One hour before exercise, subjects ingested capsules containing placebo and 1.5 or 3 mg.kg BW of caffeine using a double-blind administration protocol. Trials consisted of 120 min steady-state cycling at approximately 70% V O2peak, immediately followed by a 7-kJ.kg BW time trial (TT). During exercise, subjects were provided with fluids containing C-glucose every 20 min to determine exogenous CHO oxidation.


RESULTS
No significant TT performance improvements were observed during caffeine-containing trials (mean +/- SD: placebo = 30 min 25 s +/- 3 min 10 s; 1.5 mg.kg BW = 30 min 42 s +/- 3 min 41 s; and 3 mg.kg BW = 29 min 51 s +/- 3 min 38 s). Furthermore, caffeine failed to significantly alter maximal exogenous CHO oxidation (maximal oxidation rates: placebo = 0.95 +/- 0.2 g.min; 1.5 mg.kg BW = 0.92 +/- 0.2 g.min; and 3 mg.kg BW = 0.96 +/- 0.2 g.min).


CONCLUSIONS
Low and moderate doses of caffeine have failed to improve endurance performance in fed, trained subjects.
Desbrow
Ben
B
School of Public Health, Griffith University, Queensland, Australia. b.desbrow@griffith.edu.au
Barrett
Clare M
CM
Minahan
Clare L
CL
Grant
Gary D
GD
Leveritt
Michael D
MD
D000328:Adult; D001642:Bicycling / Q000502:physiology*; D002110:Caffeine / Q000008:administration & dosage / Q000378:metabolism*; D002237:Carbohydrate Dehydrogenases / Q000187:drug effects*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005947:Glucose / Q000032:analysis; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000187:drug effects; D013647:Task Performance and Analysis
D000697:Central Nervous System Stimulants; D002110:Caffeine; D002237:Carbohydrate Dehydrogenases; D005947:Glucose