Effect of Repeated Caffeine Ingestion on Repeated Exhaustive Exercise Endurance

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Authors
  1. Bell, D.G.
  2. McLellan, T.M.
Corporate Authors
Defence R&D Canada - Toronto, Toronto ONT (CAN)
Abstract
Caffeine is known to prolong exercise times during a single bout of exhaustive exercise yet the effect on performance with repeated dosing of the drug has not been determined. Thus the purpose of this study was to examine the effect of repeated doses of caffeine on exercise performance. Nine male caffeine users performed exercise rides (ER) to exhaustion at 80% after ingesting a placebo, 5 mg/kg of caffeine or 2.5 mg/kg of caffeine one hour before the ER. Two ERs were performed weekly on the same day once in the morning (AM) and five hours later in the afternoon (PM). There were 4 treatments containing either caffeine or placebo (a dietary fibre) i.e., trial A representing 5 mg/kg caffeine in the AM and 2.5 mg/kg caffeine in the PM; trial B which was placebo in both AM and PM; trial C representing 5 mg/kg caffeine in the AM and placebo in the PM; and trial D representing a placebo in the AM and 5 mg/kg caffeine in the PM. The order of the treatment trials was double-blind and randomized. Caffeine ingestion significantly increased exercise time to exhaustion in the AM (trial A 24.9 ± 10.2 min and trial C 21.8 ± 4.9 versus trial B 18.0 ± 6.4 min and D 17.7 ± 4.3 min). This effect was maintained in the PM and greater than placebo (B 18.3 ± 4.8 min) regardless of whether redosing (trial A 21.5 ± 8.6 min) or placebo (trial C 21.0 ± 6.8) followed the initial morning dose. Caffeine dosing in the PM (trial D 22.4 ± 7.2 min) also increased ER following placebo trial D in the A

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Keywords
time to exhaustion;ergogenic aids;re-dosing;carry-over effects;repeated exercise
Report Number
DRDC-TORONTO-SL-2002-194 — Scientific Literature
Date of publication
01 Jan 2003
Number of Pages
8
Reprinted from
Medicine and Science in Sports and Excersise, vol 35, no 8, 2003, p 1348-1354
DSTKIM No
CA025730
CANDIS No
523441
Format(s):
CD ROM

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