Effects of different doses of caffeine on exercise responses in young children.


Journal Article

INTRODUCTION/PURPOSE: This study investigated the effects of three different doses of caffeine on physiological responses to exercise in young children. METHODS: Forty healthy children (20 boys and 20 girls) volunteered for a random, double-blind, counterbalanced study where they received either placebo (PL), 1 mg.kg(-1) (CAF-1), 3 mg.kg(-1) (CAF-3), or 5 mg.kg(-1) (CAF-5) caffeine, 60 min prior to preexercise measures, followed by cycle ergometer exercise at 25 W and then 60% VO2peak. During this time, heart rate (HR), oxygen consumption (VO2), and respiratory exchange ratio (RER) were measured continuously, while blood pressure (BP) was measured every 2 min. RESULTS: There were no significant gender x treatment interactions, and so the boys' and girls' data were combined. At preexercise, CAF-5 SBP and DBP were significantly (P < 0.05) higher than PL. Both CAF-1 and CAF-3 DBP were also significantly (P < 0.05) higher versus PL at preexercise. There were no treatment effects for exercise BP. At rest and during both exercise intensities, HR was significantly (P < 0.05) lower in CAF-3 (approximately 5 bpm) and CAF-5 (approximately 6 bpm) versus PL. There were no significant effects of CAF on metabolism (VO2 or RER) except for a lower RER in CAF-1 versus CAF-5 at 60% VO2peak. CONCLUSION: Low, mild, and moderate (1, 3, and 5 mg.kg(-1)) doses of caffeine have no effect on substrate use as reflected by RER. Further, caffeine intake resulted in an increase in BP and decrease in HR at preexercise and a slight decrease in HR with CAF-3 and CAF-5 versus PL during exercise.

Full Text

Duke Authors

Cited Authors

  • Turley, KR; Bland, JR; Evans, WJ

Published Date

  • May 2008

Published In

Volume / Issue

  • 40 / 5

Start / End Page

  • 871 - 878

PubMed ID

  • 18408611

Pubmed Central ID

  • 18408611

International Standard Serial Number (ISSN)

  • 0195-9131

Digital Object Identifier (DOI)

  • 10.1249/MSS.0b013e318165984c


  • eng

Conference Location

  • United States