The effect of pre-exercise glucose ingestion on performance during prolonged swimming.
The purpose of this study was to determine if pre-exercise glucose ingestion would improve distance swimming performance. Additionally, pre-exercise glucose was provided at 2 different feeding intervals to investigate the affects of the timing of administration. Ten male triathletes (mean +/- SD: age, 29.5 +/- 5.0 years; VO2peak, 48.8 +/- 3.2 ml.kg-1.min-1) swam 4000 m on 3 occasions following the consumption of either a 10% glucose solution 5 min prior to exercise (G5), a 10% glucose solution 35 min prior to exercise (G35), or a similar volume of placebo (PL). Despite a significant difference (p < .01) in blood glucose concentration prior to exercise (mean +/- SD in mmol.L-1: G35 8.4 +/- 1.1 vs. G5 5.2 +/- 0.5 or PL 5.3 +/- 0.4), no significant differences were observed in total time (mean +/- SD in minutes: G35 70.7 +/- 7.6, G5 70.1 +/- 7.6, PL 71.9 +/- 8.4), post-exercise blood glucose (mean +/- SD in mmol.L-1: G35 5.1 +/- 1.1, G5 5.1 +/- 0.9, PL 5.3 +/- 0.4), and average heart rate (mean +/- SD in bpm: G35 155.8 +/- 10.8, G5 153.6 +/- 12.6, PL 152.0 +/- 12.5; p > .05). While not reaching statistical significance, glucose feedings did result in improved individual performance times, ranging from 24 s to 5 min in 8 of the 10 subjects compared to the placebo. These results were found despite significant differences in blood glucose between trials immediately prior to exercise.
J.M. Buchanan Exercise Science Laboratory, School of Human Kinetics, University of British Columbia, Vancouver, B.C., Canada V6T 1Z1.
Gareth J
GJ
Smith
Edward C
EC
Rhodes
Robert H
RH
Langill
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001786:Blood Glucose / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D005947:Glucose / Q000008:administration & dosage* / Q000378:metabolism; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010807:Physical Endurance / Q000187:drug effects*; D013550:Swimming / Q000502:physiology*; D013997:Time Factors
D001786:Blood Glucose; D019344:Lactic Acid; D005947:Glucose