The influence of dietary carbohydrate and pre-exercise glucose consumption on supramaximal intermittent exercise performance

Jenkins, D.G., Hutchins, C.A. and Spillman, D. (1994) The influence of dietary carbohydrate and pre-exercise glucose consumption on supramaximal intermittent exercise performance. British Journal of Sports Medicine, 28 3: 171-176. doi:10.1136/bjsm.28.3.171


Author Jenkins, D.G.
Hutchins, C.A.
Spillman, D.
Title The influence of dietary carbohydrate and pre-exercise glucose consumption on supramaximal intermittent exercise performance
Journal name British Journal of Sports Medicine   Check publisher's open access policy
ISSN 0306-3674
Publication date 1994-09
Sub-type Article (original research)
DOI 10.1136/bjsm.28.3.171
Volume 28
Issue 3
Start page 171
End page 176
Total pages 6
Place of publication London, United Kingdom
Publisher B M J Group
Language eng
Formatted abstract
The present study examined whether a pre-exercise consumption of glucose by subjects having adhered to a 3-day low carbohydrate (CHO) or normal CHO diet would influence supramaximal intermittent exercise performance. Sixteen moderately active men volunteers (mean(s.d.) age 20.0(1.3) years) agreed to undertake three exercise tests over an 8-day period; in addition to completing a V̇o(2max) test, the subjects performed two identical maximal interval tests (MIT1 and MIT2). Periods of 3 days separated each of the three tests. The interval tests involved five 60-s 'all-out' cycling bouts working against a resistance of 0.075 kg kg-1 body mass; each bout was separated by 5 min of passive recovery. For 3 days preceding the first interval test (MIT1), all subjects adhered to a 'moderate' CHO diet which comprised 59.1% (approximately 4.1 g kg-1 body mass) of the daily energy intake as CHO. Following MIT1 and for 3 days before MIT2 subjects were randomly assigned to follow either a moderate CHO diet (60.8%) or a low CHO diet (14.4% or 1.1 g kg-1 body mass). All food and drink consumed during the experimental period was weighed and recorded for later dietary analysis. One hour before MIT2, eight subjects were administered (in single blind fashion) a 15% glucose solution (1 g kg-1 body mass) while the other eight subjects consumed a low-energy sweetened placebo. During both interval tests, values of work, exercise V̇o2, plasma glucose, plasma lactate and venous blood pH were statistically analysed. No changes in performance between MIT1 and MIT2 across conditions were found (P>0.05). However, those subjects who consumed the glucose solution before MIT2 (irrespective of their dietary CHO intake) consumed significantly less oxygen during exercise than those who had been given the placebo solution (P<0.05). While these findings question the ergogenic potential of consuming glucose before supramaximal exercise, the V̇o2 data implicate a possible shift in substrate utilization during repeated sprint exercise after pre-exercise glucose ingestion.
Keyword Supramaximal exercise
Dietary carbohydrate
Glucose ingestion
Glycogen
Metabolism
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Human Movement and Nutrition Sciences Publications
 
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Created: Wed, 09 Mar 2011, 08:50:04 EST