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Carbohydrate ingestion immediately before exercise does not improve 20 km time trial performance in well trained cyclists.
Int J Sports Med. 1998 Aug; 19(6):415-8.IJ

Abstract

This study examined the effects of carbohydrate ingestion on 20 km cycle time-trial (TT) performance in 14 well-trained cyclists (11 males, 3 females; peak oxygen uptake [VO2peak] 4.52 +/- 0.60 l/min; values are mean +/- SD). All subjects performed two experimental trials on their own bicycles mounted on an air-braked ergometry system (Kingcycle). Subjects were instructed to maintain the same training and dietary regimens before trials, which were conducted in a random order, 3-7 days apart, and at the same time of day for each subject. On the day of a trial, subjects reported to the laboratory and ingested an 8 ml/kg body mass bolus of either a 6.8 g/100 ml commercial carbohydrate-electrolyte (CHO) beverage (39 +/- 4 g of CHO), or a coloured, flavoured placebo. Ten min after finishing the drink, subjects commenced a 5 min warm-up at 150 W, before commencing the 20 km TT. The average power output (312 +/- 40 vs 311 +/- 38 W) and heart-rate (171 +/- 6 vs 171 +/- 5 beats/min for CHO and placebo, respectively) during the two rides did not differ between treatments. Accordingly, the performance times for the two TT's were the same (27:41 +/- 1:39 min:sec, for both CHO and placebo). We conclude that the ingestion of approximately 40 g of carbohydrate does not improve maximal cycling performance lasting approximately 30 min, and that carbohydrate availability, in the form of circulating blood glucose, does not limit high-intensity exercise of this duration.

Authors+Show Affiliations

School of Life Science, Kingston University, Kingston Upon Thames, Surrey, England.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

9774209

Citation

Palmer, G S., et al. "Carbohydrate Ingestion Immediately Before Exercise Does Not Improve 20 Km Time Trial Performance in Well Trained Cyclists." International Journal of Sports Medicine, vol. 19, no. 6, 1998, pp. 415-8.
Palmer GS, Clancy MC, Hawley JA, et al. Carbohydrate ingestion immediately before exercise does not improve 20 km time trial performance in well trained cyclists. Int J Sports Med. 1998;19(6):415-8.
Palmer, G. S., Clancy, M. C., Hawley, J. A., Rodger, I. M., Burke, L. M., & Noakes, T. D. (1998). Carbohydrate ingestion immediately before exercise does not improve 20 km time trial performance in well trained cyclists. International Journal of Sports Medicine, 19(6), 415-8.
Palmer GS, et al. Carbohydrate Ingestion Immediately Before Exercise Does Not Improve 20 Km Time Trial Performance in Well Trained Cyclists. Int J Sports Med. 1998;19(6):415-8. PubMed PMID: 9774209.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Carbohydrate ingestion immediately before exercise does not improve 20 km time trial performance in well trained cyclists. AU - Palmer,G S, AU - Clancy,M C, AU - Hawley,J A, AU - Rodger,I M, AU - Burke,L M, AU - Noakes,T D, PY - 1998/10/17/pubmed PY - 1998/10/17/medline PY - 1998/10/17/entrez SP - 415 EP - 8 JF - International journal of sports medicine JO - Int J Sports Med VL - 19 IS - 6 N2 - This study examined the effects of carbohydrate ingestion on 20 km cycle time-trial (TT) performance in 14 well-trained cyclists (11 males, 3 females; peak oxygen uptake [VO2peak] 4.52 +/- 0.60 l/min; values are mean +/- SD). All subjects performed two experimental trials on their own bicycles mounted on an air-braked ergometry system (Kingcycle). Subjects were instructed to maintain the same training and dietary regimens before trials, which were conducted in a random order, 3-7 days apart, and at the same time of day for each subject. On the day of a trial, subjects reported to the laboratory and ingested an 8 ml/kg body mass bolus of either a 6.8 g/100 ml commercial carbohydrate-electrolyte (CHO) beverage (39 +/- 4 g of CHO), or a coloured, flavoured placebo. Ten min after finishing the drink, subjects commenced a 5 min warm-up at 150 W, before commencing the 20 km TT. The average power output (312 +/- 40 vs 311 +/- 38 W) and heart-rate (171 +/- 6 vs 171 +/- 5 beats/min for CHO and placebo, respectively) during the two rides did not differ between treatments. Accordingly, the performance times for the two TT's were the same (27:41 +/- 1:39 min:sec, for both CHO and placebo). We conclude that the ingestion of approximately 40 g of carbohydrate does not improve maximal cycling performance lasting approximately 30 min, and that carbohydrate availability, in the form of circulating blood glucose, does not limit high-intensity exercise of this duration. SN - 0172-4622 UR - https://www.unboundmedicine.com/medline/citation/9774209/Carbohydrate_ingestion_immediately_before_exercise_does_not_improve_20_km_time_trial_performance_in_well_trained_cyclists_ L2 - http://www.thieme-connect.com/DOI/DOI?10.1055/s-2007-971938 DB - PRIME DP - Unbound Medicine ER -