Effect of carbohydrate ingestion and ambient temperature on muscle fatigue development in endurance-trained male cyclists

Abbiss, Chris, Peiffer, Jeremiah, Peake, Jonathan, Nosaka, Kazunori, Suzuki, Katsuhiko, Martin, David, & Laursen, Paul (2008) Effect of carbohydrate ingestion and ambient temperature on muscle fatigue development in endurance-trained male cyclists. Journal of Applied Physiology, 104(4), pp. 1021-1028.

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The aim of the present study was to determine the effect of carbohydrate (CHO; sucrose) ingestion and environmental heat on the development of fatigue and the distribution of power output during a 16.1-km cycling time trial. Ten male cyclists (Vo(2max) = 61.7 +/- 5.0 ml.kg(-1).min(-1), mean +/- SD) performed four 90-min constant-pace cycling trials at 80% of second ventilatory threshold (220 +/- 12 W). Trials were conducted in temperate (18.1 +/- 0.4 degrees C) or hot (32.2 +/- 0.7 degrees C) conditions during which subjects ingested either CHO (0.96 g.kg(-1).h(-1)) or placebo (PLA) gels. All trials were followed by a 16.1-km time trial. Before and immediately after exercise, percent muscle activation was determined using superimposed electrical stimulation. Power output, integrated electromyography (iEMG) of vastus lateralis, rectal temperature, and skin temperature were recorded throughout the trial. Percent muscle activation significantly declined during the CHO and PLA trials in hot (6.0 and 6.9%, respectively) but not temperate conditions (1.9 and 2.2%, respectively). The decline in power output during the first 6 km was significantly greater during exercise in the heat. iEMG correlated significantly with power output during the CHO trials in hot and temperate conditions (r = 0.93 and 0.73; P < 0.05) but not during either PLA trial. In conclusion, cyclists tended to self-select an aggressive pacing strategy (initial high intensity) in the heat.

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20 citations in Scopus
22 citations in Web of Science®
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ID Code: 58016
Item Type: Journal Article
Refereed: Yes
Additional Information: Articles free to read on journal website after 12 months
Keywords: exercise, carbohydrate, heat, fatigue
DOI: 10.1152/japplphysiol.00683.2007
ISSN: 8750-7587
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > HUMAN MOVEMENT AND SPORTS SCIENCE (110600) > Exercise Physiology (110602)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Deposited On: 13 May 2013 01:05
Last Modified: 03 Feb 2015 03:00

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