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

Abiss, C. R., Peiffer, J. J., Peake, J. M., Nosaka, K., Suzuki, K., Martin, D.T. and Laursen, P. B. (2008) Effect of carbohydrate ingestion and ambient temperature on muscle fatigue development in endurance-trained male cyclists. Journal of Applied Physiology, 104 4: 1021-1028. doi:10.1152/japplphysiol.00683.2007


Author Abiss, C. R.
Peiffer, J. J.
Peake, J. M.
Nosaka, K.
Suzuki, K.
Martin, D.T.
Laursen, P. B.
Title Effect of carbohydrate ingestion and ambient temperature on muscle fatigue development in endurance-trained male cyclists
Journal name Journal of Applied Physiology   Check publisher's open access policy
ISSN 8750-7587
Publication date 2008-01-01
Year available 2008
Sub-type Article (original research)
DOI 10.1152/japplphysiol.00683.2007
Open Access Status
Volume 104
Issue 4
Start page 1021
End page 1028
Total pages 8
Editor J. A. Dempsey
Place of publication Bethesda, MD
Publisher American Physiological Society
Language eng
Subject C1
950102 Organised Sports
110602 Exercise Physiology
111101 Clinical and Sports Nutrition
920411 Nutrition
11 Medical and Health Sciences
1103 Clinical Sciences
Abstract 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 ((V) over dot O-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.
Formatted abstract
 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 (O2max = 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°C) or hot (32.2 ± 0.7°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.
Keyword Heat
Integrated electromyography
Power
Thermoregulation
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID R01 DK 49779
M01-RR00032
P30-DK56336
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Human Movement and Nutrition Sciences Publications
 
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Created: Sun, 22 Mar 2009, 21:12:01 EST by Deborah Noon on behalf of Faculty Of Health Sciences