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Sports Med. 2015 Nov;45 Suppl 1:S5-12. doi: 10.1007/s40279-015-0400-1.

Carbohydrate Dependence During Prolonged, Intense Endurance Exercise.

Author information

1
The Mary MacKillop Institute for Health Research, Centre for Exercise and Nutrition, Australian Catholic University, Locked Bag 4115, Fitzroy, VIC, 3065, Australia. John.hawley@acu.edu.au.
2
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK. John.hawley@acu.edu.au.
3
The Mary MacKillop Institute for Health Research, Centre for Exercise and Nutrition, Australian Catholic University, Locked Bag 4115, Fitzroy, VIC, 3065, Australia.

Abstract

A major goal of training to improve the performance of prolonged, continuous, endurance events lasting up to 3 h is to promote a range of physiological and metabolic adaptations that permit an athlete to work at both higher absolute and relative power outputs/speeds and delay the onset of fatigue (i.e., a decline in exercise intensity). To meet these goals, competitive endurance athletes undertake a prodigious volume of training, with a large proportion performed at intensities that are close to or faster than race pace and highly dependent on carbohydrate (CHO)-based fuels to sustain rates of muscle energy production [i.e., match rates of adenosine triphosphate (ATP) hydrolysis with rates of resynthesis]. Consequently, to sustain muscle energy reserves and meet the daily demands of training sessions, competitive athletes freely select CHO-rich diets. Despite renewed interest in high-fat, low-CHO diets for endurance sport, fat-rich diets do not improve training capacity or performance, but directly impair rates of muscle glycogenolysis and energy flux, limiting high-intensity ATP production. When highly trained athletes compete in endurance events lasting up to 3 h, CHO-, not fat-based fuels are the predominant fuel for the working muscles and CHO, not fat, availability becomes rate limiting for performance.

PMID:
26553495
PMCID:
PMC4672006
DOI:
10.1007/s40279-015-0400-1
[Indexed for MEDLINE]
Free PMC Article

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