Carbohydrate Dependence During Prolonged, Intense Endurance Exercise

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

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.

Publication types

  • Review

MeSH terms

  • Adaptation, Physiological
  • Competitive Behavior / physiology
  • Diet, Carbohydrate-Restricted
  • Diet, High-Fat
  • Dietary Carbohydrates / administration & dosage
  • Dietary Carbohydrates / metabolism*
  • Energy Metabolism
  • Exercise / physiology*
  • Humans
  • Muscle, Skeletal / metabolism
  • Oxidation-Reduction
  • Physical Education and Training
  • Physical Endurance / physiology*
  • Sports Nutritional Physiological Phenomena

Substances

  • Dietary Carbohydrates