Considerations for ultra-endurance activities: part 1- nutrition

Res Sports Med. Apr-Jun 2019;27(2):166-181. doi: 10.1080/15438627.2018.1502188. Epub 2018 Jul 28.


Ultra-endurance activities (≥ 4h) present unique challenges that, beyond fatigue, may be exacerbated by sub-optimal nutrition during periods of increased requirements and compromised gastrointestinal function. The causes of fatigue during ultra-endurance exercise are multi-factorial. However, mechanisms can potentially include central or peripheral fatigue, thermal stress, dehydration, and/or endogenous glycogen store depletion; of which optimising nutrition and hydration can partially attenuate. If exercise duration is long enough (e.g. ≥ 10h) and exercise intensity low enough (e.g. 45-60% of maximal oxygen uptake), it is bio-energetically plausible that ketogenic adaptation may enhance ultra-endurance performance, but this requires scientific substantiation. Conversely, the scientific literature has consistently demonstrated that daily dietary carbohydrates (3-12g/kg/day) and carbohydrate intake (30-110g/h) during ultra-endurance events can enhance performance at individually tolerable intake rates. Considering gastrointestinal symptoms are common in ultra-endurance activities, effective dietary prevention and management strategies may provide functional, histological, systemic, and symptomatic benefits. Taken together, a well-practiced and individualized fuelling approach is required to optimize performance in ultra-endurance events.

Keywords: Carbohydrate; Energy; Epithelium; Gastrointestinal Symptoms; Ketogenic; Protein.

Publication types

  • Review

MeSH terms

  • Athletes*
  • Athletic Performance / physiology*
  • Dehydration / prevention & control
  • Diet, Ketogenic
  • Dietary Carbohydrates / administration & dosage*
  • Energy Metabolism / physiology*
  • Exercise / physiology*
  • Fatigue / prevention & control
  • Gastrointestinal Diseases / prevention & control
  • Humans
  • Nutritional Requirements / physiology*
  • Physical Endurance / physiology*
  • Sports Nutritional Physiological Phenomena / physiology*


  • Dietary Carbohydrates