REF-663 · Costa, Knechtle, Tarnopolsky & Hoffman, 2019 · International Journal of Sport Nutrition and Exercise Metabolism, · Paper · PubMed
Nutrition for ultramarathon running (trail, track, road)
Review: daily carbohydrate up to 12 g/kg, ~90 g/h multiple-transportable carbohydrate for ≥3 h efforts (tolerability in ultra competition questionable), LCHF not supported for performance, drink to thirst
Key Findings
Daily carbohydrate up to 12 g/kg/day and multiple-transportable carbohydrate at ~90 g/h during exercise for running distances ≥3 h support endurance-training adaptation and enhance real-time endurance performance.
Whether ~90 g/h is tolerable during ultramarathon competition is questionable from a practical and gastrointestinal perspective.
Glycogen manipulation and low-carbohydrate high-fat (LCHF) diets are popular among ultrarunners; LCHF raises fat oxidation during submaximal exercise, but a role in enhancing ultramarathon performance is currently not supported.
Hydration: ultrarunners can develop hypohydration or hyperhydration (with exercise-associated hyponatraemia) depending on duration and environment; euhydration can generally be maintained by drinking to thirst.
A well-practised, individualised nutrition strategy is required, for single-stage and multistage events alike.
Pre-race "gut training" as a named technique is not in the abstract (full text; not checked against the abstract) — the abstract's wording is "well practiced and individualized".
Practical Application
Narrative review of ultramarathon nutrition (trail, track, road): the evidence supports daily carbohydrate up to 12 g/kg and ~90 g/h of multiple-transportable carbohydrate for runs ≥3 h, while noting that such intake may not be tolerable during ultra competition; LCHF diets raise fat oxidation but are not supported for better ultra performance; and euhydration is generally maintained by drinking to thirst — so plan a high-carbohydrate strategy, rehearse it until it is tolerable, and do not chase a fixed drinking schedule.
Rehearse the exact race fuelling in long training runs; treat tolerance as something to practise (the review's "well practiced" strategy — see REF-008 for gut-training evidence).
Hydration: drink to thirst rather than to a schedule — both under-drinking (hypohydration) and over-drinking (hyponatraemia) occur in ultras, and the balance shifts with duration and heat.
Limitations
Expert synthesis, not pooled trials; targets are ranges requiring individual tuning and testing.
The ~90 g/h figure comes from endurance research ≥3 h, and the review itself questions its tolerability in ultra competition — it is a ceiling to work towards, not a race-day given.
How this entry was checked and changed
Content correction 2026-09-27
Sport "trail running" -> running, trail running (review covers trail, track and road ultramarathons).
Added the abstract's numbers and positions: daily CHO up to 12 g/kg, ~90 g/h multiple-transportable CHO for ≥3 h with the tolerability caveat, LCHF not supported for performance, drink to thirst (avoid hypohydration and hyponatraemia).
"Pre-race gut training" marked as full text, not in the abstract.
2026-09-28: PMID 30507268 belonged to an unrelated paper; replaced with 30943823, the PubMed record for this entry's own DOI.