REF-528 · Tiller et al., 2019 · Journal of the International Society of Sports Nutrition, Vol. 16, Art. · Paper
ISSN Position Stand: Nutritional Considerations for Single-Stage Ultra-Marathon
Key Findings (recommendations)
Training
Meet the caloric demands of training with an individualised, periodised, varied, food-first strategy
Plan nutrition early enough to permit adaptations that enhance fat-oxidative capacity
Carbohydrate: the evidence overwhelmingly supports a moderate-to-high carbohydrate diet (~60% of energy, 5-8 g/kg/day) to mitigate chronic training-induced glycogen depletion
Limiting carbohydrate before selected low-intensity sessions and/or moderating daily intake may enhance mitochondrial function and fat oxidation — but may compromise high-intensity performance
Protein: ~1.6 g/kg/day to maintain lean mass and support recovery; up to 2.5 g/kg/day may be warranted during demanding training when calorie needs are greater
Racing
Energy: 150-400 kcal/h from a variety of calorie-dense foods — carbohydrate 30-50 g/h, protein 5-10 g/h; account for palatability, individual tolerance and the growing preference for savoury foods in longer races
Fluid: 450-750 mL/h (~150-250 mL every 20 min); to limit hyponatraemia risk, electrolytes (mainly sodium) may be needed above what most commercial products provide (>575 mg/L sodium); fluid and electrolyte needs rise in hot/humid conditions
GI: evidence supports progressive gut training and/or low-FODMAP diets to alleviate GI distress during racing
Ketogenic diets / ketone esters: evidence for improving ultra-marathon performance is lacking
Caffeine: strategic use to sustain performance in the latter stages, particularly when sleep deprivation may compromise safety
Practical Application
ISSN position stand for single-stage ultra-marathon: in racing, 150-400 kcal/h with carbohydrate 30-50 g/h and protein 5-10 g/h, fluid 450-750 mL/h (~150-250 mL every 20 min) with sodium that may need to exceed what most commercial drinks provide (the stand's figure: >575 mg/L); in training, ~60% carbohydrate (5-8 g/kg/day) and protein ~1.6 up to 2.5 g/kg/day; gut training and/or low-FODMAP for GI symptoms; ketogenic strategies unsupported; caffeine late in the race. The in-race carbohydrate target is deliberately lower than marathon-style fuelling — calorie-dense mixed foods and tolerance matter over many hours.
Masters athlete in an ultra: rehearse the race nutrition and hydration in long training sessions (the stand's periodised, individualised framing)
Fluid by the stand's rate, not "ahead of need": 450-750 mL/h scaled up in heat, with enough sodium to hold plasma sodium — over-drinking plain water is the hyponatraemia route
Limitations
A position on SINGLE-stage ultras; multi-day events have different needs
The ultra evidence base is thinner than for the marathon (fewer controlled studies)
Great variability in conditions (heat, altitude, distance) complicates universal recommendations
How this entry was checked and changed
Content correction 2026-09-27
"Carbohydrates: up to ~90 g/h (glucose:fructose)" -> the position stand recommends carbohydrate 30-50 g/h during racing (within 150-400 kcal/h) plus protein 5-10 g/h; corrected.
"Hydration: to thirst (ad libitum)" and "hyponatremia risk is higher in slower finishers" -> the stand gives 450-750 mL/h (~150-250 mL every 20 min) with sodium >575 mg/L; the slower-finisher claim is not in the abstract and was removed.
Added the training recommendations (~60% CHO, 5-8 g/kg/day; protein ~1.6-2.5 g/kg/day; carbohydrate periodisation caveat), the ketogenic and caffeine points, and the low-FODMAP support. "Individualize sodium via a sweat test" removed (not in the abstract).
2026-09-30: the lead read as if most commercial drinks held >575 mg/L sodium; the stand says sodium may be needed ABOVE what they provide, i.e. >575 mg/L. Reworded to match the Key Finding. For drinking volume the base's safety rule is thirst (REF-776, SYNTH-68).
Full text (checked 2026-10-12)
The stand recommends ~150–300 kcal/h for races up to and including 50 miles (~81 km) and ~200–400 kcal/h for longer races, and does not recommend persistent intakes of < 200 kcal/h (full text).
Athletes should follow a contemporary carbohydrate-loading approach in the 48 h before racing (full text).
The body text sets sodium at 500–700 mg/L of fluid, ~300–600 mg/h of sodium (1000–2000 mg NaCl) in hot (> 25 °C) and/or humid (> 60%) conditions, and advises avoiding fluid sodium above ~1000 mg/L because of palatability (full text).
After key training sessions, a fluid volume of 150% of that lost plus at least 460 mg/L of sodium is recommended (full text).
For caffeine, frequent 4–6 mg/kg boluses are not recommended; lower doses of 1–2 mg/kg (70–140 mg for a 70 kg athlete) or repeat doses of 50 mg/h, mainly for night running and the latter stages, are suggested (full text).
Runners should abstain from NSAIDs because of increased renal load, and use other analgesics conservatively (full text).
Carbohydrate of 7 to 10 g/kg/day may be warranted for runners with greater mileage and/or pace, and protein of ~1.6–2.1 g/kg/day is sufficient to optimally stimulate muscle protein synthesis (full text).
Highly concentrated carbohydrate (e.g. > 500 mOsm/L and > 8% CHO) is named as the primary nutritional cause of GI upset during ultra-marathon (full text).