Endurance Fueling
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Endurance performance depends on carbohydrate availability — fuel high daily, take in 30–90 g of carbs per hour during long efforts, and hydrate strategically.
Detail
Endurance exercise is limited largely by carbohydrate (glycogen) availability (see Glycogen — Stored Carbohydrate Fuel); running low forces a drop in pace ("the wall"). Fueling spans three phases:
- Daily base: match carbohydrate to training load — 5–7 g/kg/day for ~1 h/day, 6–10 g/kg/day for 1–3 h/day, and 8–12 g/kg/day for extreme volume (see Carbohydrates — Types, Glycemic Index, and Requirements). Chronically under-fueling carbohydrate undermines training quality.
- During exercise: for efforts over ~60 minutes, take in carbohydrate to spare glycogen and maintain output — ~30–60 g/h for 1–2.5 h, and up to ~90 g/h beyond that using a glucose-fructose blend (~2:1) that exceeds the single-sugar ~60 g/h absorption ceiling (see Carbohydrate Timing for Endurance). Pair with a fluid and sodium plan (see Hydration Strategy During Exercise).
- Before/after: top off glycogen with a pre-event carbohydrate meal, consider carbohydrate loading for events over ~90 min (see Carbohydrate Loading), and refuel promptly after.
Gut training matters: the ability to absorb 60–90 g/h is trainable — practice race-day intake in workouts to avoid GI distress. Protein needs remain elevated for endurance athletes (~1.2–2.0 g/kg/day) for repair and adaptation, but carbohydrate is the performance lever during the event.
Key facts
- Daily carbohydrate: 5–7 (1 h), 6–10 (1–3 h), 8–12 (extreme) g/kg/day.
- During >60 min: ~30–60 g carb/h; up to ~90 g/h via glucose:fructose (~2:1).
- Single-sugar absorption caps ~60 g/h; train the gut to tolerate more.
- Pair carbohydrate with fluid and sodium during long efforts.
- Endurance protein ~1.2–2.0 g/kg/day; carbohydrate is the in-race lever.
Connections
- Glycogen — Stored Carbohydrate Fuel / Carbohydrates — Types, Glycemic Index, and Requirements — the limiting fuel and daily needs.
- Carbohydrate Timing for Endurance / Carbohydrate Loading — timing and pre-event maximization.
- Hydration Strategy During Exercise — fluids and sodium during events.
- Long Slow Distance (LSD) — training context for fueling.
Sources
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Educational content only — not medical advice. Always consult a qualified professional for individualized guidance, especially around injury, pregnancy, or medical conditions.