Half-marathon fueling is early, boring, and practiced; waiting until you feel empty is already late.Stack-kit editorial
For most half-marathoners over the 90-minute mark, the working plan is carbs early, water with gels, sodium when conditions demand it, and no race-day experiments. The longer-event source protocol targets 60-90 g carbohydrate per hour; for a half, many runners live near the lower end unless they have trained higher intake.
The simple race math
Your stored carbohydrate can cover roughly 90 minutes of hard racing before the margin gets thin. That is why a fast half marathon may need only pre-race breakfast and maybe a late gel, while a two-hour half should be fueled like an endurance event.
The source protocol's on-course target is 60-90 g carbohydrate per hour, starting at 30-45 minutes. If your gut is sensitive or you did not train fueling, do not make race day your first 90 g/hour attempt. The source is blunt: gut training is a 3-8 week process.
What to carry
Energy gels are the clean foot-race default. Maurten Gel 100 provides 25 g carbohydrate per gel, and the source likes it for its hydrogel format and Informed Sport certification. Two per hour gets you 50 g; two to three per hour puts you near the protocol range. Take gels with water, not with a concentrated sports drink you have never practiced.
Drink mix works when fluid carry is realistic. Maurten 320 provides 80 g carbohydrate in a 500 ml bottle, which is useful on the bike and less convenient in a road half unless you are carrying a bottle. SiS Beta Fuel 80 is the lower-cost source-backed alternate, with 80 g carbohydrate per 600 ml and a 1:0.8 glucose-to-fructose ratio.
Sodium is situational but not cosmetic. The source uses Precision Hydration: PH 1000 before the race and PH 500 or PH 1000 on-course at 45-60 minute intervals for longer efforts. For a cool half marathon, you may need less. In heat, heavy sweating, or a slower half that runs long, sodium matters more.
Caffeine is a performance tool if practiced. The source dose is 3-5 mg/kg 45-60 minutes pre-start, with optional on-course caffeine later in longer events. For a half, pre-start caffeine is usually cleaner than stacking caffeinated gels unless you know your tolerance.
Do not overdrink plain water
Exercise-associated hyponatremia is not caused by failing to buy enough supplements. It is usually too much plain water without enough sodium. Drink to a plan built from sweat rate, weather, and tolerance. If you use concentrated gels, take water with them; if you use drink mix, do not force fluid just to hit a carb number.
When to skip or simplify
If your race is under 90 minutes, your stomach is fragile, and you have never trained gels, keep the plan simple: normal breakfast, maybe one practiced gel, and water as needed. If you have hypertension, kidney disease, heart failure, a history of exercise-associated hyponatremia, or physician-directed sodium restriction, do not copy endurance sodium loading without individualized guidance.
Evidence notes
- Currell and Jeukendrup 2008: multiple-transporter carbohydrates improved time-trial performance versus glucose alone in trained cyclists.
- Jeukendrup 2008, Nutrition Reviews: dual-transporter carbohydrate logic supports the 90 g/hour ceiling used by modern endurance fuels.
- Montain and Coyle 1992 and the ACSM Position Stand: dehydration and sodium-fluid balance affect cardiovascular performance and thermoregulation.
Where to go next
The full race-day protocol covers longer events, sodium loading, caffeine, nitrate, beta-alanine, and exact on-course timing.
FAQ
Do I need gels for a half marathon?
If you will finish well under 90 minutes, maybe not. Once the race pushes beyond the glycogen comfort window, start fueling early and practice toward the lower end of the source protocol's 60-90 g/hour range.
Are gels or drink mix better?
On foot, gels with water are usually easier to dose. Drink mix works if you can carry enough fluid without forcing overdrinking; the format has to serve the carb plan, not the other way around.
How do I avoid stomach problems on race day?
Train the gut for 3-8 weeks, start fueling at 30-45 minutes, use products you practiced with, and do not chase 90 g/hour if your long runs never trained that dose.
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