Heat / fluids
Heat, sweat rate, and hydration mistakes
On average, men have higher muscle mass and sweat rates than women — which helps cooling but increases fluid and sodium losses. Hyponatremia from over-drinking plain water is a real race-day risk too.
Headache, nausea, confusion, or muscle cramps in hot weather; weighing much less after long runs; or bloated feeling from chugging water without electrolytes.
Signs to watch for
- ·Salt crust on skin or stinging eyes from sweat
- ·Cramping in calves or hamstrings late in hot runs
- ·Dark urine or minimal urination despite drinking
- ·Swelling in hands or fingers from over-hydration
- ·Performance cliff in heat that doesn't match fitness
How to avoid
- ·First hot-weather long run at full winter pace — heat acclimation takes 1–2 weeks
- ·Only drinking water on runs over 90 minutes — sodium matters
- ·Alcohol the night before a summer long run
- ·Running midday in peak heat when you're new — go early or late
How to fix / recover
- ·Acclimate: shorten pace and distance for the first week of real heat
- ·Drink to thirst on most runs — for 90+ min in heat, use electrolytes or sports drink
- ·Weigh yourself before/after occasional long runs to estimate sweat loss (rough guide only)
- ·Cool down with shade, cold towel on neck, and fluids with sodium after hot efforts
Practical hydration
- ·Pre-run: 400–600 ml water in the 2 hours before; stop if you're sloshing
- ·During: 150–250 ml every 15–20 min in heat on runs over an hour — adjust to thirst
- ·Post-run: rehydrate over hours, not minutes — include sodium from food or electrolyte mix
When to see a specialist
- ·Confusion, fainting, or vomiting during or after hot runs — emergency care (heat stroke)
- ·Recurrent cramping despite electrolytes — discuss with sports medicine or GP
Related: Bad weather tips · Nutrition basics
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