Training in heat is fundamentally harder than training in cool weather. Your core temperature climbs faster, your heart works harder, and you can lose 1-3 liters of sweat an hour — carrying up to 1-2 grams of sodium with it. Performance drops measurably above 80°F, and falls off a cliff past 90°F.

The fix isn't toughing it out. It's a different hydration and fueling game plan. Here's what actually matters.

The Heat Game Plan

Three things that move the needle.

Sodium · the one that matters most

Sodium is the electrolyte you lose most through sweat — aim for 500-1,000mg per hour on long efforts. Salt stains on your shirt, burning eyes, frequent cramps? You're a salty sweater and need the high end. Plain water alone on long sessions risks hyponatremia, which is genuinely dangerous.

Carbs · you burn more in heat

Heat accelerates glycogen depletion — you burn through fuel faster at the same intensity. For sessions over an hour, target 30-60g of carbs per hour. A session that feels fine in spring can leave you bonked and empty in July without fueling.

Pre-hydration · start hours early

The biggest mistake is starting to hydrate when you arrive. By then you're already behind. Drink 16-24oz with ~500mg sodium 2-4 hours out, top up 15-30 min before, then 16-32oz per hour during. Showing up hydrated beats chasing it mid-session.

Ease In — Don't Hero Day One

Your body adapts to heat, but it takes 10-14 days of progressive exposure. Sweat rate rises, sweat sodium drops, plasma volume expands. Jumping into full-intensity training on day one of a heat wave is the fastest route to heat illness. Start at 60-70% for the first few days and build.

Know When To Stop

Headache, nausea, dizziness, confusion, or — most dangerous — you stop sweating despite the heat. These aren't toughness tests. They're warning signs of heat illness, and heat stroke is a medical emergency that kills healthy athletes every year. If they show up, stop immediately, get cool, and get help if it doesn't pass fast. Mental toughness doesn't beat physiology.

Where Motion Fits

Heat training is the exact problem Motion was built for: carbs and electrolytes in one bottle. 25g of Cluster Dextrin for sustained fuel — and because it's low-osmolality, it clears the stomach fast without the gut distress sugary drinks cause in the heat. Plus sodium and potassium to replace what you sweat out. Sip it through the session and you're hitting the carb and electrolyte targets at the same time.