CoachingDIAGNOSIS

HEAT PERFORMANCE DROP — WHEN SUMMER WRECKS YOUR NUMBERS

Winter numbers look like a different rider than your summer numbers. On anything over 25°C your HR climbs 15 bpm, your power falls 10-20%, and efforts that felt controllable in March feel impossible in July. You assume you've lost fitness. You haven't — you've lost heat tolerance.

THE SHORT ANSWER

Most often, this is because skin blood flow redirects blood from working muscles to cooling — reducing power at a given HR. The fix: start a 10-14 day heat acclimation block — gradual heat exposure rewires thermoregulation — the gains are significant.

WHY THIS HAPPENS

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Skin blood flow redirects blood from working muscles to cooling — reducing power at a given HR

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Dehydration compounds the blood-volume squeeze (~1% body mass loss = ~2% power loss)

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Core temp rise slows pacing as the brain protects against hyperthermia

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Sodium losses from sweat disproportionate for heavy sweaters

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No heat acclimation — the body adapts within 10-14 days, but only if you train in the heat

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Poor clothing choices — dark kit, no ventilation, hot lids

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Over-pacing early — a 'normal' early-ride effort becomes a heat disaster 90 minutes in

WHAT TO DO ABOUT IT

Start a 10-14 day heat acclimation block

Gradual heat exposure rewires thermoregulation — the gains are significant

Fuel and hydrate heat-specifically

750-1000ml/hour with 700-1000mg sodium for heavy sweaters

Pre-cool before key efforts

Ice slushy, cold towels, or a cold shower 20 minutes before reduces starting core temp

Pace by HR not power in extreme heat

Above 32°C, HR becomes a more honest signal than power

FREE DIAGNOSTIC

Plan hot-weather fuelling + fluids

Or apply for coaching →

WHAT THE EXPERTS SAY

John WakefieldWorld Tour coach, Bora-Hansgrohe; works with Primož Roglič and Jai Hindley

Wakefield coaches around internal load — the cost of a session to the rider, not just the watts on the screen. Heat is the clearest case: the same power costs more when it's hot, so the answer is a structured 10-14 day acclimation block and monitoring day to day, rather than forcing through and turning an adaptation week into overreaching.

Hear it: How Team Bora Build Endurance: John Wakefield on Ultra Cycling Training