Hot Out? Stop Chasing Pace and Start Chasing Feel

Here's the practical version first: once it's warmer than about 22°C, your pace watch becomes less useful. Run by how hard you're breathing or by heart rate instead, and expect to go 15-30 seconds per kilometer slower than you would in cooler weather. That's not you getting weaker — that's your body doing exactly what it's supposed to do.

The science behind this is pretty simple. When it's hot, your body has to send blood to your skin to dump heat, which means less blood available for your working muscles. Your heart ends up beating faster just to keep up with both jobs — cooling you down and fueling your legs. So at the same pace you'd normally hold, your heart rate climbs higher and you fatigue faster. Chasing a fixed pace target in heat basically means ignoring a system that's already working overtime.

Hydration timing matters just as much as hydration volume. Drinking a ton of water right before you head out doesn't help — it just sits in your stomach or sends you looking for a bathroom. Instead, aim for 400-500 mL in the two hours before your run, which gives your body time to actually absorb it. Once you're running, small and frequent beats big and occasional: 150-200 mL every 15-20 minutes keeps you topped up without sloshing around. If you're out longer than an hour, or it's genuinely brutal out, add electrolytes — plain water alone won't replace what you're sweating out.

The runner-facing takeaway: in the heat, slower isn't a failure, it's the correct response. Let effort and heart rate be your guide, hydrate on a schedule rather than when you remember, and save the pace PRs for cooler days.