Hot, Bothered, but Still Moving: Running Smarter in Scorching Conditions
Ah, summer. That magical time when parks are alive, the days stretch long, and your morning run feels like a jog through a hairdryer. Whether you're training under a blazing July sun or jetting off to a tropical getaway where every run feels like a sauna session, exercising in the heat can make even the most seasoned runner feel like they’re dragging a backpack full of bricks.
But before you grit your teeth and push through, let’s unpack exactly why heat makes running feel so tough—and how you can stay cool, hydrated, and faster than a sweaty bullet train.
☀️ The Science of Why You Feel Like a Melted Ice Cream Cone
Running in the heat isn't just about a bit of sweat and sunburn. It actually puts your body through the physiological wringer. Here’s what’s happening under the hood:
💓 1. Your Heart’s Doing Double Duty
In hot conditions, your body prioritises cooling itself down. That means sending more blood to the skin so it can offload heat via sweat evaporation. But you also need blood going to your muscles to, you know, run. The result? Your heart is basically working overtime to do both jobs—cue higher heart rates, more fatigue, and feeling like your usual pace suddenly belongs in the Olympic trials.
And this is all before dehydration… running dehydrated can exacerbate the stress on your heart, leaving less blood volume to be pumped round to those muscles which are working their socks off.
🔋 2. You Burn Through Fuel Faster
Heat also accelerates muscle glycogen usage. Translation: your energy stores get torched more quickly in hot conditions. So, the same run you smashed last week in 12°C might leave you gasping by mile 7 when it’s 30°C out.
🧠 3. Brain Fog and Central Fatigue
Ever feel like the heat makes your brain go “nope”? That’s real. Central fatigue—where your brain starts pulling the plug before your body’s actually done—is more common in high heat. Think of it as your internal governor trying to keep you from overheating… and possibly face-planting on the trail.
You can’t control the weather, but you can try to outsmart it.
🏜️ Heat-Tested, Runner-Approved: Real-World Adventures
Don’t believe the heat is a worthy opponent? Just ask anyone who's dared to toe the line at the Marathon des Sables—a six-day, 250 km ultra-marathon through the Sahara Desert, a.k.a. “the furnace of the running world.” Or those who’ve tackled the Badwater 135, a soul-scorching race through California’s Death Valley.
These athletes battle 40–50°C conditions on purpose. The good news? They’ve taught us a few tricks that even casual runners can steal.
🧊 Stay Cool, Run Happy: How to Beat the Heat
You can’t control the weather, but you can try to outsmart it. Here’s your summer running toolkit:
💧 1. Hydrate Like a Boss
Sweating buckets = water loss. But it’s not just H2O—you’re also losing electrolytes (especially sodium), which are crucial for muscle function and avoiding that dreaded cramp. Understanding how your body sweats can be an absolute game changer in the heat.
Sweat Testing gives you all of the info you need to tailor your hydration to match what you are losing with every drop that runs from your brow. Measuring sodium losses and how much fluid you are losing, giving you the upper hand against the heat.
Pro Tips:
Pre-hydrate before longer runs and races. Pre-load with strong electrolytes the night before and the morning of the run to give your strategy a bit of forgiveness out on the trails
Use electrolyte tablets or sachets which are high in sodium and match your sodium losses. Many electrolyte supplements don’t have enough sodium to replace what you’re losing in your sweat, something like Precision Hydration’s PH1000 are perfect
Measure your sweat rate in training—this can be an easy tool to help guide the amount of fluid you need to drink on race day. If you need help calculating your sweat rate, feel free to reach out to Dan in the lab at dan.west@trailmed.co.uk
❄️ 2. Get Ahead with Pre-Cooling
Want to start cooler so you don’t overheat as fast? Pre-cooling strategies are your new best friends.
Try This:
Drink an ice slushie or ice lolly (yep, that’s a legit sports science hack) before heading out. Research shows it’s one of the most effective ways of lowering core temp and improves endurance in the heat.
Take a cold shower before your run.
Soak hat/wristbands in cold water
Use cooling vests or ice towels or instant ice packs to cool your body during rests.
🧊 3. Mid-Run Cooling Is a Gamechanger
In super-hot conditions, mid-run cooling can help stave off overheating and central fatigue.
Options Include:
Pick up an ice lolly on route or at a break/rest stop.
Carrying a handheld bottle with ice water to sip and splash.
Running routes with fountains or shaded areas.
Wearing a cap and soaking it in cold water every few kilometers.
Travel smart. Rehydrate aggressively post-flight and take it easy for the first day or two
Mid-Run Cooling Is a Gamechanger
