1: You will get tired and you will want to sit, crouch, hang your head or even lay down. DON’T.
If you’re running on pavement, the low heat reflectivity means that it absorbs heat and stores it. So if you need to rest, try and find some shade and walk around a little, slowly and with your head held high.
2: If you think you’re the type of runner who doesn’t need to replenish the water they lose through sweat particularly often. Hot weather changes this.
Hydration is far, far more important in extreme temperatures. You need to drink double, perhaps triple, what you would on a regular run. You’ll probably make it through the first mile or two just fine, but after that remember that blood thickens as you lose liquid, a condition known as polycythemia. This increases the stress on your heart, and can lead to pulmonary embolism and lung problems, whilst your brain can suffer dizziness and confusion. So – drink, and drink often. Ideally you should take regular small mouthfuls.
3: Slow down. Running in the heat is exhausting.
Essentially, exercising and extreme temperatures make the same demands on your body (particularly blood and oxygen), meaning that one of those demands is likely to go unsatisfied. When you’re running, the body shifts blood and oxygen to the muscles. When you’re overheated, it shifts them to the skin to help with the cooling process. If you’re running at a normal pace in the heat, the body will not keep up. That means you need to slow the workrate of the muscles, giving yourself the chance to use some of that blood for cooling. And slowing the workrate means slowing down. Apologies for the extremity of the tips. Get our there and RunThrough (sorry) the conditions and enjoy it. Good weather like this doesn’t happen as often as it should.