The Heat Tax: What to Expect From Yourself at Thirty Degrees
Marion asked me a question last week that I suspect half the gym has been thinking. What difference does heat make to our training?
Your blood has two jobs during a session: deliver oxygen to the working muscles, and carry heat out to the skin so you can shed it. At thirty degrees they compete. Blood gets diverted to the skin to cool you, which means less of it is doing the work you actually want it to do. So your heart beats faster to move the same amount of oxygen.
Expect your heart rate to sit 10 to 15 beats higher at any given pace in real heat. Expect longer engine pieces — anything over about ten minutes — to come in 5 to 10 per cent slower.
What barely changes is strength. In fact for some of us, being warm can help. The heat tax is levied on the engine.
Taper your effort to the heat. If a piece is prescribed at a pace, and that pace is getting you to a heart rate you can't sustain, slow down. On any conditioning piece longer than ten minutes, hold yourself at a level where you could still say a short sentence. That's the ceiling in this weather.
Drink before you're thirsty, and salt it if it's long. This means taking on water and electrolytes before the workout starts. Water is fine for most sessions. If you're going past forty-five minutes and sweating hard, put electrolytes in it. Plain water at volume, with a lot of salt lost, is not a good combination.
Give it two weeks. Your body adapts to heat properly — more blood plasma, earlier and more efficient sweating — and it takes about seven to fourteen days of training in it. The first hot week is genuinely the worst one. It does get better.
One caveat, and it isn't optional. If you stop sweating, get a headache, feel dizzy or go cold and clammy in a hot session, that is not a problem to work through. Stop. Sit down. Take on some electrolytes. Tell a coach. There is no session on the whiteboard worth that.
Remember, training in the heat is harder but you'll see the benefits from it when the weather cools down.
If the thought of walking into a gym makes you wince, this is exactly who we built the place for. Book a free, no-obligation 15-minute chat with Jeremy or Beth at crossfitchiltern.com — no hard sell, and most of us hadn't trained in years when we started. We'll build a plan around your life, not a generic template.
