Running in the heat is really hard. These last summer days in Sacramento have been toasty! Every day this week has a predicted high of over 100, up to 107. That's really really ridiculously hot. So while we all know running in the heat is difficult, let's talk about some of the pros and cons, and what is actually happening to you when you run in the heat.
What is happening to my body!?
You're getting sleepy, you're getting very sleepy! When your core body temperature goes up, it causes fatigue! This leads to your run getting slower, or your decision to bail. When you run in super hot temps, your body tries to regulate heat in an anticipatory way. It monitors how much heat your body is storing and basically slows your muscles down to prevent overheating. This anticipatory regulator leads you to either slow down, or stop running. This essentially means that if you can slow down the rate at which you store heat, you can keep going for longer, thus improving your endurance.
What else is happening?
Your blood is being diverted away from your muscles and towards your skin in order to help keep you cool. This would also, clearly make you slower as you are losing blood volume in your muscles, which need that to go fast.
Yes. When really hot, your muscles are producing less ATP (adenosine triphosphate) which is broken down for energy.
How do I stay cool?
Your body naturally wants to stay cool, so employs mechanisms to do so. When your skin is hotter than the air around you, it radiates heat into the environment. This is actually how you lose the vast majority of heat, up to 60%. Also, you sweat. Sweating provides a good chunk of heat loss, as long as it is able to evaporate. So if it is super humid, sweating is probably not going to help you out that much as the process of evaporation is what actually helps cool you down. Sweating and evaporation allows for 25% of your heat loss.
So if you live in a hot, dry place, what happens? Well...if the air outside your body is the same temperature or hotter than your skin, that 60% of heat loss is not going to happen at all and that becomes 0%. This means you're only able to lose some of that heat by sweating and evaporation.
So how do I make it so I'm better able to run in the dry heat?
Sweat more! The more you sweat, the more sweat will evaporate, and the more heat you will lose! This is easier said than done, as it take some acclimatizing in order to trigger an ongoing sweat response. The more acclimatized you are to the heat, the more you will sweat. A lot more. What this basically means is that if you get used to running in the heat over time, you could improve your endurance because your body is working harder at slower paces.
But it's so hard!
I know. Running in the heat is miserable. But, if you do it repeatedly, it gets less miserable!!
If running in the heat is so miserable for you that you find yourself cutting your workouts short, or bailing on your runs, then maybe choose a time to run when it is not so hot. It's better that you get the run done, than make yourself into an Alex Mack puddle in the heat of the afternoon.
Also, maybe don't start with 400 repeats in 100 degree heat? Perhaps your first hot run is an easy few miles.
The bottom line is, while this may be beneficial for you, it's also not necessary to destroy your own soul in order to get some kind of adaptation. Know yourself. If you're more likely to get your workout done in the morning when it is 70 degrees and feel good about what you've done, than feel sorely disappointed at 5:00pm when it is 105 outside, then please. Do what feels good. Everything doesn't have to be so hard. If you can make a decision that will be less stressful on your mind and body, then why not do it? At the end of the day, being kind to yourself is the most important thing.