Running in the Heat


It's hot out there! If you live in or around Austin, you already know that, but running in the heat (and humidity) is especially tough.

Our bodies try to compensate for the conditions. You're out in the heat, you sweat. That's the body's way of trying to cool off. But when you're out in the heat running, there's a lot more going on that you need to pay attention to and adjust for.  

It takes at least two weeks to acclimate to the heat and humidity, but even after that, you're still not going to run as fast as you do in cooler weather. You still need to pay attention. As you acclimate, your body, in it's amazing way of adapting to things, will become more efficient at dissipating heat and regulating your core body temperature making it more comfortable to run.

The most common issues associated with running in the heat and humidity (other than it just feeling harder) are:

Dehydration: Weigh yourself before and after your run. If you've lost more than 4% of you're weight, you're approaching unsafe levels of dehydration.

Heat-related cramps: Hydrate and if necessary take something with electrolytes (sodium, magnesium, potassium, calcium, and phosphate). Slow down.

How to Run With Joy in the heat and humidity

  • Run by effort, not by pace. If you've got a heart rate monitor, use it and run at 70% of max heart rate. If not, ignore the Garmin (or whatever you use). You're going to run slower in the heat and humidity.

  • Run when you're most comfortable. It's coolest first thing in the morning so most people will find running in the heat and humidity is most tolerable then. It's also more humid in the morning, so there's a chance you might be one of those people who runs better in the evening, when it's hotter, but less humid. Experiment to find what works best for you. Don't make your runs more uncomfortable than necessary—run in the shade or before the sun comes up whenever possible.

  • Pay attention to your body's needs. Nutrition, hydration and sleep. In the summer, you can't get away with ignoring your nutrition and hydration as you might do in cooler temps. Make sure you're eating properly and staying hydrated (although don't overdo it). Getting sufficient sleep will also help your body be more efficient and handle the heat better.

  • "Pre-cool". You can delay the effects of running in the heat and humidity by pre-cooling the body. It can be as simple as eating a frozen slushy (you can make a Gatorade one even) or a cold shower/ice bath (or dip in Barton Springs) before your run. Anything that cools your body temperature down will delay the effects of the heat during your run. It won't eliminate the effects, just delay them a little.

  • Embrace it, don't fight it. There's always a mental component to running and even more so with running in the heat and humidity. Adjust your expectations for each run to be realistic based on the conditions. Be optimistic and the body will follow.

Dew Point

One way to determine how much impact weather conditions will have on your run is to look at the dew point. You can use a dew point calculator (or it's provided on many weather sites) to determine the dew point based on the temperature and humidity. For example, a temperature of 75 degrees with 80% humidity is a dew point of 69. Then use the following guidelines to know how to adjust:

Dew Point Range: Adjustment to pace/effort
60-65: 2-3%
65-70: 3-5%
70-75: 5-8%
75-80: 12 - 15%
Above 80 - be careful and just go for a really easy run

For reference, the dew point is often in the 70-75% range in Austin in the mornings this time of year.

Oh, and in case you think running in hot but dry climates is any better, think again. Your sweat evaporates so quickly in dry conditions, it can easily cause dehydration which leads to additional problems. So wherever you are in the summer, be mindful of the heat and stay safe.