When It Might Be Safer to Run Indoors This Summer

Your Summer Running Guide: How to Avoid Heat Exhaustion, Dehydration and Lightning
Photo: Pond5

While most people welcome warm weather, the runners among us might be watching climbing temperatures with dread. Jog outside when it’s 88 degrees and humid and you may discover that your relationship with summer becomes more love-hate than love-love. But should you just power through those sweat-drenched runs, no matter how miserable they may be?

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With the dog days of August yet to come, we broke down the physical effects of some of summer’s toughest weather obstacles. Here’s what to do when the going gets hot — or when thunderstorms strike — and how to know when you’re better off hitting the treadmill, instead.

How Hot Is Too Hot for an Outdoor Run?

“High humidity is particularly rough on the body because sweat forms quickly on your skin but doesn’t evaporate off.”

It will come as no surprise to anyone who’s toughed out a race in the heat that temperature can have a big effect on performance. Still, different people handle climate changes in different ways — with everything from your weight to your gender to how fast you run impacting your body’s ability to tolerate heat.

In general, it’s best to avoid running outside if the thermometer reads in the upper 90s or above, says Luke Titus, a personal trainer based out of Lancaster, Pa. He adds that a good rule of thumb is to stay indoors whenever it’s hotter outside than your normal body temperature.

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Why play it safe? High temps require your body to work harder, which can quickly throw off your pH and electrolyte balances, leading to dehydration. Signs that your body isn’t coping well — or that you may be at risk for heat exhaustion — include dizziness, cottonmouth, cold sweats, excessive sweating, or even the absence of sweating, which signals that your body can no longer cool itself, says Titus. Here’s how to beat the heat (and when to give in):

  • Avoid running during the middle of the day when the sun is at its strongest, Titus says. Instead, aim for early morning or evening runs, and stick to workouts that you’ve done and know you can handle.
  • Hydrate before and during your run. Titus also recommends adding electrolytes to your water (you can purchase dissolvable packets at most sports stores).
  • Wear the proper gear. Think: Lightweight, sweat-wicking clothing. “Don’t be the guy who’s running in sweatpants when it’s 90 degrees out,” Titus says.
  • Eat right. There’s some evidence that consuming antioxidants can improve performance during hot runs (although more studies are needed). Eat lots of colorful produce on a daily basis to make sure you’re fueled.

If you start noticing any signs of heat exhaustion, don’t tough it out. Stop running, get home immediately, and rest, says Titus. If you’re planning a long run, be sure to bring a phone in case you need to call a friend to pick you up. Contact a doctor if your symptoms worsen, if you don’t improve after one hour or if your body temperature reaches 104 degrees or higher.

Your Summer Running Guide: How to Avoid Heat Exhaustion, Dehydration and Lightning
Photo: Pond5

Is Humidity a Runner’s Worst Enemy?

“Taking it easy doesn’t make you weak; it means you’ll be healthy enough to run as soon as the weather’s better.”

High humidity is particularly rough on the body because sweat forms quickly on your skin but doesn’t evaporate off, says Titus. This prevents heat from leaving your body — which causes you to lose electrolytes. You could be at serious risk for dehydration, which can impair cardiovascular function and decrease blood flow to your muscles, skin and other tissues.

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Signs that you’ve overdone it include dizziness, lightheadedness, increased heart rate, and shortness of breath, says Titus. If you continue to push yourself, your brain temperature may rise and you may start to develop sloppy form, a headache, confusion or disorientation. In other words: If the humidity’s high, it’s smart to run indoors. Taking it easy doesn’t make you weak; it means you’ll be healthy enough to run as soon as the weather’s better. Here’s what to keep in mind:

  • Before heading out, check the heat index in addition to the temperature, says Titus. The higher the moisture content in the air, the hotter it feels outside — and the more grueling your workout will be. If relative humidity is over 40 percent, consider taking your run indoors.
  • If you’re set on running outside, choose a shaded path or run close to a body of water where it may be cooler. Allow yourself to take walk breaks as needed and drink plenty of water.

Keep an eye out for the signs of heat exhaustion listed above — feeling any of these symptoms is a sign that it’s time to stop running and give your body a rest immediately, says Titus. Contact a doctor if your symptoms don’t improve.

Can You Ever Run in a Thunderstorm?

Running in the rain might feel hardcore — but if the forecast calls for thunder, rethink your plans. Given that lightning can strike within several miles of a storm’s origin, it’s best not to risk running, says Titus. The National Weather Service concurs and strongly recommends staying indoors during thunderstorms. Lightning strikes hundreds of people every year; the risk simply isn’t worth it. Even non-fatal strikes can result in serious long-term health problems. Here’s how to prepare for summer storms:

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  • Check the forecast and radar to see if storms are headed your way; if they are, take your workout indoors.
  • If you’re already out for a run and you hear thunder or see lightning, get inside a car or building ASAP. If you can hear thunder, lightning is close enough to strike you. Stay sheltered until at least 30 minutes after the last sign of lightning or thunder.
  • If no shelter is in sight, avoid elevated areas and stay away from bodies of water. You’ll also want to steer clear of objects that can conduct electricity (e.g. barbed wire fences, windmills, and power lines).
  • If you or someone else is hit by lightning, call 911 immediately.

The moral of the story: If the weather stinks, stay inside. But never fear, indoor workouts don’t have to be a drag. Check out these boredom-busting treadmill workouts or get your cardio fix on the rowing machine, instead.

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