Around this time of year when many of us are basking in the heat and enjoying the outdoors, it's important to remember that, as glorious as the warm weather is, heat can be dangerous. Between heat rash, heat stroke, and excessive sweating, there are plenty of reasons to be careful — especially if you exercise outdoors.
One "heat injury" that you should be aware of if you work out in warm weather is heat cramp. A heat cramp is almost exactly what it sounds like: a painful, involuntary muscle spasm that happens during intense exercise in the heat, according to the Mayo Clinic. Heat cramps can strike in any of your muscles, but they usually occur in the calves, arms, abs, or back. These types of cramps should be taken seriously, because they can be a sign of the first stages of heat exhaustion and heat stroke.
Luckily, heat cramps don't just pop up out of nowhere when you're in warm weather. Heat cramps seem to be caused by excessive sweating, and they're slightly more intense than your run-of-the-mill cramp caused by fatigue or overuse. If it's really hot or humid outside, your body has a harder time cooling down, because sweat can't evaporate on your skin, so you end up sweating more. All that sweating causes you to lose sodium, an essential electrolyte, which makes you susceptible to muscular cramps.
Usually heat cramps happen when you're in the midst of exercising (which is almost as bad as getting a Charley Horse in the middle of the night), and they're common in tennis players because they often play outdoors in the sweltering heat. Compared to a Charley Horse or foot cramp, a heat cramp tends to last longer and feels worse. If you get a heat cramp it's important to cool down ASAP. Find a cool, shady place to rest, and drink something that will help replenish your electrolytes, like orange juice or sports drinks.
To help relieve the muscular pain you might be experiencing, you can do some easy, range-of-motion stretches, or gently massage the area until your feel like it subsides, according to the Mayo Clinic. Once you feel better, it's a good idea to call it a day or wait several hours before you start exercising again. And, if your symptoms don't get better in an hour, you should to call a doctor.
This all might sound scary, but it's just an important reminder to be extra cautious when you're exercising in the heat. That means, always wear lightweight, breathable clothing, like cotton, to help cool you down as you move. If you're not used to working out in the heat, make sure you give yourself about a week to acclimate to the higher temps, and consider doing lower-key workouts during that time. And of course, stay hydrated. As a general rule, you should drink 17-20 ounces two hours before exercising, then drink 7-10 ounces every 10-20 minutes during a workout. After a workout, keep hydrating to replenish the fluid that you've lost.
At the end of the day, you just have to use your judgement before you get sweaty outside, and head to an air-conditioned gym if you're not sure (the National Weather Service also has a helpful heat index chart that lets you know the likelihood of heat illness based on the temperature and humidity). And hey, there are also cold workouts if you really don't want to risk heat-related illness.