When temperatures soar, it can be tough to get fired up for a workout. When it’s hot, even the same pace feels tougher. But there’s good reason to keep your training on track through summer months.
In the near term, braving the heat of the moment can give your fitness a boost. But it can also have benefits that will last long after the seasons change. “There are both physiological and psychological adaptations to training in the heat,” says exercise physiologist and running biomechanist Adam St. Pierre, owner of ASTP Coaching in Boulder, Colorado. Sure, you can avoid the heat of the day by running early in the morning or late in the evening. “But you lose out on the benefits of heat training,” St. Pierre says.
It’s not just your imagination: your easy pace will feel tougher in the heat. Try not to take it as a sign that you’re losing speed or power. It’s not your fitness; it’s your biology. Studies have shown that for every 10-degree increase above 55 degrees F, your pace slows by up to 3 percent. “In the heat, blood must not only power your muscles, it must also travel to the skin to help cool your body” through sweat, says St. Pierre. You lose some blood volume when you sweat. Without as much blood volume, your heart has to beat faster to pump the same amount of blood. As a result, your heart rate is going to be elevated, and so will your sense of effort. For instance, if you usually run 9 minutes per mile and your heart rate is 140 beats per minute, and your rate of perceived exertion is about a 3 on a scale of 1 to 10, in the heat, that same 9-minute-mile might boost your heart rate to 150 beats per minute, and feel like more of a 4.5 on a rate of perceived exertion of 1 to 10.
If you’re aiming for an easy run, you might slow your pace until your heart rate or rate of perceived exertion falls more in line with what it usually is in cooler conditions.
Here are four reasons that can help you get out the door during the hottest months of the year:
1. Training in the heat will make you into a better sweater
When you train in the heat, you’ll become more efficient at sweating, and that’s a good thing, says St. Pierre. As you become acclimatized to the heat, you begin to sweat earlier in your workout—and at a lower core temperature. What’s more, your sweat becomes more diluted—so it contains more water and less electrolytes. This prompts your body to increase plasma (fluid) volume in your blood. That means, on your next hot-weather workout, you won’t lose as much blood volume to sweat, and your heart rate won’t increase so the same pace will feel easier. Increased plasma volume is also one of the first beneficial adaptations to altitude, he adds, so heat training can help when preparing for a high altitude event. A few caveats, in order to maintain an elevated blood plasma volume you will have to drink more fluids, before and after your run, and throughout the day. For runs over an hour you may want to carry water with you on your run.
2. Hot-weather running provides valuable race-day rehearsal
Most half and full-marathons start mid morning which means you’ll be on the course during the hottest part of the day. “This can be a real shock to the athlete if they aren’t prepared for the heat,” says St. Pierre. So training in the summer will help you get accustomed to running in those conditions. Just knowing that you have experience handling this heat will give you a confidence boost as the mercury rises. “If you’re training for a fall marathon, by working out daily at 5:30 am to miss the heat of the day, you’re missing that opportunity,” he adds.
3. Training in the heat will make you faster by fall
Even if you’re blessed with cool conditions on race day, you’ll still get the benefit from hot-weather training. If you’ve ever experienced this you can vouch for what research has shown: when you train in the heat, you feel faster when the temperatures fall. A study published in the October 2010 issue of the Journal of Applied Physiology concluded that heat acclimation improves aerobic performance in temperate to cool conditions. In the study, cyclists who worked out at a low intensity in a 104 degree Fahrenheit room saw improved performance in cooler conditions.
4. You’ll make new friends
Sunshine and warmth bring everyone outdoors, and summer is an ideal time to meet and make new running friends. Many training groups for fall races begin in the summer, and joining a group is a great way to explore new routes that you might not find on your own. Many training groups provide water and refreshments for long training workouts, which along with the camaraderie you get from other runners, can help the miles roll by much easier. And over the salty, sweaty miles you’ll have a chance to forge bonds that will last long after the finish line.
Beneficial as hot-weather running is, there are some steps you can take to make it more comfortable, and to keep it safe. Summer training should feel tough, but it shouldn’t feel like torture. Wear light-colored, loose-fitting clothing made of technical materials that wick sweat away from the skin, so you don’t feel soaked. Be sure to stay hydrated; sip calorie-free fluids throughout the day. Avoid chugging fluids right before a run; that could leave you with GI distress. To avoid sunburn, apply broad-spectrum sunscreen 20 minutes before your run, and reapply every two hours, even if the formula says that it is sweat proof. If you start to feel dizzy, confused, nauseous, or weak, slow down, walk, run on the treadmill, or call it a day. Save your long runs, speed sessions, and tempo runs for cooler conditions, when you’ll have more energy, and it’s safer to push yourself.
Jen has spent the past six years working as Special Projects Editor for Runner's World magazine, and writing stories for the magazine. Her book The Runner's World Training Journal for Beginners, (Rodale Books, April 2014) is available wherever books are sold. She also contributes stories to The Portland Press Herald.