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Don’t let the heat of the dog days spoil your training. Use these tips to run safely and effectively all summer long.
Training in hot weather is not always pleasant, but it’s not always avoidable, either. If you live in an area where the summers are toasty and you want to be in peak shape for a fall race, then you have to get out there and sweat in June, July and August.
While training in the heat is not as enjoyable as running on cool days, it need not be any riskier. Heat illness is relatively rare among endurance athletes, and if you take the following precautions, it will never happen to you.
Listen to your body.
Early signs and symptoms of heat illness include fatigue, discomfort, lightheadedness, cessation of sweating, disorientation and nausea. Stop exercising and find a cool environment as quickly as possible if you begin to notice any of these signs or symptoms while exercising in the heat.
Take baby steps.
The fitter you are, the better your body can tolerate exercise in the heat, so try to build your fitness to a high level in the spring, before the first heat wave of the year. When the first really hot day comes, do a shorter- and slower-than-normal workout. On each subsequent hot day go a little farther and a little faster. It takes about 10 days for the body to fully acclimatize to the heat. The body adapts by increasing its sweating capacity and reducing the electrolyte concentration of the sweat to boost your ability to maintain a safe core body temperature. After this process is complete you can train more or less normally through the summer.
I said “more or less normally” above because it is never possible to train as hard in the heat as in temperate conditions. Research has shown that the brain protects the body during exertion in the heat by constantly monitoring the core body temperature and limiting muscle activity to prevent the core body temperature from rising to dangerous levels. (It’s actually the heat produced by the muscles, not environmental heat, that causes heat illness to occur. Environmental heat merely prevents body heat from dissipating.) So don’t expect or try to perform at the same level on hot days. Instead, maintain your normal level of exertion and understand that you will not go as fast at this level of exertion as on cooler days.
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Run early-or late.
If you take the time to acclimatize to the heat, and you adjust your pace properly on hot days, you can train safely in very high environmental temperatures. However, because you have to slow down, you can’t train as hard or get as fit in such temperatures as you can in cooler temperatures. That’s why very few American runners and triathletes went to “heat camps” ahead of the Beijing Olympics, where very hot days were expected. They preferred to train at a higher level in cooler environments until they left for China, and then acclimatize over there.
By the same rationale I recommend that you train early in the morning and late in the evening-and perhaps even indoors sometimes-to avoid the highest temperatures of the day. You’ll have better workouts and you’ll feel more comfortable, too. I lived in Phoenix for one year, where I quickly discovered that the local endurance athletes routinely work out before the sun comes up and after it goes down. After suffering through a few broiling midday workouts I quickly fell in line with the locals, and boy what a difference it made!
Dress to sweat.
Sweating is the body’s primary cooling mechanism. When you train in hot weather, be sure to dress in clothes that allow this mechanism to do its job. Avoid wearing everyday clothes such as cotton t-shirts, which trap sweat and heat against the body. Instead wear technical apparel that is designed for your sport and made from moisture-wicking fabrics such as CoolMax, which soak sweat from your skin and transfer it to the outer surface of the garment for evaporation. Light colors that reflect the sun are also preferable.
Drinking during hot-weather workouts will help your sweating system do its job better. By drinking throughout each training session you will keep your blood volume close to normal levels, which in turn keeps your sweat rate high. And since oxygen is delivered to the muscles through the blood, maintaining your blood volume through drinking also enables your heart to deliver more oxygen per contraction, so you perform better than you can if you allow your body to become too dehydrated.
Research has shown that athletes perform better in hot environments when they cool their bodies beforehand. Pre-cooling doesn’t make a huge difference, but if you want to gain a little bit of performance in important workouts that must be done in the heat, turn your air conditioning down low or spend time in a cool bath before you head out the door.