The Heat Is On: Maximize Your Workout as Temperatures Climb

When I moved my clock forward in March, I bemoaned the lost hour of sleep. But I was immediately cheered by the thought of extra daytime. Daylight savings comes at about the time when I need a change of scenery from the dimly lit, indoor cycling class or noisy gym, and taking my workout outdoors is literally a breath of fresh air.

But depending on where you live, when daylight increases so does the temperature, and along with it, humidity. However, with a little planning, it shouldn't put too much of a damper on exercising outdoors.

Keep Cool: Your Body's "Air Conditioning" System

The environment can help or hinder our body's sophisticated cooling system. Whether we exercise in an air-conditioned gym or outside on a hot day, our muscles generate heat, which must be dissipated to avoid overheating or hyperthermia.

The way our body's cooling system works is to transfer the heat generated by the muscles to the blood. It's then circulated to the skin to release the heat, also known as the dry heat exchange, and stimulate sweating (evaporation) to keep the body cool. The cardiovascular system also plays a role in keeping us cool, and in fact does double-duty to assist in our workout. Not only does it pump oxygen to the muscles you're working, but it also pumps blood to the skin to help dissipate heat.

Let's face it: Outside is the perfect place to exercise on a cool, dry and breezy day. It's also easier on our bodies, because it can better facilitate the dissipation of body heat to the environment. However, as summer heats up and the humidity increases, we need to beware of the impact it has on us, and prepare for it.

It is much more difficult for the body to get rid of heat on a sunny and hot day when the high air temperature limits dry heat loss from the skin, and a lack of a breeze only compounds the problem. Additionally, humid conditions make it even more difficult for the body to regulate temperature. Since sweat doesn't evaporate readily off of our skin on a humid day, it puts a kink in the body's cooling system.

On these dog days of summer, sweating a lot may be the primary means of keeping our bodies cool. It's important to keep in mind that the sweat evaporating from our skin's surface cools the body. While not intuitive when sweat is dripping off our nose, wiping it off with a towel may not be the best idea on a hot day!

Run in the Sun: Training in the Heat

If you're not concerned about performing at the top of your game in the heat, then by all means head inside to the treadmill and take advantage of climate control. However, if you're training specifically for a race in late summer, you should be doing the majority of your runs in similar conditions and interspersing indoor training.

In the air conditioning, you'll have less heat-induced stress on your body, which means you can devote more of your cardiovascular capacity to intense and fast running. It can also serve as a much-needed reprieve on days that are particularly muggy, or when your only time to work out is midday under the blazing sun.

On the days you exercise outdoors, make sure you set performance expectations. When running in the heat, you'll likely notice -- at least at first -- you can't go as far or fast as you would be able to in cooler conditions without expending more effort. Remember, when exercising in the heat, you're putting more stress on your body and asking your cardiovascular system to do double-duty. So, expect to find working out on a hot day more demanding than in an air-conditioned gym.

The good news is that you can adapt to the summer heat, as long as you give yourself adequate time and training. Like any exercise program, you've got to do it regularly and progressively. Spend a few times each week outdoors, and your body will become more efficient at sweating and sending blood to the skin without compromising blood flow to the muscles. While the sweating part might not be ideal for social situations, it's good for training!

Bottom line: Take precautions when you exercise outside. Your body -- and your race time -- will thank you.

Here are some tips for working out in the heat:

-- Plan to exercise during the early morning or later in the evening when it's cooler to avoid peak midday heat.

-- Get used to the heat gradually by acclimating with regular, short, moderate-intensity workouts over two weeks.

-- Check the weather before you go outside, and be prepared.

-- Get hydrated by drinking plenty of water at least four hours before exercise. You'll know you're hydrated when your urine is pale yellow or straw colored.

-- Stay hydrated and keep your body cool by sipping cold water regularly during your workout -- either take water with you or locate the water fountains.

-- Drink plenty of water after your workout.

-- Wear light, loose-fitting and breathable (wicking) clothing to allow the body to dissipate heat and don't wear hats. Also, expose as much skin as you can to allow maximum body heat loss.

-- Don't forget to wear water and sweat-resistant sunscreen to protect your exposed skin.

-- Avoid lengthy warm-ups on hot, humid days.

-- Lower your exercise expectations. Decrease your exercise intensity and duration when working out on a hot day, and include longer -- or more -- rest intervals.

-- Exercise with a partner so you can check on each other.

-- Listen to your body. Stop and find a cool environment if you experience signs or symptoms of heat-related illness, such as fatigue, dizziness or muscle cramps, clumsiness, headache, nausea or confusion. If your symptoms don't resolve with rest, fluids and cooling, call 911 or get emergency help.

-- Don't exercise if you are ill, especially if you have a fever, respiratory infection, diarrhea or vomiting.

Chris Jordan, MS, CSCS, NSCA-CPT, ACSM HFI/APT, is the Director of Exercise Physiology at Johnson & Johnson's Human Performance Institute. He designed and implemented the movement/exercise components of the Corporate Athlete Course, including the widely-known 7-minute workout, and is responsible for the development and execution of all corporate fitness programming. As an experienced international keynote speaker and performance coach, he trains hundreds of corporate executives of FORTUNE 500 companies each year. Chris is a Certified Strength and Conditioning Specialist and Certified Personal Trainer through the National Strength and Conditioning Association and a Certified Health Fitness Specialist and Advanced Personal Trainer through the American College of Sports Medicine, and a Certified Performance Enhancement Specialist through the National Academy of Sports Medicine. He co-authored the peer-reviewed article "High-Intensity Circuit Training Using Body Weight" in the American College of Sports Medicine's Health & Fitness Journal, which led to the Gretchen Reynolds' blog "The Scientific 7-Minute Workout" in The New York Times and generated significant media coverage. Chris has been interviewed about the workout by ABC World News with Diane Sawyer, NPR, CNN, Sirius XM's Doctor Show, The Laura Ingraham Show, Men's Journal, Women's Health, Shape, and more.