By Dorene Internicola

NEW YORK, July 8 (Reuters) - Can't take the heat?

Fitness experts say one way for outdoor exercisers who dread the long, hot summer days of steamy runs and breathless aerobics during a heat wave is to embrace it.

"It takes most healthy people 10 to 14 days to fully acclimate to exercising in the heat," said Dr. Cedric X. Bryant, chief science officer of the American Council on Exercise. "In order to achieve that you need to be exercising in heat."

The heat-acclimated individual will sweat sooner and that sweat will be more dilute, Bryant said. There will be a lower risk for dehydration and a reduction in the heat gained through exercise that will help maintain a lower core temperature and heart rate response.

He said as much as 25 percent of the healthy population is estimated to be heat intolerant in an unacclimated state. Once they get acclimated that drops to 2 percent.

A 2011 report from the U.S. Centers for Disease Control showed that about 6,000 people a year seek emergency treatment for heat illnesses suffered while playing sports or participating in other recreational activities outdoors.

While acclimating to the physiological demands of the heat, Bryant said, be sure to tone down your workout.

"Strictly adhere to the talk test (the ability to talk as a gauge of correct exercise intensity)," he said. "It's not a time to do intervals or high-intensity exercises. Afterwards, when you're fully acclimated, you can ramp up intensity."

Connecticut-based fitness instructor Ellen Barrett said a daily dose of hot yoga primed her for the heat wave that slammed the U.s. East Coast in June.

"I did the Bikram yoga challenge every day for a month, so when that heat wave hit I didn't even notice it," said Barrett, author of the upcoming book, "The 28 Days Lighter Diet."

She said Swiss tennis ace Roger Federer trains in Dubai.

"He plays all day in the hot sun so when he's at the U.S. Open at the end of summer in New York City, he looks fresh as a daisy," she said.

Exercise physiologist and running coach Tom Holland is a veteran of more than 60 marathons and 21 Ironman triathlons, many held in sweltering conditions including an Ironman in Malaysia, where the temperature soared to 104 degrees (40 Celsius) and humidity to 99 percent.

"I actually love running in the brutal heat and humidity and have trained myself accordingly," said Holland, author of "The Marathon Man."

When running in the heat, he recommends adjusting speed and goals and said runners should expect to run more slowly and should focus on covering the distance.

"I paced a 60-year-old client in the 2012 Boston Marathon where the race hit 90 degrees," he said. "When I saw how hot it would be, we adjusted his race goal from 3:40 (three hours, 40 minutes) to just finishing."

Running in heat is difficult, Holland explained, because blood has two conflicting interests - supplying working muscles and going to the skin to cool the body down.

"So there is less blood for the muscles, our hearts have to work harder, our heart rate increases, and the relative intensity of the run increases," he said. "You simply cannot run as fast in hot conditions."

Bryant said that even the fully heat-acclimated exerciser reverts rapidly when the training stops.

"Unfortunately the benefits of heat acclimation are lost quite quickly," he said. "For every two days an individual abstains from heat exposure, one day of acclimation is lost. So after two to three weeks you're back to starting over." (Editing by Patricia Reaney and Bill Trott)





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  • Improved Attention And Focus


    A small study from the University of Illinois at Urbana-Champaign found that kids with ADHD were <a href="http://www.ncbi.nlm.nih.gov/pubmed/18725656?ordinalpos=6&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum" target="_hplink">able to concentrate better after a 20-minute walk in a park</a> rather than a walk through city or neighborhood streets.

    "What this particular study tells us is that <a href="http://well.blogs.nytimes.com/2008/10/17/a-dose-of-nature-for-attention-problems/" target="_hplink">the physical environment matters</a>," Frances E. Kuo, director of the university's Landscape and Human Health Laboratory and one of the study's co-authors told <em>The New York Times</em>. "We don't know what it is about the park, exactly -- the greenness or lack of buildings -- that seems to improve attention."

    <em>Flickr photo by <a href="http://www.flickr.com/photos/quacktaculous/3143079032/" target="_hplink">quacktaculous</a></em>




  • Greater Likelihood To Keep Exercising


    While every little bit of exercise counts, let's be honest: most of us could probably afford to do a little bit <em>more</em>. The <a href="http://www.cdc.gov/physicalactivity/everyone/guidelines/adults.html" target="_hplink">2008 Physical Activity Guidelines for Americans</a> recommend the average adult get two hours and 30 minutes of moderate-intensity cardio every week, plus two or more sessions of strength training.

    It's all too easy to skimp on workouts. However, a 2011 survey found that exercising outdoors is a reinforcing behavior -- the study found that outdoor exercisers "declared a <a href="http://www.ncbi.nlm.nih.gov/pubmed/21291246" target="_hplink">greater intent to repeat the activity</a> at a later date" than gym-goers.




  • Lower Risk Of Being Overweight


    The fresh air, the sunlight, the scenery, the open space -- there's a lot about being outside that can inspire more activity, especially when contrasted to the beckoning couches and screens of indoor spaces. And the extra movement adds up. A 2008 study found that rates of overweight among children who spent more time outside were <a href="http://www.nature.com/ijo/journal/v32/n11/full/ijo2008171a.html" target="_hplink">27 to 41 percent lower than in kids who spent more time indoors</a>.




  • More Energy


    Exercise itself is sure to reinvigorate you when you're feeling sluggish, but fresh air can up the effect. A 2009 study from the University of Rochester found that <a href="http://www.intrinsicmotivation.net/SDT/documents/2010_RyanWeinstenEtAl_JEVP.pdf" target="_hplink">just 20 minutes outside</a> can rev you up <a href="http://www.telegraph.co.uk/science/science-news/7803320/20-minutes-outdoors-as-good-as-cup-of-coffee.html" target="_hplink">as much as a cup of coffee</a>, <em>The Telegraph</em> reported.

    "Often when we feel depleted we reach for a cup of coffee, but this suggests a better way to get energized is to connect with nature," lead author <a href="http://www.psych.rochester.edu/faculty/ryan/" target="_hplink">Richard M. Ryan, Ph.D.</a>, a professor of psychology at the university told the publication.

    <em>Flickr photo by <a href="http://www.flickr.com/photos/galant/688642298/" target="_hplink">thebittenword.com</a></em>




  • Faster Healing And Less Pain


    A 2005 study of spinal surgery patients found that patients staying on the sunny side of the hospital reported <a href="http://www.psychosomaticmedicine.org/content/67/1/156.abstract" target="_hplink">less pain, less stress and needed less medication</a> for pain than patients housed on the shady side of the building.

    Of course, recovering from a surgery will temporarily put a damper on most fitness plans, but if sunlight is the key ingredient, an outdoor workout may just boast some of the same benefits for more minor injuries.




  • Higher Vitamin D Levels


    Taking your workout outside is a great (and free!) way to soak up some additional vitamin D. A 2011 study that found vigorous exercisers had higher levels of vitamin suggested that <a href="http://yourlife.usatoday.com/fitness-food/exercise/story/2011-10-04/Vigorous-exercise-boosts-vitamin-D-while-lowering-heart-risk/50660716/1" target="_hplink">outdoor exercise may be the reason why</a>, <em>USA Today</em> reported.

    It may be especially helpful for people with a few pounds to lose, according to Everyday Health, since overweight people are almost <a href="http://www.everydayhealth.com/fitness/outdoor-exercise-benefits.aspx" target="_hplink">twice as likely to not get enough vitamin D</a>.

    <em>Flickr photo by <a href="http://www.flickr.com/photos/wonderlane/4775285017/" target="_hplink">Wonderlane</a></em>




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