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ACSM In The News

ACSM is fortunate to be the go-to source on sports medicine and exercise science for several national and international media outlets. You can find some of our most recent coverage below, or you can view archived articles.  

Heat and Hydration: Important Concerns for Outdoor Workouts

by User Not Found | Aug 01, 2011
Expert says risks could increase with global climate change

LONG BEACH, Calif. – Avoiding heat stroke, heat exhaustion, and dehydration is crucial for those exercising in hot weather, says an expert at the American College of Sports Medicine’s 12th-annual Health & Fitness Summit & Exposition.

W. Larry Kenney, Ph.D., FACSM, gave advice that echoes recommendations previously published in ACSM’s Position Stand on Exertional Heat Illness During Training and Competition. He also speculated that hot-weather risks may increase even more in the future.

“Right now, it’s difficult to tell from available data if global warming and climate changes have played a role in increasing heat-related injuries during the past few years,” Kenney said. “But global warming can increase the frequency and intensity of heat waves, which, of course, can lead more heat illness casualties.”

Kenney was careful to dispute recent studies claiming that (1) dehydration of 2 to 4 percent body weight loss does not impact exercise performance, and (2) body weight loss is not a good way to monitor the body’s fluid needs. Instead, he encouraged athletes to monitor their pre- and post-exercise weight in order to maintain proper hydration. According to Kenney, and ACSM’s hydration guidelines, athletes should:

Calculate their body’s sweat rate (by adding weight lost in one hour of exercise plus amount of fluid consumed during the hour of exercise). Athletes should aim to replace all fluid lost during exercise, and rely on sweat loss, rather than just thirst, to monitor fluid needs.

Drink fluids before exercise and periodically during exercise, instead of practicing rapid fluid replacement in the middle of exercise. Drinking at intervals will provide more adequate hydration and urine production.

Avoid extreme excessive water consumption, which can lead to hyponatremia (over-hydration that may dangerously reduce sodium concentrations in the body), in rare cases.
Kenney also explained the physiological differences between heat stroke and heat exhaustion.

“During heat stroke, the body essentially shuts down its mechanisms for heat release, including sweating,” he said. “Heat exhaustion, however, is basically severe dehydration that affects the cardiovascular system. Fluid is lost from all body compartments, including the blood, forcing the heart to work harder to maintain output.”

Warning signs of heat illness and dehydration include thirst, irritability, headache, dizziness, muscle cramping, unusual fatigue, nausea, vomiting, hyperventilation, and confusion or problems walking.


The American College of Sports Medicine is the largest sports medicine and exercise science organization in the world. More than 20,000 International, National and Regional members are dedicated to promoting and integrating scientific research, education and practical applications of sports medicine and exercise science to maintain and enhance physical performance, fitness, health and quality of life.

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