Summer Heat & Hydration

Fri, 22 July 2011 - 4:11 p.m. MT
Credit: American Running Association

During this heat wave or generally anytime in the peak summer months, dealing with heat and humidity is an everyday occurrence.  The July 2011 heat dome over the eastern half of the U.S. is more unusual and highly dangerous.

If you’re like most runners, warm weather invites more outdoor running.   When the high heat arrives, extra caution is necessary.   Exercising in the heat can pose special problems.  Many runners and athletes carefully regulate their diet or fuel intake, but pay little attention to their body’s fluid needs.  This can be deadly, especially when it comes to heat conditions.  Proper fluid intake is essential for optimum performance and to reduce your risk of dehydration.

Hot Weather Running Survival Tips:

  • Cut back on your perceived effort on runs.  Throttle back on your speed to borrow an auto racing term. 
  • Run or exercise in the morning preferably.  Evenings in the hour prior to sunset can be tolerable too.
  • Wear light-colored and wick-away or polyester lightweight apparel
  • Wear sunglasses to protect your retinas from the intense sunlight
  • Use sunscreen on exposed neck, arms, backs of legs
  • Wear a lightweight light-colored hat or visor
  • As mentioned below, pre-hydrate in the 30+ minutes prior to a run
  • Run with a friend or buddy to monitor each others’ medical state in the heat
  • Run in shaded areas on trails or wooded parks; avoid all runs on sun-baked asphalt and concrete where temps will skyrocket and reflect back on you
  • Take it easy and don’t set any PRs on your running circuits

How often should you Drink Fluids?

Thirst is a good indicator of your fluid needs in many instances, but heat conditions warrant pre-run hydration.

  • Drink at least 16 oz of water or a combo of sports drink and water an hour before a run
  • Drink another 4 oz to 8 oz 15min to 30min pre-run

Post-run hydration:   drink enough fluids to regain lost weight in sweat.  It is good idea to figure out one’s sweat rate by weighing yourself sans clothing (nude) pre-run and again after a run.   Drink the amount of lost weight after a run.  Don’t overdrink and monitor your urine or pee color.

Electrolyte replacement:   water and a sports drink with a 6% solution of carbohydrates can help bring back lost electrolytes.

Hydration pre-Run helps(Running & Fitnews)

You're in the last few miles of your long run. It's hot and you're beginning to fade and slow down. You might have been able to avoid the slow-down, even in warm, humid conditions, by drinking a carbohydrate supplement before your runs, according to Mindy Millard-Stafford, Ph.D., and colleagues at Georgia Institute of Technology in Atlanta.

Trained runners ran three 15K trials on treadmills, at their own pace at about 82 degrees Fahrenheit and 62% relative humidity. The experiments were carried out in a lab during fall, and the runners were not used to hot weather, according to the researchers. An hour before running, the subjects drank a liter of either water, or one of two sports drinks.

There was no significant difference between the trials up to 13.4K, but during the last 1.6K the runners didn't slow down when they had taken the sports drinks before they began, but they did when they drank only water. The drinks were of different composition, but both provided benefits. Before your runs in hot, humid weather, drink about a quart of your favorite sports drink. The carbohydrate may help you to avoid running out of gas during the last mile or so, and you should feel good all the way.

(International Journal of Sport Nutrition, 1997, Vol. 7, No. 1, pp. 26-36)

Volume 16, Number 7, Running & FitNews
© The American Running Association.



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