Runners know it's important to stay hydrated to run their best, especially in the summer. "Being more than two percent dehydrated in warm environments causes a decline in performance," says Robert W. Kenefick, Ph.D., a physiologist with the U.S. Army Research Institute of Environmental Medicine.
To keep fluids handy, you probably stash a water bottle in a gym bag or leave sports drink in your car. But to really improve performance, you need to be more than a casual sipper. A number of recent studies offer runners smarter ways to stay hydrated while also giving their running a boost. Here's how you can apply some of these strategies to your own hydration plan and run your best.
PRE-HYDRATE TO RUN FAST
WHY: In a study in the April 2010 Journal of Athletic Training, runners who started a 12K race dehydrated on an 80°F day finished about two and a half minutes slower compared to when they ran it hydrated. Dehydration causes your blood volume to drop, which lowers your body's ability to transfer heat and forces your heart to beat faster, making it difficult for your body to meet aerobic demands.
DRINK UP: Drink eight to 16 ounces one to two hours before a run. Sports drinks and water are good choices, says running coach Cassie Dimmick, R.D. Iced coffee and tea are fine, too. Didn't plan ahead? Fifteen to 30 minutes before going out, drink at least four to eight ounces of fluid.
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GO COLD FOR LONGER RUNS
WHY: In a study published in 2008 in Medicine & Science in Sports & Exercise, cyclists who drank cold beverages before and during their workout exercised nearly 12 minutes longer than those who drank warm beverages. And in a study published this year, runners who had an ice slushy ran about 10 minutes longer than when they had a cold drink. In both cases, the drink that was colder lowered body temperature and perceived effort, allowing participants to exercise longer.
DRINK UP: Before going for a hot run, have a slushy made with crushed ice and your favorite sports drink. To keep drinks chilled while you run, fill a bottle halfway, freeze it, and top it off with fluid before starting. Running a loop? Stash bottles in a cooler along your route, says Dimmick.
What to drink when: All fluids are not created equal.
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STAY ON SCHEDULE
WHY: According to a study in the July 2009 Journal of Sports Sciences, when cyclists recorded their plan for hydrating during workouts—including exact times and amounts—they drank more frequently and consumed more fluid midworkout than their nonplanning peers. "Planning helps people remember how much and when they need to drink," says lead author Martin Hagger, Ph.D., of the University of Nottingham in the United Kingdom.
DRINK UP: Note your thirst during your runs, and write down how often and how much you drink.
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REVIEW: your notes to help you plan when to drink. Set your watch to beep every 15 minutes as a reminder to consider your thirst. "Drinking smaller amounts at regular intervals can help you absorb fluid more effectively," says Dimmick, "and avoid stomach sloshing."