In the 1990s, endurance athletes were advised to stay ahead of their thirst and drink as much as they could stand during training and races. A decade later, almost everyone had been schooled with the knowledge that hydrating to excess can cause hyponatremia—essentially, intoxication caused by consuming too much water, a potentially fatal condition in which cells swell with the excess fluid.
However, whether dehydration is equally troublesome and a hindrance to peak performance remained up in the air. But according to a 2011 review of time-trial studies of dehydration, losing up to 4 percent of body weight during exercise does not alter performance. Results from endurance events seem to bear that out: during the 2009 Mont-Saint-Michel Marathon in France, researchers measured the weight loss of 643 competitors and compared it with their finish times. The runners who lost the most water weight were also the fastest. Most of those who finished in less than three hours lost at least 3 percent of their body weight to sweat.
Get over it: “Drink when you feel thirsty,” says James Winger, M.D., assistant professor at Loyola University’s Stritch School of Medicine in Chicago, who conducted a survey of distance runners last year and found that misconceptions about hydration were rampant, even among endurance athletes. “Thirst is an exquisitely finely tuned indicator of your body’s actual hydration status,” Dr. Winger says. “Listen to it.”
Comments
Australian Institute of Sport would beg to differ. http://www.ausport.gov.au/ais/nutrition/factsheets/hydration2community nrifif
Flag ThisJoe Friel, Chris Carmichael, and other cycling coaches beg to differ. Turning point is supposed to be 2.5% of body weight during activity. I would tend to agree.
Flag ThisDA 29, what are they basing that on? And on what basis are you agreeing?
Flag ThisThis article is not titled well. The argument they are making actually does not have to do with hydration levels. Their argument is that weight loss or some percentage, regardless of being over or under hydrated was not measured to alter performance. That is quite different than saying that dehydration does not alter performance. The athletes might have started over hydrated and returned to only slightly below or at a normal weight level due to the excercise. Granted Outside isn't a scientific journal, but when dispelling myths or attempting to disseminate scientific evidence, you should be very careful about the claims being made. Otherwise, you might just create new myths that people will believe.
Flag ThisSo what was this "2011 review"? references??
Flag ThisThe importance of hydration also depends on ambient temperature. Dehydration doesn't hurt as much in the cold, but can become a very big issue in heat. Under some conditions, such as heat, drinking when feeling thirsty can get you in trouble. The statement that dehydration hurts performance does not deserve to be called a myth.
Flag ThisAll of these articles about "Fitness Myths" seem to be based on flawed research, or taking research from one very specific study and trying to extrapolate it to a broader situation that the research cited doesn't necessarily support. Measuring body weight pre vs. post exercise says absolutely nothing about the hydration levels, perhaps those who lost 3% of body weight and finished fastest were also those who were best hydrated before the race started. Magazines write articles like this to sell copies and get page views, even if the science doesn't necessarily back up exactly what they say it does.
Flag ThisTo the author. I thought dehydration worries were more about heat stroke and exhaustion and injuries. NOT about performance. Maybe I'm wrong.
Flag ThisI just ordered this magazine and after reading this article I am really wishing I would have read this first. Terrible article and I'm shocked that a magazine would let flawed information like this go out with it's name on it!
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