Dehydration hurts performance, right? Not necessarily. But don’t ignore it.
Pro racers ride so hard their guts can’t absorb enough fluid to replace all that they sweat out. Race rules may restrict when a rider can get a bottle toward the end of a stage. Although somewhat dehydrated, the pros sprint quite well! Despite the dehydration pro, we rarely read about cramps in the peloton. In lab experiments, dehydration has not been shown to cause cramps.
We’ve all seen pictures of runners collapsing at the end of a marathon or triathlon. Must be because the runner is dehydrated, right? Wrong. When an athlete stops, the runner’s pulse and blood pressure fall significantly so less blood gets to the brain and the runner faints.
For more read my column on 12 Myths About Hydration .
The average male’s body is 60% water; the average female’s is 50%. The typical athlete has another 10% water because glycogen is stored with water. If we don’t replace most this, we die. However, almost all of the heat-related deaths every summer are shut-ins living in homes with no air conditioning. Your body has about 2 quarts (liters) of free water in your intestines. You don’t even start to feel thirsty until you’ve lost 1.5 to 2 quarts of water!
The American College of Sports Medicine recommends avoiding dehydration of more than 2%, i.e., 2% of your weight. If you weigh 150 lbs, then 2% dehydration is three pounds. Three pounds is about 1.5 quarts of water.
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