Sunday, March 4, 2012

Giant Bags of Mostly Water

     I recall an episode of Star Trek Next Generation where an alien life force described humans as “giant bags of mostly water”.  So why is it that most of us drink very little water?  Second to oxygen, your body needs hydration to function properly. 

     For runners, the need for appropriate hydration is even more important.  Hydration will impact your performance and help to prevent injury.  The good news is that it’s not particularly complicated to meet your typical person’s hydration needs.

     If your typical exercise session is around 60 minutes or less, and doesn’t involve vigorous activity outdoors in hot, humid weather, you probably don’t need to interrupt your exercise session for a drink unless you prefer to.  Listen to what your body is telling you during and after your run.

     Dehydration isn’t something to be taken lightly.  Some of the symptoms of dehydration may include starting to feel lightheaded, confused, uncoordinated, or having muscle cramps.  Dehydration can also lead to elevated heart rate and body temperature. 

     So what’s a runner to do?  Taking into account individual differences, the chart below is a general guideline for water intake before, during, and after vigorous exercise.  

Drink Water
How Much?
Before Exercise
8-16 oz
At least 15 minutes before workout
During Exercise
4-8 oz
Every 15-20 minutes
After Exercise
16-24 oz per pound* lost
As soon as possible

     Two hours of vigorous exercise can deplete the fuel supply (called glycogen) that your muscle cells use during vigorous activity. Commercial sports drinks containing 6% to 8% carbohydrate solution from various sugar sources are recommended for exercise events lasting longer than 1 hour.  In addition to hydration, they replace lost potassium and sodium that your body needs.

     So how do you know if you are hydrated adequately?  There are two areas to take a look at.  If your urine is regularly light yellow to almost clear, then you are adequately hydrated.  Sweating at a rate that causes you to lose more than 2% of your body weight is another indicator of dehydration.  This would require weighing both before and after exercise.  Keep in mind that hot and humid weather will impact you greater.

     Drinking on an interval, during long exercise sessions will help adequately hydrate your body.  Don’t wait until you are thirsty to drink  After all you are a giant bag of mostly water!

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