Years ago I went on a road trip with some friends. We had a long drive and I have a teensy tiny bladder so I made the decision to not drink anything for most of the trip as I didn’t want to be the reason we’d have to stop every 5 miles so I could pee. We arrived to our destination late in the evening and the following day I was exhausted. Exhausted to the point that I fell asleep around dinner time and my friends were unable to wake me (screwing up our plans for that evening). I slept for about 14 hours straight which was very unusual for me. A few days later, once we’d returned home, it was discovered that I was severely dehydrated. DUH! But I was young and hadn’t thought about it at the time but looking back on that weekend I’d drank very little – next to nothing. I get dehydrated very quickly and from that trip I learned my lesson.
Other than oxygen, your body needs water more than anything else. This is especially important for people who are exercising. You need to drink water before, during and after your workout, however, If your 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. But you do need to replenish what your body loses (thru sweat, urinating, etc.).
The goals of fluid intake during exercise are to prevent dehydration from occurring and to not drink in excess of one’s sweating rate. One good way to figure out whether you need to drink something during your workout is to simply weigh yourself (without clothes) just before and after a typical workout. If your weight change is more than 2% of your starting weight, then in the future, you should plan to drink enough water during your workout to keep your post-workout weight within that 2% range. Typically, drinking a cup (8 oz) of water every 15-20 minutes will do the trick in all but the most extreme situations.
If you’re like me and sometimes work out vigorously for two hours or more you’ll likely require something other than water to replenish your fuel supply (glycogen) that your muscle cells use during vigorous activity. Your body may need something to drink that contains carbohydrate for energy and to sustain performance. Commercial sports drinks containing 6% to 8% carbohydrate from various sugar sources are recommended for exercise events lasting longer than 1 hour. Higher carbohydrate amounts should be avoided because they impede the rate at which the drink leaves the stomach thereby slowing down the hydrating benefit. To estimate your carbohydrate need during sustained exercise, aim for about 30-60 grams of carbohydrate per hour of endurance exercise.
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Wedro, Benjamin C. “Heat Exhaustion,” accessed July 2011. MedicineNet.com.