Wednesday, July 16, 2008

Staying Hydrated

If you want your workouts to be more enjoyable (easier) and perform at your best you will need to stay hydrated. A loss of just 5% of your body weight in sweat is enough to significantly decrease your performance (that works out to 7.5 lbs for a 150 pound person). Even a loss of 2% (3lbs for a 150 pound person) can result in a reduction in your performance, as well as placing greater stress on your heart. In addition, all of us remember the Gatorade advertisements stating that thirst is a poor guide for hydration.

Maintaining hydration is especially important when engaging in longer duration exercise in hot weather (greater than an hour) or even high intensity exercise for a shorter period of time. These are just guidelines – the harder you exercise the greater the sweat loss and the more you need to drink (water and electrolytes). Electrolyte replacement is especially important if you are a salty sweater (do you get white salt stains on your cloth’s? – then you need to replace more electrolytes, especially sodium).

The first step in staying hydrated during exercise is to stay hydrated during the rest of the day. As a minimum you should be drinking a half-gallon of water (or at least total fluid – not counting alcohol) over the course of the day. If needed, you can flavor water with sugar free drink mixes or mix juice half and half with water. Drinking flavored water has repeatedly been found to increase fluid intake (most of us can down a glass of juice or other beverage faster and with greater ease than the same volume of plain water). PowerBar now makes an electrolyte drink mix that is a good low carb alternative for the electrolytes that you loose in sweating (think Gatorade without the sugar). Chilling your drinks also helps increase consumption, especially on hot days.

It is actually better to drink small amounts over the whole day instead of drinking all your water in just a few sittings – this is because too much water at once just results in more of it being lost in urination.

I make it a practice to keep 32 and 16oz refillable bottles of water in my refrigerator at home and the office. Anything larger than that becomes warm before I can drink the whole thing (some people I know use just use 8 oz bottles).

Hydration during workouts:

Prior to your workout

  • When to eat – any meal should be eaten at least 2 hours before your workout, to soon before your workout and you could end up with cramps, nausea or worse vomiting. What you eat is something you’ll have to experiment with, as a general rule eat something light and easy to digest. – you will want to experiment with what you can eat before your workouts to find out what you can tolerate.
  • About 2 hours before your workout drink 17oz of water or sports drink.
  • Weigh your self as soon before your workout as possible and record it!
During your workout

  • Aim for about 8 ounces every 20 minutes. You may need to adjust this depending on weight lost during previous workouts as well as your opportunity to drink during your workout (between rounds have a bottle handy that you can drink from with your gloves on).
  • On workouts longer than one hour you also need to pay attention to electrolytes and carbohydrate.

Sports drink guidelines:

  • Max of 15g of carbohydrates per 8 ounces (any more and absorption slows down)
  • 70mg Sodium per 8 ounces
  • After your workout

Weigh yourself at the end of your workout and compare to pre workout weight.

If you have maintained hydration you should weigh the same, if you weigh less after a long workout you didn’t drink enough to keep up with fluid loss (you aren’t going to lose pounds of fat in one workout). To replace fluid loss you will need to drink 23 ounces of water for each pound lost (eat some salty snacks with the water or consume a sports drink that has sodium).

If you want more detailed information on hydration during exercise I encourage you to follow the links below:

American College of Sports Medicine Position Stand: Exercise and Fluid Replacement

National Athletic Trainers Position Statement: Fluid Replacement for Athletes

Gatorade Sports Science Institute

(Please post comments, suggestions or questions to “Comments” below)

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