Hydration

Staying hydrated

If you want your runs 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% (4lbs 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 long duration endurance exercise (greater than an hour) or even moderately long exercise (greater than half an hour) in hot weather.

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). Chilling the water you drink 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 32oz 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 16 or 8 oz bottles).

Hydration during the long runs:

Prior to your run

• When to eat – any meal should be eaten at least 2 hours before your long run, to soon before your run and you could end up with cramps or 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 runs to find out what you can tolerate.


• About 2 hours before your run drink 17oz of water or sports drink.
  Weigh your self and record it!

During your run

• Aim for about 8 ounces every 20 minutes. You may need to adjust this depending on weight lost during previous runs as well as your opportunity to drink during your run (most of us don’t have access to drinks every 20 minutes). Personally I place 32ounce bottles every 2-3 miles along my course. I go back later to pick up the empty bottles (I try and go by the naturalist adage “Take only pictures and leave only footprints” – in this case meaning don’t leave your garbage behind).
  


• On runs longer than one hour you need to pay attention to electrolytes and carbohydrate.
  


• Sports drink guidelines:
  Max of 15g of carbohydrates per 8 ounces
  70mg Sodium per 8 ounces

After your run

• Weigh yourself and compare to pre run weight.


• If you have maintained hydration you should weigh the same, if you weigh less after a long run you didn’t drink enough to keep up with fluid loss. 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 with 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
http://www.acsm-msse.org/pt/pt-core/template-journal/msse/media/0196.htm

National Athletic Trainers Position Statement: Fluid Replacement for Athletes
http://www.nata.org/statements/position/fluidreplacement.pdf

Gatorade Sports Science Institute
http://www.gssiweb.com/