By Nancy Clark, MS, RD, CSSD

drinking-water Proper hydration is essential for top athletic performance.

Unfortunately, many runners pay too little attention to this and fail to include adequate fluids in their sports diet. They fatigue early and needlessly hurt their performance.

Photo courtesy of © Kristian Sekulic | Dreamstime.com

If you sweat heavily and fail to replace your sweat losses, you reduce your ability to provide adequate circulation to both the muscles and body surface.

This not only hurts your performance but also can endanger your health.

Fluid in blood transports glucose to the muscles and carries away lactic acid. Urine eliminates waste products. Sweat dissipates heat via the skin.

Use the following tips to keep well hydrated:

During Training
Fluids Before Hard Endurance Workouts
Fluids During Hard Workouts
Water vs. Sports Drinks
After Workouts
Sodium Replacement

Hydration During Training

On a daily basis, make sure you drink enough fluids. You can easily determine if you have had enough to drink by monitoring the volume and color of your urine.

  1. You should urinate a significant volume of urine every two to four hours throughout the day. The urine should be a light color, like lemonade. If the urine is dark, concentrated and scanty, you need to consume more water, juice, etc. Note: If you take vitamin pills, your urine may be dark. Monitor hydration by the quantity of urine rather than the color.
  2. To learn how much sweat you lose during running, weigh yourself before and after a hard workout. Each pound lost represents one pound (16 ounces) of sweat. During training, practice replacing sweat losses accordingly, and try to lose less than 2-percent of your weight (three pounds for a 150-pound runner).
  3. You don't have to drink only water. Juice, sports drinks, soft drinks, and watery foods such as yogurt, oranges, melon and soup, all have a high water content that contributes to overall fluid balance.
  4. Be aware that beer, wine and alcohol can hurt your performance. If you choose to drink alcoholic beverages, be sure to first quench your thirst with other fluids (and eat carbs to fuel your muscles). That is, drink water, eat some pretzels, then have a beer, if desired.
Fluids Before Hard Endurance Workouts
  1. The day before, drink extra water, juice, etc to be sure your body is well hydrated.
  2. The morning of the event, drink at least 16 ounces of liquids up to two hours prior to the start. Because the kidneys require 45 to 90 minutes to process liquids, two hours allows adequate time for you to empty your bladder before the start of the event.
  3. Five or ten minutes before start-time, "tank up" on another 8 to 16 ounces of water or sports drink.

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Fluids During Hard Workouts

  1. Prevent dehydration by drinking adequate liquids early in the event before you get thirsty. By the time you feel thirsty, you will have lost 1% of your body weight (1.5 lb or 24 oz sweat for a 150-lb person). Your heart will need to beat 3 to 5 more times per minute.
  2. Ideally, you will have learned your sweat rate and can drink to match your sweat losses. That is, if you lose 1.5 lbs (24 oz) per hour, that's 8 ounces of water, sports drink or diluted juice every 20 minutes.
Water vs. Sports Drinks

For the casual runner, water is always appropriate. Water is convenient, familiar, and satisfies your body's needs.

For highly competitive runners who workout intensely for an hour, and for endurance runners who expend large amounts of energy for more than an hour, a sports drink during the run optimizes fluid retention, delays dehydration, and enhances endurance.

The beverage should offer 50 to 80 calories per 8 ounces plus 110 to 170 mg sodium. Be sure to experiment during training to learn which flavors of sports drinks settle best in your stomach.

Hydration After Workouts

  1. Drink to quench your thirst, and then drink even more. Because the thirst mechanism inadequately indicates whether or not you've consumed enough fluids, monitor your urine. If several hours pass without a need to urinate, you are dehydrated. Keep drinking.
  2. Chocolate milk replaces not only fluid but also offers carbohydrates to refuel muscles and protein to repair muscles. Drinking 12 to 20 ounces within the hour after a workout can enhance recovery and reduce soreness.
Sodium Replacement

Sweat contains not only water but also small amounts of sodium (and other electrolytes) that keep your body in fluid balance. You lose small amounts of sodium when you sweat, but you do not deplete your body's stores––except possibly under extreme circumstances such as working out greater than 3 hours in the heat. (In such cases, you should consume a few salty foods before, during and after your workout.)

Commercial liquid replacement drinks are generally weak sources of sodium compared to what you can get in standard foods. The sodium in sports drinks is added to enhance fluid retention, not to replace sweat losses. Most sweaty runners can consume adequate sodium via pretzels, soup, pizza, and other salty foods pre- and post-workouts.

Copyright: Nancy Clark, MS, RD, CSSD
Nancy Clark's new Sports Nutrition Guidebook (2008), Food Guide for Marathoners, and Cyclist’s Food Guide are available at her website

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