Dehydration will hinder your performance and it can seriously affect your health. Getting enough fluids is important whether you exercise or not, but exercise increases your fluid needs, making adequate hydration especially important. Dehydration can result in an increased heart rate and body temperature, impaired mental function, heat exhaustion and even heat stroke. How much fluid you need depends on your body size, your sweat rate, how long you exercise, the intensity of exercise, climate and even the type of clothing you wear. Because fluid needs are so variable and individualized, there is no one-size-fits-all amount that is appropriate for everyone. There are, however, guidelines that can help you stay adequately hydrated during a workout.
Hydration Zone
Your hydration zone is the range at which you can lose fluid weight and still be properly hydrated. To be within your hydration zone, you should not lose more than 2 percent of your total weight and you shouldn't gain weight. A weight loss of 1 to 2 percent allows you to still perform at your best. You calculate your hydration zone by multiplying your normal body weight by 0.02. If, for example, you weigh 175 lbs., your hydration zone would be 171.5 to 175 lbs., since 175 x 0.02 = 3.5. You should not weigh less than 170.5 lbs. and not more than 175 lbs.
Recommended Guidelines
To stay in your hydration zone, the American College of Sports Medicine, or ACSM, has come up with recommendations on how to hydrate when exercising. The ACSM recommends that you drink 16 to 17 oz. of fluid one to two hours before exercise and 8 to 16 oz. of fluid 15 minutes before exercise. During exercise, your fluid needs can vary from 4 to 16 oz. every 15 to 20 minutes, depending on your activity, intensity and climate. Sports drinks are preferred if you exercise longer than 60 minutes or at high intensity. Sports drinks provide electrolytes and energy to help you stay hydrated and prevent cramping. After exercise, it is recommended you drink 24 oz. of fluid for every pound of fluid lost.
Additional Tips
Because your thirst mechanism is blunted during exercise, thirst is not a good indicator of hydration. To ensure you stay properly hydrated when exercising, make sure you always carry fluids with you and drink on schedule.
And drink plenty of fluids before exercise. This will not only ensure that you are properly hydrated but it prevents fluids slushing around in your stomach. Because a full stomach empties quicker than a few gulps of water. Monitoring urine color is also an easy method to determine if you are properly hydrated. If you are sufficiently hydrated, your urine should be light in color and plentiful. If your urine is the color of apple or orange juice, it indicates you need more fluids.
Electrolytes
When you exercise at high intensity or for long periods of time, it is also important to replenish your electrolytes. Electrolytes are minerals such as potassium and sodium, which help regulate fluids in your body. If you work out for more than two to three hours at a time, you not only lose 4 to 5 qts. of sweat, but 300 to 800 mg of potassium and 1,800 to 5,600 mg of sodium. The best way to replenish these electrolytes is by eating foods and fluids that contain electrolytes. Good sources of potassium and sodium are: grapefruit juice, bananas, oranges, sports drinks, nuts, or pretzels. You can also be more liberal with the use of salt and salty foods before you work out and it helps to eat more potassium rich foods every day.
References
- Power Bar; Nutrition Articles:Hydration during Training and Guidelines for Optimal Hydration to Avoid Dehydration and Hyponatremia
- American College of Sports Medicine Position Stand; Exercise and Fluid Replacement; Michael Sawka, et al.; February 2007
- RD411.com: Hydration for Athletes
