Hydration basics

Every body needs enough water. Inadequate fluid intake can lead to dehydration that affects your mental and physical performance. The first step to being well hydrated is to drink fluids throughout the day. Try to drink half your body weight in fluid ounces every day. For example, if you weigh 150 lb, then you need about 75 fl oz daily. Here are a few more tips to help you stay hydrated during and after exercise to optimize performance and recovery.

Hydration during exercise

Many factors affect hydration needs, including the type and duration of exercise, environment, and type of equipment worn. Don’t rely on thirst as a good indicator of your fluid needs. Try to drink regularly throughout your activity.

In general, drink 16–32 oz of fluid every 60 minutes during exercise. Adjust your fluid intake based on your environment, how much you sweat, and your opportunity and availability to drink. In addition, heat and humidity, heavy clothes or equipment, increased exercise intensity, or exercise longer than one hour require Warfighters to drink more fluids.

Limit your fluid intake during exercise to 48 oz per hour. For exercise lasting less than one hour, drink water. If it’s hot or humid, a sports drink might be better for hydration. For exercise lasting longer than one hour, drink water, sports drinks, or both for optimal hydration.

Sports drinks should contain (per 8 oz):

  • Carbohydrates 12–24 g
  • Sodium 82–163 mg
  • Potassium 18–46 mg

Hydration after exercise

Dehydration greater than 2% of body weight can impair heat regulation and mental and physical performance. Check your hydration status by weighing yourself before and after exercise whenever possible. More than a 2% weight loss indicates dehydration. (For example, 2% weight loss in a 150-lb warrior is 3 lbs.) Or use the urine color chart below to estimate how hydrated you are.

Are you hydrated? Take the urine color test. Nearly clear to pale yellow urine indicates optimal hydration and a high level of performance readiness.   When your urine darkens to medium yellow, you’re probably still well hydrated, but slightly less performance ready than when your urine is light yellow.  The darker your urine is, the less hydrated you are and the more likely you are to have decreased performance.  You’re considered dehydrated—and unable to perform at your best—when your urine is dark yellow. You need to drink more water.  If your urine is brown, you might have a severe medical issue. Seek medical aid. You may have blood in your urine or kidney disease.   The color chart is not for clinical use. Some vitamins and supplements might cause a darkening of the urine unrelated to dehydration.  From Human Performance Resources by CHAMP, the Consortium for Health and Military Performance, HPRC-online.org.

Rehydrate with fluids and foods. For every pound of body weight lost, drink 20–24 oz of fluid—water, sports drinks, milk, and milk alternatives (soy, almond)—to restore fluid losses.

High-water-content foods can help contribute to your fluid intake too. Choose fruit (watermelon, grapes, peaches, etc.), high-water-content vegetables (zucchini, celery, cucumbers, tomatoes), soup, yogurt, and sherbet/sorbet throughout the day.

Replenish sodium by consuming drinks or foods that contain sodium (salt). Sodium helps you more quickly and completely rehydrate. Drinking too much plain water and/or not consuming enough sodium can result in hyponatremia (low sodium levels in your blood), which can be very serious if not treated. Be aware of the signs and symptoms: headache, vomiting, swollen hands and feet, confusion, and wheezy breathing.

You might find it challenging to drink enough fluids, but some simple reminders can help. First, keep a bottle on hand. Just seeing your water bottle reminds you to drink more. Also, always drink water with meals and snacks. Tip: Add sliced lemon, lime, mint, cucumber, or fruit to your water. Or add them to a water pitcher in your refrigerator.

References

Academy of Nutrition and Dietetics, Dietitians of Canada, & American College of Sports Medicine. (2016). Nutrition and athletic performance. Medicine & Science in Sports & Exercise, 48(3), 543–568. doi:10.1249/mss.0000000000000852

American College of Sports Medicine, Sawka, M. N., Burke, L. M., Eichner, E. R., Maughan, R. J., Montain, S. J., & Stachenfeld, N. S. (2007). Exercise and fluid replacement. Medicine & Science in Sports & Exercise, 39(2), 377–390. doi:10.1249/mss.0b013e31802ca597

Baker, L. B., & Jeukendrup, A. E. (2014). Optimal composition of fluid-replacement beverages Comprehensive Physiology (pp. 575–620). doi:10.1002/cphy.c130014

Institute of Medicine. (2005). Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. Washington, DC: National Academies Press. doi:10.17226/10925.

Karpinski, C., & Rosenbloom, C. A. (2017). Sports Nutrition: A Handbook for Professionals, Sixth Edition. Chicago, IL: Academy of Nutrition and Dietetics.