Hydration Basics

By Tom Holland, MS, CSCS, CISSN on August 23, 2016 , categorized in Health


H20: It makes up more than half of the human body and it is essential to life. Water plays an integral role in numerous life-sustaining functions including the regulation of body temperature, the transportation of nutrients to the cells, the elimination of waste products from the cells, aiding in digestion, and more.1ACSM “Selecting Hydration for Fitness” https://www.acsm.org/docs/brochures/selecting-and-effectively-using-hydration-for-fitness.pdf Not taking in enough water, namely being dehydrated, can lead to headaches, fatigue, dizziness and more. Severe dehydration can result in more serious complications.2Murray B. Hydration and physical performance. J Am Coll Nutr. 2007 Oct;26(5 Suppl):542S-548S.

You can’t live without water, yet confusion still exists as to exactly how much we should consume, both daily as well as during exercise. Here are the current basic guidelines for both:


Your Daily Water Intake

One of the more frequently cited recommendations is that you should drink eight ounces of water, eight times per day. A 2002 study in the American Journal of Physiology examined the current hydration recommendations and found little evidence to support these numbers.3Valtin H. “Drink at least eight glasses of water a day.” Really? Is there scientific evidence for “8 x 8”? Am J Physiol Regul Integr Comp Physiol. 2002 Nov;283(5):R993-1004 In 2004 The Institute of Medicine issued new guidelines, but based them on total fluid intake (all beverages as well as food), recommending 11 cups of fluid per day for women and 15 cups per day for men.4Institute of Medicine. (2004)  Dietary Reference Intakes: Water and Electrolytes. http://www.nationalacademies.org/hmd/~/media/Files/Activity%20Files/Nutrition/DRIs/DRI_Electrolytes_Water.pdf Once again, these numbers are for total fluid intake from all sources, not just drinking water.

Realize that the fluid you consume in all drinks (water, juices, and even caffeinated beverages) as well in the food you eat, such as fruits and vegetables, all count towards your total fluid intake.5Institute of Medicine. (2004)  Dietary Reference Intakes: Water and Electrolytes. http://www.nationalacademies.org/hmd/~/media/Files/Activity%20Files/Nutrition/DRIs/DRI_Electrolytes_Water.pdf


Your Hydration Needs During Exercise

One of the primary ways the body cools itself during exercise is by sweating. Your sweat contains both water and electrolytes, and we need to replace both to keep your body performing optimally. How much you sweat is dependent upon a variety of factors including fitness level, duration and intensity of exercise, and temperature.6Benardot D.  Learn the factors affecting fluid loss http://www.humankinetics.com/excerpts/excerpts/learn-the-factors-affecting-fluid-loss Here are the current recommendations for hydration during exercise by the American College of Sports Medicine (2011).7ACSM Hydration for Fitness” https://www.acsm.org/docs/brochures/selecting-and-effectively-using-hydration-for-fitness.pdf

  • Immediately Before Exercise: eight to 12 ounces of water8Athletes may achieve euhydration prior to exercise by consuming a fluid volume equivalent to 5–10 ml/kg BW (~2–4 ml/lb) in the 2 to 4 hours before exercise to achieve urine that is pale yellow in color while allowing for sufficient time for excess fluid to be voided Athletes may achieve euhydration prior to exercise by consuming a fluid volume equivalent to 5–10 ml/kg BW (~2–4 ml/lb) in the 2 to 4 hours before exercise to achieve urine that is pale yellow in color while allowing for sufficient
  • During Exercise:
    • Less than one hour: three to eight ounces of water every 15 to 20 minutes
    • Significantly longer than one hour: three to eight ounces of a sports beverage every 15-20 minutes9
  • After Exercise: 20-24 ounces of water or sports drink for every pound of weight lost 10The fluid plan that suits most athletes and athletic events will typically achieve an intake of 0.4 to 0.8 L/h,104

Simple rule: For exercise lasting less than one hour –drink water.  If you’re working out for significantly more than an hour–consider consuming a sports drink.


What You Need to Know About Sports Drinks

Sports drinks were originally created to support the performance of competitive athletes exercising intensely for long periods of time in hot environments and are generally comprised of three parts:  fluid, carbohydrates, and electrolytes. The popularity of sports drinks has exploded over the past decade and they are now widely consumed. Once again, the American College of Sports Medicine recommends consuming sports drinks when exercising in excess of one hour.11Carbohydrate Gels and Energy Bars” https://www.acsm.org/docs/brochures/selecting-and-effectively-using-sports-drinks-carbohydrate-gels-and-energy-bars.pdf Look for sports drinks with a carbohydrate content between 4-8%. Vega® Clean Energy is a sports drink with 20 grams of sugar as well as 125mg of sodium per 12 oz.

These drinks generally contain calories in the form of simple sugars as well as varying amounts of sodium, two things that may not be necessary for shorter workouts.

Rule of Thumb: If you are exercising causally (less than an hour), water is most likely all you need. If you are training for an event, like a half marathon or a triathlon, a sports drink may be recommended during your longer workouts.  If you’re curious about your specific hydration needs during training, speak to a sports dietitian about your unique needs.


Don’t Fall For “Enhanced” Water

Similar to the sports drink market, the sales of bottled water is also booming. There now exists a myriad of differing kinds of “enhanced” waters, a category of beverages that includes water that has been flavored, pH-balanced, vitamin-enriched and more. And, like the sports drinks, be aware that many of these added ingredients (sugar and sodium) may not be beneficial to your overall exercise and health goals. Plain water, or water that contains some electrolytes, can be the best choice for basic workout hydration.


Can You Drink Too Much Water?

The short answer is yes: Hyponatremia, or “water-intoxication,” can occur when blood sodium levels become too low due to excessive fluid intake.12Danz, Matthias, , Pöttgen, Klaus, , Tönjes, Philip M., Hinkelbein, Jochen, Braunecker, Stefan, . (2016) Hyponatremia among Triathletes in the Ironman European Championship. New England Journal of Medicine 374:10, 997-998 A potentially serious condition that generally occurs during endurance events like marathons and longer distance-triathlons. If you’re concerned about hyponatremia speak to a sports medicine doctor about ways to avoid it.


Keep it Simple                                                                                                        

As is so often the case in fitness, the answers are often much more simple than they are made out to be and the same holds true with basic hydration. By eating a well-rounded diet rich in fruits and vegetables and consuming moderate amounts of water and good-for-you beverages, you will be well on your way to good hydration all summer long.

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tom holland

Tom Holland, MS, CSCS, CISSN

Tom Holland, MS, CSCS, CISSN is an internationally-recognized exercise physiologist, certified sports nutritionist, freelance writer, and regular contributor to Vega’s Expert Panel. He is the author of “Beat the Gym”, “The Marathon Method”, “The 12-Week Triathlete” and “Swim, Bike Run, Eat! The Complete Guide to Fueling Your Triathlon”. He has hosted numerous best-selling fitness DVDs including “Supreme 90 Day”, “The Abs Diet Workout” and “Herbalife 24 Fit”. Tom’s workouts and fitness articles have been published in Men’s Health, Men’s Fitness, SELF, Women’s Health, Oxygen, Men’s Journal, Fitness, Time, The New York Times, Runner’s World, Triathlete, Inside Triathlon and more. Holland is an elite endurance athlete with 23 Ironman triathlon and over 60 marathon and ultramarathon finishes around the world, including races in Malaysia, South Korea, New Zealand, Australia, China, Brazil. South Africa, Germany, Italy, France and Ireland. Tom is a frequent fitness expert on television with appearances on The TODAY Show, Good Morning America, CNN, FOX, QVC & HSN.