During pre-season, staying hydrated is one of an athletes' top priorities. Accurate hydration regulates body temperature, fluid, and electrolyte balance, and is essential for comfort, optimal performance, and safety. Hot humid weather, padding and uniforms, along with two-a-days can increase sweat and electrolyte losses tenfold.
Sweating helps the body to stay cool. However, sweat losses of just 1 to 2 percent of body weight result in mild dehydration. Symptoms of mild dehydration include cramping, dizziness, fatigue, and an increased chance of heat exhaustion and heat stroke. If more than 2 percent of weight is lost in sweat, overall performance is compromised: blood thickens, heart rate increases, and it's more difficult to move oxygen around the body. This is extremely detrimental to health, and can even be life-threatening. Exertional heat stroke is the third leading cause of death in the United States among high school athletes and has accounted for the deaths of more than 20 high school and collegiate players in the past decade:
Signs of heat illness
- Little or no urination
- Muscle weakness
- Dry mouth
- Excessive thirst
Efficient heat removal is especially important for large athletes. Research suggests offensive linemen appear to lose more fluid than other players. A lineman can lose 1.5 to 2 liters/hour (1 liter = 1.05 quart) of sweat on a hot day, causing some players to lose 14 liters (about 6 to 12 pounds) by the end of a two-a-day practice.
How much is enough?
Athletes should drink at least 3.7 liters daily, which is the minimum recommended by the Institute of Medicine (IOM) and up to 10 liters to match losses. Unless weight gain is desired, the fluids used should be low in sugar, including water, low sugar flavored water, juices, low fat milk, and an occasional low sugar ice tea or soft drink.
Before practice, athletes need about 16 to 24 ounces (2 to 3 cups) of water, two to three hours before training and games. While on the sidelines and in the locker room, players should drink at least 8 to10 ounces every 15 to 20 minutes, or more if they sweat heavily. After training, replenish with at least 64 ounces (8 cups) fluid, and even up to
1 ½ times that amount (96 ounces) to be completely rehydrated. Beverages that are cooler than room temperature are absorbed best, since they move throughout the bloodstream to the muscles faster. Fluids that taste good are also more likely to be consumed, so find your favorite and drink up!
After practice, replacing fluids at a rate of 1 to 1.5 times the amount lost, or about 16 to 24 ounces of fluid for every pound lost at practice, is critical to remaining hydrated. Weighing before and after practices is a good way to estimate fluid losses during training.
One of the simplest ways to measure hydration levels is by urine color. Urine that is slightly darker than lemon juice in the toilet, or is a lemon juice color in a urinal is good. If it's as dark as apple juice, an athlete is dehydrated. If it's completely clear, the athlete is hyper-hydrated.
Note, however, that players cannot always rely solely on urine color as a measurement of hydration status because some dietary supplements, such as the B vitamin riboflavin, can add a yellowish hue to urine. Certain medications and Vitamin C can also affect the color of urine.
Lisa Dorfman, MS, RD, CssD, LMHC, the Running Nutritionist®,is a licensed nutritionist, licensed psychotherapist, certified coach, Board Certified Specialist in Sports Dietetics, and a Board Certified Professional Counselor. She is an adjunct professor in the University of Miami Department of Exercise Sciences, and, as Director ofSports Nutrition and Performance for the Miami Hurricanes. A personal nutritionist for numerous professional athletes, Lisa is also national Olympic and Paralympics Team Nutritionist for US Sailing. Her latest book, Performance Nutrition for Football (Momentum Media 2010) is available at www.primeathlete.com and on her website at http://www.foodfitness.com.