By Heather (Hedrick) Fink, M.S., R.D. — Assistant Director of Educational Services at NIFS and a registered dietitian

Adequate hydration and consumption of fluids during training and competition has long been recognized as a key to peak performance. However, in recent years, research studies have refined the recommendations on the amounts, types and timing of fluids that lead to optimal hydration.

The following guidelines highlight the most current hydration recommendations.

Fluid Needs Before Exercise

Athletes should be well hydrated at the start of a training session or competition.

• Pre-exercise body weights should be relatively consistent.
• Urine should be copious and the color should be pale.
• Two to three cups of fluid should be consumed 2–3 hours prior to exercise.
• One cup of fluid should be consumed 10–20 minutes prior to exercise.
• Drinking beverages containing carbohydrates 2–3 hours prior to exercise will help to maximize glycogen stores.

Fluid Needs During Exercise

Athletes should maintain hydration status by consuming fluids during exercise to match sweat and urinary losses.

• Weight loss during exercise should be less than 2% of pre-exercise body weight.
• One cup of fluid should be consumed every 10–20 minutes during exercise.
• Cool beverages encourage consumption.
• A fluid-replacement beverage containing 6% carbohydrate (i.e., sports drinks) should be used if exercise lasts longer than 45 minutes, or if the exercise is intense.
• Sodium chloride should be included in the fluid-replacement beverage (i.e., sport beverages contain appropriate amounts of sodium chloride) if the activity lasts longer than four hours or during the initial days of exercise in hot weather.

Fluid Needs After Exercise

Fluid losses during exercise should be regained, ideally within two hours.

• Rehydration should contain water to restore hydration, carbohydrates to rebuild glycogen stores, and electrolytes (mainly sodium and potassium) to speed rehydration.
• 100% juice is a perfect rehydration beverage, supplying fluid, carbohydrate and potassium.
• Two to three cups should be consumed for every pound of body weight lost during exercise, ideally within two hours of completion of the activity.
• Recognize the basic signs and symptoms of dehydration.
• Thirst, irritability, and general discomfort.
• Headache, weakness, dizziness, cramps, chills, vomiting, nausea.
• Decreased performance
• Early detection of dehydration can decrease the occurrence and severity of heat illnesses.
• Dehydrated, conscious individuals without gastrointestinal distress can be rehydrated orally.
• Athletes who are mentally compromised, or with gastrointestinal distress, should be transported to a medical facility for treatment.

Resources:

1. Casa, DJ, et al. National Athletic Trainers‘ Association. Position Statement: Fluid replacement for athletes. Journal of Athletic Training. 2000; 35: 212–224.
2. American College of Sports Medicine. Position stand: Exercise and fluid replacement. Medicine and Science in Sports and Exercise. 1996; 28(1): i–vii.

For additional information please contact NIFS at 317.274.3432.