Nutrition and Athletic Performance – What is the optimal level of hydration for the athlete?
From: Joint Position Statement of the American Dietetic Association and Dieticians of Canada.
- Rodriguez, N.R., Di Marco, N.M., Langley, S., 2009. American College of Sports Medicine position stand. Nutrition and athletic performance. Med Sci Sports Exerc 41, 709–731.
- A review of all identifiable studies with specific exclusions.
- The paper is a systematic review / meta analysis of all relevant trials.
- This means that the data from all similar trials has been grouped to form an overall outcome.
Being well hydrated is an important consideration for optimal exercise performance.
At least 4 h before exercise, individuals should drink approximately 5–7 mL/kgbody weight (approximately 2–3 ml/lb) of water or a sport beverage. This would allow enough time to optimize hydration status and for excretion of any excess fluid as urine.
Depending on the sport and condition, sweat rates can range from as little as 0.3 to as much as 2.4 L/hr
Consumption of beverages containing electrolytes and carbohydrates can help sustain fluid and electrolyte balance and endurance exercise performance.
Fluids containing sodium and potassium help replace sweat electrolyte losses, whereas sodium stimulates thirst and fluid retention and carbohydrates provides energy. Beverages containing 6%–8% carbohydrate are recommended for exercise events lasting longer than 1 h
Hyponatremia (serum sodium concentration less than 130 mmol/L) can result from prolonged, heavy sweating with failure to replace sodium, or excessive water intake. Hyponatremia is more likely to develop in novice marathoners who are not lean, who run slowly, who sweat less, or who consume excess water before, during, or after an event.
Skeletal muscle cramps are associated with dehydration, electrolyte deficits, and muscle fatigue and is more common in profuse sweaters who experience large sweat sodium losses.
Rapid and complete recovery from excessive dehydration can be accomplished by drinking at least 16–24 oz (450–675 mL) of fluid for every pound (0.5 kg) of body weight lost during exercise.
Consuming rehydration beverages and salty foods at meals/snacks will help replace fluid and electrolyte losses
- As per the results given above