National Athletic Trainers’ Association’s Position Statement: Fluid Replacement for Athletes
ABSTRACT & COMMENTARY
Synopsis: Implementation of a hydration protocol for athletes will only be successful if athletes, coaches, athletic trainers, and team physicians take the steps necessary to assure proper hydration.
Source: Casa DJ, et al. National Athletic Trainers Association’s position statement: Fluid replacement for athletes. Athletic Training 2000;35:212-224.
Dehydration is a consequence of physical activity and can compromise performance and increase susceptibility to exertional heat injury. The purpose of this position statement by the National Athletic Trainers’ Association is to provide useful recommendations to optimize fluid replacement for athletes, emphasize the physiologic, medical, and performance considerations associated with dehydration, and identify factors that influence optimal rehydration during and after athletic participation. Casa and colleagues include certified athletic trainers, physicians, and physiologists, and provide 19 recommendations regarding fluid replacement before, during, and after athletic participation. The recommendations are supported by a review of 220 references from the scientific literature.
The statement emphasizes the importance of a rehydration strategy that considers sweat rate, sport dynamics, environmental factors, acclimatization state, exercise duration, exercise intensity, and individual preferences. An athlete’s sweat rate is calculated as: sweating rate = preexercise body weight - postexercise body weight + fluid intake - urine volume/exercise time in hours. This can be most easily approximated by weighing athletes before an intense one-hour practice session and then reweighing them at the end of the session. To approximate hydration status, body weight should be measured before, during, and after exercise. Perhaps the most simple method for an athlete to assess hydration status is to monitor urine color. A scientifically validated urine color chart is provided as a figure in the statement.1,2
The statement further emphasizes that a proper hydration protocol should consider each sport’s unique features, as well as the effect of heat acclimatization on sweat rate. For example, sweat rate increases after 10-14 days of heat exposure, and thus requires a greater fluid intake for a similar bout of exercise. Approximate amounts of fluid are recommended to ensure proper preexercise hydration, and include 500-600 mL (17-20 fl oz) 2-3 hours before exercise and 200-300 mL (7-10 fl oz) 10-20 minutes before exercise. The fluid replacement regimen during exercise should approximate sweat rate and urine loss and attempt to maintain hydration at less than 2% of body weight reduction. The general recommendation in this regard is 200-300 mL (7-10 fl oz) every 10-20 minutes.
The statement also addresses the role of carbohydrates and sodium chloride in fluid replacement. Athletes engaged in intense exercise or exercise lasting longer than 45-50 minutes benefit from ingestion of a 6% carbohydrate drink, such as found in most sport drinks. Modest amounts of salt (0.3-0.7 g/L) are recommended in fluid-replacement beverages only in cases of inadequate access to meals, physical activity exceeding four hours duration, or during the initial days of hot weather. The importance of monitoring relative humidity with the Wet Bulb Globe Temperature in hot environments is emphasized, as is the importance that those supervising athletes recognize the basic signs and symptoms of dehydration. These include thirst, irritability, and general discomfort, followed by headache, weakness, dizziness, cramps, chills, vomiting, nausea, head or neck heat sensations, and decreased performance.
COMMENT BY DAVID H. PERRIN, PhD, ATC
Dehydration of 1-2% of body weight during physical activity begins to compromise physiologic function and performance, and levels greater than 3% can increase susceptibility to exertional heat illness. Thankfully, great strides have been made in recognizing the importance of fluid replacement before, during, and after practices and games. The withholding of fluid from an exercising athlete is universally known to be an act of "malpractice" by anyone supervising athletes of any age. Failure to implement a carefully designed hydration protocol for athletes essentially represents negligence on the part of the responsible athletic administration and medical team. This position statement from the NATA’s Pronouncements Committee provides practical and scientifically based recommendations for fluid replacement for athletic participation.
Reprints of the NATA Position Statement on Fluid Replacement for Athletes are available by contacting: National Athletic Trainers’ Association, Communications Department, 2952 Stemmons Freeway, Dallas, TX 75247
References
1. Armstrong LE, et al. Urinary indices of hydration status. Int J Sports Nutr 1994;4:265-279.
2. Armstrong LE, et al. Urinary indices during dehydration, exercise, and rehydration. Int J Sports Nutr 1998;8:345-355.
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