Recognizing And Preventing Dehydration In Athletes

By Mark A. Caselli, DPM, and John Brummer, DPM

   Fluid replacement is an important part of any athletic regimen, but proper hydration is one of the most neglected aspects of the athlete’s diet. Now that podiatrists are active members of the medical teams servicing many types of athletic events (and often act as medical directors and co-directors), it is vital to have a working knowledge of the signs and symptoms of dehydration. Active sports medicine podiatrists should also be able to develop a plan for establishing hydration protocols at sporting events.

   When athletes engage in sport, they will lose a percentage of body weight through water loss. When their sweat loss exceeds fluid intake, athletes become dehydrated during activity. Dehydration of 1 to 2 percent of body weight begins to compromise physiologic function and negatively influences performance. Dehydration of greater than 3 percent of body weight further disturbs physiologic function and increases the athlete’s risk of developing heat cramps or heat exhaustion. Loss of 5 percent or more body weight can result in heatstroke.

   These levels of dehydration are common in sports and can occur in just an hour of exercise or even more rapidly if the athlete is dehydrated before exercising or participating in a sports activity.

   When supervising the medical care of athletes, it is important to recognize the basic signs of dehydration. These include thirst, irritability and general discomfort followed by headache, weakness, dizziness, cramps, chills, heartburn, vomiting, nausea, head or neck heat sensations and decreased performance. Thirst is a notoriously poor indicator of dehydration because it is a delayed response. An athlete can lose over 1.5 liters of body water before becoming thirsty.

   The athlete’s level of hydration is influenced by many factors. The energy level or intensity of the sport (e.g., badminton vs. football) is a major factor in how much fluid is lost. If the sport requires helmets and padding, this will increase the amount of perspiration and result in greater fluid loss. Rest breaks and fluid access are important factors that affect hydration. If hydration opportunities are frequent, as in baseball, football and track and field, the athlete can consume smaller volumes of liquid at a convenient pace. In sports such as soccer, lacrosse and distance running, athletes must consume fluids at specific times, making it more difficult to rehydrate.

   Another important factor in dehydration is the environment of play. Hot, humid areas and high-pressure altitudes will also influence physiologic response and increase fluid loss. Children involved in sports activities are more susceptible to dehydration and heat illness in hot weather than adult athletes. Therefore, it is necessary to consider the athlete’s age, sport and climate conditions when developing a plan to prevent dehydration.

How To Determine Hydration Status

   One should evaluate the hydration status of athletes before starting any rigorous sports activity. Athletes should begin all exercise sessions well hydrated. A recent study found two-thirds of the pediatric athletes evaluated were dehydrated before practice.

   There are several ways to approximate hydration status. Assuming the athlete is properly hydrated, pre-exercise body weight should be relatively consistent throughout the entire exercise session. One should determine the percentage difference between the post-exercise body weight and also determine the baseline hydrated body weight. The post-exercise weight should be no more than 2 percent less than the pre-exercise weight.

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