Water Essential to Performance During Hot Weather

Athletes in Sports Camps Urged to Drink Plenty of Fluids

July 17, 2006

Student athletes are at risk for exertional heat injuries as summer sports camps kick into high gear. High temperatures combined with high exertion, unless tempered with adequate fluid intake, can lead to heat cramps, heat stroke and heat exhaustion according to Andrew Duncan, P.T., A.T.C., director of sports rehabilitation at University Sports Medicine. 

“Many of the camps do not have athletic trainers or medical staff present to monitor rehydration. In addition, the camps are typically held during the hottest point in the year, and consequently athletes are at a higher risk for heat injuries,” Duncan said.

Water plays a critical role in how the body responds to physical activity. The body regulates its temperature by sweating, a process dependent on the amount of water in the body. If the amount of water drops below a certain level, the body cannot adequately sweat, and consequently, body temperature rises rapidly. This increase in core body temperature can negatively impact physical performance as well as cause one or more heat injuries.

“Dehydration of just one to two percent of body weight can negatively influence athletic performance. Dehydration of greater than three percent of body weight increases an athlete’s risk of developing an exertional heat illness,” Duncan said. “This level of dehydration is common in sports—just one hour of exercise is enough, and even less time if the athlete enters the exercise session dehydrated.”

Duncan added that the psychology changes associated with exercise in a dehydrated state should not be overlooked. Dehydration increases the rating of perceived exertion, impairs mental functioning. It also decreases the motivation to exercise and decreases the time to exhaustion, even in instances when strength is not compromised.

Most athletes can avoid heat injuries by following simple steps that includes drinking water before, during and after exercise.

“It’s not enough to drink water during practice—in fact, if you are thirsty during practice, that’s a pretty good indication you are already dehydrated,” Duncan said. “It’s important that athletes NOT use thirst as an indicator of how much water they need to drink.”

Here are additional tips from Duncan to ensure a well-hydrated work-out:

  • Know your sweat rate: The amount of fluid necessary to prevent dehydration is different for every person, and is very much dependent on how much an athlete sweats during exercise. To get a good idea of how much weight you tend to sweat off in a typical workout (and consequently how much fluid you will need to replace), weigh yourself before and after a workout for a week. Average the results to come up with the amount of fluid you need to replace. Rule of thumb—drink 20-24 fluid ounces post-exercise for every pound of weight lost due to sweating.
  • Keep ahead of the curve: Make sure you are adequately hydrated before exercise. The best way to do this is to consume about 20 ounces of fluid two to three hours before exercise, and another 10 ounces of water or a sports drink 10 to 20 minutes before exercise.
  • Customize rehydration to the sport: Take into account each sport’s unique features to determine when and how much fluid you should drink during activity. If rehydration opportunities are frequent (i.e., baseball, track, football), you should consume smaller volumes at a convenient pace. If rehydration must occur at specific times (soccer, lacrosse, distance running), then you must consume fluids to maximize hydration within the sport’s confines and rules. In general though, try and drink 10 ounces of fluid every 10-20 minutes.
  • Make it convenient and visible: Use a water bottle that is easily accessible during practice. Clear water bottles marked with increments provide visual reminders on how much you should drink so that you are not just satisfying an initial thirst.
  • Water or sports drink?: While a sports drink contains carbohydrates to replenish glycogen stores, and electrolytes to speed rehydration, ANY fluid, including water, will do. Drink what tastes good to you. If water tastes too plain, and you are less likely to drink it, then a sports drink is a good choice.
  • Beware the hazy, hot and humid days: Pay special attention to exercise on hot, humid days. Very high relative humidity limits your body’s ability to sweat, which means your core temperature will increase more rapidly due to the inability to dissipate heat.
  • Recognize the signs: The basic signs and symptoms of dehydration include thirst, irritability, and general discomfort, followed by headache, weakness, dizziness, cramps, chills, vomiting, nausea, head or neck heat sensations, and decreased performance.

Early diagnosis of dehydration decreases the occurrence and severity of heat illness. If you are still conscious and cognizant, and do not have any nausea, chances are you’ll be able to counteract the symptoms by drinking lots of fluids. However, if you begin to show signs of mental compromise or gastrointestinal distress, you will need to be transported to a medical facility for intravenous rehydration.

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Germaine Reinhardt
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