It’s summer (finally!), and there’s nothing better than some quality playing-time in beautiful weather. But, with the mercury rising, dehydration is a serious concern whether you’re having a marathon practice session or match, and can affect performance when as little as 2% of your body mass is lost through sweat. Since tennis players can lose more than 2.5 liters of sweat per hour in warm weather, it’s easy to fall behind on your fluid intake if you’re not careful.
The key to staying hydrated during practice and competition is to be prepared, know how much you need to drink and stay on top of your individual hydration needs. Follow these three easy steps to help keep your cool on the court:
Drink early
Thirst may not be perceived until 1.5 liters of sweat has already been lost, which means that when you’re thirst, it’s too late! It’s just as important to drink adequate fluids in the days and hours coming up to a match or big practice as it is to drink during play. Aim to drink at least 2.5-3 liters of fluid daily, and at least 16-20 ounces of electrolyte-enhanced sports drink two hours before your practice or match to help prevent the effects of dehydration early on.
Drink often
The stop and go nature of tennis makes it difficult for the body to maintain optimum temperature in the heat, but it gives many opportunities to rehydrate and drink fluids. A good rule of thumb is to take in at least 200-400ml of fluids every 15 minutes (or every changeover) in warm weather, but keep in mind hydration and sweat rates are individually different for each player. Take the “sweat test” to determine how much fluid you lose during a typical practice or match in hot conditions and how much you need to drink per hour. Weigh yourself before and after a practice or match and keep track of the fluids you drink. Plug the numbers into the formula below and get your total fluid loss. Divide that number by hours to determine how much you should be drinking every hour to stay hydrated.
Sweat Test
[pre-exercise weight – post-exercise weight ] = pounds lost
[pounds lost (in ounces) + fluids taken in during activity (in ounces)] = Total Fluid Loss
Drink Smart
Heat-related muscle cramps are a major concern for tennis players, especially towards the end of a hot match. Contrary to popular belief, these cramps are often caused by sodium loss through sweat, not potassium. For every pound of sweat, we lose between 500 and 1500mg of sodium depending on how “salty” of a sweater we are. It’s important to take in sodium before, during and after hot matches and practices in addition to fluids to replace these losses and help maintain plasma osmolality and sodium concentration in the body. Not only can adequate sodium intake help prevent muscle cramping, but it can also conserve your biological drive to continue drinking fluids. Aim for salty snacks such as whole grain pretzels, salted pita chips or tortilla chips before a match and have electrolyte-enhanced beverages on-hand during your play, such as Gatorade or Powerade.
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Kelly Hogan, MS, RD, CDN is a clinical dietitian at The Mount Sinai Hospital
Jaclyn London, MS, RD, CDN is a senior clinical dietitian at The Mount Sinai Hospital
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