There have been a number of high profile cases of tennis players not being able to complete matches due to hydration-related issues, heat exhaustion and cramps in recent years, so it’s important to understand the science behind hydration in order to make sure you’re doing the right things before, during and after your matches…

Why is sweat so important?

Staying hydrated is crucial to your performance on the court.

Your body is under considerable strain when you’re pushing yourself during a match or intense training session. It’s pumping blood around your body to supply your working muscles with oxygen, dissipate heat and regulate your core temperature.

Dehydration increases the stress your body is under during these processes and this hampers your performance. 

Tennis is a high intensity sport and it’s often played in hot conditions, these two factors tend to drive high sweat rates.

In fact, a study showed sweat rates in excess of 1 liter (34oz) per hour for juniors and up to 2.5 liters (85oz) per hour for older adolescents and adults.

But your sweat rate is only part of the equation. 

How much sodium you lose in that sweat is also critical as this electrolyte helps you absorb and retain fluid, topping up your blood plasma volume.

Sodium also plays an important role in nerve impulse transmission, the absorption of nutrients in the gut, maintaining cognitive function and in muscle contraction.

To understand your sodium losses, take our free Online Sweat Test or booked in for an Advanced Sweat Test at one of our Sweat Test Centers. 

Image credit: Michael Darter ©

You’ve probably noticed that your sweat tastes salty and some of you will have noticed that you get white marks on your skin and kit after a hard fought match. That’s because sodium is one of the main ingredients in your sweat.

What many people don’t know is that the amount of sodium you lose in your sweat is largely genetically determined, stable and it varies dramatically from person-to-person.

At Precision Fuel & Hydration, we’ve Sweat Tested thousands of athletes (including pros from the NFL, NBA, MLB, Premier League, and, of course, the tennis world) and found huge variance in how much sodium each athlete loses per liter of sweat – from as little as 204mg/l to as high as 2,314mg/l!

The differences in both sweat rate and sweat sodium concentration (how much sodium is in your sweat) can mean that two players on opposite sides of the court can experience very different sodium losses over the course of a match, up to 15 times different in fact.

As well as affecting the bodily processes mentioned above, inadequate sodium and fluid replacement can also cause cramp.  

What are the hydration challenges for tennis players?

The intensity of tennis and the conditions often mean sweat rates are high. The fact that the length of your match can vary significantly from one round to the next is also a challenge. 

These factors mean that sweat and sodium losses can be very high for an individual player, especially if you lose a lot of sodium in your sweat.

Recovery time in between matches can also be relatively short in tournament play. There’s evidence to suggest many players run the risk of starting matches in a less than perfectly hydrated state. All of these challenges mean that it’s crucial to plan ahead when it comes to staying hydrated.

How can tennis players stay hydrated during matches?

A good tennis hydration strategy should encompass the following…

1) Aim to start the match hydrated

You can help ensure you’re starting your matches hydrated by preloading on sodium before a match by taking a strong electrolyte supplement, like Precision Fuel & Hydration’s 1500mg/l product

To ‘preload’ effectively:

  • Drink 1 x PH 1500 tablet or packet with 16oz of water the night before a match
  • Drink 1 x PH 1500 tablet or packet with 16oz of water about 90 mins before you walk on to the court

Image credit: Oliver Sjostrom via StockSnap (copyright free).

2) Make sure you have enough drinks and supplements on hand to get you through the longest possible match

You should always listen to your body and drink to thirst, which is the mechanism your body has evolved to tell you what it needs. It’s also a good idea to have plain water to hand, as well as electrolyte drinks. That way, your taste buds can help dictate what your body wants at a given point in time.

Don’t wait until it is too late as it’s not always clear how long a match will last. There are, of course, lots of opportunities for in-game rehydration with changes of ends and the breaks between sets, so there’s no excuse for not taking on some fluids and electrolytes.

You need to replace the electrolytes you lose in your sweat too. And, by ‘electrolytes’, I mainly mean sodium, as that’s the electrolyte you lose the most of in your sweat - potassium, calcium and magnesium losses are generally small in comparison.

If you only drink water over an extended period of exercise where you’re sweating, you’re actually further diluting your blood sodium levels and are at risk of giving yourself a condition called hyponatremia (literally meaning ‘low blood sodium levels’) which has nasty side effects like headaches, nausea, vomiting and even coma and death (in extreme cases!). 

3) Recovery and (re-)hydration

You’ll end each match dehydrated to some point and – when your sweat losses have been low - the food and drinks you consume after your match will normally be enough to help top your sodium levels back up.

However, if you’ve got another match later that day or the following day, a more aggressive approach to rehydration and recovery will be needed to help restore your body’s equilibrium.

Taking in electrolytes with your post-match fluids will help fluid retention, so try drinking 1 x PH 1500 mixed with 16oz of water in the few hours after your match.

If you follow these steps and refine your hydration strategy in training and competition, you'll be better equipped to perform at your best when it counts. 

Keen players, parents and coaches may wish to read this paper for more information and tips on dealing with playing in hot and humid environments.

For more information or any queries about your hydration strategy, email

Further reading