Phil Holmes BA (Hons), PGCE, Adv Dip.Nut MRSPH

The recent heatwave is clearly an example of extreme weather. Sports performance benefits from being correctly hydrated though all year round. Having a consistent approach to hydration, the balance between water taken in and water lost, will aid training performance thus progress in the sport and ultimately stronger performances when it matters; in game time.

Typically if you are a games player you will have at most 45 minutes of play before being able  to rehydrate at half time. Usually there are stoppages in play which allow for drinks to be taken on board before we reach the end of a half.

Water is the primary choice for nearly all sports activities which last less than one hour. For younger athletes, playing 30 minute halves is around standard form up to under 15 or under 16. Therefore water will suffice. In fact, even for adult games players, water is a good choice. 

In fact one piece of advice to parents of young athletes is to be aware that with carbohydrates comes more calories. Think of how many young people we see who are overweight and yet carry sports drinks with them as a go to drink. As we see sports drinks sold in sports centre vending machines it gives off a message that they are healthy. Please consider the desired shape and weight for your child’s sport and then consider if they are better with using water as their normal drink. An example is seeing an under 12 cricket match where a player bats for 1 over, bowls for 2 overs and then stands in the field. How much energy do you think they have used (expended) and what levels of dehydration would they reach? 

As a quick guide

Young athletes should drink water. It really is that simple. 

Games players in normal UK temperatures should also drink water. The duration of matches in average heat doesn’t really call for anything extra. A weak form of diluted squash may prove beneficial for older athletes who play longer than an hour.

Endurance athletes such as marathon runners, triathletes and cyclists will benefit from carbohydrate content in their drinks. The amount will depend upon duration and intensity of the event plus other food sources they may be taking in as this affects the time taken for a fluid to be ingested and then absorbed.

And now, the science behind this advice…

Do I need to drink 2 litres of water each day?

This is a figure based on averages, a little like 2000 calories for the average adult female. Sports performers typically require more than this. The rate at which we use water can be influenced by the

  • duration of the session or match (including if we are a substitute and playing time) 
  • intensity of the activity (hockey versus darts as examples) 
  • temperature of the environment we are in (UK summer, Winter Olympics, TV cameras indoors)
  • heat from the sun’s rays
  • quality of clothing we are wearing

The general pattern to follow for most performers would be to drink between 250 and 500 ml at regular intervals through the day. You don’t want to drink too many fluids close to kick off as this may cause issues in the gut and negatively affect performance.  And a healthy diet will include foods which have water content and help us stay hydrated also.  The easiest method to check your level of hydration is by looking at the colour of your urine. Straw coloured is desirable. Dark yellow is a sign you are dehydrated.

From the above bullet points, a hot day with high humidity and playing a full match will require greater fluid intake than being a substitute on a cold day in autumn. 

So when should I start to hydrate?

A routine which allows water to be drunk each morning is beneficial. Clearly there are different start times for events and you would shape your waking time to include suitable nutrition and hydration. We are looking for frequent intake of fluids to give us the best chance of being euhydrated (or at normal levels of hydration).  500ml with breakfast would be a good place to start. 

Then use your start time as a guide for when you take in your final pre-performance drink. We want to feel alert and able to function without hindrance. Thankfully we can use training sessions to rehearse more than just the skills for our sport; we are able to train our gut to deal with differing amounts of fluid. You may compromise your performance in a couple of sessions but to know what works best for you when it comes to competition is the pay off. This may be from the amount you can take in (if you are set to travel to hotter climes) or the type of drink you choose to use.

But you’ve just been singing the praises of water. Why would I use anything else?

Certain sports will benefit from added carbohydrate content in order to support our use of glycogen for energy. If we are working in extreme heat or competing for over an hour (marathon running for example) we will need to replenish our glycogen stores. 

A small amount of glucose and sodium can even increase the rate at which our bodies absorb water. How much we add to the drink depends on certain key factors. 

Blood plasma is a key part of the equation. Plasma is the liquid in the blood which helps transport nutrients, water, salts and enzymes to the cells in the body that need them. If we are well hydrated, the plasma works efficiently. An example would be a road with free flowing traffic. When we become dehydrated, the flow of traffic is reduced as some vehicles are limited to certain speeds and then traffic backs up. In hot weather this can mean that we are less able to get the blood to the skin surface to allow us to cool off. It also inhibits the blood flow to the working muscles. The knock on effect here being that we gradually begin to overheat and so fatigue sets in forcing us to perform at a lower level. 

If we hydrate with water we are able to keep the plasma free flowing. This means we can promote sweating, allow our heart rate to avoid being elevated above the level of exercise demand, control body temperature and ultimately perform better for longer.  Fluids help us once they have made their way into the bloodstream. The rate at which they move from our stomach is affected by their carbohydrate content. Imagine having a weakly diluted orange squash. This would be hypotonic or ‘thinner’ than the plasma in our blood. So it transfers quite quickly and begins to help us replace glucose lost during performance. Sports drinks are marketed as isotonic. These are designed to be in balance with our body’s plasma levels yet they take longer to move across into the bloodstream as they have a higher carbohydrate content. A very strong drink of squash, where you might almost wince as you drink it, will be hypertonic, or ‘thicker’ than the plasma. This takes a much longer time to be absorbed. This form of rehydration may suit distance runners on hot days but requires the athlete to familiarise themselves with the strength of the drink so their body doesn’t become hindered due to any gastrointestinal issues.

But surely if I’m sweating I need to replace the salt I lose?

For games players this is not an area to panic over. The duration of the competition means a euhydrated athlete will not be adversely affected from sodium loss. In fact, sodium within hydration powders is there to maintain an awareness of thirst which reminds us we need to drink. So it’s a clever system. Water is ideal in most cases.

Can I drink too much water?

Yes. There have been some cases of athletes drinking so much that they saturate their cells. This brings the sodium levels to dangerously low levels; imagine having a glass of water with a pinch of salt in and then a bucket full with the same amount of salt. This is termed hyponatremia and is not a good state to be in at all. 

To summarise

Regular intake of water helps on all days.

A good nutrition routine will include a hydration plan and help the athlete be more consistent in their approach to training, improvement and performance.

Urine colour helps us see our current level of hydration.

Young athletes and games players will aid their performance with water.

Adult athletes and those involved in events or sessions lasting over an hour, or on extremely hot days, would benefit from carbohydrates in their drinks.

Test timings and choice of drink in training sessions so you can be confident of what will work in your competition phase.

A simple way to build your own carbohydrate drink is dilute orange squash with a pinch of salt added.

A good time for carbohydrate loaded drinks would be post-performance as we look to quickly replenish our glycogen stores and energy levels.