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Hydration and running performance: 4 key hydration tips for runners


We are all told about the importance of staying hydrated. After all, up to 60% of the human body is made up of water! But how does hydration affect running performance? In this blog I’d like to share some key hydration tips for runners. 

Humans must consume a certain amount of water to survive. This varies according to age and gender, and also where someone lives, but generally an adult male needs about 3 litres of water per day while an adult female requires about 2.2 litres per day. 

According to The Water Science School, water is a vital nutrient to the life of every cell in our bodies. It also regulates our internal body temperature by sweating and respiration. 

When you run, you lose fluid by sweating and breathing. As soon as you start to run, you start to dehydrate. It is thought that approximately 75 percent of the energy you put into exercise is converted into heat and is then lost. Your body keeps cool by sweating, which makes the replacement of these fluids crucial. 

If you fail to rehydrate, your blood will thicken, therefore reducing your heart’s efficiency, increasing your heart rate and raising your body temperature. 

In this blog I’d like to share four key hydration tips for runners so you can stay hydrated on your runs and maintain optimal performance. 

hydration tips for runners

Hydration and running performance: 4 key hydration tips for runners

Hydrate before your run

One of the key hydration tips for runners is hydrating before your run. It’s crucial that you are fully hydrated before you begin running otherwise you will risk dehydration early in the session. This can affect your stamina, speed and performance, and cause fatigue, headache and dizziness.

If you run in the evening, ensure you drink plenty of water during the day. If you run early in the morning, have a glass of water when you wake up. You will know if you’re properly hydrated from the colour of your urine. It should be pale straw coloured, not deep yellow, and should not have a strong odour. 

For runs lasting less than an hour, water is the best choice. It is absorbed rapidly and hydrates the body.  For longer runs, consuming extra carbohydrate in the form of a drink (e.g. squash, cordial or a sports drink) will also help maintain blood glucose levels and fuel the muscles. 

The best advice is to drink when you’re thirsty and listen to your body – this is one of the simplest hydration tips for runners!

hydration tips for runners

Consider drinking sports drinks for those long runs

As I mentioned earlier, you may choose to drink sports drinks on longer runs to help maintain your blood glucose levels. 

It’s important to note that plain water is a good choice for fluid replacement, but if you’ve been running hard for longer than an hour, drinks containing sugar or slow-release carbohydrates and sodium may help to speed your recovery.

Research has shown that sports drinks provide advantages over water during moderate to vigorous exercise lasting longer than an hour or so, especially in hot weather. So consider drinking sports drinks on those long training runs or during race events such as a half or full marathon. 

There are different types of sports drinks on the market, each with their own purposes and benefits. Here’s a rundown of the three main types:

  • Hypotonic. A hypotonic drink is more diluted than your body fluids, which means it can be absorbed faster than plain water. For example, squash diluted 1:8 with water.
  • Isotonic. A isotonic drink has the same concentration as your body fluids, which means it is absorbed as fast or faster than water. Examples include Lucozade Sport or squash diluted 1:4 with water. 
  • Hypertonic. A hypertonic drink is more concentrated than body fluids and will be absorbed more slowly than plain water. Examples include cola, lemonade and neat fruit juice. These types of drinks are better as post-run drinks as they offer a higher dose of energy. 

Make sure you don’t get sports drinks confused with energy drinks. Energy drinks contain lots of sugar and caffeine, which will probably do more harm than good in terms of keeping you hydrated.   

Related: 6 smoothie recipes for runners to optimise recovery

hydration tips for runners

Drink plenty of fluids after your run

The recommendation is to drink one and a half times the fluid loss. This accounts for the fact that you continue to sweat and lose fluid after you exercise, and that urination is usually increased during this time. 

According to the American College of Sports Medicine, the speed with which rehydration is needed and the magnitude of fluid deficits will determine if an aggressive fluid replacement program is merited.

Aim to replace about 80 percent of what you lost during exercise is seen as an achievable target. A simple way to work this out is to drink at least 500ml of fluid. After a particularly hard session, you may choose to rehydrate with a sports drink as described above.

If you’ve exercised for an hour or more, aim to drink at least a litre of water and keep drinking regularly for the next few hours until your urine is the colour of pale straw or lighter.

Related: What to eat before a run

hydration tips for runners

Supplement fluids with snacks

For endurance runs lasting longer than an hour, consuming extra carbohydrates can help you maintain your pace and keep going longer. You may prefer to supplement fluids with food in the form of bananas, raisins and energy gels. 

Aim to consume between 30 and 60g per hour in the form of a drink or solid food. The following provide 30g of carbohydrates:

  • 500ml diluted squash 
  • 500ml isotonic sports drink 
  • 1 1/2 bananas 
  • 2 x 30ml energy gels 
  • 40g raisins 
  • 60g dried apricots 
  • 2 x date and cashew bars 
  • 6 jelly babies 
  • 4 energy chews

Related: 4 common pre-run eating mistakes you’re probably making

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Caroline Geoghegan
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