Why Do Runners Need To Be Hydrated

Whether you run short distances or you regularly run marathons, being sufficiently hydrated is of paramount importance. Without proper hydration levels, not only will your performance be impaired but you also put your body at risk of serious health complications.

Firstly, let’s establish why hydration is important for running performance. When you run, you put your muscles under pressure. They get hot and use sweat to disperse this heat. This is why you lose fluid. So if you don’t replace lost fluid, you put added pressure on your heart to work harder, pumping blood round your body. Additionally, you run the risk of overheating your body and you lose glycogen. Glycogen stores glucose in the body and you need glucose for energy. When you lose glycogen, you reach a point of “hitting the wall” when you feel sapped of energy and unable to continue.

It’s believed that even just 2% of fluid lost from your total body weight can make it much harder to perform. Drinking water is a huge priority but not just during your run. You need to be hydrated enough beforehand so you can cope with it and also you need to drink afterwards, to make sure you restore correct levels of fluid. It’s not just water that’s lost, it’s fluid which contains sodium, electrolytes and minerals which means that plain old water is not enough for runners. There are other hydration options for runners to help performance and protect your body. Using an O.R.S hydration tablet in your water is something which will help to restore hydration levels and properly replenish the body with lost sodium, electrolytes and minerals.


Obviously it’s important to drink sufficient amounts of water – but how much is the right amount? This is the question lots of people ask – even seasoned runners. The truth is everyone reacts differently. Some people sweat more than others, temperature and climate also play their part. It is a good idea to determine what you need for your own healthy running performance and devise your own hydration plan.

If you sweat a lot when you exercise or you work-out on top of running then it’s really important to make sure you sufficiently replace the lost electrolytes and fluid. This is why a hydration supplement tablet such as O.R.S is invaluable. O.R.S fully supports hydration levels and stops you losing vital minerals present in your body. It’s especially important to use one of these hydration tablets if you are planning to exercise again within 12 hours of your last run.

Before you go out for your run, you should make sure to drink approximately 30 ml per 4.5 kg of your body’s weight. Do this between 2 and 4 hours prior to going out. You can check hydration levels by looking at the colour of your urine, it should be pale yellow. Now, for those of you who run first thing in the morning the important thing here is to be properly hydrated before you go to bed. Adding one O.R.S tablet to your water will keep your sodium levels up – particularly important if it’s going to be a hot day ahead but whether hot or cold it is advised.

One thing you shouldn’t do is fill your belly with water just before you go running. Doing this will affect your performance and you’ll be conscious of the water moving around inside you. Obviously if you go for a morning run you won’t be able to drink as much beforehand which is why being hydrated the night before is important.

For a run lasting more than 45 minutes in warmer months, you need to plan to stay hydrated as much as possible during your run. The International Marathon Medical Direct Association guidelines say to drink when you feel thirsty. However, don’t be tempted to over-drink because this can also lead to medical problems such as liver and kidney failure and hyponatremia. Hyponatremia occurs when sodium levels drop to abnormally low levels and symptoms include headache, confusion, seizures, nausea, muscle spasms and vomiting. Without wishing to frighten you – sever hyponatremia can lead to coma.

When you run it’s important to have a guideline of what you need to stay hydrated and everyone is different. As you know, some people sweat more than others so will need more hydration. It’s easy enough to calculate and it’s wise to work it out because there’s the risk of over-hydration too. Drinking too much water dilutes sodium levels in the blood which affects electrolytes. Drink when you need to – so always take a bottle of water with you.


To work out the best hydration for runners, weigh yourself before you run and straight afterwards, this determines how much fluid you’ve lost. You need to replace the fluid so you don’t lose any more than 2% of your total body weight. It’s not just fluid loss which needs replenishing, sodium does too. When you sweat you lose salt as well so an O.R.S tablet will combat that salt loss. The average loss of salt in sweat is approximately 1g per litre.

What To Do Post-Run

As well as making sure you drink sufficient amounts of water before running and during running, you should also think about post-running and what you should consume. You will never stay fully hydrated during your run which is why it’s important to properly replenish any lost fluid. Drink often for up to 24 hours after your run. Choose water-based food which help to replenish lost fluid. Melon, strawberries, oranges and watermelon are all excellent for rehydration.

Best Hydration For Runners

So what is the best hydration for runners?

  • Drinking water 2 to 4 hours before running. Remember, if you are an early morning runner you must be sufficiently hydrated before going to bed.
  • The best hydration drink for runners is using a sports tablet. These are used to prepare a hydration drink for runners which is much better than plain water. An O.R.S hydration tablet (oral rehydration salts) is soluble, containing a blend of glucose, electrolytes and minerals. It is scientifically balanced and is designed to help maintain normal balance of fluid. It is not a hydration gel for runners as it is formulated as a tablet to dissolve in water making it a far more convenient solution as there is no risk of leakage or bursting. You don’t need sports drinks; regular water with a suitable tablet gives you all the hydration the body needs and replenishes all those lost minerals – quickly and efficiently.
  • Make sure to carry on drinking post-run as you will still need to replenish lost fluid for up to 24 hours afterwards.
  • Avoid diuretics such as tea, coffee and alcohol.
  • Never over-drink, calculate what you need through working out how much fluid you lose during your run.

For more on O.R.S. hydration tablets visit ORShydration.ie