Dehydration is a natural part of running (or any exercise) as our bodies are only designed to deal with limited water for a short period. It’s an essential part of keeping alive, we couldn’t go longer than a couple of days without water. Our bodies are made up of around 60% of our body weight and help to run most of the crucial functions inside us.
As soon as you start running you become dehydrated, so you need to pay attention to this when you train. We lose a lot of energy through running as we generate 20 times more heat than when we rest. In warmer temperatures, this can be even more acute.
When you sweat your body loses water, and electrolytes (including sodium and potassium) and so your body can become dehydrated, you get tired and have an increased heart rate. Performance can also be impacted.
We run through the basics of hydration and any products we have that can help you.
What to drink
Water is the ultimate go-to for hydration, but is it the best thing to have? Research has found that runners drinking a sports drink (5.5g carbs/100ml) improve running time by 4 minutes compared to drinking water.
Electrolyte tablets are good for replacing those lost through running and can be used either during or after you finish.
Sports drinks containing carbs also increase water absorption, which really makes a difference when you’re sweating. Drinks containing 6g carbs per 100ml are absorbed most rapidly. Also, you’re more likely to drink a flavour that you enjoy, so get something that you like.
Aim for 500ml about 2 hours before you run (along with your snack) and another 200ml 15 minutes before. Water should be all you need for this.
The recommendation is 300ml - 800ml per hour of exercise, but everyone is different so it’s good to practise this as part of your training to see what your body likes. Water with a hydration tablet in can also keep your electrolytes topped up.
A scientific (ish) way to see how much you’ve lost through dehydration is to weigh yourself before and after a run. You can assume that the difference in fluid and replenish is 1.5 times this amount in liquids. For example, if you lose 1kg in weight then it’s recommended you drink 1.5 litres of water (ideally with a hydration tablet).You can also take a recovery drink when you finish, which not only replenishes your fluids but helps to promote muscle repair.