The lowdown on exercise hydration

Emma Brown - Nutritionist | 11 Oct, 2021

We know it's important to stay hydrated – especially when exercising. In fact, being dehydrated by just 2% of our bodyweight can significantly affect our exercise performance. If you want to get the most out of your workouts, read on to get my tips on how and why we should hydrate appropriately.

How important is hydration for exercise performance?

Whether you are an avid gym goer or exercise once a week – hydration can be the key to having an enjoyable and effective workout. Rehydrating correctly is also important for exercise recovery, so it should be considered before, during and after all workouts. Dehydration can cause us to become fatigued faster and our core temperature can also rise quickly, making exercise much harder.

What should I drink?

As a general rule, if you're exercising at a moderate intensity for an hour or less, drinking just water will be adequate to help you stay hydrated. For more intense exercise or when exercising for more than an hour, sports drinks may come in handy, as they help replace lost electrolytes as well as carbohydrates for energy. That said, there are cheaper alternatives to sports drinks which can be just as effective!

Are sports drinks necessary?

Sports drinks like Lucozade were originally developed to help high-level athletes stay hydrated during workouts by replacing water and minerals lost. Nowadays, there is a huge array of choice and it's harder to know exactly what we need. Sports drinks are marketed as functional, and consumers can buy into this – but there's really no need to go to this extra expense in most cases. For many of us, simply sticking to water is adequate.

Although the amount we sweat and its composition can be quite different between individuals, if you are exercising heavily for longer than an hour, you can easily and cheaply rehydrate and replace any lost minerals. Having something like sugary squash or even diluting orange juice with some water and adding a pinch of salt would be sufficient – and cheap!

Effective rehydration strategies

Sports research into the best hydration strategy has identified 4 things to consider for post exercise hydration. Getting these four things right has been shown to improve exercise performance, aid recovery and even boost energy levels!

  1. Volume of water: Aim to replace 150% of the weight you lose as fluid. So for example, if you lose 1.5kg after exercise, this is a loss of 1,500ml of water. Multiply this by 1.5 and this is how much you should drink in total. So in this case, you'd need to drink 2,250ml of fluid. This should be spread out and consumed before you start, throughout the workout and after you finish.
  2. Timing: Drinking lots of fluid all at once will most likely just make you want to go to the toilet, keeping you from retaining water and not actually hydrate you. The best strategy is to drink around 12.5% of the total fluid you need every 30 minutes, as this has been shown to be the most effective ingestion rate. In my example, that would be around a glass of water every 30 minutes. So you would drink this throughout the workout and every 30 minutes after finishing until you had taken in the full amount. This should mean you completely rehydrate yourself.
  3. Composition of your drink: If you're exercising for more than an hour or doing high intensity exercise, it's important to include electrolytes in your drink. This is to replace those lost in sweat. Around 100mmol of sodium per litre of water (5.8g of salt or 1 level tsp). This will help regulate electrolyte concentration and ensure your kidneys return to normal functioning.
  4. Taste: Adding a carbohydrate to your water such as a flavoured sugar-free squash will enhance the taste, and the more we like the taste of our drink, the more we drink! Also, some research has shown that just tasting something sweet – even if it doesn't contain carbohydrates for extra energy – can boost our exercise performance. Sugar-free squash is fine for moderate exercise or go for squash with a little sugar boost when doing more intense, longer duration exercise.

A final note…

Being well hydrated can have a significant effect not only on exercise performance but also general wellbeing! Drinking enough water has been shown to increase energy levels, boost brain function and aid appetite regulation – so there’s no denying, if you hydrate, you'll feel great!

Nutritionist Emma Brown (ANutr), MSc Human Nutrition is passionate about how food science applies to the human body, and how the nutrients in what we eat affect us and ultimately have an impact on our health.