Posted in Run
Everything you need to know about Isotonic Sports Drinks

There are a lot of sports drinks out there and we get that it can be tough to choose the right one for you, as well as understand what each one does and how it helps you and your performance. One word that comes up a lot in the sports world is ‘isotonic’ so we reached out to HIGH5 Sports Nutrition to give you everything you need to know about isotonic sports drinks.

What does isotonic mean?

First up, let’s start with the basics – what even is isotonic? Well, the term ‘isotonic’ is used to describe a solution that is a similar ‘thickness’ to another solution.

In the context of sports drinks, an isotonic drink is a similar concentration, or tonicity to use the scientific term, to our blood. Our blood has an osmolarity of 280 – 300 mOsm/L and put simply osmolarity is the measurement for the concentration of the blood.

So, both isotonic sports drinks and our blood have an osmolarity of 280 – 300 mOsm/L, which means they have a similar concentration of water, carbohydrates, sugar, salt etc.


Why should I use isotonic drinks for sport?

The concentration, or tonicity, of a drink is important when it comes to sport or exercise because it impacts the amount of carbs, electrolytes and fluids that go into your bloodstream and how quickly they take effect.
Because isotonic drinks have a concentration similar to your blood, it means your body can quickly replace the fluid you’re losing through sweat and provide a boost of carbohydrate. 

Why are fluids and carbohydrates important during sport?

Carbohydrates are your body’s fuel, giving you quick release energy to boost your endurance performance. Your body can only store enough carbohydrate for around 90 minutes of exercise and therefore you need to top up in order to stay at your best. Sports drinks are an easy way to do this while you’re on the go.

Similarly, staying hydrated is key to performing well. You actually lose more than one litre of fluid for every hour that you exercise and that fluid needs replacing. The fluid you lose is more than just water, it is water and electrolytes, key minerals that your body needs to function. Again, sports drinks typically contain electrolytes as well as water and carbohydrates.

How should I fuel before and during an endurance event?

Former Team GB run coach and High5 Ambassador Nick Anderson shows you how to shop like an athlete; what to buy, how it could affect your performance, and even what treats you include while maintaining your progress. From concepts like the training triangle to guidance on avoiding GI discomfort, Nick's tips will help you decide what's best to throw in your basket or leave on the shelf.

How to choose the right sports drink for you?

Isotonic is one factor but there are a few others to look out for.

Taste – Whether you like the taste of the drink matters! HIGH5 offer great-tasting sports nutrition, using natural flavours and real fruit juice to get some delicious flavours. Want to try before you commit? Take a look at their trial packs.

Digestibility – How a product sits on your stomach is something to consider. Everyone is different so our advice is to build new nutrition products into your training rather than not using anything in training and then going all out on race day. It’s also worth considering products that contain added ingredients like postbiotics and calcium which aid digestion and avoiding products with artificial flavours.

Performance – Have a think about what you need to perform better. Are you after energy? Choose nutrition with carbs. If you’re after hydration look for electrolytes. Not sure where to start? HIGH5 offer a number of trial packs to get you going.

Ready to buy an isotonic sports drink?


HIGH5 have launched a new product, Isotonic Hydration, designed to refresh your workout. Isotonic Hydration is a scientifically formulated hydration drink which has been optimised to keep you energised and hydrated during exercise. It is isotonic and it contains a fast-release multi-carbohydrate blend and five electrolytes, which are essential to replenish as they are lost through sweat. It also contains postbiotics and calcium to support digestion. Available in two great-tasting flavours, Tropical and Blackcurrant.

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