Know the difference between hypotonic, isotonic and hypertonic sport drinks and when you should take each? We demystify the jargon

Know the difference between hypotonic, isotonic and hypertonic sport drinks and when you should take each? We demystify the jargon

The amount of sports drinks on supermarket shelves can be overwhelming, so where do you start? Here's everything you need to know about them.

Published: April 23, 2025 at 6:37 pm

Alongside caffeine, energy bars and gels, sports drinks are a common performance booster, whether you're pounding the pavements or hitting the trails. But not all sports drinks are alike: find out the different types, when to use them and how much you actually need.

What are sports drinks made from?

There are three core ingredients that make up the bulk of your energy drink and that’s water for hydration, sugar for energy, and salt (sodium) to replace electrolytes lost when you sweat.

What are the different types of sports drinks?

“There are three types of sports drink: hypotonic, isotonic and hypertonic,” says sport scientist, athlete and founder of Precision Fuel & Hydration Andy Blow. “The term ‘isotonic’ describes a solution that is of a similar ‘thickness’ or concentration (tonicity) as another solution. In this case it refers to a drink being of similar concentration to human blood (which has an osmolarity of around 280 to 300 mOsmol/L).

“This matters in the world of sports drinks because whether a drink is hypotonic (lower concentration than blood), isotonic (about the same concentration) or hypertonic (higher concentration) affects how much energy it can deliver and how quickly you can absorb it into your bloodstream to replace the fluid you’re losing in your sweat.”

How do isotonic drinks work?

“Isotonic drinks (such as Gatorade, Powerade and Lucozade Sport) are usually around 6-8% carbohydrate and so deliver nearly twice the amount of carbohydrates that most hypotonic drinks do,” says Blow. “This is generally most useful for shorter duration, high-intensity exercise where getting carbohydrates in quickly can be more important than warding off dehydration.

How do hypertonic drinks work?

“Hypertonic drinks are more concentrated than your blood. That’s usually because they’re formulated with lots of carbohydrates in order to maximise energy delivery as a way to fuel high-intensity activities. The relatively new breed of ‘Hydrogel’ drinks fall into this category. Where they can cause issues is if you’re trying to use a hypertonic drink at times when fluid intake is the priority and dehydration is a concern, such as a long, sweaty hot event.”

Hypotonic drinks work?

“Hypotonic drinks are absorbed into the bloodstream the fastest, but they deliver lower amounts of carbohydrate per unit volume. Hypotonic drinks are usually of a low concentration because they’re formulated using small amounts of carbohydrate (up to a 6% solution). Hypotonic drinks should therefore be your preferred option if the primary goal of your drink is hydration rather than delivery of large amounts of energy.”

Can you make your own sports drink?

You can, albeit there may be a degree of trial and error regarding taste and how smoothly your concoction is absorbed by the gut. You'll likely need water, sugar, salt (or an electrolyte tablet) and citrus juice to taste. Cycling website BikeRadar has a homemade sports drink recipe here.

How much sports drink do you need while exercising?

“The standard fluid intake guidelines are around 500ml an hour, but they’re fundamentally flawed. For instance, a person’s size will play a big part in how much fluid they can tolerate, so recommending 500ml across the board fails to consider individual differences.

For example, an athlete who weighs in at 55kg will arguably need less than someone hitting the scales at 100kg. By all means use the guidelines as a starting point, but from our experience a personalised approach is best. That means you should combine an element of drinking to thirst, using your experience and listening to your body,” says Blow.

Why is sodium important?

Sodium’s vital for hydration because it helps channel water from the blood into working muscle cells. Lack of sodium means water just flushes through and is urinated out. It’s also important for muscle and nerve function, which is why a lack of sodium has been linked to cramping.

How do sports drinks differ from fizzy drinks?

Sports drinks tend to have less sugar than many carbonated drinks, meaning they’re more easily broken down and used by the body. They’re also not carbonated. You try running on a few cans of Sprite and you’ll be burping for England. Uncomfortable for you, anti-social for your running companion. In many sports drinks, there’s a much greater sodium content for hydration purposes.

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