Isotonic drinks

Isotonic drinks

There was a time when having a drink after a workout meant a beer at the club bar. Not any more. Even the humble glass of water from the gym cooler has fallen out of favour with fitness enthusiasts. These days, we are encouraged to down a bewildering array of products, from energy-replacing isotonic drink to zero-calorie flavoured water loaded with electrolytes (mineral salts) that help keep the body’s fluid levels in balance.

But does the average keep-fitter need to drink unnaturally coloured bottled drinks or mix their own potions from powder during and after their thrice-weekly turn in the gym? Last month, experts warned that thousands of gym-goers were not only wasting their money on energy sports drinks, they were expanding their waistlines, too: as many of these drinks are full of calories, the report concluded that you would actually have to train even longer or harder to prevent the excess energy from the drink itself being stored as fat.

Manufacturers, meanwhile, maintain that isotonic drinks – which not only replace the fluids lost by sweating but also provide a carbohydrate boost, enabling you to train for longer – are the ideal way to replenish depleted energy levels, which water alone cannot do. This is because they contain the same ratio of sugars as the body, so are said to be more easily absorbed into the bloodstream. The trapped Chilean miners were each given 1.5 litres of isotonic energy drinks a day to ensure they were properly hydrated.

However, sport scientists say that while isotonic drinks are vital for keeping energy levels up during endurance events such as marathons – or 69 days spent underground in a hot mine – they are unnecessary for those spending an hour on the treadmill.

And yet a new generation of sports drinks claims to quench thirst and replace lost salts and minerals such as potassium and magnesium, but without piling on unnecessary calories. The makers claim the electrolyte-enriched drinks are more suitable for shorter work-outs. Here we put their claims to the test.


Price 99p, 500ml Calories: 5

The UK’s first fitness drink marketed as being free of sugar and calories (well, almost free…), manufacturers Coca-Cola claims this is the ideal liquid accompaniment for general gym-goers. It comes in two flavours, Red Fruits, and Berry and Tropical Fruits – both are unnaturally coloured, with the latter looking more like dentist’s mouthwash, and tasting like a watered-down version of its more calorific sibling, “full-fat” Powerade. When it came to quenching thirst after a gym session, however, it hit the mark.

Expert view: “Yes, it’s hydrating,” says Anita Bean, a registered nutritionist and author of The Complete Guide to Sports Nutrition (A&C Black, £16.99), “but so is drinking water, which will do the job just as well. Plus, the maker claims this is made with 'natural flavours and no added preservatives’ – but it does contain artificial sweeteners.”


Price 99p, 500ml Calories 50

A low-calorie alternative to Lucozade Sport – a standard 500ml bottle of which contains 140 calories. But the “Lite” version, which comes in Summer Berries and Lemon and Lime flavours, packs just 10g of carbs, and 70 per cent less sugar than conventional sport drinks. It is also fortified with B vitamins, which help your body release energy and keep your muscles working efficiently. The lemon and lime flavour tasted great after an hour’s run.

Expert view: “While B vitamins help your body use or release energy present in food, I’d be very cautious of making claims about them in a sports drink,” says Dr Justin Roberts, a research nutritionist and senior sport and exercise science lecturer at the University of Hertfordshire. “Expecting to exercise any harder is unrealistic – your body just doesn’t work like that. Like probiotics, you would need to drink this every day for it to be beneficial.”


Price £32 for 24 bottles (500ml) Calories 10

A non-carbonated drink fortified with the amino acid L-carnitine, which can help control the rate at which the body’s fat stores are burned. L-carnitine helps carry fatty acids in food to the mitochondria in cells, where the acid is oxidised into energy. Containing just 10 calories, the 1,000mg dose delivered by a 500ml drink is believed to promote weight loss as well as helping power a workout. The drink is surprisingly pleasant, with a pineapple flavour.

Expert view: While studies have suggested L-carnitine is linked to enhanced athletic performance and endurance, to date it has not been proven. “L-Carnitine is involved in the fat-burning process within muscle cells, but consuming it as a supplement won’t necessarily increase your fat burning,” says Bean. However, research indicates that L-carnitine can make sperm more vital and active and thus may be a potentially effective treatment for male infertility.


Price: £6 for a pack of 12 sachets Calories: 7.5 per 500ml

A low-calorie, low-carb electrolyte drink mix developed to help Britain’s sailing team cope in the heat of the Beijing Olympics; the high sodium content provides maximum hydration in intense conditions. Lemon-flavoured and fortified with antioxidants to reduce muscle soreness, the powder’s sachets look like those for treating upset stomachs – but, when mixed with water, taste a lot better, and surprisingly sweet.

Expert view: “There is an argument for topping up on antioxidants after exercise, as they are thought to help eliminate metabolic waste produced during training,” says Dr Roberts. “But you can just as easily get them from a cup of green tea. Also, at 0.3g per drink, this has a higher sodium content so is more suited to serious athletes working out in the heat rather than general use at the gym. One for the professionals only.”


Price: £6.99 for 20 tablets Calories: 7 per 500ml

The makers of this “new electrolyte sports drink tablet” claim this zero-calorie electrolyte replacement will help you burn more fat during exercise – 41 per cent more, they claim – than regular sports drinks. Pleasant to taste, it’s virtually calorie-free (1.4 calories per 100ml), and contains magnesium to help combat cramp, and caffeine to keep you focused on your workout.

Expert view: “There is a link between magnesium and anti-cramp, while caffeine can have an enhancing effect,” says Dr Roberts. “Electrolytes also increase the flavour of a drink, so you’ll end up increasing your fluid intake almost without noticing.”


Price: approx 50p Calories: approx 120

Nothing quite beats a homemade isotonic juice, which is easy to make. Dilute fruit juice of your choice with water to a 50/50 ratio, and add a pinch of salt. Alternatively, mix 200ml of supermarket squash with 800ml of water, and add a quarter teaspoon of salt. Either way it tastes good and will reydrate you as well as providing an antioxidant-rich energy boost. “It’s the perfect sports drink,” says Bean.

Vegetables may hydrate your body more than water

Researchers have found that some fruits & vegetables may hydrate your body twice as effectively as a glass of water. In the hot summer these fruits & vegetables can be made a refreshing snack option. The fruits & vegetables contain hydrating salt, minerals & sugars. They work in a similar way to the isotonic drinks favored by athletes.

These water rich fruits & vegetables act as two-in-one meal & drink which provide the minerals salts, natural sugars, amino acids & vitamins that are lost while exercising. This combination helped the people to hydrate more effectively than water or even sports drinks.

The plant chemicals lutein & zeaxanthin, found in fruit such as watermelon & papaya, help boost hydration even further. Top of the list are watermelons, which are 92 % water, 8 % sugar & contain essential re hydration salts calcium, magnesium, potassium & sodium. Watermelon is also rich in Vitamin C , as well as beta carotene & lycopene which will give the body protection from ultra violet light.

Due to its 96 % water content & mineral balance, a cucumber can produce similar hydration levels to twice the volume of water. It also contains almost ideal levels of calcium & magnesium, along with potassium, sodium & other minerals. Two or three mineral-rich celery sticks replenish levels of sodium, potassium, magnesium, calcium, phosphorus, iron & zinc. These salts help carry the 96 % water in which they are dissolved around the body.

Dr Susan Shirreffs said, “To be properly hydrated, you need to replace fluid lost from the body with one that's similar to the body's natural composition. Watery fruit & vegetables often contain levels of minerals & sugar that mirror this, so they can hydrate you more effectively than water alone.”