Traditionally thought of as ‘the evil’ in the health and fitness world, sugars can actually be an athlete’s energy boosting best friend – provided they are taken properly…

Sugars seem to have got a bad press in recent years. Yet they have an important function in a triathlete’s diet – they are the basic building blocks of all carbohydrates.

When used during racing they can delay fatigue and improve performance. Use them during training sessions and they can help prevent overtraining,

Here are the main sugars in your sports drinks and foods:

Glucose is probably the most common sugar in sports drinks and foods. It can be used directly by the muscles as energy and is one of the few fuels for the brain. The human body absorbs around 60g of glucose per hour, but if a drink has too much glucose in it (more than 8%) then the absorption of water can be slowed. You’ll find glucose naturally in fruits and vegetables.

Sports Nutrition - SugarsFructose is a naturally occurring sugar you’ll find in fruits. It’s absorbed directly by the intestine, but the liver has to convert it into lactate before the muscles can use it as energy. This means fructose is used by the muscles more slowly than glucose. However, fructose has its own transporter in the intestine, so if you add fructose to a glucose drink you’ll actually increase the amount of ingested sugars used as fuel during exercise to around 90g per hour. Mixtures of glucose and fructose have been shown to improve performance over a glucose-only drink by 8%. Some people have fructose intolerance when large amounts are ingested, causing diarrhoea.

Sucrose, more commonly known as table sugar, is a disaccharide, made up of glucose and fructose. You’ll find natural forms of it in fruits and vegetables.

Lactose is a disaccharide made up of galactose and glucose. You’ll find lactose in milk and dairy products. It’s not usually used in sports drinks, but you might find it in recovery drinks. Some people are lactose-intolerant, so should avoid lactose-containing products.

Maltodextrin is a polysaccharide made up of long chains of glucose molecules and it’s used by the muscles at the same rate as glucose. The advantage to maltodextrin over glucose is that fluid absorption doesn’t decrease at large concentrations (greater than 8%).