Spoonful of sugar before long running kills fatigue

If you are a long-distance runner and feel "marathon fatigue" quite often, try a spoonful of sugar first and hit the ground running like never before.

According to researchers, stirring in table sugar from the baking cupboard into a water bottle before a big physical event could be the difference between success and failure.

This helps stave off tiredness faced by weary marathon runners - or other long-distance athletes - when they hit the wall, said the team from University of Bath in Britain.

Both sucrose - in the form of table sugar - and glucose are important carbohydrates often referred to as "simple sugars".

It appears combining different sources of sugars improves the rate at which we can absorb these from the gut.

Although many sports-performance drinks designed to provide energy during exercise now use sucrose, or mixtures of glucose and fructose, many still rely on glucose alone.

The researchers warn that such glucose-only drinks could produce gut discomfort and suggest sucrose-based alternatives, or sugar in water, can help make exercise easier.

The carbohydrate stores in our liver are vitally important when it comes to endurance exercise as they help us to maintain a stable blood sugar level.

"However, while we have a relatively good understanding of the changes in our muscle carbohydrate stores with exercise and nutrition, we know very little about optimising liver carbohydrate stores during and after exercise," lead researcher Javier Gonzalez said.

They tested various sucrose and glucose-based drinks to see how different carbohydrates could help.

Their experiment, conducted on long-distance cyclists, showed that ingesting carbohydrates in the form of either glucose or sucrose prevents the decline in liver glycogen "carbohydrate stores" and can avert tiredness.

"Our study showed that ingesting carbohydrates during exercise can prevent the depletion of carbohydrate stores in the liver but not in muscle. This may be one of the ways in which carbohydrate ingestion improves endurance performance," the authors said.

The researchers also found that the exercise felt easier and the gut comfort of the cyclists was better, when they ingested sucrose compared to glucose.

"This suggests that when your goal is to maximise carbohydrate availability, sucrose is probably a better source of carbohydrate to ingest than glucose," the authors said.

So if your goal is optimal performance during exercise lasting over two and half hours then consume up to 90 gram of sugar per hour - diluted to eight gram sugar per 100 ml.

The findings were published in the the American Journal of Physiology - Endocrinology & Metabolism.