London, Oct 22 (IANS) Marathon runners need never ‘hit the wall’ again after a scientist devised a formula to ensure they always have a strong finish.

Hitting the wall occurs when those stored carbohydrates are completely depleted, forcing the body to start burning fat.

When that happens, the runners’ pace can drop about a third and byproducts from the fat, start building up in the body, causing pain and fatigue – and often forcing runners to pull up, according to the Telegraph.

A researcher has worked out a mathematical model that calculates how much carbohydrate each individual runner needs to eat in order to stop their body reserves running out during the race, reports the journal PLoS Computational Biology.

Benjamin Rapoport, a Harvard medical student, has devised the Marathon Formula which uses simple factors such as body weight, age, resting heart beat and fitness levels, to work out range of times that can be achieved and how best to ‘load up on carbs’ before the 26.2 mile (42km) race.

Using the calculator, which is available online, a 70 kg man, who is 35-year-old and wants to run 4 hours, 30 mins, is told to eat 1,600 calories of carbohydrate – eight bowls of rice or five of pasta, in addition to their normal diet before the race.

If he wants to run faster, it calculates he should eat 3,000 calories – 15 bowls of rice or 10 of pasta.

‘People think hitting the wall is inevitable, but it’s not,’ said Rapoport, who has run 18 marathons, including a personal best of 2hr:55min at this year’s Boston Marathon.