8 August 2012 Last updated at 10:16

Why is the Marathon 26 miles and 385 yards in length?

The marathon is hailed as the ultimate test of endurance. But why is it exactly 26 miles and 385 yards long? The answer has less to do with ancient Greece , and more to do with the British Royal Family.

When London held the games in 1908, there was still no official marathon length. The British Royal family requested that it start at Windsor Castle and end at the Olympic Stadium's royal box. At a length of 26.2 miles, it was the longest marathon since the modern games began.

The race grabbed public attention when Italian front-runner, Dorando Pietri, collapsed in the stadium and had to be helped to his feet - which caused him to be disqualified. Semi-conscious, he stumbled across the finish line. False rumours of his death began to spread. The Olympics had found a new Pheidippides .

In honour of what was described as the most thrilling athletic event since the ancient Olympics, The International Amateur Athletic Association ruled in 1921, that all marathons must match the distance of the London 1908 Olympics - 26.2 miles.

Can you compete under pressure? Take the BBC Lab UK test . Try it against the clock and an opponent and get psychological training from Michael Johnson.