Running: The sub-two hour marathon

The world marvelled when Roger Bannister broke the four-minute mile barrier. Now some wonder if a sub-two hour marathon is possible.

The short answer is, yes, probably.

But it will take a combination of the perfect athlete on the perfect course on the perfect day. Some believe it will happen within a decade, others are more circumspect and there's still a school of thought that it can't be done.

Kenya's Dennis Kimetto recently broke the world record for the 42.195km distance, running 2:02.57 at the Berlin Marathon. It was significantly faster than American John Hayes, who clocked 2:55.18 at the 1908 London Olympics.

In 1967, Australian Derek Clayton was the first under 2.10 and it has since creeped down an average of five seconds a year. By that measure, a sub two-hour marathon is only a matter of time - 28 years to be specific - but it ignores many variables, not least it will get more difficult as the time drops.

Kimetto's average speed in Berlin was 20.591km/h. To crack two hours, an average of 21.082km/h is required - an extra 491m an hour. That might not sound a lot but means a 1:59.59 runner would finish about 1km ahead of the current world record holder.

There are probably only about six courses suitable for a record attempt.

London is one but the prestige of the event often sees athletes watch one another rather than risk losing to chase times. New York isn't suitable because runners must climb 250m and navigate 26 sharp turns.

The last six men's marathon world records have been set in Berlin. Just six courses around the world - Berlin, Dubai, Rotterdam, Frankfurt, Chicago and London - account for all 41 times under 2:05.

The weather also needs to be perfect. It's believed a cloudy day and 16-degree temperatures are the optimal conditions.

Physiology plays a big part. The Nandi sub-tribe in Kenya, with a population of less than one million, has out-performed every continent outside Africa in terms of distance track medals won and elite marathon performances since 1990. They have won 59 medals in that time, while Europe, with 700 million people, have accumulated 31 medals.

Nandi people are more inclined to have the right height, weight and calf structure, live at altitude and are more motivated because of the financial rewards. Sports scientists also found East Africans tend to have superior running economy rather than enhanced aerobic capacity.

Key factors:

Location: Only six courses in the world are suitable for a record attempt: London, Berlin, Dubai, Rotterdam, Frankfurt and Chicago.

Weather: 16C and cloudy with no wind.

Physiology: Kenya's Nandi people live at an ideal altitude Wand have the optimum weight,
height and calf structure to be record-breakers.