LONDON (Reuters) - This weekend, aided by a host of technological and environmental advances, three carefully-selected elite African athletes will attempt to run the first sub-two hour marathon.

The "Breaking2" project is the latest enterprise of American sportswear giant Nike and has split opinion in the world of athletics, not to mention physiology.

In one camp are the purists, who claim that the host of benefits being bestowed on the runners, including revolutionary shoes, a pack of interchangeable pacemakers and a non-traditional course, mean the attempt is a marketing gimmick.

Nike, and others, however, insist such projects show that a combination of talent, training and technology can produce astounding results without the need for chemical assistance.

Many people are intrigued to see just how much difference such a collection of marginal gains can make and suggest that, at a time when athletics is reeling from relentless bad news, such a quantum leap in human endurance is something to be welcomed and celebrated.

Here are the key aspects of the project.

The world record and its progression

Kenyan Dennis Kimetto set the world record of 2hr 2min 57sec in Berlin in 2014, which is about four minutes faster than it was in 1988.

Since Ethiopia's Belayneh Dinsamo clocked 2:06:50 in April 1988, the world record has been broken nine times.

The trio who held the mark before Kimetto are Ethiopia's Haile Gebrselassie (2:03:59) and Kenyans Patrick Makau (2:03:38) and Wilson Kipsang (2:03:23).

In 2014, the respected Runners World magazine published a data-driven analysis of more than 10,000 top marathon performances over 50 years that predicted a sub-two under normal race conditions would not happen until 2075.

Should anyone go sub-two, the attempt will not be an officially sanctioned world record due to a host of variables, detailed below.

Who is running?

Eliud Kipchoge: The 32-year-old Kenyan is the stand-out performer. Last year's Olympic marathon gold medallist and former 5,000m world champion has won seven of his eight marathons.

His best of 2:03:05 is the third-fastest in history.

Zersenay Tadese: The 35-year-old Eritrean is the half-marathon world record holder (58:23).

Lelisa Desisa: The 26-year-old Ethiopian has a marathon best of 2:04.45. He is another athlete whose numbers in the area of VO2 max, which measures the maximum rate of oxygen consumption, lactate profile, which provides an indicator of fatigue during exercise, and running economy, are second to none.

The shoes

The 200g Zoom Vaporfly Elite are central to the whole project. Nike says the combination of a new foam and curved carbon insert, which also helps change the angle of the foot, means runners require 4 per cent less energy to go at the same speed in comparison with their previous best shoe.

The shoes have been custom-fitted for the three athletes.

A recent meeting of the IAAF technical committee ruled the shoes and their technology to be within their rules.

The kit

Nike is also kitting their intrepid trio out in new socks, shorts and singlet, all of which are claimed to offer an advantage in terms of aerodynamics and/or ventilation and support.

The course

The sub-two attempt will be run on about 17 laps of a 2.4km loop that forms part of the Monza F1 track in northern Italy.

After extensive research it was selected due to a combination of environmental factors, including average temperature, air pressure and wind levels.

The surface, with no kerbs or cambers, was also considered optimal.

The course satisfies the rules on elevation that, for example, rule out records set on the overall downhill route of the Boston Marathon.

One area where the Monza track could give a tangible advantage is that the athletes will run exactly the marathon distance.

Pacemakers/drafting

This is another area where quantifiable benefits can be seen - and is the one that seems to have turned many people against the attempt.

The three runners will be sheltered throughout the attempt by a group of pacemakers, who will dip in and out at various times to ensure they maintain the demanded pace.

Mobile drinks

Nike organised a practice event at Monza in March, when the athletes ingested core-temperature pills and used taped-on muscle oxygen and skin-temperature sensors. The runners followed a car with a large clock on the back showing elapsed time, splits, and projected finish time.

They were also served drinks on the move, avoiding the need to slow and lose rhythm at traditional drinks stations - another innovation the IAAF have concerns about.