The voting will take place at the Tokyo 2020 Athletes’ Village during next year's Games and four athletes, from four different sports, will be elected.

The athlete members are unique in that they are the only members of the IOC who are formally elected from outside the organisation.

Ever since the early days of the IOC, there have been many with an athletic past. Future president Avery Brundage was an athlete in the pentathlon at Stockholm 1912, while Lord Burghley, destined to become IOC vice-president, won 400 metres hurdles gold at the 1928 Amsterdam Olympics. Japan’s Masaji Kiyokawa was Olympic backstroke champion in 1932 and later became the first IOC vice-president from an Asian country.

Zimbabwe’s double Olympic swimming champion Kirsty Coventry leads the Athletes' Commission in an IOC headed by Olympic fencing champion Thomas Bach.

It is 20 years since major reforms in the wake of the Salt Lake City bidding scandal created the new category of membership, although an Athletes' Commission already existed.

Back in 1981, Bach and Sebastian Coe were among those who made widely-praised presentations at the IOC Congress in Baden Baden. It signalled a change in attitudes to athletes and both became leading figures when the Commission was officially launched the following year. At that time it did not carry with it IOC membership.

The big change came in 1999, when the report of the IOC's 2000 Commission included the recommendation for "15 active athletes, chosen from the summer and winter sports in equitable proportions. In order to be considered "active" athletes must have taken part in the Olympic Games".

Even before that, Sergey Bubka and Charmaine Crooks from athletics and swimmer Alex Popov were among a group chosen as the first IOC athlete members. Swimmer Susie O’Neill joined the ranks the following year in Sydney.

The term of office is limited to eight years, although they "may be re-elected for one or several terms".

Those chosen next summer will join a receive a copy of the very latest edition of the Olympic Charter, decorated with a photograph of the new Olympic House in Lausanne.

This volume describes IOC members as "natural persons" who must "represent and promote the interests of the IOC and the Olympic Movement in their countries".

They must also "inform the President of all events liable to hinder the application of the Olympic charter or to otherwise adversely affect the Olympic movement in his or her country".

When the IOC was founded 125 years ago, the driving force was the French nobleman Baron Pierre de Coubertin. He had been greatly impressed by the system of co-option used by the great gentlemen’s clubs in London and by the organisation of the annual Henley Royal Regatta. They did not so much elect new members but invite them to join.

Coubertin deliberately invited those who were unlikely to attend the meetings on a regular basis. This was because he needed, what he called, "elbow room".

The earliest existing Olympic Charter sets out the responsibilities of the IOC members for ensuring "regular celebration of the Games and making the Games ever more worthy of their glorious history and the high ideals which inspired their revival".

In the years that followed, the make-up of the committee included many European aristocrats. It had more than just a sprinkling of Princes, Dukes and Counts.

In 1903, these included the Belgian Comte Henri Baillet-Latour, destined to succeed Coubertin as IOC President. He had been brought up in a privileged household and was a close friend of the future King of the Belgians.

Other notable members included the surgeon Don Antonio Maria de Lancastre, personal physician to the King of Portugal.

The rarefied make-up of the committee was little changed before the Second World War. The majority of meetings were held in Europe, often in the grandest of surroundings. A notable exception was a session in Egypt which took place on the Nile.

A few weeks after the Second World War ended, the Executive Committee (nowadays known as the Executive Board) met in London. They decided on a recruiting drive for IOC members. "Each member of the Executive Committee was charged with the duty to find in various countries, new men with active interests in sport and suitable qualities as members of the IOC. Said candidates should then be proposed to fill the vacant places in the IOC," a report from the time reads.

At the first full Session after the war, held in Lausanne, new President Sigfrid Edström had read a long list of members who had died since the last formal meetings before the war.

Even when future IOC President Lord Killanin was co-opted in 1952 it remained an exclusive club.

Prince Rainier of Monaco had even briefly become a member before having to resign when he became head of state.

Olympic sport itself remained steadfastly amateur and the Olympic Charter noted that the IOC "selects such persons as it considers qualified to be members" and charged them with "guiding and leading amateur sport along the right lines".

As Killanin observed: "Members were expected to pay their own expenses as well as a subscription to the IOC as is the custom in every club."

Joining him as part of the new intake that year was Aleksey Romanov, the first Soviet member. This was a sign of change.

It would be almost 30 years before an even more dramatic change to the membership came when woman were co-opted for the first time. By then, the IOC President was Juan Antonio Samaranch of Spain. When he joined in 1966, it was with the support of the then IOC President Avery Brundage who told him "one day you will be President".

Flor Isava Fonseca of Venezuela and 400m runner Pirjo Haggman of Finland who had competed in the 1976 Olympics were soon followed by Dame Mary Glen Haig of Great Britain and Princess Nora of Liechtenstein as the few became many.

When the new athletes members take their place after Tokyo, they almost certainly will instantly lower the average age of the IOC.

The upper age limit for IOC members is now 70, although those elected before 1999 are permitted to continue until they reach the age of 80. Those elected before 1966 were not subject to any such restriction.

General Stoychev of Bulgaria was co-opted in 1952 and remained a full member until 1987, by which time he was 95 years old. João Havelange of Brazil, later to become the long serving president of FIFA, joined in 1963. He was still an IOC member at the age of 95 when he resigned in 2011 to forestall investigations into his affairs by the IOC Ethics Commission.

As a matter of course, there is now  a background check on every prospective member. In May, the Members Commission, chaired by the Princess Anne, proposed 10 new members which were then considered by the IOC Executive Board.

At present there are 105 full members. They are not national delegates but instead "represent and promote the interests of the IOC in their countries".

Although nations such as Afghanistan and Lesotho have had members for the first time in recent years, there are still some 80 countries which have never had one. Many believe that if the IOC were expanded to include a member in every country, it would become impossibly unwieldy.

What does seem likely is that, when the time comes to elect a president to succeed Bach, he or she will come from the ranks of athlete members, perhaps even one of those who will take their place in Tokyo next year.