Philip Barker head and shouldersNever mind the 2012 Games in London, 2013 is shaping up to be the most important Olympic year in decades.

The International Olympic Committee (IOC) will elect a new leader and they'll choose between Istanbu, Madrid and Tokyo as 2020 host city.

Yet,perhaps the most important question of  all is which sports will make up the Olympic landscape in the third decade of the new Millennium. This particular contest happens every four years, and what makes it so intriguing, is that for any new sport admitted, one must make way.

A total of 26 sports were contested in London, but Rio will have the full complement of  28. The decision to include golf and rugby sevens was taken at the IOC Session in Copenhagen in 2009.

Sports federations now lobby for inclusion  as energetically as candidate host cities. In fact, the International Rugby Board's campaign was masterminded by Mike Lee, the man behind the London and Rio's victories. The great New Zealand All Black Jonah Lomu even pitched up at the IOC Session in Copenhagen to help seal the deal.

Jonah Lomu at IOC Session October 2009Jonah Lomu (far left) helped rugby sevens in its successful bid to be admitted to the Olympic programme for Rio 2016

Golf's delegation included Michelle Wie and a specially recorded message from Tiger Woods was part of the package .

Both sports are automatically included in 2020 but the other 26, known as the "core programme" will have to fight for their place and one could lose its place  at the IOC Session in Buenos Aires this September.

It will be a tense time - but the composition of the Olympic programme has always been a  burning question.

At the first Games of the modern era held in Athens in 1896. there were only nine sports,and  all for men only. More had been planned. An early  IOC bulletin in 1894  had also promised football, (Rugby and Association) and cricket "according to the laws of the Marylebone Cricket Club". They did not happen.

There was a cricket match in 1900, but although draft plans for 1904 and 1908 included the great summer game, it was left on the drawing board.

The Influence of the man who revived the Olympics was a major factor in those early years. Rugby union was part of the Games "on and off" until 1924.Baron Pierre de Coubertin was a keen "Rugbyman" who'd refereed the first French Championship final. He was also enthusiastic about the  inclusion of equestrian events. The horses came in at the 1912 Games and that year also heralded the arrival of the multi event modern pentathlon, devised of course by Coubertin himself to achieve what he called "real all-round athleticism".

He was unhappy about the inclusion of some events. "Team sports are out of place in the Olympiad," he wrote and gave his support to "a strictly individual programme".

Even so, between the wars, football, hockey and basketball became fixtures in the Olympic Movement.

Incidentally roller sports, on the shortlist for 2020, had applied as early as 1939.

The President, Count Henri Baillet -Latour, "read a petition for its inclusion". The discussion aroused the interest of some distinguished figures including Prince Axel of Denmark, Lord Aberdare and Count Bonacossa but to no avail. It was rejected, along for the time being with women's gymnastics.

Roller sportsRoller sports launched its bid to be on the Olympic programme in 1939 and nearly three quarters of a century later is still trying

In those days the Olympic Movement had fewer than 60 member nations and the number of athletes at any given Games was half that seen today. Only a small proportion were women and it stayed that way immediately after the Second World War.

Back then, the Olympic Charter set out a list of core sports "which must be included". They were athletics, gymnastics,combative sports (boxing fencing, shooting (sic), wrestling), aquatic sports (rowing, swimming), equestrian, modern pentathlon, cycling, weightlifting and yachting.

Tothese a further nine could be added: football (soccer) or rugby, hockey, polo, water polo, handball, basketball, canoeing and, strangest of all, gliding which had been demonstrated at the 1936 Games in Berlin.

"Only sports practised in at least ten countries, of which six must enter, may be included in the Olympic Games," it said.

Even so, the Olympic Programme Commission was soon facing an uphill battle.

In the last 50 years tennis and archery returned to the fold and badminton, baseball, handball, judo,softball table tennis, triathlon, taekwondo and volleyball have all taken their place as the Olympic programme grew and grew.

Existing sports like cycling expanded their programmes to embrace BMX and mountain biking, gymnastics introduced the balls and ribbons of rhythmic gymnastics and trampolining. Swimming and diving became synchronised and hockey, football and others introduced women's competitions, meaning that the numbers have soared.

Team GB in action v Brazil women football London 2012Female competitors are more represented in the Olympics than ever thanks to the introduction of sports like women's football

In the early eighties, Juan  Samaranch, later the IOC President described the task of the Programme Commission as "a delicate one a balance between the desire shown by so many to increase the number of sports and events against the need to avoid the 'gigantism' which was talked about so much."

Its  long suffering chairman at the time, the Hungarian Arpad Csanadi lamented, "One of the reasons for the uneven development of the Olympic programme was that some personalities in authority had often tried to influence the IOC by their personal opinions."

The host city was also given a degree of freedom in what they could put on. In 1952, the Finns chose pesapallo  - a form of baseball - as an exhibition. There was a special Aussie Rules football match four years later in Melbourne.

pesapallo at Helsinki 1952Pesapallo appeared at the 1952 Olympics in Helsinki as an exhibition sport featuring a match between the Finnish Baseball Federation and the Finnish Workers' Sports Federation

Demonstration sports were also allowed. In 1972 and 1988 badminton staked its claim for full medal status  Also, in 1988, the Koreans introduced taekwondo at their home Games in Seoul.

No official medals were offered for these competitions but the infrastructure for staging them cost just as much so demonstrations and exhibitions were effectively dropped in the nineties.

By now, the Charter expected sports to be "practiced widely" and though it did not define the phrase, it specified the geographical reach required. At the turn of the Millennium, this was in 50 countries and three continents for men and in 35 countries across three continents for women.

A total of 28 sports were contested and this number was maintained for Athens and Beijing. It was the first time in over 20 years that new sports had not been added. The Olympic Charter now sets a limit of 28 sports and around 10,500 participants.

When Jacques Rogge became IOC President in 2001, he made it clear he wanted greater controls on the size of the Games and a working party started putting the entire Olympic programme under the microscope.

"Any changes in the structure of the programme must result in a benefit for the Olympic Movement and an increased value and appeal of the Olympic Games," said a report presented to the IOC Executive Board.

Gone was the simple formula in the Charter, in its place a detailed questionnaire which examined every aspect of a sport in seven themes. These  include the history of each sport, media coverage for World Championships, spectator attendance, how a sport is presented and where the medals went. It examines gender equity, the provision for the next generation,health of the athlete, impact made on the environment and how the sport deals with doping

The questionnaire faced by the candidates for 2020 included one important addition at the very forefront of the dossier: "IIlegal and Irregular betting – measures in place to fight against competition fixing."

Rogge has even hosted conferences in Lausanne to try and combat the problem. "'The IOC is working very closely with Governments and betting operators to try and have prevention, it is a dangerous issue for sport," he said.

WakeboardingWakeboarding is one of seven sports in contention for inclusion in the 2020 Olympics

Baseball/softball, climbing,karate, roller sport, squash, wakeboarding and wushu made their case for inclusion to the IOC late last year. Next, the existing Olympic core sports appear  in front of  the Executive Board who then choose  25 to be contested at the 2020 Games. The one sport excluded at this stage will be allowed  to plead its case along with the seven new sports in a sort of "'repechage".

But, unlike reality television the final say remains with the judges, in this case the members of the EB. Their  recommendation is usually what counts, but technically the decision will not become Olympic law until that vote by the full IOC membership in the Argentinian capital.

Born in Hackney, a stone's throw from the 2012 Olympic Stadium, Philip Barker has worked as a television journalist for 25 years. He began his career with Trans World Sport, then as a reporter for Skysports News and the ITV breakfast programme. A regular Olympic pundit on BBC Radio, Sky News and Talksport, he is associate editor of the Journal of Olympic History, has lectured at the National Olympic Academy and contributed extensively to Team GB publications.