This morning at 5.30 local time a recorded rooster crow set some 12000 people off on a gruelling 90 kilometre (55 mile) run from Pietermaritzburg to Durban, in the South African province of kwaZulu-Natal. The run ended exactly 12 hours later in the famous Kingsmead Stadium with amazing scenes of courage and physical endurance.

For the duration of the race, the longest, oldest and probably toughest ultra-marathon in the world, large numbers of South Africans sat in front of their TVs marvelling at the latest unfolding of what is an enduring tradition in South African sport. The race is covered live on national TV every year - the whole length of it from start to finish.

The Comrades Marathon was started in 1921 by World War I veteran Vic Clapham as a memorial to the thousands of South African soldiers killed in that war. The race was run, like this year's one, from Pietermaritzburg to Durban, and had 34 participants. It was won by Bill Rowan in a time of 8 hours 59 minutes and of the 34 starters only 16 finished.

In the years since then many legends have developed and the race has achieved a level of interest and charisma not matched by any other race in the country, and, quite possibly, the world. It alternates each year between the race from Pietermaritzburg to Durban (called the "down run"), and the race from Durban to Pietermaritzburg (the "up run"). Which is the more difficult race is always a subject of discussion.

The Comrades has been run every year except for the war years between 1941 and 1945, always, until the 1990s, in the month of May. The first race was run on Empire Day, 24 May, so this year's event was on the exact anniversary of the first one.

Over the years individual runners have become legends in the rich lore of the Comrades.

The first of these is Arthur Newton, who entered the Comrades for the first time in 1922 (the first "up run") and won. He dominated the race in the 1920s, winning it a total of six times.

The second legend,and one of the most popular, is the famous Wally Hayward, who first won in 1930 on his first attempt at the age of 21. He next won the race in 1950, then again the next year, then again in 1953 and 1954. He only missed the 1952 race as he had decided to take his place in the South African marathon team at the Helsinki Olympics. He came in 10th in that race. Hayward ran his last Comrades at the age of 80 in 1989.

During the 1960s, the 1970s and the 1980s the popularity of the Comrades grew with entries increasing each year. The 1980s also were the years of the dominance of the unofficial "King of the Comrades", the phenomenal Bruce Fordyce, who won nine times, recording his first win in 1980 and only missing the race in 1989. His missing of that race allowed another record to be recorded - the first win by a Black runner. Blacks and women were excluded from the race until 1975. Sam Tshabalala won in 1989.

The woman who made the most impact was the tiny schoolteacher Frith van der Merwe who set records in 1988 and 1989. In the 1989 Comrades she came 15th overall and set a record of 5 hours 54 minutes and 43 seconds which has not been broken since.

Since the late 1990s the race, both the women's and men's, have been dominated by runners from Russia or Eastern Europe.

The race has also had its fair share of political controversy, and Fordyce was a good example of this. In 1981 the Republic of South Africa, the apartheid state, would have its 20th anniversary and Comrades organisers associated the race with this celebration. As an outspoken opponent of apartheid Fordyce announced that he would boycott the race in protest. He eventually ran, but wearing a black armband to indicate his protest.

Today's men's race was won for the first time by a Zimbabwean, Stephen Muzhingi, and the women's race was won, yet again, by Russian Olesya Nurgalieva with her twin sister Elena in second place. These twins have dominated the women's race since 2003.

But the Comrades is much more than records and politics. It has become a national event with participants from all walks of life, from all age and race groups. And the motivations to participate is as varied as the participants.

Watching the race one sees young people for whom it is a fun event, housewives, retired business executives. The participants dress up in fancy dress, carry banners proclaiming religious beliefs or asking girls to marry them, all sorts of strange sights are out on the road.

What makes the event so incredibly special is that the participants live up to the name - strangers become truly Comrades on the road. They help each other across the finish line (though that is rather frowned upon by the officials these days), the urge each other on when the muscles cramp up and breathing becomes painful.

And at the end there are scenes of respect and affection that would be unthinkable in normal circumstances - elderly white women embrace young black men, Christians and Muslims share experiences, foreigners become friends.

Next year's Comrades will again be a down run - the first time that the race has been in run in the same direction in consecutive years - so that the finish can be at the new soccer stadium in Durban, which is a host city for the 2010 Fifa Soccer World Cup, and so contribute to the general festivities surrounding that great event. Organisers are hoping for a record number of entries next year, in excess of 20000.

Oh yes - the rooster crow at the start? That was started in 1948 when runner Max Trimborn needed to release some pent-up anxiety at the start and through cupped hands made the "cock-a-doodle-do" sound which was so enjoyed by his fellow-runners that they asked him to do it again, and again, and again, for a total of 32 starts. And luckily his crowing was recorded and that recording is still the signal for the start of the race. Trimborn himself died in 1985. Just another Comrades legend.