AS Karen Dixon sets off in the Olympic three-day event in Sydney, it's to be hoped she's aware of how it could damage her health. The Barnard Castle rider might be an experienced Olympian but had she been around when the modern Olympics began 104 years ago, there's no way she would have been allowed to compete.

When the games were revived in 1896, female competitors were banned. Apart from being considered unfeminine, it was thought that the exertions of physical sport at the highest level might damage them, in particular 'knot their tubes' and leave them unable to have children. There was even a belief that sporting women might turn into men.

The prospect of a woman eventer in a world-class field would have been anathema to the organisers; goodness knows what they would have thought of Karen climbing back in the saddle two weeks after her having her son Rory by caesarean section last year.

Centuries earlier, women did have a place in the ancient Olympic games - as prizes in the men's chariot races. Married women weren't even allowed to watch; female spectator seats were reserved for prostitutes and virgins.

Once women were allowed to compete, the top prize they could hope for was a pomegranate, the symbol of fertility. Other rewards were olive wreaths and a slice of a sacrificial cow.

Although women couldn't take part in 1896, Greek marathon runner Stamati Revithi did compete unofficially. She was not allowed to take part in the men's race, but ran by herself the next day, though she was forced to completed the final lap outside the stadium on being refused entry. After her marathon run, officials couldn't remember her name so they labelled her Melpomene after the Greek muse of tragedy, which was how they perceived her extraordinary feat.

Four years later things began to change. In Paris in 1900 the all male International Olympic Committee (IOC), which was against women taking parts in sports, had little influence. Twenty-three women from five countries (Great Britain, Switzerland, France, USA and Bohemia) competed in ballooning, croquet, golf, equestrianism, yachting and tennis.

British women, however, did not take part in croquet as it was considered objectionable to stoop in a corset, according to chronicler Maurice Thompson.

The first woman to win a gold medal was Britain's Charlotte Cooper, the reigning Wimbledon champion in 1900. Great Britain also won the first women's team medal, in the 4x100 metres freestyle relay in Stockholm in 1912, the year that swimming and diving events for women were first introduced.

In spite of the fears for women's health in 1896, by 1904 they were invited to take part in boxing as a demonstration event. Archery was also introduced for women at the games in St Louis, USA.

Athletics might be the focus of the modern Olympics but it proved the biggest hurdle of all for women competitors to overcome. Frustrated at not being accepted, they even set up their own games in the early 1920s. Five events were introduced eventually in Amsterdam in 1928.

However, there were still concerns for their safety and the 800 metres was only run once between 1928 and 1956 as it was thought dangerous for women. Edith Robinson, now 94, who competed for Australia in the Amsterdam race, was a guest of honour at the opening ceremony in Sydney.

Although the number of female competitors continued to rise - there were 290 by 1928 - they had to try and not look like women at all.

Modesty was the order of the day during the early part of last century; today it's more about finding aerodynamic kit that helps you go faster, further, higher and longer.

Breasts had to be bound and the compulsory dress of blouses and ties underneath tunics kept female competitors covered up. This was especially difficult when most were mature, married women, not the lithe, young athletes of today.

The British gymnastics team of 1928 were heavily criticised when they posed for their team photograph - and revealed too much of their shapely legs. They had to wear black stockings under their gym tunics.

Recalling her kit in the book A Proper Spectacle: Women Olympians 1900-1936, Dutch 800 metre-runner Mien Duchataeu says: "We wore orange woollen shorts that we knitted ourselves... Old gents said how outrageous it was - a woman in shorts!" Another Dutchwoman would become the most successful Olympic mother - Fanny Blankers-Koen won four gold medals in London in 1948.

The dress restrictions didn't put off the male competitors. Sweden's Maud Sundberg's recalls: "My greatest memory from Amsterdam was that the men from the Mexican team followed the blue eyed girls from Sweden everywhere, and threw roses over them."

Nor did the modest outfits stop Britain's Ethel Seymour becoming the oldest medallist in gymnastics - she took bronze at the age of 46.

The oldest female Olympian ever was British rider, Lorna Johnson, who competed in 1972, aged 70.

By the Los Angeles Olympics of 1932, 127 women competed in swimming, athletics and fencing, which had first appeared in 1924.

High jump silver medallist Dorothy Odam-Tyler recalls that women still weren't fully accepted by the 1936 "Hitler Olympics" in Berlin: "The women were still second-class citizens. We didn't travel with the men, and we were not allowed to stay in the Olympic village."

Women's gymnastics may have caught the world's imagination thanks to stars like Nadia Comaneci (memorable not least for her perfect ten at Montreal at 1976) and Olga Korbut in the 1970s, but after being introduced as an official team event in 1928 when the Netherlands took gold, it was dropped from the 1932 games. It returned as an individual Olympic event in 1952.

While female competitors eventually made their mark on track and field, it took them until 1981 to have any influence in the organisation of the Olympics, when the first woman was accepted onto the IOC.

Thirteen years earlier, Enriqeuta Basilio of Mexico had become the first woman to light the Olympic flame.

Apart from the Los Angeles Games of 1932 and 1952 when Australia hosted the event (the cost of teams travelling long distance meant women were left behind), the number of female competitors has continued to grow. At the last Olympics in Atlanta, 3,626 women representing 169 countries competed in 21 sports.

In Sydney, women will take part in 25 of the 28 sports - boxing is no longer a female event. Women don't compete in baseball or wrestling.

Among the events at the 27th Olympiad thrown open to women for the first time are modern pentathlon, pole vault, synchronised diving, taekwondo, trampoline and water polo.

With modern sport have come added pressures for competitors, both male and female. The Olympics today is as much about television as it is sport and with that comes closer scrutiny.

Then there is the increase in drug testing as organisers pledge to keep the Olympics clean of banned substances and allegations of cheating. No one wants to see a repeat of the saga involving Irish swimmer Michelle Smith who collected three golds and a bronze in Atlanta only to have them taken from her for tampering with a drugs test.

There have been tragedies too - flamboyant Florence Griffith-Joiner, Flo-Jo, picked up three golds in 1988, ten years later she was dead following a heart seizure.

South African-born Lillian Board took the silver medal in the 400 metres at the Mexico City Olympics in 1968. Two years later, aged just 22, she died of cancer.

For many, it's the achievements they remember. Among the British greats have been javelin throwers Tessa Sanderson and Fatima Whitbread, Munich golden girl Mary Peters and Sally Gunnell, who took gold in the 400 metre hurdles in Barcelona in 1992.

A century on, women Olympians are still breaking records.

Blazing the trail in Sydney is American Marion Jones, who could go one better than Fanny Blankers-Koen - the American athlete will enter the history books if she wins five gold medals in the 100 and 200 metres, long jump and 4x100 and 4x400 metre relays.

Whether women can go faster, higher, further remains to be seen but at least their place in the Olympics is guaranteed thanks to those who have gone before.

As Paula Radcliffe, British women's team captain in Sydney, writes in the introduction to A Proper Spectacle: "The bravery, commitment and above all the achievements of these women provide excellent inspiration for the many women competing at all levels in sport today. We have the chance to go out and prove what we can do - the rest is up to us."

A Proper Spectacle: Women Olympians 1900-1936 by Stephanie Daniels and Anita Tedder (ZeNaNa Press, £16.95) can be ordered online at www.olympicwomen.co.uk