The images of Kathrine Switzer being attacked by the race organiser and being screamed at to “get the hell out of my race” were broadcast around the world. The incident illustrated perfectly the hostility towards women competing in sport. And shockingly, it was only 50 years ago.

There are a number of women who have changed sport forever. From Billie Jean King to Nadia Comaneci to Alice Coachman, they have all had a considerable impact. Kathrine Switzer is as significant as any of these women in the development of women’s sport and without her, it is likely the current landscape of women’s distance running would be entirely different. Monday will mark the 50th anniversary of the American woman completing the Boston Marathon for the first time. To this day, her story of that remarkable race half a decade ago remains compelling.

Switzer began running at the age of 12 but as she progressed through her teenage years, she began to take her sport more seriously. As there was no women’s running team at her university, Syracuse, she trained with the men’s cross-country team. It was here she joined up with her coach, Arnie Briggs, a veteran of 15 Boston Marathons, a race he constantly talked about. Finally, in December of 1966, Switzer snapped, declaring that she too wanted to run the race. “No woman can run the Boston Marathon”, Briggs retorted, before claiming that the distance was too long for fragile women to complete. This was not an atypical viewpoint; running long distances was extremely questionable for women, with suggestions that their uterus might fall out or that such strenuous activity would mean they would grow a moustache or back hair.

After much persuasion- and a 31 mile training run- Switzer convinced her coach that she should enter. Since its inception in 1897, the Boston Marathon had been a male-only race but there were no gender-specific regulations in the rule-book so she registered under the name K. V. Switzer to prevent blowing her cover. Women had run the race previously but Switzer was the first who had ever dared to enter in an official capacity. Few could have anticipated quite how much of a threat to the status quo she would be regarded and quite how badly this would be received by some.

Switzer lined up on the start line on the 19th April, 1967. She was on the receiving end of a number of double takes from her fellow runners who were, obviously, exclusively male. At around mile four, the press truck caught up with Switzer and the bank of photographers scrambled to take a picture of a woman wearing a race number. Moments later, one of the most significant moments in the development of women’s sport happened. Switzer heard someone frantically approaching from behind and as she describes it: “A huge man with bared teeth was set to pounce and before I could react, he grabbed my shoulder and flung me back.” He was screaming: “Get the hell out of my race and give me those numbers!” before the man in question, Jock Semple, the Scottish race manager who has now become inextricably linked with Switzer’s story, tried to rip off her bib number. After a significant scuffle- of which the photographers caught every minute- Switzer’s boyfriend and coach fought off the official. Switzer felt, she said, sick in the heart and humiliated. She just wanted out of there.

But then a thought ignited in her brain: “I knew if I quit, nobody would ever believe that women had the capability to run 26-plus miles,” she wrote in her memoir. “If I quit, everybody would say it was a publicity stunt. If I quit, it would set women’s sports back, way back, instead of forward. If I quit, I’d never run Boston. If I quit, that race manager and all those like him would win. My fear and humiliation turned to anger.”

Switzer slowly resumed the race, despite how much the incident had taken out of her. She knew she had to finish. She slowly began to build some momentum and finally, she crossed the finishing line in 4 hours 20 minutes. The following day, her photograph was all over the newspapers. That day changed Switzer’s life forever- she became a figurehead for equality in sport and has been inducted into the National Women’s Hall of Fame. And she continued to run, ultimately winning the New York City Marathon in 1974.

Switzer’s 1967 Boston Marathon also changed women’s sport forever. Five years later, women were officially allowed to enter the race, the first major marathon to admit women. Switzer gave women belief that they could achieve anything. And she proved that women were not weak.

On Monday, the 121st Boston marathon will take place on what will be the 50th anniversary of Switzer’s historic run. At the age of 70, she will race wearing bib number 261, which she wore 50 years ago and which was the number the official tried to tear off her chest. On Monday, half of the field will be female runners. Every one of those athletes owes a debt to Switzer. Sport still has a way to go before true equality is achieved. But without Switzer and others like her who refused to bow down, parity would be much further away.