It was 1999 and the two premier national teams in women’s soccer were facing off in the Rose Bowl in Pasadena California to determine the champions of the second FIFA World Cup Championship.

The United States and China were locked in a scoreless draw through regular and extra time, with victory coming down to a penalty shootout. After goaltender Briana Scurry stopped a shot in the third round, victory rested in the left foot of Brandi Chastain. And when she rocketed the ball into the upper right hand corner of the net, Chastain immediately ripped off her jersey, fell to her knees, her arms extended in ecstatic triumph, and her black Nike sports bra exposed for the entire world to see.

Lisa Lindahl was at home in Vermont when her phone rang and her friend told her to switch on the TV. Lindahl was an entrepreneur who established the market for sports bras in the late 1970s, so when she saw Chastain raise her arms in victory, she said was astonished, and proud. “It was her confidence, her preparation and her long journey that came to fruition in that moment,” said Lindahl in this 99% invisible podcast. “And that is perfect because I could say that about my journey of the jog bra.”

One of my favorite podcasts, 99% Invisible, is not about sports, but about design. And strange as it may seem today, the sports bra was non-existent before 1977. No sportswear or sports equipment manufacturer ever imagined why women would ever need a sports bra.

Dr. LaJean Lawson, who is the Sports Bra Science and Marketing Consultant to Champion Athleticwear, and has been shaping the design of the sports bra for three decades, said that the environment for women in sports when she was growing up was very different.

When I started high school we weren’t allowed to run full court because there was the assumption that girls were too weak, and we couldn’t run any races longer than 400 meters. So women participating in sports having/needing a sports bra is so recent.

The more Lawson promoted the sports bra and the idea of better fitness for women, she even got hate mail.

This letter said “If God had intended women to run he would not have put breasts on them.” There was a whole socio-cultural stereotype of how women should behave, and it wasn’t vigorously and badly. It was more calm and sweet, and how to comport yourself with more steadiness, and not the sort of enthusiasm and passion you see with sport.

But in the 1970s, circumstances were conspiring in the United States to make it easier for women to participate and compete in sports.

In the United States, a section of the United States Education Amendments of 1972, famously called “Title IX,” was created, and subsequently had a huge impact on American society. While the overall goal was to ban gender discrimination within federally funded schools and universities, encouraging greater access for women to higher education, protecting pregnant women and parenting students from being expelled, and challenging gender stereotypes about whether boys or girls were strong in a particular academic category like math and science, Title IX has had a tremendous impact on women in sports.

According to this article, “the impact of Title IX on women’s sports cannot be overstated: the NCAA says the number of female college athletes is at an all-time high, and the numbers of girls playing high school sports has swelled from fewer than 300,000 in 1974 to more than 3.1 million in 2012.”

Additionally, getting into shape and staying fit became a huge part of the American pop culture in the 1970s and 1980s. With bestselling books like The Complete Book of Running by Jim Fixx, which came out in 1977, and Jane Fonda’s Workout, published in 1981, women were running and working out more.

And the more women ran, the more obvious it became that they had a problem men did not. Here’s what Lindahl had to say about that:

My whole generation started exercising, and I had a friend introduce me to what was then called “jogging”. When you have at-shirt over bouncing nipples, you get chafing. So the answer to that is to put a bra on. Because I did try running without any bra. And then of course I got a lot of comments from passing motorists, and certain male runners. So you wear a bra and that poses problems of different sorts, like the straps that fall off your shoulders so you’re always jigging them back up, hardware can dig into your back, and they’re hot and sweaty.

One day, Lindahl’s sister, who also ran, called to ask this obvious, painfully obvious, question: “‘What do you do about your boobs? I am so uncomfortable when I’m running! Why isn’t there a jock strap for women?’ That’s when we really laughed. We thought that was hilarious.”

But Lindahl couldn’t get the idea out of her head, and started to think about the ideal bra for female runners – a bra with straps that wouldn’t fall off the shoulders and wide enough so they wouldn’t dig in. Lindahl recruited a friend, Polly Smith, who was a seamstress and costume designer. And they worked through multiple prototypes for this bra, but could not hit upon the design that made it easier for her to run. Then one day, Lindahl’s husband came down the steps with a jock strap not where it was supposed to be – over his head and across his chest – and said playfully, “Hey ladies, here’s your new jock bra!”

The three of them had a great laugh, and Lindahl thought to continue the joke by pulling the jock strap off her husband and putting it on herself….except that when Lindahl put the jock strap over her breast, she had an epiphany. “Oh!”

The next day, Lindahl went running in a contraption that featured two jock straps sewn together, and realized she had a design that would work. Lindahl, Smith and Smith’s assistant, Hinda Schreiber decided to build a business. Schreiber’s father lent them $5000, the team built a relationship with an apparel manufacturer in South Carolina, and by 1978, they were distributing the “Jog Bra.”

Despite the initial reaction of sports retailers, who thought that the jog bra should go in a lingerie department and not in a sporting goods store, sales of the $16 bra took off. Jog Bra had annual sale increases of 25%, and created an entirely new market. More importantly, it enabled women to enjoy their sporting activities more fully and freely, whether it was taking part in a Jane Fonda workout, playing point guard on a high school basketball team, or running a marathon. The sports bra that Lindahl, Smith and Schreiber created liberated a whole generation of women athletes.

That feeling of liberation came to fruition that moment Brandi Chastain ripper off her jersey in 1999. But that vision was in Lindahl’s head in 1977.

It should be modest enough I could take off my t-shirt on really hot summer days because I had a running partner who would do that. He would take off his shirt in the middle of his run, pull it over his head and tuck it in the back of his shorts. I was so jealous because I couldn’t do that.

Today, millions of women can and do, thanks to the Jog Bra. Happy 40th!