In CrossFit gyms around the world, women deconstruct the longstanding myth of “the weaker sex” and continue the march toward true equality.

In 1973, 55-year-old Bobby Riggs—the 1939 Wimbledon champion—challenged 29-year-old Billie Jean King to a tennis match. Riggs said he could beat any female player even though he was in his 50s.

The tennis match, dubbed “The Battle of the Sexes,” took place in front of a crowd of 30,492; an estimated 90 million people watched it on TV. Although the odds favored Riggs going into the match, King dominated from the beginning. She won all three sets—6-4, 6-3, 6-3—and threw her racket in the air when the match ended.

Women’s equality had a long way to go in 1973. Second-wave feminism was just gathering steam, with the goal of changing the commonly held belief that women’s biological differences from men made them intellectually inferior, more emotional and best suited for domestic life.

The realization that strength is a social construct might be the hallmark of feminism in the 2000s. The worldwide influence of CrossFit—from the affiliate level to the CrossFit Games—has played a role in this shift, helping to destroy the idea that women are the weaker sex.