It makes sense that this retreat from competition is happening in Brazilian jiu-jitsu ("BJJ"), which is a close-contact sport in which women can get hurt, unlike racing. At a recent women's BJJ competition, men completely dominated the event, with some events having only male competitors.

I did BJJ for almost a decade, although I started too late in life ever to be any good, and my joints got damaged before I got my advanced belts. However, I know a lot about the sport. At the dojo where I trained, men and women rolled together. This means I have experience grappling with both men, who were holding back as hard as they could, and with women, who were not.

Even with their settings on low, the men were more formidable opponents than the women were. They had greater bone mass and greater muscle mass. Where women, because of biology, had a lot of space and softness between hip and head, men did not. They were solid, without a forgiving waistline or more delicate neck. Theoretically, I could have choked out one of my women partners; I could never have choked out the men, whether in theory or fact.