Beyond bans, there is the issue of comfort. Female Muslim athletes have struggled with finding headgear that will not slow them down or distract them from arduous physical exercise. It was Ms. Haddad’s difficulty in acquiring a hijab that met her requirements for competition — namely, that it would not shift when she moved and that it would be more breathable — that inspired the Pro Hijab project.

“The one obstacle that’s always there if you’re a hijabi is, what is she going to wear on her head?” Ms. Rostom wrote.

She explained that she usually buys a special two-piece hijab in Kuwait that is made with polyester and cotton. “Cotton is extremely uncomfortable, especially if you are training outdoors or if you are running long distances, and especially when we live in one the hottest countries in the world,” she said.

There are companies that manufacture sport-specific hijab, like Capsters in the Netherlands and Friniggi in Botswana, but none of them have as global and as visible a reach as Nike.

“For us, we come up with ideas, and ways to be comfortable in what we wear, but to have the No. 1 sport and fitness brand in the world facilitate this process for us?” Ms. Rostom wrote. “To provide something we can grab and wear in 10 seconds? It’s going to change everything.”