Because of the slightly different shapes of women’s bodies compared to men, the athletes themselves prefer the “bikini cut’ bottoms because of comfort running which leads to better performance. Wider hips with powerful thick thighs can mean running in more old fashioned shorts could be problematic and uncomfortable.
Should female athletes wear bikini briefs when competing?
Female track and field athletes aren’t required to compete in bikini briefs, either, but many are most comfortable doing so because it’s what they’re used to.
Why do beach volleyball players wear bikinis?
I’ve read that most female beach volleyball players prefer the bikini uniforms because the more modest uniforms trap sand, are hotter to wear, and are harder to move in. But female soccer players, who are competing under very different conditions, wear t-shirts and shorts.