A runner with jiggly breasts Now that is unusual. Most high performance runners have very little to jiggle and these days they flatten them further with skin tight sports bralets. But let's say a female athlete jiggled or wanted to go braless and some men found that arousing? Men do find jiggling breasts arousing. It's sort of in the job description for most of them. At least he was masterbating in private and not feeling entitled to grope her, or hiss at her in the street for being a harlot.
What should we do? Insist that women can only participate in sports if they are able to do them in baggy 'modest' clothing, like in Saudi, Iran or Afghanistan? Is it more misogynist to want women in tight leotards and swimming costumes, crop tops and teeny tiny shorts, or to insist that they cover up in baggy stuff so no-one is triggered into needing to rape them, or wanting to masterbate at the sight of them?
I imagine what most female athletes want is the choice to make their own decision based on what works best for them, with their sporting performance as the first consideration beyond everything else. If certain confines or requirements of a specific sport make that difficult then it's probably not the right sport for them, at least not at international competition level.
What exactly is it that we want for women? Can we decide once and for all please? On the one hand we are told that we should never judge any woman or girl for dressing 'inappropriately' (usually taken to mean looking too 'sexy' or too scantily clothed) in social or professional settings, and that men in particular should never imply anything at all by it, or see it as an invitation for male attention.
On the other hand, here we are arguing that these women gymnasts are indecently clad and the assumption is that they have no say in what they wear to compete, the level of body coverage and how 'pretty' or not, they should look.
So women shouldn't have to cover up due to pressure from misogynists when on the street or in the office, but they should cover up while performing in sport? And they should also examine why they feel a need to wear very revealing performance wear, because misogyny. 
What do those athletes want? What do they feel they need in order to perform best and feel most comfortable, never mind anyone else who thinks they know best? I'm sure gymnasts don't all think like one homogenous mass, some will like the skimp and the sparkles, others won't. But certain things are a requirement for good reason. Watching the women's skateboarding yesterday, they ranged from wearing lycra crop tops to hugely baggy t-shirts that came to their bums. Obviously totally their choice, but neither would affect their ability to skateboard to the best of their ability, or for judges to score them accurately. It's not the same in gymnastics.