I totally disagree that there is anything wrong with frum girls riding bikes or jogging or doing anyting necessary for exercise, if they are dressed properly. The most unhealthy thing in the world is not to exercise. Even the Rambam says so in Hilchos Dayos. Anybody who asurs girls from exercising is a chosid shoteh who thinks that his conception of “tznius” is more important than saving a life.
Men, it is all in your own head. It is up to you to control your own yetzer hara, and not to let your own failures cause you to make women’s lives miserable and unhealthy.
If a man has a problem, then should we asur women from even walking? Maybe not let them outside at all. Maybe go to the burka. There are halachos of what is permissible dress. If these are kept, it is up to the men to do the rest, not to force women to do more because of men’s weakness.
Doesn’t gemara in beginning of Sota say it was normal for men and women to converse in the marketplace? It says that if a man was mekanai his wife, then it is painful for the women because everybody will say mai hai dka bodeles min haanoshim (what is going on with this woman that she stays away from men). The gemara says clearly that it is abnormal for a woman not to be able to converse with men, as long as its not excessive (al tarbeh), but not a normal amount of pleasant everyday menschlach conversation.
Anybody who thinks that meeting an old friend at a wedding and speaking to him and his wife or something similar should be forbidden, is trying to Talibanize our religion of menschlachkeit. I have never seen any outlandish, inapropriate behavior at a wedding between married couples.