I did aerobics for several years. The reason I gave up was not because I was intimidated by being surrounded by females, but because it knackered my right knee in a way that even running up and down hills wasn't doing. Oh, and I will be able to indulge my inner dirty old man next Monday when I am at Wimbledon and can watch athletic young ladies playing tennis.
"In the wild", I do see many women out running, both on the suburban streets and on the rural footpaths where I do most of my running; but of course the numbers in competitive events in the wild are smaller.