I'm not keen on men I don't know trying to talk to me at park run. (I'm female). I'm there to run hard, not chat with strangers. I usually finish in the top 4 when I do park run so less serious women runners might be different. I wouldn't mind one of the top 4 men talking to me actually, but they never do (I know them all anyway and socialise with some of them so theres time to chat then) but its usually some random 20 minute plus guy who thinks I'm interested in him describing his race to me or how he saw me at some point during the race and he decides to tell me about it. Not cool. As I say, other women might be different.
Theres quite a good social scene around park run usually and thats the place to have conversations and meet new people, not before, after or during the event itself.
I've experienced guys do some odd things at park run. One time, an older male athlete ran behind me for nearly the entire run, right on my heels, as if he was glued to me. I could hear his breath, and he refused to overtake even when I slowed down. That was pretty weird. Another runner actually came up to me after the run and asked me if I was aware and how strange it was.
Another regular guy at our local park run got invited to a party at another runners' house. There was a WhatsApp group for it and I said I was willing to give people living near me a lift in my car there, as I'm teetotal. This guy at totally the other side of town contacted me privately to say he would like me to give him a lift, and I very politely said I couldn't make a big detour just to collect him and take him home, and arranged him a lift with another person who was nearer to him. At the party, he kept staring at me angrily and bumped into me a couple of times, and at park run after that when I saw him he would barge into me and try and knock me over after the run. Horrible guy.
I'm quite wary of runners now.