Pump,
are you having sexual thoughts while you workout and then ejaculate during the exercise? Also, are you erect during?
Or is this orgasm fully from just working out and focusing on working out? My process has had me orgasm twice from quad extensions purely focused on the exercise (so, I stopped doing them), and I often feel near to orgasm after pullups and it happened after a run once as well [again, without sexual thoughts -- I just start to feel extremely sensitive -- and while essentially completely flaccid].
I haven't really seen other people on the forum with our issue, so I am curious how many others are experiencing this to some degree as well.