Is there a verb that describes the act of regularily particpating in track and field? You don't play track and field. We often use "do" for karate or other matial arts, but do you do track and field?
This sounds perfectly natural to me (and I did track in high school):
I do track.
That may be considered mildly informal. In a more formal context I would just say:
I'm on the track team.
We use track constantly to mean track and field, but this would be fine with track and field too. And if you specifically run as opposed to doing field events, it would also be fine to say:
I run track.