Horse Race Training- What is the terminology?

At the racetrack in the early morning a rider was out on the track with a horse. In the center of the track a man stood with what might have been a watch.

One could assume that the man with the watch was timing the horse but is there any official or slang name for that type of workout? Would the man with the watch be the horse owner?

I have searched the internet and the archives here with no luck only coming up with rules regarding timing on actual races.

Any help with terminology would be helpful.