A “teen” comes up from behind.
The first guy to push or the guy that was paying back the push?
The way I read it was the “pusher at the end” was asked by the white runner to get out the way when he was on the track. Later the “pusher” pushed the white runner on the track due to the earlier incident. I haven’t figured out if the “pusher” was a runner in the race or a spectator.