I have no idea how track cyclists train. But I do imagine they do lots of roadwork for base miles and then probably train for their individual events in ways that mimic those events. I don't think they spend 9 hours a day doing 10 minutes on 10 minutes off. All I'm saying is that messengers are in pretty good shape but that the nature of their work means that they can't condition as well as people who just put in 4 straight hours every morning.