I am wondering if any of you have tried interval training, such as the "Tabata" training described on Clarence Bass' and Richard Winett's websites. It seems to work for me if I do it infrequently, such as once a week. If I do it more often, I don't seem to improve. I'm thinking maybe it's a bit too structured (always 20 sec hard, 10 sec easy), and that a more varied approach would be better.