I just started reading "Running with Lydiard", and I'm a bit confused about some of the schedules in the back of the book. Lydiard has two time trials listed per week in the base phases (to be completed "for as long as possible") of all the training programs. Isn't this a bit excessive, considering a time trial is anaerobic and the goal of the base phase is to build maximum aerobic capacity? Someone please clarify.