Interval training is just fantastic. I do a 90 minutes power based interval workout 2 times a week. 3 weeks of Feb was focused on building to long intervals at a pretty high threshold power (close to 200 watts building up to 30 minutes at a time, varying 90 - 110 RPM).

I can really see amazing improvement from just that 3 weeks of 3 hour a week work. Looking forward to seeing what's in store for March. Some zone 4 (>200 watts) I suspect. Ack!