1.) Active Recovery - VERY easy, like taking a stroll on your bike. Your TL should be tiny from rides in this zone.

2.) Endurance - this focuses on building your aerobic base. Think of it as the foundation of your "fitness house."

3.) Tempo - This is the first floor. It's where you start to build a bit of speed and bed in your endurance.

4.) Sweet Spot Training - the top of Zone 3 (Tempo) through the lower part of Zone 4 (LT). It's where you get the most "bang for your buck" - that is, the highest return for the recovery cost.

5.) Lactate Threshold (LT) - this trains you at the very top end of the intensity that you can sustain for an hour.

6.) VO2 - this is the attic of your "Fitness House." It's where you build top end speed and the ability to recover from intense efforts. This zone has a high recovery cost, so you can't spend a lot of time there.

7.) Anaerobic Capacity - This is the very top of the intensity scale. It's hard to sustain for more than a few seconds and it helps to build leg strength.

8.) TuneUp - Preparation for longer efforts and target events –  loosens up the muscles and opens circulatory pathways.