Base Building 102

(Second in a series of posts on how to build a base.) 
You've begun to build your base with some regular training.  You are spending most of your time in Zone 2 ("steady") and doing some short, neuromuscular accelerations.  What do you add next?

Hills.  For runners and cyclists, add some hill repeats - starting with 30 seconds and building to 1-2 minutes uphill.  Recover with easy walking/jogging/spinning down the hill.  Don't charge up the hill, do these at one hour race effort - "comfortably uncomfortable."  Start with 2-4 repeats and build up to 10-12 repeats.  Hills are speed work in disguise (and with lower injury risk). 

So now your training week should include three key workouts:

1. Hills
2. Long training session in Zone 2
3. Neuromuscular training session with strides or accelerations and drills.

This pattern should fill a block of 3-4 weeks before you need to add the next base building element.