"How to Run a Personal Record: Cover the Ground in Front of You Faster Than Ever Before," by Dave Kuehls, pg. 15-16.
The other cornerstone workout of the Strength Work phase, tempo runs, take a little time getting used to, but once you do, they will be an effective tool that carries over to the Track Work phase. Tempo runs are done on Thursdays Following your hill work (Note: Fridays in my case because of my shifted schedule). On a flat, soft surface run 20 to 40 minutes at a pace that is just below the point where you would be uncomfortable trying to hold that pace for a good length of time. This will be tricky at first, and you may go out too fast only to slow down severely after a couple of minutes of running, blowing your first attempt at a tempo run. Instead, start slowly, gradually work up to a pace that is uncomfortable, then back off slightly to find tempo pace. A flat surface is key because you are getting your body to push your anaerobic threshold up by holding a pace that is just below it for a consistent amount of time - and this would be hard to do on an up-and-down course. Warm up for a mile or two before beginning a tempo run, and cool down afterward with the same distance.