This article was originally posted by Ryan at the original HillRunner.com Blogs.
I find myself repeatedly talking about the importance of running your easy days slow enough. There’s a two part reason for that.
1) It really is that important.
2) Most runners don’t run slow enough on their easy days.
Why is it really that important? Let’s think about building your running fitness like building an engine. You want both a big engine that can produce a lot of power (aerobic capacity) and one that is fine tuned so it performs at its best (fine tuning for speed).
You build your running engine by running a lot. To an extent, the more running, the better. How do you run more? By slowing down so you don’t break down. The cool thing is that the aerobic engine is built just as well at slower paces as it is at faster paces. Time matters more than intensity.
Next, you fine tune the engine for speed on the hard days. Faster/higher volume at speed is better. Any guess how you maximize the speed and volume of those hard days? That’s right, by going slower on your easy days so you can recover more completely.
So what does this add up to? Building and fine tuning that engine requires making sure you’re not running too hard on your easy days.