I didn’t have great cross-country coaches either in high school or college. For both, it seemed cross country was an afterthought, so we didn’t learn much at all about running or training to run, we were just supposed to do it.
I always knew pace was important in training, but I never knew the point of running slower paces. I mean, it’s obvious when you’re doing a track workout that you need to run at tempo or faster. Because who doesn’t want to get faster?
But why on earth would you deliberately run slow? Junk miles.
Just like junk food uses up your caloric bandwidth so that you are too full of calories to eat food with real nutritional value, junk miles use up your available energy so that you are too worn out for quality running.
Here’s how it works: each workout that you do to prepare for a race takes all the components needed during a race—speed, endurance, fitness—and parses them out so your body is only working on one piece of the puzzle at a time. Speed workouts focus on speed, so you run a shorter distance. Long runs build endurance, so you back off the speed. Maintenance runs keep your fitness up so you back off both speed and distance.
And if you don’t? That’s where you get junk miles. Junk miles are simply a maintenance run that wears you out. It’s taking away from part of your workout instead of adding to. Since maintenance runs are simply to maintain fitness, you don’t need to run them fast, although because they are shorter distances, many people feel like they should.
Some of the workout plans for more experienced runners take out maintenance runs altogether. These are the 3-4 days a week plans that I mentioned in an earlier blog. These are great for older runners who have the fitness component in place because of years of running, and also have a greater risk of injury due to age.
To avoid running junk miles, you have two options: don’t run them at all, or run them :45 to a minute off your race pace. This will help you maintain fitness while reducing risk of injury and keeping your energy levels up for more taxing workouts.