I'm a big fan of the 80 / 20 rule, also known as the Pareto principle. It helps me understand so many phenomena, so it's no surprise that running should be included.
In brief, the rule states that 80/20 is a good rule of thumb. For instance, you're most likely to adhere to a healthy way of eating if you choose whole, nutritious foods 80% of the time and get 20% of your calories from less nutritious choices. In terms of management, one often finds that 80% of income comes from 20% of customers (or alternatively that 80% of complaints come from a noisy 20%).
The exact percentages don't matter here, but the principle or guideline holds true when it comes to running slowly.
When I was training for a marathon back in 2008, I wasn't following any guidelines other than a cookie cutter plan I found online through a quick search. It didn't dictate effort levels, paces, what anything should feel like - only what miles to cover on which day. So I adhered to it loyally, switching perhaps switching a workout day or two here or there. As far as pacing, I knew what felt good for longer distances and what my ego would let me do.
My line of thinking was that I need to train at the pace I want to run the marathon at. If I can hold the pace for 1 hour, after a few weeks, maybe I could hold the pace for an hour and 20 minutes, or so I thought. Later, when I switched to shorter distances like the 5k and 10k, I did the same thing. I would run at my race pace for as long as possible during the workout, almost every workout.
If you want to be fast, practice running fast - right?
This was soooo wrong.
What I was essentially doing was a mediocre workout on a regular basis, neither gaining the full benefit of the slower long runs nor able to do the speedwork optimally because I was so burnt out running the other miles at a pace that was too fast.
What most elites do and what runners
following a program usually do is "polarized training", which follows the 80 / 20 rule. In this model, you spend 80% of your time running slowly.
Yes, I said slowly!
Running slowly has so many benefits:
Allows you to put in the heavy miles (or km) at a lower risk of injury
Trains your respiratory, cardiovascular and muscular systems to be more efficient
Encourages your body to burn fat for fuel
Allows you to push hard when you really need to push hard (etc. for tougher speed workouts)
Promotes greater capillary density, so oxygen can get to your muscles more efficiently
If you're wiping yourself out with every workout, you won't want to stick with it
What is running slow? For the numbers geeks, that would be 65% of your maximum heart rate. For the rest of us, that means at a comfortable conversational pace where you could chat with a friend. For newer runners, this might mean slowing down to a walk sometimes.
The bottom line is that it actually requires running slowly in order to run fast. There are no shortcuts. It takes time to become a better runner - there is no rushing that.