This is a topic I find myself revisiting with athletes on a regular basis. It is a difficult concept to grasp as it is counter intuitive to run slowly if you want to run faster. Yet the biggest breakthroughs I have seen in athletes from distances as short as 800m have come after increasing the amount of long slow miles in the training plan. And actually reducing the high intensity work!
Why does this work? And why does it sometimes seem to not work?
To simplify the science, the bigger your oxygen supply to your muscles, and the bigger your mitochondria factory (basically the engine room that turns all that oxygen into energy), the faster you can run without having to rely heavily on your lactate engine. This is the one that if taken into overdrive explodes spectacularly leaving you wobbling along like jellyfish to the finish. Anyone who has gone out too hard in a 5k race will know what I am talking about!
Most runners wanting to get faster are not slow. They can pull off a really fast kilometer sprint, but then crash. So the problem is not being slow, the problem is they are too reliant on that powerful little lactate engine instead of the big boy oxygen engine. You can almost think of it like running a headlight on electricity vs battery. Strong and steady vs bright and die.
So that is why it works. Why does it sometimes not work?
To build this engine efficiently you need to be running really really slow to be focusing almost purely on your oxygen engine and for long periods. That is why LSD is your cornerstone workout! If done right. Running at a pace slow enough so that you are almost purely using your aerobic system (we are always using all systems to some degree) is not only key to developing this oxygen engine effectively but also key to you being able to spend more time on your feet running. Keeping it super slow gives you big benefit with less fatigue. So you can do more and get more benefit. Problem is, most runners slow is actually medium and this is where things don't work out so well. To get the maximum gains, slow down your slow.
Doing your slow really slow will not only build a better oxygen engine so you can do your fast really fast, but will also leave you less fatigued so that you are able to turn out a higher effort on your interval workouts.
In the past I believe runners have incorrectly labelled a lot of easy miles as junk miles. The reason they were junk is not because they were easy, but because they were not easy enough. I would like to say junk miles is more just doing a lot of same pace medium miles.
So slow down your slow, fly on your fast and go smash some PBs.
Onwards and upwards!
Coach Kathleen
Professional running coach
Cape Town, South Africa