Effectively, the theory is that you should spend 80% of your workouts at a low intensity and then 20% at a high intensity. It's a pattern that's been observed across elite athletes across all sports, so not just running.
So effectively if you did 5 workouts per week for an hour each. 4 of them would be a really slow easy jog at conversational pace, and then the 5th might be something like sprints or hill repeats. As mentioned above by @SPG it can take around 3 months before the effects really become apparent and it can feel a bit backwards because you end up running slower than you do currently for the majority of your running (something i'm currently struggling with as someone fairly new to applying the approach!)
This book highlights a lot of the science behind it and references the guy in the above video and his research a lot.
https://www.amazon.co.uk/80-20-Running-Stronger-Training-ebook/dp/B00IIVFAEY
I'm currently reading through it.
So effectively if you did 5 workouts per week for an hour each. 4 of them would be a really slow easy jog at conversational pace, and then the 5th might be something like sprints or hill repeats. As mentioned above by @SPG it can take around 3 months before the effects really become apparent and it can feel a bit backwards because you end up running slower than you do currently for the majority of your running (something i'm currently struggling with as someone fairly new to applying the approach!)
This book highlights a lot of the science behind it and references the guy in the above video and his research a lot.
https://www.amazon.co.uk/80-20-Running-Stronger-Training-ebook/dp/B00IIVFAEY
I'm currently reading through it.