I have been running for 4 days per week for quite a long time now - but have to admit that I have been doing too much "hard" running - and am nowhere near the concept of 80/20 ( 80% easy running/20% hard running)
Reading the 80/20 book, I have previously discarded the concept as it seems that it was aimed at possibly more competitive runners - running 6-7 days per week. BUT - after spending this weekend going through the Arthur Lydiard "jogging" book that I posted here last week, I am inspired to do more easy running. So for the three days of the week that I now currently do nothing (not really interested in things like cross-training) , I am going to start to do easy jogs of only 15 minutes on each of these days. Lydiard makes it quite clear why he believes that we need to get our heart rates up to around Zone 2 numbers ( although he came before heart rate monitors were readily available) - he calls his easy runs to be a situation where you run for whatever time you intend but finish in a position where you are happy to finish, but also feel that you could have gone on for a bit longer) . He explains how the heart works to "pump up" the vascular system - it needs a certain minimum blood pressure over a certain time to push blood into the many tiny places where blood should go - but doesn't in unfit people Hence his call for even non-competitive runners to run easily EVERY day - but only for so long as they do it by feel. In his words it is better to stop a run early than to "struggle through" !!! This is not what we normally hear .
So - I will start out doing this tomorrow - a really easy 15 minute run from my house - it will be so short and easy that I won't really need to think too much about what clothes or shoes I should wear- the object being to just get my HR into zone 2 for 15 minutes. After a month of this, if I am feeling OK, I may then increase the times of these "recovery" days by a few minutes - and go ahead from there. I currently do about 1+ hours of HARD workouts during a week- including parkrun- so I really need to do up to up to 4 hours of easy to match that. These 4 hours will of course include a long run - but longruns tend to start out easy and finish "hard" so long longruns cant be considered to be easy!!