80/20 rule -- 80% easy / 20% intensity (and February/March training summary)

One of my teammates asks me if I really think that the easy runs are essentially "worthless", and that we should just focus on quality training and drills such as the bounding that I had mentioned in the earlier post.  

I tell him that my sense is that training follows the 80/20 rule - intensity (speed, quality) should be no more than 20% of weekly mileage and the other 80% should be at an easier conversational pace.  Moreover I have felt that 80% of my training benefit comes from the 20% quality sessions - and so the easy runs are not "worthless" - just generating less benefit for the time spent.  

I was under the vague impression that I had come upon this keen insight myself,  but then I googled "80/20 endurance training" and it turns out there are whole books on this subject --

I check out a digital copy of 80/20 Running from the Mukilteo Library, skim through it, and learn about the copious research going back to Arthur Lydiard suggesting that this 80/20 training ratio is the optimal formula for improved race performance. The book's author, Matt Fitzgerald, is much more fervent than I have been regarding the benefits of slower runs for depleting glycogen, releasing IL-6 and building cognitive strength.  I have been focused mostly on run training over the past year or so and ask myself whether given my prioritization of group camaraderie, racing frequently and enjoying scenic routes am I at all close to this magic ratio.

Granted, as noted in previous blog post, I have always been the most "polarized of runners" - in fact a coach had pointed to me as an example of extremely polarized training, pointing to all my markedly slow 6 or 7-minute per kilometer sessions posted on Strava juxtaposed with my intense hill repeats and track intervals at a pace bordering on race speed.  

Given my low mileage along with fact that I have been doing all those bounding drills and adding speed at end of a weekly longer run in recent months I wonder if I have started doing too much speed?

So here is a snapshot of my recent training --

 The yellow and dark green bubbles of “intensity” above entail:

- my customary mid-week track intervals - roughly 6k of intensity
- hill repeats (incorporating bounding and sprint) - roughly 2k of intensity
- longer run pick-up pace on about the final 25%  - roughly 4k of moderate intensity

So (taking into account warm-up and cool-down), I am pleased to see that at least for the moment I seem to be hitting this golden ratio, doing 12k of actual intense running out of about 55k of weekly mileage or 22%