80/20 Running, by Matt Fitzgerald

If you have ever used a training plan from Runners World or similar source, you've probably practiced the 80/20 running rule.  Matt Fitgerald develops this idea in 80/20 Running: Run Stronger and Race Stronger by Training Slower.  Drawing on research, data, and the training experiences of runners from Arthur Lydiard, the father of modern distance running, forward to contemporary Olympians and marathoners, Fitzgerald describes training with the bulk of your miles run at low intensity.

Fitzgerald writes in such a way that runners at all levels of experience can implement and customize his plans.  Wherever you are in your running, or whatever distance race you are preparing for, you will be able to apply Fitzgerald's plans.  The 80/20 of the title refers to running 80 percent of your training miles at low intensity and 20 percent at high intensity.  Fitzgerald provides some scientific and anecdotal evidence that this works.  He also is happy to direct you to his 80/20 training app (it's not a hard sell, just a suggested resource).

For many runners, 80/20 Running is a great resource and remedy for overtraining.  For some runners, especially lazy runners like me, it's a reminder to increase intensity 20 percent of the time.  According to Fitzgerald, most recreational runners run mostly at moderate intensity.  For real improvement, moving toward an 80/20 balance will help.