I think your "quick calculation" should be more like 100% slower than date pace 400, e.g. a 5:00 miler with a 60s 400 should be running 8:00 for easy runs in order to get the most benefit from workouts as well as true aerobic gains. By your 50% they would be doing 6:00 miles which is tempo pace, and definitely NOT recovery.
coach_rodney wrote:
I define an easy run as a run at a pace fast enough to provide an aerobic benefit but slower than the pace of your anaerobic threshold, typically at a speed 65%-70% of vVO2max. A quick calculation would 50% slower than what you can run your current date pace 400m.
The purpose of the run is to help in recovery from harder effort days by "massaging" waste from the muscle tissue damaged on quality days as well as long term development with structurally changing the body (bigger lungs, bigger heart, more capillaries, larger blood vessels, more mitochondria, etc.) if there is a sufficent volume of this effort of work being done.