This is a red pen.
I’m doing a recovery run.
Two statements, with each quite possibly as much truth as the other.

Calling a pen a red pen doesn’t make it a red pen unless it is actually a red pen.
Equally, calling a recovery run a recovery run doesn’t make it a recovery run unless it is actually, wait for it…..a recovery run!
The purpose of a recovery run is to speed up the body’s recovery process. To heal, adapt and improve from the previous hard efforts of, say a race the day or morning before.
It should be short, enjoyable, gentle and sustainable.
If you were asked to gauge the intensity of the run, it should be around 5/10 – 6/10
After the run, your blood flow to the previously damaged muscles will have increased. It will bring with it additional nutrients to feed the muscle, and take away any harmful by-products of intense exercise. It is in essence, a free sports massage.
Very often, especially with the increased usage of online running logs like Strava, I see that somebody has gone and done a race at for example, a pace of 7 minutes per mile. This is quite often an effort level of 9/10 – 9.5/10. The damage done, not just to muscles, but also to the aerobic and anaerobic systems is un thinkable, so the perfect solution is to do a gentle recovery run to kick start the repair and adaptation.
So, in line with the trend, where it seems everybody is heading straight back out of the door and doing a ‘recovery run’ (so they can stay inline with everybody else???) off they go and do 5 miles, because it’s a nice round number and will run it at a pace of 7 mins 15 seconds per mile. Probably an effort level of 8/10 – 8.5/10.
Now, instead of running for 5 miles at an intensity of 8/10, if they ran for 15-30 mins at an intensity of 6/10 and a pace closer to 9.5 – 10 minutes per mile and did that twice a day for the next 2 days, after only a short time they’d see a much better adaption to their hard efforts.
They would also be much fresher and prepared for times when it came to doing hard intense training. Within not long at all, where previously they were racing at 7 minutes per mile, perhaps they could race at 6 minutes 50 seconds per mile for the same effort. Over a half marathon, that is a 2 minute 10 second improvement. For doing less. But sensibly.