The purpose of slow runs after hard runs

Totally a running post today. So you go out and do a hard workout or a 23.4 mile long run and your legs are trashed. Instead of taking the next day off you decided to double (run twice) the next day. Why would this help at all? It seems this would ruin your body not make it better. Well, here's my take:

1. By doing a workout and running the next day you teach your body to be hungry and store up all the glycogen it can. This is repeated every day but it is most noticeable on the day after a long workout. If you plan to race longer races like the marathon you can't afford to fake it. It is important for your body to store up as much energy as possible. So your body anticipates being depleted of glycogen and uses more fat to offset that. In other words your metabolism becomes more efficient and your gas tank is bigger.
2. Unless you are sprinting full out you are not using 100 percent of your muscle fibers. So when you do a hard workout and use the same 40 percent of your muscles they get tired. When you run later that day or the next day your brain tries to reduce the stress on your muscles and recruits some of the other 60 percent to do some of the work. If you can distribute the work amongst even a few dozen more muscles fibers that will help you go faster. Benji Durden suggested doing a long run of over three hours and then running another half hour later that day to get used to spending time on your feet. Same concept but honestly, that's sounds pretty pretty tough, I can 't wait to try it!
3. Although it seems there is not much proof of this, if at all, a slower run after a hard workout works to flush the legs of waste. Not sure if I believe this one but I do know that for some reason I usually feet better after a shorter and slower run. If not immediately then the next day.

(This is all part of my secret plan to get my friends that are competitive runners to run more miles. I mean that's really the basis of it. To get better at running you have to run. But don't tell them because they might get offended that they aren't working hard enough.)