For runners: do you ever feel like utter hell after not running for a few days? Why is this?

I think its called a runners high. Your endorphin levels drop when you stop doing any physical activity that your body is use too. So you feel like crap because you got addicted to the raised levels. Its not like a drug addiction. But it affects you the same as when your hormone levels change.

@Pandora So what, if anything, can I do? And will this feeling go away as my body acclimates to the lack of running?

This happens to me when I stop too. I never bothered asking why. GQ.

You’re not suffering from debilitating atrophy, get that out of your head. I sometimes stop exercising for a few months (AKA winter) and when I start again my habitual 5K run takes only 110% longer than before the hiatus.

I would look for some other workout, maybe swimming or weightlifting to give you that feeling.

Even if you have no nearby facilities, you can do sets of pushups and situps, which are fun day-to-day tests, because you can alway strive to beat the previous day’s count.

@mirifique Eat chocolate, do stretches, have plenty of sex (careful of the shins). :D http://www.ehow.com/how_2063616_release-endorphins.html
go to this link. They mention more stuff

my habitual 5K run takes only 110% longer

P.S. That is hosed up math but you know what I mean.

Endorphins are naturally produced by the body to block pain from over doing it. It is about equivalent to morphine in potency and almost as addicting. Your body misses the high and craves it get your butt off the couch and go run!

I know the feeling. I normally exercise every other day or so but I took a few days off from running and tried to jump back into my routine last night and had to stop after my first mile. :/

My body and my soul both feel so much better when I run or do something physical enough to make me winded and sweaty. Then a shower and a bottle of cold water afterward, feel all clean and shiny and proud of myself. It’s great. People who don’t run ask why I do it and I say “Because I can!” And because it makes me feel so good when it is over.

So I know exactly what you mean and the only solution is to find an alternate form of exercise that makes you work as hard but without aggravating your injury. I have found swimming laps to be almost as good as running, I also like cycling and using an elliptical trainer.

there’s the endorphin drop thing mentioned multiple times above complicated by slowing your whole physical system down including elimination systems, you know what I mean. You may need to modify your diet for less activity too.
psychologically you’re probably a bit disoriented too, like wanting to go home.