When I run, after I have run enough to feel tired, if I stop, for even a bit, it becomes incredibly painful to restart. The pain is muscle pain, in all the muscles that I use to run.

I am often able to slow down enough to get a rest without stopping and restarting. If I do this, I feel no pain.

Why does this happen? Is there anything that can be done to mitigate it?

  • Good question! In my experience, this happens for some people but not for others. A few years ago, I used to run an 8km race every year with my boyfriend at the time. It was most comfortable for him to alternate walking and running, but that killed me. I have to keep going--once I stop I lose my momentum. I don't really know why. – Barbie Mar 28 '11 at 4:44
  • You are running blind. BUY A HEART RATE MONITOR - they cost ten dollars, less than your socks. Wear it Every Single Time! – Fattie Oct 17 '11 at 20:12

If slowing down instead of stopping seems to help then why not just go that route. When I was in the Army, we didn't stop running. We slowed down, but we didn't stop.

Part of it is keeping a rhythm and is mental, the other part is adrenalin.

Keep in mind that in order to increase your aerobic fitness, you must keep your heart rate up above a certain threshold over a sustained period of time. If you stop running, you risk letting your heart rate drop below the level necessary to increase your level of aerobic fitness.


I will take a stab at it and say it lactic acid build up in the muscles. It has to do with your muscles not efficiently burning its energy due to a lack of oxygen and so you get a build-up of lactic acid.

It used to happen to me when I was younger, but not as much now.

Lactic Acid Build Up and Soreness in Muscles

  • 1
    +1 If the op it talking about stopping between sprints this is definitely the right answer. If you stay within the aerobic range (or slightly below) after a hard spring your body is still taking in a lot of oxygen that it uses to break down lactate. If you stop suddenly, you maximize the lactate buildup because you're depriving your body of the oxygen it needs to break it down. Lactate becomes lactic acid, which is what causes the muscle soreness. – Evan Plaice Mar 29 '11 at 1:28

The "incredible pain" you state is what jumps out at me:

  1. You should not run through pain, you will get hurt, maybe not that day but continuing to do so will get you injured enough to force you to stop running altogether. This I know from experience. "No pain, no gain" does not work all the time.
  2. Are you simply running too hard? It sounds like your body likes the slower speed since it's not sending you pain signals then.
  3. You should warm-up a little bit to loosen your muscles before your "real run" and also cool-down after a run to clear out any lactate and adrenaline. A warm-up and cool-down will help prevent injury.

I would suggest getting a running watch that tells you your speed if you don't have one already. Once I get loose (after 1st mile), my body just starts taking off. I have to use my watch to curb my speed because of my knee. If I do too much too soon that knee acts up and I can't run for 4-6 months.

  • Added a bit more details: it's muscle pain. – luispedro Mar 28 '11 at 20:51
  • That's def. better than bone pain :) Assuming you are surgery-free and free of other medical conditions, it sounds like you just need to find your running rhythm. Keep running, your body will get used to it. I still don't recommend running through pain if you feel it. You ever hear the phrase "walk it off"? They don't say "run it off"...edited answer to remove bone pain ref. & added warming up since it's muscle pain – Rhea Mar 28 '11 at 22:01

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