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
    Commented Mar 28, 2011 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
    Commented Oct 17, 2011 at 20:12

5 Answers 5


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. Commented Mar 29, 2011 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
    Commented Mar 28, 2011 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
    Commented Mar 28, 2011 at 22:01

Both contraction and relaxation of muscle require energy therefore, when you break you lose both the summative effects of repetitve muscle stimulation, known as summation of tetany, and you use extra energy as relaxation is an active process. Basically when you stop your muscle tension becomes less as the muscle relaxes so when you try to run again reaching the same muscle tension will require more energy and thus be more difficult to regain after you relax.


There are a few questions I would like to clarify with you to get a better understanding of your situation!

  1. On a scale of 1 (no pain) - 10 (extremely pain), how “painful” do you feel?
  2. How long does the pain take to go away after you have stopped?
  3. What intensity (as a % of your maximum capacity) do you think you are running at from the time you started to the time you stop?
  4. How frequently do you run in a week? Does this occur everytime you run or after you have stopped running for a few weeks?
  5. Do you currently have any injuries?

What I’m guessing is that you may be running at a high intensity (>60% of your maximum VO2max, or “maximum capacity”) and when you do stop, you find it hard to “restart” as there is an oxygen debt your body needs to pay off due to mainly using anaerobic system to produce energy.

If you’re not running frequently and you jump into long distances or high intensities, your body will not be “used” to it. You will have to train at a lower intensity and gradually progress so your body can adapt and muscles that aid in running and respiration that become stronger and better equipped to deal with the demands. Our body is a use it or lose system, they do not want to hold unnecessary muscle mass. Our heart works the same way, the more you train, the stronger it will get, which will have an impact on your VO2 max (higher the “fitter”).

Lactate per se doesn’t cause that burning feeling. It is the build up of protons that cause the acidic environment which gives us that burning sensation - a protective mechanism of our body to tell us to slow down or stop.

What I will suggest is alternate between running and doing some resistance training to strengthen muscles for running - thigh, hamstrings, glutes, calves, core. Got to give all attention to prevent any imbalances that would then give rise to compensations and injuries.

For running, go at a lower intensity, if you need a rough gauge, you can calculate your maximum heart rate (220- age) and go at 40-50% of that. This is just a rough estimate for maximum heart rate. Breathe in through the nose while running so the oxygen goes “deeper” and eat 1-2 hours before your meal. Some carbs will be good and if we want to be geeky here, go for Low GI carbs.

I always believe we should go quality > quantity ! Stay safe

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