From time to time during aerobic workouts such as running or heavy cycling, I get side stitches that force me to slow down my effort.

What causes side stitches?

I know that reducing your effort reduces the stitch, but is there something that you can do to prevent them from occuring in the first place?

And lastly I only ever seem to get them on one side (my right) and never on the other. Is that typical of a stitch?

  • Interesting question. I only get 'em on the right also. Mar 30, 2011 at 2:01
  • What are stitches? Are they like cramps from heavy exhaustion?
    – Salsero69
    Mar 30, 2011 at 3:45
  • It's pain on the side, usually the right, in the lower part of the rib cage. It's very different from cramps. Mar 30, 2011 at 21:21

5 Answers 5


Not clear why they happen, though there are several theories.

For running, exhaling on the left foot has helped me a lot.

I would also get them sometimes while practicing kicks. This was trickier to work with, but a powerful exhale while kicking seemed to also help here (breathing exercises were indirectly useful as well).

  • How interesting, who would think that exhaling with your left foot would help. I'll have to try it.
    – Walter
    Mar 30, 2011 at 12:30
  • It is based on the idea that side stitches are due to atretching of the liver's ligaments. When stepping on your right foot, there is a higher tension in the ligaments than when you step on the left foot. Exhaling brings the diaphragm up, and this puts increased tension on the ligaments. Since you have to exale, it might be better to do it when on the left foot. Aug 20, 2014 at 16:33

Stitches can happen for a lot of reasons: breathing issues, eating too recently, dehydration.

To get rid of them, focus on exhaling as you step with the foot on the opposite side of the stitch. I've gotten stitches hundreds of times, and this has never failed to fix them.

  • Eating and going too fast are usually the cause
    – Chris S
    Apr 2, 2011 at 16:56

The general consensus in the athlete population, and between trainers as well, is that the cause is unknown. However, in med-school I was told that it is, at least in the medical community, known. And in my pathology book, which was in Serbian though (but translated from an American one; I don't remember which one).

The idea is that classical side stitch (that which affects the right side) occurs due to stretching of the liver capsule (fibrous covering), which is highly innervated by pain receptors. When exercising, a larger volume of blood has to be transported at every given instant. A large portion of that blood gets directed back to the heart via the liver (entering via the large portal vein, and exiting via smaller hepatic veins).

When there is a larger volume of blood coming into the liver, which has to be drained into the heart, there are two factors which counteract that: the fixed and narrow lumen of the hepatic veins, and the output of the heart.

We cant do much about the width of the hepatic veins. The heart is, in this respect, much more interesting.

In order to remove the blood that is pooling within the liver, so as to relieve the tension on the capsule, the heart must have a higher output than input. If the output is not higher than the input, then there is an increase in pressure in the venous system.

This can be seen in cardiac patients, which have a higher proportion of liver cirrhosis and varicose veins. And I can only assume, side stitches from minor activity (unless the receptors have become desensitized from prolonged stimulation).

One simple thing you can do is to exhale when you step on your left foot. When stepping on your right foot, there is a higher tension in the ligaments (which are part of the capsule) than when you step on the left foot. Also, exhaling brings the diaphragm up and away from the liver, and this puts increased tension on the ligaments and capsule. Exhaling when stepping on your left foot thus decreases the tension on the capsule.

Another, less comfortable thing, is to put your hand below the rib cage on your right side, and press upwards. This increases the pressure on the liver and thus forces more blood into the heart and out into circulation, relieving the tension on the capsule.

The idea that stretching of the capsule causes the side stitch explains why it occurs when you start running quickly without having warmed up or increase the tempo during longer runs too steeply: it increases the circulation, without an accompanying increase in adrenaline to stimulate the heart. It also explains why it can help to bend forward, and why extending your back hurts more: extension stretches the capsule.

Some people mention getting side stitches if they eat right before exercising. This can be due to distension of the stomach on the left side. However, if the pain is localized on the right side, then that can, indirectly, be because eating increases parasympathetic stimulation (it counteracts the effect of adrenaline), but also, directly, because of an increase in blood flow to the digestive organs (including the stomach) which all drain into the liver, thus, again, increasing the pressure on the capsule.


Stitches commonly occur if this is the first time you are running in a while. They also occur if your stomach is somewhat full.

If you are a new runner or have not run in a while, just run at a slower pace where the pain does not occur. Also, run only after a couple of hours or more after having food or drink.

More info on stitches can be found at this Cool Running article.

  • I got stitches all the time as a kid, and ran around constantly. I don't think it can be limited to "the first time you are running in a while." Mar 30, 2011 at 14:39
  • Matthew: There are exceptions for everything :-) Mar 31, 2011 at 3:19

Most people would chalk this up to a lack of conditioning, but focusing on your breathing can help.

Try breathing in your nose, and out your mouth. Also, time your breathing as some people described as exhaling on a certain foot. I always timed my breathing by inhaling for an even number of strides and exhaling for one. That means you'll exhale on the opposite foot each time.

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