Why Does Side Hurt When Running

Have you ever experienced a sharp pain on the side of your body while running? If so, you’re not alone. Many runners, including myself, have encountered this discomfort known as a side stitch. Though it can be quite bothersome, understanding what causes it and how to prevent it can greatly improve your running experience.

A side stitch is a cramp-like pain that typically occurs on one side of the abdomen, just below the rib cage. It can range in intensity from a dull ache to a sharp, stabbing pain. While the exact cause of side stitches is still a topic of debate among experts, there are several theories that can provide some insight into why this discomfort occurs.

1. Diaphragm Stress

One widely accepted theory is that side stitches are caused by stress on the diaphragm, the primary muscle involved in breathing. As you run, your diaphragm contracts rhythmically to allow your lungs to take in oxygen. This constant movement can lead to fatigue and spasms in the diaphragm, resulting in the characteristic pain on the side.

2. Abdominal Muscle Imbalance

Another possible explanation for side stitches is an imbalance in the strength and flexibility of the abdominal muscles. When certain muscles in the abdomen, such as the obliques or the transversus abdominis, become overly tight or weakened, they can pull on the diaphragm and cause it to cramp.

3. Poor Breathing Technique

Proper breathing technique is crucial for runners, not only for maximizing oxygen intake but also for preventing side stitches. Shallow and rapid breathing can put unnecessary strain on the diaphragm, increasing the likelihood of cramping. It is important to take deep, diaphragmatic breaths while running, allowing your belly to expand as you inhale and contract as you exhale.

Preventing Side Stitches

Now that we’ve explored some possible causes of side stitches, let’s discuss how you can prevent them and continue running pain-free:

  • Warm-up: Always start your runs with a proper warm-up routine, including dynamic stretches and gentle exercises that target the abdominal muscles.
  • Proper hydration and nutrition: Staying hydrated and fueling your body with balanced meals before running can help prevent muscle cramps, including side stitches.
  • Gradual increase in intensity: Avoid sudden increases in running intensity or distance. Gradually build up your endurance to give your body time to adapt and prevent excessive stress on the diaphragm.
  • Focus on breathing: Pay attention to your breathing technique while running. Take slow, deep breaths and try to exhale forcefully to fully empty your lungs.
  • Relax the abdominal muscles: If you feel a side stitch coming on, try to relax your abdominal muscles and take a short walking break to allow the cramp to subside.

By implementing these preventive measures and listening to your body, you can significantly reduce the occurrence of side stitches and enjoy your runs to the fullest.


While side stitches can be frustrating and uncomfortable, they are usually not a cause for concern. By understanding the possible causes and taking preventive measures, you can minimize their occurrence and continue to pursue your running goals without pain. Remember to always listen to your body, and don’t hesitate to seek medical advice if the pain persists or worsens.