Although the exact cause of side stitches has yet to be proven, theories abound. Sports-medicine physician Jordan Metzl, M.D., coauthor of The Athlete's Book of Home Remedies, says the most likely cause is a diaphragm spasm. The diaphragm, a sheet of muscle that extends across the bottom of the rib cage, plays an important role in breathing.
Just like your leg muscles, your diaphragm can fatigue and cramp when put under too much stress. That's why side stitches tend to strike beginner runners or those stepping up pace or distance. The good news is that there are a variety of effective strategies—ones that I put to the test with the runners I coach—that can help prevent this common problem.
Shore Up Your Core
Performing just 10 minutes of core-strengthening exercises, like planks and donkey kicks, three times a week (or practicing yoga or Pilates on a regular basis) can strengthen weak diaphragm muscles, making them more resilient to fatigue and less likely to cramp.
Bonus: A stronger core will also help you run more efficiently and reduce your overall vulnerability to injury. Try these 9 New Core Moves.
What and when you eat before a run may contribute to side stitches. If your body is still digesting food, there will be less blood flowing to the diaphragm, which can induce spasms. Foods that are high in fat and fiber take longer to digest, and so should be avoided one to two hours before you run.
Studies have also found that fruit juices and beverages that are high in sugar can contribute to stitches. So consider keeping a log of the foods and drinks you consume pre-run and when you experience a stitch so you can recognize triggers.
Going from standing to a full sprint may save you time on the watch, but it can create irregular, rapid-fire breathing patterns, which can leave you bending over in pain. Invest in two to three minutes of brisk walking, and then gradually work into an easy running effort before launching into your planned workout pace.
Increase Your Breath
If breathing is too shallow, it doesn't provide adequate oxygen to working muscles, including the diaphragm. Inhaling and exhaling fully and deeply can help reduce the occurrence of side stitches. Research shows that breathing "faster"—as in, inhale for two steps, exhale for one step—increases the depth of breath. Watch our video demo to learn the Breathing Tips Every Runner Should Know.fitness class.