Side stitches are one of the most frustrating interruptions in fitness, arriving without warning and bringing even the strongest workouts to a grinding halt. That sharp, stabbing sensation just below the ribs is something nearly every active person has encountered at some point, yet most people have no idea what causes it or how to make it stop. Understanding the mechanics behind this common phenomenon is the first step toward keeping it from sabotaging your training.
What side stitches actually are and why they happen
Clinically referred to as exercise-related transient abdominal pain, side stitches are a localized, sharp discomfort that surfaces in the abdomen during physical activity, most commonly on the right side of the body just below the rib cage. The sensation is distinct from muscle cramps, which tend to feel like tightness, and from general gastrointestinal distress, which typically involves bloating, nausea, or an urgent need to use the restroom.
The leading explanation for what triggers side stitches involves irritation of the parietal peritoneum, a thin layer of tissue lining the abdominal cavity. Repetitive motion during activities like running and swimming can jostle and aggravate this lining, particularly when a runner has significant vertical bounce in their stride or a swimmer rotates the torso excessively during freestyle or backstroke.
A second theory points to reduced blood flow to the diaphragm during intense exercise. As the body redirects circulation toward working muscles, the diaphragm can become fatigued while still being called upon to support breathing. That fatigue may register as the stabbing pain so many athletes recognize.
Food and fluid intake before exercise can also play a role. Eating a large meal or drinking significant amounts of liquid shortly before a workout leaves undigested content sitting in the gastrointestinal tract. The movement of exercise causes that content to shift and press against the abdominal lining, which can be enough to bring on side stitches in susceptible individuals.
How to stop side stitches when they strike mid workout
The fastest way to address side stitches once they begin is to reduce workout intensity immediately. Slowing a run to a jog or taking a brief rest between swimming laps decreases the mechanical stress on the abdomen and typically allows the pain to ease within a few minutes.
Deliberate diaphragmatic breathing can also help. Taking several slow, deep breaths that allow the belly to expand fully reduces strain on the diaphragm and encourages the abdominal region to relax. Pressing fingers gently into the tender spot while bending slightly forward at the waist offers another form of relief by introducing a different physical sensation at the point of irritation, which can interrupt the pain signal.
Preventing side stitches before they start
Building a stronger, more stable core is one of the most effective long term strategies for reducing the frequency of side stitches. Exercises like the bear plank, side plank, and Pall off press develop the abdominal strength and control needed to stabilize the torso during high intensity movement. Runners benefit from leaning slightly forward during their stride and focusing on keeping the ribs drawn inward rather than flared, which helps recruit the core muscles more effectively throughout the run.
Managing pre-workout nutrition and hydration matters as well. Avoiding large meals within one to three hours before intense exercise and spreading fluid intake consistently throughout the day rather than drinking heavily right before a session reduces the gastrointestinal conditions that make side stitches more likely.
When side stitches become a reason to see a doctor
Most side stitches resolve quickly once intensity drops and pose no lasting health concern. However, abdominal pain that persists outside of exercise, worsens progressively over time, or arrives alongside symptoms like nausea, dizziness, or chest discomfort warrants a conversation with a medical professional. The same applies when side stitches continue despite consistent form corrections and preventive measures.
