It often arrives without warning. One minute you’re cruising through a workout—breathing steadily, feeling strong—and the next, a sharp, stabbing pain strikes just below your ribs. Suddenly, finishing the run becomes less about endurance and more about simply getting home.

This uncomfortable sensation, commonly known as a side stitch, is one of the most frustrating interruptions during exercise. Clinically referred to as exercise-related transient abdominal pain (ETAP), it is far more common than many people realize.

A Widespread Workout Problem

Sports medicine experts say side stitches affect athletes across a wide range of activities, particularly those involving repetitive torso movement. Running and swimming are among the most frequently reported triggers.

Research published in Medicine & Science in Sports & Exercise found that nearly 70 percent of runners and 75 percent of swimmers reported experiencing a side stitch within a year. While the pain is typically harmless, it can be intense enough to force athletes to slow down or stop exercising altogether.

The discomfort usually appears in the abdomen, just below the rib cage, and is often described as a stabbing or sharp pain. Many people notice it on the right side of the body, although it can occur on either side.

Importantly, experts say a side stitch differs from other exercise-related abdominal issues. Muscle cramps tend to feel like tightness, while gastrointestinal distress often includes symptoms such as bloating, nausea, or an urgent need to use the bathroom.

Why Side Stitches Happen

Despite how common the condition is, researchers have yet to agree on a single definitive cause.

One widely accepted explanation involves irritation of the parietal peritoneum, a thin layer lining the abdominal cavity. Repetitive movement during exercise—especially activities that involve bouncing or twisting—may irritate this lining and trigger pain.

For runners, excessive vertical movement, sometimes called “bouncing,” may increase the likelihood of irritation. Swimmers, particularly those performing freestyle or backstroke, may also experience side stitches due to repeated torso rotation.

Another possible explanation involves the diaphragm, the muscle responsible for breathing. During intense exercise, blood flow is redirected toward the working muscles in the arms and legs. This shift may reduce blood supply to the diaphragm, potentially leading to fatigue and the familiar stabbing sensation.

Diet may also play a role. Eating large meals, drinking large amounts of fluid, or consuming certain foods shortly before exercise can leave undigested material in the digestive system. The movement of these contents during activity may irritate the abdominal lining and contribute to side stitches.

Quick Fixes That May Help

Although side stitches can appear suddenly, experts say they usually resolve quickly with simple adjustments.

One of the most effective solutions is to reduce the intensity of the workout. Slowing from a run to a jog—or even walking briefly—often allows the pain to settle.

Deep breathing can also help. Taking slow, diaphragmatic breaths may relieve pressure on the diaphragm and relax the abdominal area.

Some athletes find relief by pressing gently on the painful area while bending slightly forward, which may change the sensory feedback and ease discomfort.

Longer term, strengthening the core muscles may help reduce the risk of recurring stitches. Exercises such as planks, side planks, and anti-rotation movements can improve stability and reduce excessive torso movement during exercise.

Experts also recommend avoiding heavy meals within one to three hours before high-intensity workouts and staying hydrated throughout the day rather than drinking large amounts of water immediately before exercise.

When to Seek Medical Advice

In most cases, side stitches are harmless and disappear once activity slows. However, persistent or severe abdominal pain—especially if it occurs outside of exercise or is accompanied by symptoms like dizziness, nausea, or chest pain—should be evaluated by a healthcare professional.

Staying Active Without the Pain

For runners, swimmers, and anyone pursuing an active lifestyle, a side stitch can feel like a sudden roadblock. But with better breathing, improved core strength, and smarter workout habits, most people can reduce the chances of it disrupting their routine.

And the next time that familiar twinge strikes mid-run, the solution may be simpler than expected: slow down, breathe deeply, and let your body reset before picking up the pace again.