Nothing halts an otherwise awesome workout quite like the dreaded side stitch. Clinically referred to as exercise-related transient abdominal pain, or ETAP for short, the side stitch is a remarkably common phenomenon among athletes and everyday fitness enthusiasts alike. According to Sydney Lopez, a licensed athletic trainer with The Stone Clinic in San Francisco, these sharp torso pains plague people across various fitness levels. An older but widely cited survey of 965 athletes, published in 2000 in the academic journal Medicine & Science in Sports & Exercise, found that nearly 70 percent of runners and 75 percent of swimmers reported experiencing at least one side stitch over the course of the preceding year.
However, just because the side stitch is exceptionally common does not mean that athletes need to passively suffer through it. Understanding what causes these sudden aches, exploring expert-backed strategies for banishing them, and knowing the specific red flags that warrant a conversation with a medical professional can help keep your training on track.
What Exactly Is a Side Stitch?
The side stitch is characterized as a sharp, localized pain that suddenly emerges during physical exercise and manifests in the abdomen, typically just below the rib cage. Hunter Carter, an exercise physiologist at the Hospital for Special Surgery in New York City, notes that many people describe the sensation as a sharp stabbing pain located directly in the ribs. For a significant portion of individuals, this uncomfortable sensation tends to crop up predominantly on the right side of the body.
It is important to differentiate a side stitch from other types of exercise-induced abdominal issues. For instance, standard muscle cramps tend to feel more like general muscle tightness, whereas gastrointestinal distress typically involves cramping accompanied by bloating, nausea, or a sudden, urgent need to use the restroom. The side stitch stands apart as a distinct biomechanical and physiological occurrence tied directly to movement and breathing patterns.
Why Do People Get Side Stitches?
When it comes to the exact biological root causes of the side stitch, exercise scientists and medical professionals note that there is no single, universally agreed-upon mechanism. Nevertheless, the leading scientific theory points toward irritation of the parietal peritoneum, which is the specialized layer of the abdominal lining. When this sensitive tissue experiences repetitive mechanical stress or friction during exercise, it can trigger the sharp pain characteristic of a side stitch.
Runners who exhibit a high degree of vertical oscillation—meaning they bounce up and down significantly with each stride—can be especially susceptible to this phenomenon. That vulnerability arises because all that vigorous up-and-down motion constantly jostles and aggravates the parietal peritoneum. Similarly, repeatedly twisting the torso can also irritate the lining. This rotational motion is common in swimming styles like the freestyle and backstroke, which helps explain why side stitches are notably prevalent among swimmers. Excessive torso rotation can also occur during running if an athlete lacks adequate core control and stability.
Another prominent theory behind the side stitch involves diaphragmatic ischemia, a technical term describing a temporary reduction in blood flow to the diaphragm. During strenuous exercise, the body intelligently prioritizes its resources, shuttling blood away from the core—where the diaphragm is housed—and directing it toward the actively working skeletal muscles in the limbs. This redistribution can place a heavy burden on the diaphragm, which must continue performing its vital role of supporting respiration. That localized fatigue may ultimately manifest as the sharp, gripping pain of a side stitch.
Dietary habits can also play a notable role. Eating a heavy meal, consuming a large volume of liquid, or ingesting certain foods and beverages directly before or during a workout can contribute significantly to the likelihood of experiencing a side stitch. Exercise naturally diverts blood away from the intestines and toward working muscles, leaving food and fluids lingering undigested in the gastrointestinal tract. The physical presence of those substances jostling around inside the abdomen can irritate the lining enough to spark a side stitch.
What Can You Do to Ease or Prevent Side Stitches?
Side stitches have a frustrating way of sneaking up unexpectedly in the middle of an intense training session. While athletes usually cannot predict their exact arrival, they can typically bring the discomfort to a halt by dialing back the intensity of their workout. Backing off the pace reduces the mechanical stress placed on the abdomen and generally allows the localized pain to settle down quickly. For a runner, this might look like dropping down to a slow jog or a walking pace, while a swimmer might take a short rest at the edge of the pool between laps.
Taking a few slow, deliberate, deep diaphragmatic breaths can also help mitigate the pain. Focusing on deeper breathing patterns reduces strain on the diaphragm and helps relax the surrounding abdominal region. Another practical technique involves pressing the fingers directly into the tender spot while bending slightly forward. According to fitness experts, this physical adjustment may help alleviate the discomfort by providing a different sensory feedback mechanism at the exact point of irritation.
Beyond managing the pain in the moment, maintaining proper core activation throughout workouts can substantially reduce the likelihood of a side stitch developing in the first place. Abdominal bracing helps correct or prevent the abdominal lining from enduring excessive irritation from repetitive motion. Experts often recommend practicing the cue of knitting the ribs together and keeping them closed rather than letting them flare out, even during inhalation. For runners specifically, leaning the torso slightly forward during a stride can naturally encourage better core muscle recruitment.
Naturally, sustaining effective core engagement throughout an entire workout requires a solid baseline level of abdominal strength, stability, and control. For individuals who feel they are lacking in this department, specialists recommend integrating targeted stability movements into their routine, such as bear planks, side planks, and Palloff presses. If side stitches are repeatedly sabotaging workouts, getting running or training form evaluated by a qualified fitness professional can be immensely beneficial. A professional can identify subtle biomechanical errors—such as excessive vertical oscillation—and offer personalized guidance to correct them.
Additionally, because nutritional intake can heavily influence abdominal comfort, experts advise avoiding large meals within one to three hours prior to running or engaging in other high-intensity exercises. Athletes should also aim to hydrate continuously throughout the day rather than chugging large quantities of water right before stepping out to break a sweat.
Side Stitch Red Flags
While side stitches can undoubtedly be painful and deeply annoying when they interrupt a carefully planned workout, experts emphasize that they are typically not dangerous. Most side stitches are completely harmless and tend to resolve quickly once the individual slows down their pace or halts the activity.
Even so, there are specific red flags that indicate a side stitch might actually be something more serious, warranting a professional medical evaluation. Individuals should consult a doctor if they experience persistent or severe abdominal pain, particularly if that pain occurs entirely outside the context of a workout, progressively worsens over time, or is accompanied by other concerning symptoms such as nausea, dizziness, or chest pain. The same caution applies if an athlete has diligently taken all recommended steps to alleviate side stitches—including having a professional evaluate their form—yet the painful episodes continue to recur consistently.
