Breathing Through Side Stitches While Running

Target audience:This article is written for beginner runners, recreational racers, fitness walkers, coaches, parents of young athletes, and regular gym-goers who understand effort but do not want a medical textbook dropped on their lap.

 

Key points:A side stitch is usually described in research as exercise-related transient abdominal pain, or ETAP. It is common in running because running combines repeated trunk movement, impact, breathing demand, and upright posture. Breathing can help some runners manage the pain, but the evidence does not prove that side stitch is simply a diaphragm cramp. Food and fluid timing matter. Hypertonic drinks may provoke symptoms in susceptible runners. Posture and trunk control may influence risk, but they are not guaranteed fixes. Most episodes settle when intensity drops or exercise stops. Persistent, severe, unusual, or non-exercise-related pain needs medical assessment.

 

A side stitch usually arrives with bad timing. You have found your pace. Your playlist is doing its job. Your legs are not filing a complaint yet. Then a sharp jab appears under the ribs, often on one side, and your run turns into a negotiation with your own abdomen. Runners call it a side stitch, but the research term is exercise-related transient abdominal pain, or ETAP. The phrase sounds like something a committee invented after too much coffee, yet it matters because it separates a common running problem from vague labels like “cramp” or “bad breathing.” Morton and Callister’s review in Sports Medicinedescribes ETAP as a localized pain that often appears along the lateral mid-abdomen near the costal border, though it can occur elsewhere in the abdomen. The same review notes that severe ETAP is often sharp or stabbing, while milder episodes may feel cramping, aching, or pulling.1 That range explains why two runners can use the same word but mean different sensations.

 

The first practical point is blunt: running side stitch breathing can help during an episode, but breathing is not the whole story. Many runners are told that a side stitch equals a diaphragm cramp. That explanation is tidy. It is also incomplete. The diaphragm is the main breathing muscle, and it sits below the lungs like a flexible dome. During a hard run, it works while the trunk moves, the stomach shifts, and the abdominal wall absorbs repeated loading. It is reasonable that runners blame it when pain lands under the ribs. Research has not confirmed a simple diaphragm-cramp model. In their 2000 study, Morton and Callister reviewed features of ETAP and compared several proposed causes, including diaphragmatic ischemia, stress on visceral ligaments, muscular cramp, and irritation of abdominal lining tissue.2 The later review states that the exact mechanism remains unresolved, even though the characteristics of the condition are better described than they were decades ago.1 In plain English, the pain is real, common, and studied, but it has not been reduced to one neat switch.

 

Prevalence data also shows why runners keep asking about this problem. Morton and Callister surveyed 965 participants from 6 sports and reported that 61% had experienced ETAP in the previous year; the activity-specific rate was 69% for running in that sample.1,2 Another study by Morton, Richards, and Callister examined 848 participants after the 14-km Sydney City to Surf community run. The sample included 76% runners and 24% walkers. In that event, 27% reported ETAP, with runners reporting it more often than walkers, 30% versus 16%.3 Those numbers do not mean every runner will get a stitch on every run. They do show that the problem is not rare, not imaginary, and not limited to people who are “bad at breathing.” It can show up in people who train regularly. It can also appear in young or newer runners because age and exposure patterns matter.1

 

The current evidence points away from one-cause thinking. The parietal peritoneum is one structure that receives attention in the literature. It is a thin lining associated with the inner abdominal wall and diaphragm. When irritated, it can produce pain that is localized and movement-sensitive. Tissue linked to the diaphragm can also refer pain toward the shoulder through the phrenic nerve, which helps explain why some runners report shoulder-tip discomfort with ETAP.1 This does not make every side stitch a peritoneal-lining problem. It means this explanation fits several observed features better than some older explanations. Running involves repeated torso movement, vertical displacement, and trunk extension. Morton and Callister’s review notes that ETAP is especially prevalent in activities with repetitive torso movement, such as running and horse riding, and less prevalent in cycling, where the torso is more flexed and moves less.1 Think of the body during running as a controlled bounce, not a smooth glide. Even a graceful runner is still dealing with impact, organ movement, breathing pressure, and posture changes every stride.

 

Breathing becomes useful because it is one of the few things a runner can adjust immediately. When pain appears, many people react by tightening the torso and taking short breaths. That response is understandable, but it can make the run feel worse. A better first move is to reduce pace enough to regain control of the exhale. The goal is not theatrical deep breathing. The goal is to stop fighting the pain with panic. Exhale longer than feels natural for a few cycles. Let the ribs drop. Keep the shoulders from climbing toward the ears. If the pain is on the right side, some runners find relief by timing a fuller exhale when the left foot strikes; others use the opposite pattern. The published evidence does not prove one universal footstrike-breathing rhythm. It supports a more cautious conclusion: breathing changes are commonly reported as helpful, but responses vary. In Morton and Callister’s review, the most common relief technique reported by almost 600 sufferers was deep breathing, used by 40%; pressing on the affected area was reported by 31%, stretching by 22%, and bending forward by 18%.1 That list is useful because it comes from reported experience, but it is not the same as a controlled treatment trial.

 

When a side stitch hits, the cleanest action plan is simple. First, slow down before the pain forces you to stop. Do not sprint through it unless you are in a race situation where the consequence is acceptable. Second, breathe out fully for several breaths. Make the exhale quiet, long, and complete. Third, apply gentle pressure with your fingers or palm over the painful area while continuing to move at a slower pace. Fourth, lengthen the side of the torso by raising the arm on the painful side for a few steps, then release it; do not wrench the body like you are trying to open a jammed garage door. Fifth, if pain stays sharp, walk for 30 to 90 seconds and restart at an easier pace. Sixth, note what happened before the stitch: meal timing, drink type, starting pace, cold weather, posture fatigue, or sudden speed change. This is not glamorous. It is useful. A runner who tracks triggers gets better information than a runner who only mutters at the universe.

 

Food and fluid timing deserve special attention because they are among the most consistent practical factors. The 2005 Sydney City to Surf study found a positive relationship between the volume of pre-event food and drink consumed relative to body weight and ETAP, while the nutritional content of the pre-event meal was not related to ETAP in that analysis.1,3 This points toward volume and timing rather than one villain nutrient. Fluid composition also matters in laboratory studies. Morton, Aragón-Vargas, and Callister studied 40 ETAP-susceptible subjects across 4 treadmill trials involving no fluid and different fluid compositions; each treadmill trial lasted 23 minutes at a self-selected recreational running speed, reported at about 10.3 km/h.5 Their results showed that a hypertonic beverage was more provocative than isotonic and hypotonic beverages, with 83% of subjects developing ETAP after the hypertonic solution compared with 70% in the other 2 fluid trials as summarized in the later review.1,5 Plunkett and Hopkins also tested fluid ingestion during treadmill running in a small study of 10 subjects and found that a hypertonic solution provoked more ETAP symptoms than water or isotonic solution.1,6 Hypertonic means the drink has a higher concentration of dissolved particles than body fluids. Many concentrated sugary drinks fit that description. The practical rule is not “never drink.” It is “do not overload your gut before bouncing down the road.”

 

The common phrase diaphragm cramp relief should therefore be handled with care. If a runner searches for that phrase, they probably want a fix. The fix should not depend on an unproven label. Morton and Callister’s 2008 study tested whether localized electromyographic activity, or EMG activity, was elevated during ETAP. EMG measures electrical activity from muscle. The study included 14 symptomatic individuals and compared activity at the pain site while ETAP was present and after the pain subsided. The authors reported that EMG activity was not elevated during ETAP, which argues against local skeletal muscle cramp as the full explanation.7 That does not mean the diaphragm is irrelevant to running pain. It means the evidence does not support telling every runner, “Your side stitch is just a cramp.” A more accurate message is: control breathing because it may reduce distress and torso tension, but also examine food, fluid, pace, posture, and recurrence pattern.

 

Breathing measurements add another layer. Morton and Callister’s 2006 spirometry study examined breathing mechanics during ETAP episodes. Spirometry measures airflow and lung function. The study did not establish a single breathing fault that explains ETAP, and the broader review states that management strategies remain largely anecdotal.1,8 That matters for coaching. A breathing drill can be worth trying, but it should not be sold as a cure. A practical breath rhythm stitch prevention routine should focus on repeatability: start the first 5 to 10 minutes slower than your target pace, breathe through a relaxed jaw, avoid holding your breath on hills, and use a longer exhale when effort rises. During faster running, breathing will naturally become harder and more frequent. That is not failure. The mistake is turning each breath into a wrestling match. Good running breathing is organized enough to support pace, flexible enough to adapt, and calm enough to avoid extra trunk tension.

 

Posture is another factor with evidence, but the message needs precision. Morton and Callister studied 159 active young people, 104 males and 55 females, with a mean age of 18.6 years. They found that ETAP was unrelated to somatotype, or body-type classification, but individuals with kyphosis were more susceptible to ETAP, and the extent of kyphosis and lordosis influenced pain severity.1,9 Kyphosis refers to increased rounding in the upper back. Lordosis refers to inward curve, often discussed in the lower back. This does not mean a runner should obsess over posture or force a military-straight torso. Running with stiffness can waste energy. The useful target is a trunk that stays tall without strain. Imagine carrying a full cup of coffee across a room. You do not freeze like a statue. You control motion enough to avoid spilling it. That is close to the posture goal during easy running.

 

Core training enters the conversation for the same reason. Stronger trunk control may reduce excessive movement, but it is not a magic button. Mole, Bird, and Fell studied 50 runners, 28 male, with a mean age of 25.8 years, and examined transversus abdominis function using clinical trunk strength testing and ultrasound imaging. The transversus abdominis is a deep abdominal muscle involved in trunk support. Their observational study found that runners with stronger trunk muscles and larger resting transversus abdominis size experienced ETAP less often; however, the design cannot prove that strengthening that muscle alone prevents stitches.10 That is the line many articles blur. A reasonable side pain running technique plan can include planks, dead bugs, side planks, carries, and controlled breathing drills. It should also include gradual mileage, pacing discipline, and fueling experiments. If only one plank cured ETAP, every runner on Earth would already be doing it between coffee and emails.

 

The emotional part is not trivial. A side stitch can hijack a run because it feels sudden, local, and unfair. It can also embarrass runners in group settings. Nobody wants to be the person stopping at 2 km while the rest of the group floats away like a fitness-themed parade. That reaction can create a loop. The runner expects the stitch, scans the abdomen, stiffens the torso, changes breathing, starts too cautiously or too aggressively, and then interprets every twinge as the return of pain. The evidence does not prove that anxiety causes ETAP, but the experience of pain clearly affects behavior. The practical answer is not to pretend the pain is fun. It is to treat it as a signal with variables. You can change warm-up, pre-run meal size, drink concentration, starting pace, trunk position, and response strategy. That gives the runner a checklist instead of a ghost story.

 

A critical perspective is needed because ETAP advice online often outruns the evidence. The available research includes reviews, questionnaire studies, laboratory trials, small mechanistic studies, and observational work. That is useful, but it is not the same as a large set of randomized clinical trials comparing breathing techniques, posture programs, drink formulas, and strength routines across months of training. The review by Morton and Callister states that ETAP’s mechanism remains incompletely explained and that relief techniques are equivocal.1 That single sentence should shape the whole conversation. Avoiding large food and fluid volumes for at least 2 hours before exercise is a common recommendation supported by observational and experimental findings, especially for susceptible runners.1,3,5,6 Avoiding concentrated hypertonic drinks before and during runs is also reasonable for runners who repeatedly get stitches.1,5,6 Deep breathing, pressure on the painful area, stretching, bending forward, belts, posture work, and trunk exercises may help some people, but the certainty is lower.1,9,10 The best plan is tested, logged, and adjusted rather than copied from a stranger’s comment section.

 

For prevention, use a controlled experiment on yourself without turning your running life into a lab coat drama. For 2 weeks, keep pre-run eating simple. Leave at least 2 hours after a large meal before moderate or hard running. If you need calories before a longer run, use a smaller portion and test it during training, not on race day. Choose water or a tolerated sports drink rather than a concentrated sugary drink when you know you are prone to ETAP. Start easier than your ego wants. Many stitches appear when the first kilometer is run like a movie trailer instead of a warm-up. Use a steady breath rhythm, but do not force an exact pattern if terrain, pace, or fatigue changes. Check posture late in the run, when form often folds. Add trunk work 2 or 3 times per week, but keep it specific: anti-rotation presses, side planks, loaded carries, dead bugs, and slow mountain climbers train control without turning the session into circus auditions. Track only useful details: pain side, pain timing, meal timing, drink type, pace, temperature, and what relieved it. After several runs, patterns usually speak louder than memory.

 

There are also clear limits. A typical side stitch appears during exercise, is localized, and improves when intensity drops or the run stops. Pain that is severe, persistent, worsening, associated with chest pressure, fainting, fever, vomiting, blood in stool or urine, shortness of breath out of proportion to effort, trauma, or pain that continues after exercise is not something to file under “runner problems.” Recurrent abdominal pain that changes pattern also deserves medical assessment. Runners are good at bargaining with discomfort. That habit helps during training. It can also delay care when symptoms no longer fit ETAP. The line is simple: a familiar stitch that settles quickly can be managed; unusual or persistent pain needs a clinician.

 

The final message is practical. Breathing through a side stitch is not about heroic toughness. It is about lowering intensity, restoring a full exhale, reducing unnecessary trunk tension, and giving the body a chance to settle. The science does not support the claim that every side stitch is a diaphragm cramp. It supports a broader view: ETAP is common, usually temporary, often linked with running mechanics and recent food or fluid intake, and still not fully explained. Use breathing as a tool. Use fueling timing as prevention. Use posture and trunk control as supporting work. Use symptom tracking as your filter for what actually helps. Share this article with a runner who keeps getting ambushed under the ribs, and keep notes from your own runs so future guidance can be more useful. A side stitch can interrupt a run, but it does not get to own the road.

 

Disclaimer: This article is for educational purposes only and does not provide medical diagnosis, treatment, or individualized health advice. Exercise-related abdominal pain can have causes other than ETAP. Anyone with severe, persistent, recurrent, unusual, or worsening pain should consult a licensed healthcare professional. People with known medical conditions, recent injury, pregnancy, or symptoms involving the chest, breathing, fainting, fever, vomiting, or bleeding should seek medical care before continuing exercise.

 

References

 

Morton D, Callister R. Exercise-related transient abdominal pain (ETAP). Sports Med. 2015;45(1):23-35. doi:10.1007/s40279-014-0245-z

 

Morton DP, Callister R. Characteristics and etiology of exercise-related transient abdominal pain. Med Sci Sports Exerc. 2000;32(2):432-438. doi:10.1097/00005768-200002000-00026

 

Morton DP, Richards D, Callister R. Epidemiology of exercise-related transient abdominal pain at the Sydney City to Surf community run. J Sci Med Sport. 2005;8(2):152-162. doi:10.1016/S1440-2440(05)80006-4

 

Morton DP, Callister R. Factors influencing exercise-related transient abdominal pain. Med Sci Sports Exerc. 2002;34(5):745-749. doi:10.1097/00005768-200205000-00003

 

Morton DP, Aragón-Vargas LF, Callister R. Effect of ingested fluid composition on exercise-related transient abdominal pain. Int J Sport Nutr Exerc Metab. 2004;14(2):197-208. doi:10.1123/ijsnem.14.2.197

 

Plunkett BT, Hopkins WG. Investigation of the side pain “stitch” induced by running after fluid ingestion. Med Sci Sports Exerc. 1999;31(8):1169-1175. doi:10.1097/00005768-199908000-00016

 

Morton DP, Callister R. EMG activity is not elevated during exercise-related transient abdominal pain. J Sci Med Sport. 2008;11(6):569-574. doi:10.1016/j.jsams.2007.06.006

 

Morton DP, Callister R. Spirometry measurements during an episode of exercise-related transient abdominal pain. Int J Sports Physiol Perform. 2006;1(4):336-346. doi:10.1123/ijspp.1.4.336

 

Morton DP, Callister R. Influence of posture and body type on the experience of exercise-related transient abdominal pain. J Sci Med Sport. 2010;13(5):485-488. doi:10.1016/j.jsams.2009.10.487

 

Mole JL, Bird ML, Fell JW. The effect of transversus abdominis activation on exercise-related transient abdominal pain. J Sci Med Sport. 2014;17(3):261-265. doi:10.1016/j.jsams.2013.05.018