“Tonight thou shalt have cramps...side-stitches that shall pen thy breath up...Thou shalt be pinched...as thick as honeycomb…” — The Tempest: Act I, scene ii
It’s unlikely Shakespeare was an endurance athlete, but even he seemed to be aware of the dreaded pains felt by runners everywhere. Descriptions of and remedies for the “side stitch” have existed for quite some time.
If you've experienced the wrath of a nasty side stitch during a workout, you aren't alone. Athletes everywhere experience these pains during exercise. Sometimes, you feel helpless. What causes this affliction, and what is there to do about it?
Not Your Ordinary Stomach Ache
The classic side stitch is also referred to as exercise-related transient abdominal pain–or ETAP. ETAP is a harmless, but nonetheless excruciating, often one-sided and localized sharp pain in the lower abdomen, just below or under the rib cage. 62% of people report always experiencing side stitches on the same side, and pain in the right side is twice as common as left-sided pain.
When more mild, side stitches could feel like simple side cramps or an aching and pulling sensation–annoying, at best. When more severe, side stitches can upgrade to sharp and stabbing pains. As many who have experienced these pains know, side stitches are often accompanied by shoulder tip pain in the same side. It’s like exercising with a knife in the abdominals.
Unlike other exercise-related GI issues that vary widely in their symptoms, side stitches have consistent characteristics. Sports medicine researchers classify a stitch as a single condition, common to most who suffer it.
Prevalence of Side Stitch in Athletes
A side stitch is typically thought of as a runner’s malady. Sure, while runner’s are most susceptible to side stitches due to the nature of the activity, athletes in all sports report ETAP.
A study of 965 regular sports participants indicated that 69% of runners, 75% of swimmers, 32% of cyclists, 52% of dance aerobics participants, 47% of basketball players, and 62% of horse riding participants experienced a stitch within the past year.
Running and horseback riding seem to stand out. Compared to prevalence in cycling, a side stitch in running and horseback riding is about ten times more common. Why? It all comes down to motion.
These activities involve repetitive jostling of the abdomen while the torso is in an extended position.
This may be one of the causes of ETAP. More to come on this.
Factors Influencing Side Stitch
Runners and riders are more susceptible, but what other factors might predispose side stitch development?
Age plays a role, with younger athletes reporting ETAP to a greater extent than older athletes. This may be due to a greater participation of younger athletes in sports overall, or maybe it’s the fact that younger athletes can to push themselves harder.
Fitness level is also a contributing factor–athletes report experiencing more side stitches when they are less fit.
However, fitter and more experienced athletes don’t experience ETAP any less than novice athletes and beginner runners. Neither elite athletes nor weekend warriors are immune to the stitch, it seems.
The type of sport one engages in clearly has a major impact on ETAP. Activities causing the abdominal cavity to move vertically and rotate a considerable amount seem to provoke ETAP. “Jostling” motions are very irritating to the abdominals and the gut. This is why intensity of exercise may also influence ETAP. Higher intensity exercise is associated with more side stitches, so racing and interval workouts might worsen a side ache.
Causes of the Side Stitch
Frustratingly, most runners can’t point to a clear cause of the side stitch. And few can find a reliable remedy. There exist several theories about possible causes of the athletic side stitch.
External Factors: Food and Drink
Consuming any heavy food or drink close to exercise is likely to evoke a side stitch, even more so in athletes who don’t have an iron stomach. Your pre-race meal might make a big difference.
Respondents in a study of runners were more likely to report ETAP if they consumed a large mass of food in the one or two hours before the event.
Certain foods high in fat, protein, and fiber are likely to upset the GI tract and should be avoided too close to exercise. Best to eat small amounts of easy to digest food.
One strategy around this might be to experiment with nutritional supplementing, supplying high-quality energy in a small package, something that may minimize gut contents while maximizing energy delivery and efficiency. Try exogenous ketones. They contain no caffeine, no sugar, no salt, and no fat—meaning low risk of gastrointestinal side effects.
While side effects may be low, performance won’t be. The ketone body beta-hydroxybutyrate (BHB) has been shown to be 28% more efficient than carbohydrate per unit of oxygen consumed, and can enhance endurance performance by providing ketones as an alternative source of fuel on a background of ample carbohydrate intake.
Excessive fluid intake before and during exercise is a known culprit for side stitches. This is particularly related to the carbohydrate content and the osmolality (concentration) of the beverage if it’s something other than water. Hypertonic beverages (those containing a higher amount of electrolytes and sugars) are more provocative of ETAP. However, a high-volume fluid ingestion of any kind, including water, is known to increase the incidence of ETAP.
Adding carbohydrates to the beverage makes things worse, and the severity of symptoms increases with increasing osmolality. Research has investigated how the concentration of a beverage can influence ETAP. Participants completed treadmill exercise while consuming either water, a sports drink with 6% carbohydrate, or fruit juice containing 10.4% carbohydrate. The higher concentration beverage (fruit juice) led to significantly more reports of side stitch. Compared to no-fluid, the sports drink and fruit juice also increased side stitch symptoms.
Side stitches can be induced in runners by having them drink fluids. Consuming Coca-Cola, a sports drink and water all lead to the experience of ETAP during a treadmill run, however, the intensity of side stitch doesn’t seem to be different among the various beverages.
While less-supported by experimental studies, improper warm-up and exercising in colder temperatures may lead to increased incidence of side-stitches. In athletes frequently experiencing side stitches, 18% think that a “lack of warm-up” contributed to the condition, and 9% thought cold weather could be a factor.
Theories of Side Stitch
Food, beverages, and certain conditions are known to lead to side stitches in athletes, but what is the actual physical and physiological cause? Various mechanisms have been proposed to explain the tummy trouble that occurs during exercise.
Diaphragmatic Ischemia
Hard exercise demands blood flow be redistributed to working muscle, and this means taking it away from other areas in the body. We have a limited supply of oxygen-rich blood, and during exercise, supply is driven by demand. Muscles get greedy.
The theory that lack of blood flow to the diaphragm (our main muscle for breathing) leads to a side stitch is pervasive but lacks major support. Evidence in favor of this theory comes from the observation that foods and liquids cause side stitches by diverting blood to the stomach and away from the diaphragm, lowering blood flow to this region and perhaps leading to pain. This is also why you may experience shoulder tip pain with a side stitch. The diaphragm and the shoulder tip are actually both innervated by the phrenic nerve which, when aggravated by hypoxia, may yell out in agony.
However, studies have reported evidence against respiratory muscle ischemia as the main cause of ETAP. Respiratory muscle function was unchanged after treadmill exercise even in participants who experienced side stitch during the trial. This suggests the diaphragm muscles were getting enough blood for their needs, and compromised lung function probably doesn’t contribute to side stitch.
Abdominal Ligament Stress (Stretching)
The ligamentous pain theory proposes that in athletes, side stitches occur because the gut tugs on ligaments that connect the GI muscles to the diaphragm. Food and drinks that contribute to loading the gut stretch this area, causing tension. The sensory stimulus of tugging causes the sharp pain that athletes call a side stitch.
Food and beverages that delay gastric emptying or are poorly absorbed (hypertonic beverages) should intensify a side stitch, since they lead to a larger mass in the stomach and increase tugging and tension. This is the finding observed in many studies that have manipulated the side stitch.
Side stitch intensity is higher in runners who consumed a sports drink and Coca-Cola–two poorly absorbed beverages.
Ligament stretching and trauma also explains why ETAP occurs more in sports where jostling of the internal organs occurs, such as during running and horseback riding. There is a large influence of posture on side stitch occurrence. Even at a low respiratory demands of horseback riding, ETAP could occur due to the up and down motions of the rider causing stress on the GI-diaphragm ligaments.
Abdominal Wall Irritation
One of the favored and well-supported theories of side stitches: they're caused by irritation of the parietal peritoneum, the thin layer of tissue transversing the entire abdominal wall and connecting to the underside of the diaphragm. This region plays a major role in lubricating certain organs in the torso and abdominal cavity.
Exercise causes movement of the parietal peritoneum and leads to significant tension, especially when the torso is extended as in running and horseback riding. Increased tension aggravates the parietal peritoneum and cause sharp, localized pain characteristic of a stitch.
Exercise may also increase friction between the peritoneum and the organs around it like the liver and the large intestine, more so if you’ve just consumed some fruit juice or heavy food that might extend the stomach. Exercise may also lead to a reduced production of lubricating fluid from the peritoneum, causing even more rubbing. More friction means more aggravation and pain symptoms characteristic of side stitch. This theory is supported by evidence that physically aggravating this tissue even without exercise leads to symptoms and pain similar to ETAP.
The common factor among all of the prevailing theories of the side stitch is excessive motion. Exercise puts the torso on a roller coaster ride. Instead of motion sickness, we just get a stitch.
Side Stitch is Not a Muscle Cramp
Cramping of skeletal muscle is one proposed cause of side stitches. Incorrectly, side cramps are sometimes thought to be synonymous with side stitch.
While they may feel similar and both lead to a need to stop or slow down during exercise, ETAP (side stitch) and muscle cramps are not the same condition. Muscle cramps are sustained involuntary muscle contractions. Cramps can actually be experimentally measured by recording electromyography (EMG) of skeletal muscle–the electrical activity occurring during a cramp.
This is how we know that side stitches aren’t muscle cramps. Research measured EMG activity in participants experiencing side stitches, and no activity was seen while the pain was present, indicating respiratory muscle cramping was not responsible for the pain; muscles aren’t involved.
Valuable info, right? Classic wisdom says to treat muscular cramps with fluid, sports drinks, maybe even a banana–strategies that might actually provoke a side stitch.
Straighten Up
When Mom told you not to slouch, perhaps she was onto something. It turns out that the specific influence of posture may worsen symptoms of side stitch.
This hypothesis proposes an influence of the spine on side stitch–the so called neurogenic hypothesis. Nerves from the spine also innervate parts of the abdomen. As a result of “jolting” during exercise and compression that may occur in the vertebrae, these nerves may invoke pain indicative of a side stitch. In a somewhat sadistic study, researchers were able to reproduce symptoms of side stitch in runners just by manipulating the spine in certain regions.
While just an observation, people with an over-curvature of their spine (known as kyphosis) reported being more susceptible to ETAP. Improving posture and spinal alignment improves symptoms related to ETAP.
Preventing a Stitch (Before it’s Too Late)
Many treatments and remedies for side stitch are anecdotal. You know runners. They’ll leave no rock unturned when it comes to improving performance, no matter how wacky. If it works, it works.
Hydration
A side stitch as a consequence of dehydration is unlikely, research says.
Studies where subjects either abstained from or consumed fluid have shown that depriving yourself of fluids won’t prevent ETAP. If you’re looking to prevent a stitch through water fasting, tough luck.
The best advice from a water standpoint?
Drink to thirst before and during the race, taking smaller sips rather than large gulps all at once because, just as dehydration can cause a stitch, so can large quantities of fluid.
Next time you head out for a workout, listen to your thirst mechanism, it’ll tell you what your body needs.
Time food and beverage intake strategically. It’s best to avoid large volumes of food and liquid for about 1 - 2 hours before exercise, or 3 - 4 hours if you’ve got more of a sensitive stomach.
Proper fluid concentration is just as important. Hypertonic beverages (a carbohydrate concentration of 8% and above) cause more GI symptoms by slowing gastric emptying, pulling blood away from the stomach, and leading to presence of fluid in the stomach and intestines.
Physical Maneuvers
You might look like a flash-mob participant, but research has shown that certain stretches and movements you can do while running may help to prevent a side stitch from worsening.
In a study designed to test the effects of various maneuvers on side stitch intensity, it was shown that side stitches declined rapidly after runners contracted their abdominal muscles, modified their breathing, and tightened a belt around the abdomen. Remarkably, the side stitches disappeared within seconds.
Why do these actions work? This relates to the ligament theory of side stitches discussed earlier. Stretching the abdominal muscles reduces tummy tension. As for the belt? Similar to why power-lifters strap up before a lift, tightening the core using a belt while running could reduce abdominal movement, preventing the irritation that might lead to a stitch.
Strengthen Your Core
Six-pack abs don’t just look good, they may also help to prevent a side stitch. Runners with stronger trunk muscles and a larger transversus abdominis muscle (which spans the abdominal wall) experience less ETAP.
Core stability may protect against some symptoms of side stitch. Greater trunk muscle activation might be protective while running by stabilizing core structures and preventing unwanted stomach motion during exercise.
Studies on treatment of ETAP have indicated exercises that increase the length of and strengthen abdominal muscles can reduce mechanical stress and ease pain related to side stitch in runners.
Stop the Stitch
Side stitches will happen, and if you continue to exercise in spite of the pain, they may only get worse.
At the first sign of a stitch, this bit of anecdotal advice.
If this magic remedy doesn’t work, there are a few other tricks to try out.
Changing your footstrike to match breathing patterns might help ease the pain. If your stitch is on the right side and your normally exhale when your right foot strikes the ground, reverse this pattern, exhaling on your left footstrike. Vice-versa for a stitch on the left side.
Another common but unstudied technique may involve deep breathing. Take forceful inhales while contracting the stomach and forceful, full exhales while you distend your stomach. These movements are actually the opposite of the natural movements of respiration and stomach motion, one reason why they may help to relieve side stitches.
And sometimes, the best and only option is to stop running, massage the area, and pray to the running gods.
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