Sitting writing a quick blog post on this rainy Wednesday in June... it's something that I often get asked from my clients and there can be sometimes more than one answer. There's still research going into some of the reasons as to why we get a stitch during exercise (more specifically when running), but some of the current beliefs are as follows:
Simply put, you've exercised too soon after eating.
When we exercise, blood travels to our muscles that we are predominantly using in order to provide oxygen and nutrients to help our muscles to continue working during exercise. However, if you have eaten right before you exercise, food is trying to be digested by the body which requires the oxygen to assist with the digestion. Therefore, exercising too soon after a meal may mean that blood is diverted away from the digestive system towards the leg muscles for example, causing the digestive tract to cramp due to the lack of oxygen.
You may notice however that you only tend to get a stitch during cardiovascular endurance sports, such as running, as opposed to weight lifting for example. Although there is still research being conducted in this area as previously mentioned, some believe that the internal organs put pressure on the diaphragm (a muscle that is used to help us breath) and therefore causes the feeling of tightness and cramp. I would perhaps assume that when running you are more regularly taking shallow and shorter breaths, therefore the stitch occurs more commonly compared to when you are lifting weights and are more easily able to control your breathing through deeper inhalations. “Many runners say that if their stitch is on the right side, if they slow their pace and exhale as their left foot hits the ground, the stitch eases,” says McGrattan. It may be worth considering your posture and running technique to ensure that you are running as efficiently as possible - rather than stooped over and restricting blood flow around the body.
Other researches suggest that a stitch can occur from the abdominals becoming aggravated during activity when there is regular movement that could cause friction across the muscles (https://www.healthline.com/health/side-stitch#causes) - again this makes sense that a stitch would more likely occur during a run from the amount of twisting we do; our upper body tends to twist in the opposite direction to our lower body in order for us to keep balanced. Whilst weight lifting, although some twisting movements may occur, they are often done so at a slower rate with steady breathing.
To help avoid a stitch in your future training sessions, you could try some of the following ideas;
Eating and drinking small amounts often rather than one large meal before you exercise, or if possible leave a large gap (2-3 hours) before you run again after eating.
Sip your water, and if possible avoid heavy sugary drinks, as sugary drinks can take longer to digest - use these after the session to replace blood sugars and ion levels.
Increase the intensity or duration of your workout slowly over time, in order for the muscles to become accustomed to the workout.
Focus on maintaining steady breathing - inhale through the nose and exhale through the mouth to ensure a suitable oxygen supply is transported as regularly as possible round the body.
This all may sound simple enough, but it could be detrimental to the quality of your exercise regime. If you regularly get a stitch when exercising it may cause you to slow down, or stop altogether - not ideal when you may want to be improving your fitness levels. Generally stitches may go away after a minute or two, but it could be worth seeing a doctor if stitches occur each time that you exercise despite exhausting all of the above suggestions, or if pain occurs before you've even started and remains for a long time after you have finished!