How to beat a stitch

A stitch is the common cold of exercise - we all get one sooner or later - and, says Andrew Hamilton, just like the common cold we still don't really know what causes it.

Stitch can affect even the fittest athletes: witness Haile Gebreselassie's spectacular exit from last year's London Marathon all because of a mundane side stitch! Mundane it may be, but a full-on stitch is not only painful, it can also wreck the best-laid exercise plans. So what exactly causes stitch and how can it be prevented?

Despite the fact that stitch is such a common phenomenon, it is actually very poorly understood.

One of the main reasons for this is that because it's unpredictable in its occurrence, stitch is hard to study. You can't set up a simple experiment in which you induce stitch in your subjects and then try and observe the physical changes that take place because it's often not possible to induce a stitch even when you create favourable conditions (eg training on a full stomach). This means that very few properly controlled scientific studies into stitch have actually been carried out.

We know it's more common when there's lots of repetitive torso movement so a running stitch is twice as likely as a walking stitch and ten times more likely as a cycling stitch.

The older you are, the less likely you are to suffer stitch.

Fitness level does not appear to be a factor although the more frequently you train, the lower appears to be. Food or drink prior to exercise increase risk; fruit juices and carbohydrate drinks seem to increase stitch risk over plain water.

Despite the dearth of data on stitch, there are a number of theories about the causes.

• One of the most popular theories is that stitch is caused by an insufficient flow of blood to the diaphragm, which in turn causes a muscular spasm or 'cramp'.
• Another theory is that the movement of the stomach and liver during activities such as running places stress on the diaphragm ligaments and/or the ligaments supporting the abdominal organs, causing discomfort.
• A third and more recent theory proposes that stitch is caused by an irritation of the lining of the abdominal cavity, which occurs as a result of friction generated between the (moving) abdominal organs and the relatively static wall of the cavity. 

All these theories are plausible but the scientific jury is still out as to the actual cause.

It may be hard to carry out controlled experiments on stitch, but there's plenty of data out there about the nature and most commonly observed circumstances of stitch.

This is gathered by looking at large numbers of cases where stitch occurs and then trying to tease out any common factors - a so-called epidemiological approach. Although it's not the same as measuring direct cause and effect, it does give scientists a very useful insight into what might lie behind its occurrence.

Putting the pieces of the jigsaw together from the evidence above, a pattern begins to emerge, which implicates torso movement and the diaphragm.

Most stitch occurs in the mid or lateral abdominal area, although it can sometimes lead to referred pain the right shoulder - indicative of the association of the diaphragm muscles.

The fact that food or fluid in the stomach increases the chance of stitch suggests that organs close to the diaphragm are involved. Stitch also occurs frequently in sports that involve jarring and/or twisting of the torso suggesting that it is linked to the movement of the body's internal organs. Last, but not least, given that stitch makes breathing very uncomfortable, its hard to escape the conclusion that the pain of stitch and diaphragm function are inextricably linked.

The diaphragm muscles play a key role in expanding the chest cavity and therefore in the inspiration of air into the lungs and are also intimately involved in stabilising the torso.

Research has shown that during the preparatory phase of most limb movements, the diaphragm is activated subconsciously and in doing so, it raises the pressure inside the abdomen, which acts to increase spinal stability. Thus, the diaphragm muscles work together with the core stabiliser muscles encapsulating the abdominal compartment of the body, as well as deep muscles surrounding the spine, to stabilise the spine and pelvis during movements involving the torso such as throwing or lifting.

Given this dual role, it's possible to see how these diaphragm muscles could become overloaded; combine the demands of heavy breathing with those of stabilising the torso, and throw in a bit of organ movement to further interfere with normal diaphragm function, and maybe the diaphragm just can't cope and you get a stitch!

This combination of factors is exactly what happens during running, especially where breathing and stride are difficult to synchronise as in, for example, a cross-country over uneven terrain. In these circumstances, the diaphragm is subjected to buffeting by large organs in close proximity as they move up and down in synchrony with the foot strike. This stretches the diaphragm, and also means that it then has to work against the buffeting forces.

If the prime cause of stitch is overload of the diaphragm muscles can they be trained to become more efficient and reduce the likelihood of a stitch?

Given that the diaphragm muscles are trainable like any other muscles, so in theory 'yes'.

 Professor Alison McConnell at Brunel University is one of the world's leading authorities in this area, and she and her team have achieved some very promising results with the use of diaphragm training devices such as 'Powerbreathe', right. These devices place a 'load' on the diaphragm during inspiration and used regularly have been shown to improve performance by making exercise feel easier, and by preventing the inspiratory muscles from diverting blood away from the legs during exercise, thus improving endurance performance.

Many people who have trained their inspiratory muscles in this way say they no longer have stitch unless they trained their inspiratory muscles within an hour or so of going for a run in which case they did. These observations are strongly indicative that stitch is a response of a tired diaphragm.

A typical session of inspiratory muscle training might consist of inhaling (using a Powerbreathe or similar device) for around 30 breaths with the resistance adjusted so that you can only just achieve 30 breaths in a time period of 2-3 minutes. Training this way twice a day for a period of 4-6 weeks will produce real benefits, not just in terms of reducing stitch risk, but also improving endurance performance generally.

You can further enhance the 'stabilisation capability of the diaphragm by performing your IMT routine while activating your core muscles - while balancing on a stability ball or wobble board, for example. And if you're prone to stitch, remember to avoid food or high-carbohydrate fluid 2-3 hours before training.

Finally, if the dreaded stitch does strike, anecdotal evidence suggests that bending forwards, tightening the abdominal muscles and pressing inwards and upwards (hard!) on the site of the pain with your palm for 10-15 seconds will help to alleviate the pain. Failing that, you can always slow down or even stop if need be. Don't be too hard on yourself - after all, stitch can strike even world champions!!

Former gym manager Andrew Hamilton is features editor of Ultra-Fit magazine where a version of this article first appeared.