Exercise can be a pain in the side, and at last sports scientists are beginning to understand why. That most common of workout ailments, a side stitch or abdominal cramp, had long puzzled researchers trying to determine its cause, but a flurry of recent studies is beginning to unravel why some people get intense stabbing pains beneath their ribcage.

Until now, the most common theory was that undigested food being jiggled about during activity was the reason for a stitch, and that remains a risk factor. Findings in the Journal for Science and Medicine in Sport show that those who consumed a large number of calories one to two hours before exercise were more likely to experience pain. However, a stitch has also been linked both to weak abdominal muscles and to the ligaments that extend from the diaphragm to hold the internal organs in place being stretched.

Poor breathing patterns don't help. Runners who exhale when their right foot hits the ground are more prone to side stitches. The heaviest organ in the abdominal cavity, the liver, is located on the right hand side of the body and as the diaphragm springs upwards each time we breathe out, the combination of the jarring of a running stride and the increased tension on ligaments leads to spasms on the right hand side of the body, the most common site for a stitch.

So what can be done to prevent it?

1 Take deep, even breaths during a workout. Shallow breathing increases the risk of cramping because the diaphragm is always slightly raised and never lowers far enough to allow the ligaments supporting it to relax.

2 Strong abdominal muscles will help to support internal organs. Try the plank (above). From lying face down, push yourself up on to your elbows and feet. Keep a straight line through the head and hips, without raising your bottom too high. You should feel no tension in your back - if you do, lift your hips a little more. Hold the position for one minute if you can, gradually progressing to longer, then lower your knees to the ground.

3 If you do get a stitch: stop, press your hand into your liver to raise it up against your diaphragm, exhaling forcefully as you do so. The pain should subside.

Explore Health

• Expert Advice

• Health Features

• Mental Health

• Alternative Medicine

• Child Health

• Health Club