Watching the Olympic Games this week has been a huge motivator for me as I continue to train hard. Observing the seemingly endless parade of treadmill runners at my gym, it would seem I am not alone in this sentiment. Now that the mystique of the gymnastics competition has tapered, all eyes are on the track and field athletes. There is nothing like watching an individual run 100 meters in under 10 seconds to get your blood flowing.

A client who recently has become a runner had an interesting question for me last week, and I have a feeling it is a topic that has plagued many a distance athlete. What causes that bothersome “side stitch” pain? This irritation seems to be more common among longer-distance runners, although sometimes it pops up within the first mile of a run.

Long believed to be due to a build-up of lactic acid, it seems that the real cause of the side stitch is a muscle spasm of the diaphragm. This is the muscle which separates the abdominal cavity from the chest cavity in the middle of the body. In addition, the diaphragm is a key component in respiration. As we inhale, the diaphragm moves downward; exhalation evokes its upward movement. The painful spasm of the side stitch is an artifact of the internal organs bouncing up and down during a run, thereby exerting a downward strain on the diaphragm as it attempts to move upward with each exhalation.

If the diaphragm is located in the center of the body, why does the stitch almost always affect the right side of the body? The liver is to blame for this phenomenon. The largest of the abdominal organs, the liver attaches to the diaphragm in the upper right side of the abdominal cavity, directly below the ribcage. If you are a runner, you might be nodding in agreement while reading this, as you pinpoint the exact spot where your side stitch generally hits.

While a scientific explanation is certainly enlightening, finding a way to circumvent the problem may be even more helpful. Taking deeper breaths while running has been found to be an effective counter-measure. Shallow breaths force the diaphragm to stay in an elevated position, never lowering long enough for the ligaments which attach the liver to the diaphragm to “relax.” Breathing more deeply while running reduces the stress on the diaphragm as it is allowed to fully lower. Periodically during a long run, a good technique to try is exhaling forcefully as if you are blowing out a candle.

Another helpful tip is to stay conscious of breathing out as your left foot hits the ground or treadmill. There are smaller organs attached to the diaphragm on its left side; as such, less strain would be put on this muscle with each exhalation.

Armed with this knowledge, take a deep breath and hit the ground running. There just may be an Olympic athlete inside of you just waiting to emerge!

Cathleen Kronemer, NSCA-CPT, is a Lifestyle/Weight Management Coach and a longtime fitness instructor at the Jewish Community Center.