A stitch is a form of cramp normally experienced in the diaphragm near the right side of the rib cage. It usually indicates that you are pushing yourself too hard.
In some cases, it can happen quickly, striking without warning and causing excruciating pain. In other cases, it can come on gradually, starting as a slightly uncomfortable tightness or tense feeling. Most people try to work their way through this type of discomfort, taking it as a normal reaction to the exercise they are doing. But as they continue, the pain increases - to the point where the cramp sets in, causing the same excruciating pain as experienced in the sudden attack.
This type of stitch is felt on the right-hand side of the chest as a direct result of a cramp in the diaphragm. If you experience a cramp on the left-hand side of the chest, this is normally caused by eating too close to your workout period.
The more common right-hand stitch, caused by cramping of the diaphragm, is usually the most painful of the two. It is caused by not warming up properly, or it can also be caused by changing the pace of your activity or workout too quickly. Both of these initiate the same reaction in your diaphragm area. There is a demand placed upon the muscles of the diaphragm to move through a greater range of deflections at a higher pace than it is prepared for.
In the case of changing the pace of your workout, suffering a stitch does not necessarily mean that you are pushing yourself too hard. It is merely an indication that you are pushing yourself in excess of what your body is prepared for at that particular point in your workout routine. It may also indicate your diaphragm is slowly constricting and should be worked on directly by releasing pressure
that is causing it to constrict in the first place.
If you eat too close to your workout period, the small intestine will still be full of food that it needs to digest. Digestion requires a significant rate of blood flow. If you then start your workout, the muscles you are using will also demand an increase in blood flow to supply enough nutrition for the energy output demanded from them. The muscles take precedence, resulting in a lack of blood flow to the small intestine to digest the food. This results in the small intestine cramping. You experience a cramp on the left-hand side of your upper stomach area in the region of the lower area of the rib cage, as this is where the small intestine is located.
You might help this situation by taking some non-hydrochloric acid digestive enzymes
an hour before the exercise activity. No food, just the enzymes.