Side aches, also known as side stitches or exercise-related transient abdominal pain, are a common phenomenon among runners and other athletes. The exact cause of side aches is still uncertain, but there are a few possible explanations:

• Diaphragm spasms: One theory suggests that side stitches are simply diaphragm spasms caused by increased stress or pressure on the diaphragm during rapid, labored breathing.

• Ligament strain: Another possible cause is the stretching of ligaments between the diaphragm and some of the organs in the abdomen due to the jolting motion of nonstop movement combined with labored breathing.

• Poor circulation: When blood is diverted away from the diaphragm, which needs blood during exercise, it can cause a cramp in the area.

• GI issues: Eating too close to a workout can trigger a side stitch. If you don’t time your meals well and if you consume the wrong things too close to a workout, you’re more likely to get a side stitch.

• Weak core muscles: Weak abdominal muscles might also play a role because your body relies heavily on its core to stabilize each stride as you run.

• Increased stress on the spine: Increased stress on the spinal column due to the vertical and rotational components of running can place increased stress on the spine, which can then show up as sharp, localized pain in the side.

To prevent side aches, it is recommended to:

• Strengthen your core muscles.
• Avoid eating too close to a workout.
• Warm up and stretch well before running.
• Pace yourself by slowly increasing your speed.
• Focus on deep breathing when you feel a side stitch coming on.
• Increase your water intake throughout the day.

If you experience side aches while inactive or they persist after you stop your activity, its recommended to seek medical care.