There are a number of various reasons. Here are a few:
1. Not enough core conditioning, need more training 2. Experiencing cramps due to disorder or illness 3. Muscles are fast twitch, not for endurance sports 4. Breathing techniques
Some athletes in running sports experience abdominal distress because jolting movements are involved in their activity. The pain is caused by a strained visceral ligament in the abdomen connected to the diaphragm. Abdominal pain is common to the younger ones and amateur athletes.
