Dana Sorensen and Jono Green, co-owners at Symbiotic Training Center, talk about the most under-utilized core exercise for pitchers: deep breathing.
The diaphragm is directly attached to the spine and ribs, so it constitutes the most powerful core system that can control spine movement. Athletes who are efficient breathers (full breaths in and full exhalation) will increase spine health by training the core muscles to support the spine.
A simple breathing technique for players to do on their own or at practice: deep breaths in and a FULL exhalation out. Many people take in too much oxygen but only exhale partially. Force the breath out of the diaphragm. A simple count for this exercise is 5 seconds inhale, 3 seconds hold, and then 8 seconds exhale. Repeat for 10 breaths.