Intra-abdominal pressure supports the body during heavy lifts like deadlifts and squats, but is worked against during abdominal exercises.

“and finally the final detail is you need to use that intraabdominal pressure as your friend uh because in lifting like a deadlift or squad or something intraabdominal pressure helps you it supports you when you're doing abdominal work you work against that abdominal pre intraabdominal pressure”