What causes coning?

Coning occurs when diastasis recti is present and an increase in intra-abdominal pressure pushes the linea alba outward. Externally, this can look like a ridge appears along the midline, or like a bulge or tenting of the abdomen when someone sits up or performs a crunch. Where coning occurs, that indicates an underlying thinning and weaking of the connective tissue between the two halves of the rectus abdominis.