Bracing abs during bench press

[Sandisk]

Is there actually any need to brace the abs during the bench press? Because it seems to reduce the back arch

[Jeff Illingworth]

Yes. Without bracing the abs, you can't really valsalva and there would also be nothing for your back to arch against.

[Bryan Dobson]

The ridgidity of the torso is more important than than the size of the arch if you use leg drive.