Focusing on the core doesn’t stop in the front.  Focus on contracting the glutes during these back extensions.

Stop me if you’ve heard this one before…We need to focus on making sure the hips are getting open in the snatch and clean.  As you get used to it you’ll probably feel like you are heading backwards.  Thats just fine.  Get off of your toes, get those hips open, and you’ll feel much more comfortable in both lifts.