90% of the time it will come down to a lack of strength and stability through the core.
Watch this video to learn how to effectively "prime" your core prior to exercise and get the stability your back needs to feel strong.
Most of the time back pain is not a reason to skip exercising - in fact it's usually very manageable and often fixed with the right approach.
Make sure you talk to your coach if you're experiencing any back pain while you workout.
Be awesome.
Coach Jake