If your core is not strong and able to stabilise your torso, then any sudden body movement or lifting has the potential to “tweak” or injure your lower back. It is very common to have poorly activated core muscles and an imbalance where the back muscles are too strong compared with the abdominal muscles at the front. Poorly functioning/moving joints in the pelvis has been shown to contribute to poor core activation and chiropractic care has been shown to significantly improve this Abdominal activation. However, once the core is back to firing better you still need to exercise the muscles to re-build full strength and a healthy strength ratio between the front and the back of your torso. Ab-Crunches are one of the most effective ways to do this:
Lie on the ground with your knees bent and the soles of your feet on the ground. Press the small of your back flat against the floor and slowly crunch your ABS tight while curling your upper body up so that only your lower spine is touching the floor. Hold for a second and then slowly revert to the starting position and repeat.