Do YOU foam roll your lower back?
This might be one of the worst things you could do! Foam rolling is a great way to mobilize your thoracic spine and soft tissue but not so much the lower back aka lumbar and pelvic spinal regions. About where the thoracic spinal region ends is where it ends for foam rolling.
If we take a look at the lumbar spinal region, it sits right below the rib cage providing zero support while you foam roll. If we look above the lumbar region we've got a rib cage and shoulder blades to disperse some of the pressure given from the foam roller.
If you decide you feel tight or stiff in your lower back and foam rolling will help it, stop and think. What if you had a fracture or spinal stenosis? If that were the case then foam rolling is probably one of the worst things you could do. Instead, we should look into other areas to fix this tightness or stiffness.
If you look at how the muscular system works, the hip flexors and other muscles wrap from around the hip into the back and the quads are connected to that. So, try foam rolling those bigger quad muscles or glutes or something around those areas to loosen or relieve some tension in your lower back.