Stabilize your lumbar vertebrae during abdominal strengthening
The majority of lower back problems I see in my back classes results from compression of the lumbar discs. Therefore, I focus on three main areas to reduce compression in that region:
Core abdominal strengthening
When it comes to abdominal strengthening, there is a wide range of possible exercises one can do, but most risk arching the lower back which may compress the lumbar vertebrae even further. Practicing abdominal strengtheners in a supine position on the floor allows the floor to assist in lumbar stabilisation and provides a clear reference point as to whether one is arching the lower back or not in the execution of them.
Core strengthener 1
In the above sequence, keeping the knees bent throughout the movement reduces the load upon the abdominal muscles as they draw the legs in to the chest and then control their descent back down with eccentric contraction. Even so, the movement back to the floor is likely to arch the lower back unless one makes a concerted effort to actively press the lower back down. This effort requires both abdominal strengthening and posterior pelvic tilting.
Core strengthener 2
In the above practice, the movement of the leg away from the core risks bringing the lumbar vertebrae into an arched position. By maintaining the lower back flat during the outward movement of the leg, one engages the core abdominal muscles while stabilizing the lumbar vertebrae at the same time.
For those with a large arch, as is the case with lordosis, it will be extremely difficult to maintain the back completely flat. However, one can vary the angle of the extended leg. Extending the leg more vertically for someone with lordosis allows one to maintain the lower back stabilized on the floor while still engaging the core abdominals. In addition, one can regulate whether the leg is extended completely or only slightly (as shown) which will allow one to fine-tune the abdominal work safely.
Take a class
There are several other safe abdominal strengtheners in my lower back yoga class with a total of 28 practices in all to alleviate lower back discomfort. It's available as an iphone app. See a preview.