A common misconception that I hear often is the idea that strengthening your back will result in reduced risk of back pain or even build a more healthy back and spine. I've had many patients that were under the belief that doing exercises like hyperextensions, deadlifts, etc would make them have a stronger back therefore decreasing their chance of having back pain. Those exercises do in fact build strength, unfortunately that is not what seems to prevent back pain.
Research shows that building muscle endurance, not strength, is a more accurate way to prevent back pain. The muscles of the low back are postural muscles which are designed for sustaining long contractions without fatiguing. In order to build a healthy spine and avoid back pain, you're goal should be to increase endurance (slow twitch fibers) of these muscles.
Obviously the way you would build endurance in a muscle is different than how you would build strength. Here are a few examples of how to build endurance of the lower back and spinal muscles to help prevent back pain.