Many people with back pain avoid lifting in fear that they will further their injuries – however, in most circumstances they are furthering the problem by not lifting. Occasionally, avoidance of certain exercise is warranted, but only temporarily.
The spine is incredibly unstable – the muscles around the spine and through the hips are the primary stabilizers and in order to do their job, they must be strong and in proper balance with one another. The extension muscles (muscle of the back, glutes, and hamstrings) are very important muscles because as they extend the spine and hips, they also stabilize the spine and increase its rigidity. When people have back pain, they avoid using the extension muscles out of fear of injury.
The trick is to start off easy with the correct exercises and techniques.
In my opinion, the best exercise for back health is the reverse hyper (pictured below). There are several variations but the most common use a reverse hyper machine or a theraball on a bench. Whichever variation you use, always lie face down on your torso with your legs hanging down. Begin the exercise by lifting your legs (keeping them straight) until they are parallel to the floor. Then, lower them back to a relaxed position.
This exercise works your major posterior chain muscles in a way that mimics normal motor firing patterns (VERY IMPORTANT) without compressing the spine. At the bottom of the motion, in the relaxed position, you actually get traction. This movement combination increases the nutrient flow throughout the spine, encouraging healing and recovery as well as maintaining back health.
Once your back is healthy again, you can resume more aggressive exercises, such as romanian deadlifts, squats, and good mornings. Remember to start light and hold your breath throughout the motions (holding your breath improves rigidity of the spine by 40%). Be sure to keep reverse hypers mixed into your workouts for recovery purposes once back health is achieved.