It should be no shock to most athletes that a primary cause of back pain is a general weakness in specific muscles of the abdomen and the spine itself. In order to lift a heavy object and move with it, numerous muscles are recruited to project force, while others function to stabilize the spine and maintain it in a position of low chance of damage.
If any of the muscles are atrophied and lacking strength, in particultar the back muscles, instability may happen and a collapsing of the spine may occur even when picking up light objects. Thus, it is important to train all of the relevant muscles of the back to reduce weaknesses causing instability.
Along with endurance, the focus should be placed on correct movements and motor control. Keeping a neutral spine and using healthy posture when lifting or moving objects is extremely important in preventing pain and injury in the back. This is why the first step in healing from a back injury is often grooving correct movement patterns in patients.