Sprains found in your lower back tend to result from an excessive amount of force experienced on the back. It's not just from car crashes that you can experience lumbar sprains. Heavy weightlifters may also experience lumbar sprains.
Some athletes may also experience sprains in their lumbar regions because of improper posture during training or when they made the wrong form. The physical trauma will cause the muscles, tendons, and ligaments in the back to stretch to unsafe proportions.
The pain isn't often diagnosed by imaging technologies. Instead, it requires a direct doctor-patient consultation to properly determine the diagnosis.