Back injury results from damage, wear, or trauma to the bones, muscles, or other tissues of the back. Common back injury include sprains and strains, herniated disks, and fractured vertebrae. The lumbar is often the site of back pain. The area is susceptible because of its flexibility and the amount of body weight it regularly bears. It is estimated that low-back pain may affect as much as 50 to 70 percent of the general population in the United States. Damage may be prevented by attention to posture, flexibility, muscle strength and fitness.