Back injuries can be extremely painful and long-lasting. OSHA reports that "Back strain due to overexertion represents one of the largest segments of employee injuries in the American workplace. Only the common cold accounts for more lost days of work." The National Safety Council has stated that overexertion is the cause of about 31 percent of all disabling work injuries. It's important to know what types of acts are likely to cause back strain and how to work in ways to reduce the risk.