It may be caused by overuse or repetitive strain, improper stretching, or pulling the muscles during one particular motion. The particular muscles affected are the paravertebral muscles that are found on either side of the spine in the lower back. The muscles are used during everyday events such as walking or sitting down, but are especially strained during lifting. For a baseball player, the area is further strained by batting. During the motion of swinging the bat, the player quickly twists or wrenches his back.
Athletes are far more likely to strain back muscles as they grow older.
But strained backs are not limited to athletes. Many people strain back muscles while lifting heavy boxes or participating in sports, as they grow older. They are most often detected when athletes complain of soreness, pain, and tightness in the back. Typical strains include mild pain and almost constant discomfort. Tests such as X-rays may be used to distinguish muscular strains from bone problems, and an MRI or CAT scan may confirm the existence and severity of the injury.