Lumbar muscle spasms are involuntary contractions of the muscles of the lumbar region of the back (the lower back).

The back's muscles and any of the ligaments can be injured or irritated. What causes trouble may be a sudden movement in the heat of a tennis match or a game of touch football, or a fall, twist, or sudden muscle contraction to avoid a fall. Sudden pain usually follows a clear-cut injury, though there may be a delay of hours or even a day or two. Specific movements tend to aggravate...