Muscle spasms are powerful involuntary muscle contractions, often with a sudden onset and quite painful. There are different types of muscle spasms, as well as different causes. But one thing that they all have in common is the fact that they interfere with voluntary movement.
Acute skeletal muscle spasms may be the result of muscle injury or overuse. They may occur, for instance, when an athlete has not warmed up or stretched prior to vigorous anaerobic exercise. They may also occur during endurance training when the athlete has not maintained proper fluid and electrolyte balance, and muscles with increased metabolic demand are depleted of nutrients.
Recurrent, widespread, or chronic muscle spasms may signify a more significant underlying medical condition related to toxic-metabolic, nutritional, vascular, or hormonal problems.
Muscle spasms may be the consequence of neurological damage or disease. For instance, a severe muscle spasm can result from irritation or damage to nerves supplying the muscle, such as in spinal stenosis or major disc herniations, which disrupt nerve root signals from the spinal cord. There are several brain regions responsible for the movement of skeletal muscles, so problems in one or several brain regions or nerve connections can result in abnormal muscle contractions.