Muscle spasms can occur due to several causes, including a lack of nutrients, muscular tension, overuse of the muscle, increased demand of
blood flow, or various underlying medical conditions.
Dehydration and imbalances of electrolytes (e.g., sodium, calcium, potassium, magnesium) can prevent muscle cells from receiving a necessary nutrient supply, causing them to become more prone to spastic and random contractions. Occupations that require working in hot environments (e.g., construction and factory workers, athletes) may predispose an individual to dehydration and subsequent muscle cramps.
Spasms due to muscular tension or overuse are typically experienced when holding a certain position for too long or when
exercising without stretching the muscles. Similarly, strenuous exercise can cause muscular tension and lead to an increased demand for blood flow to the muscles. If the
body cannot meet the demands of the muscle cells,
muscle spasms can result. The risk of muscle cramps also increases with age, excess body weight, and pregnancy. However, in many cases, the exact cause of a
muscle spasm may be unknown.
While
muscle spasms are typically harmless, they may be tied to an underlying medical condition.
Arteriosclerosis, a condition that causes narrowing of the arteries, is one example. In an individual with arteriosclerosis, blood flow to the extremities (e.g., the arms and legs) can be compromised, leading to oxygen and nutrient deprivation that may cause muscle cramps. Nerve compression in the
lumbar spinal cord, the lowest major portion of the
spinal cord, can be another trigger for
muscle spasms, specifically cramping of the legs that worsens when walking long distances. Notably, neurodegenerative conditions, such as
multiple sclerosis (MS) and
amyotrophic lateral sclerosis (ALS), are associated with
muscle spasms.