Fasciculation may be due to fatigue, cold, medications, metabolic disorders, nerve damage, or neurodegenerative disease, including amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig's disease).
These include stiffness at rest, slow muscle relaxation, and spontaneous contractions of a muscle at rest (fasciculation).
Fasciculation is a type of painless muscle spasm, marked by rapid, uncoordinated contraction of many small muscle fibers.
Most people experience brief, mild fasciculation from time to time, usually in the calves.
Fasciculation may occur at rest or after muscle contraction and may last several minutes.