There are muscles all over your body. When you need to move a particular part of your body, your brain sends a nerve signal to the muscles located in that body part. This causes the muscles to tighten, or contract.
Muscles can contract a little bit or a lot, depending on the type of signal the brain sends. After contracting, the muscles relax until the next time you need to use them.
Muscle rigidity happens when a muscle or a group of muscles stays contracted or partly contracted for an extended period. The brain continues to send nerve signals telling the muscle to contract even when the muscle is no longer needed for movement.
This can sometimes last for several hours or days. The longer your muscle remains contracted, the more pain you’ll feel.
Muscle rigidity is often triggered by stress.
Stress can adversely affect your body’s nervous system — including your nerves — and how they function.
Your nervous system may respond to stress by putting additional pressure on the blood vessels, which results in reduced blood flow to the muscles. This can cause muscle tension and pain.
Certain medications, such as statins, can also cause muscle rigidity. Some medical conditions may also contribute to it. These include:
amyotrophic lateral sclerosis, which is a progressive neurodegenerative disease that causes nerve problems and a loss of control of voluntary muscleschronic exertional compartment syndrome, which is an exercise-induced muscle and nerve condition that causes pain and swellingchronic fatigue syndrome, which is a condition that causes extreme fatigue, sleep abnormalities, and muscle painclaudication, which is a condition in which cramping occurs due to a lack of blood flow to the muscles, usually in the legsdehydration, which is a condition that develops as a result of not drinking enough waterdelayed-onset muscle soreness, which is a condition characterized by muscle pain and stiffness that develops hours or days after very strenuous exercisedystonia, which is a condition that causes random and involuntary muscle contractionsfibromyalgia, which is a chronic disorder that can cause muscle soreness, pain, and rigiditylupus, which is a chronic inflammatory disease that can cause pain and stiffness in the jointsLyme disease and Rocky Mountain spotted fever, which are tick-borne illnesses that can cause nerve damagemyofascial pain syndrome, which is a chronic disorder in which pressure on sensitive points in the muscles causes pain Parkinson’s disease, which is a progressive neurological disease that affects movementpolymyalgia rheumatica, which is a chronic inflammatory disease that can cause muscle pain and stiffness, especially in the shouldersrepetitive strain injury, which is an injury to the muscles or nerves as a result of muscle overuserheumatoid arthritis, which is a chronic inflammatory disorder affecting the joints, especially those in the hands and feetbacterial and viral infectionspinched nerves