Muscle rigidity, also known as muscle tension, rigor, or stiffness, is one of the most common causes of muscle pain.
It’s characterized by the inability of the muscles to relax normally. The condition can affect any of the muscles in the body, causing sharp pain that makes it difficult to move.
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 muscles
- chronic exertional compartment syndrome, which is an exercise-induced muscle and nerve condition that causes pain and swelling
- chronic fatigue syndrome, which is a condition that causes extreme fatigue, sleep abnormalities, and muscle pain
- claudication, which is a condition in which cramping occurs due to a lack of blood flow to the muscles, usually in the legs
- dehydration, which is a condition that develops as a result of not drinking enough water
- delayed-onset muscle soreness, which is a condition characterized by muscle pain and stiffness that develops hours or days after very strenuous exercise
- dystonia, which is a condition that causes random and involuntary muscle contractions
- fibromyalgia, which is a chronic disorder that can cause muscle soreness, pain, and rigidity
- lupus, which is a chronic inflammatory disease that can cause pain and stiffness in the joints
- Lyme disease and Rocky Mountain spotted fever, which are tick-borne illnesses that can cause nerve damage
- myofascial 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 movement
- polymyalgia rheumatica, which is a chronic inflammatory disease that can cause muscle pain and stiffness, especially in the shoulders
- repetitive strain injury, which is an injury to the muscles or nerves as a result of muscle overuse
- rheumatoid arthritis, which is a chronic inflammatory disorder affecting the joints, especially those in the hands and feet
- bacterial and viral infections
- pinched nerves
If you know that your muscle rigidity is the result of a minor injury, stress or overuse, then you can usually treat it at home effectively. However, if you suspect that your muscle stiffness is being caused by a severe injury or an undiagnosed condition, you should call your doctor.
You should also contact your doctor if your muscle rigidity doesn’t go away within one week or is accompanied by any of the following:
- a tick bite
- an unexplainable rash
- red and swollen muscles
- an increase in medication dosage or a change in medication
Call 911 or go to the emergency room right away if you experience muscle rigidity along with any of the following symptoms:
- difficulty breathing
- severe muscle weakness
- a high fever
- neck stiffness
To diagnose muscle rigidity, your doctor will first request your medical history and perform a physical exam. They may also run laboratory tests to look for muscle damage and to rule out any possible underlying conditions that may be causing your muscle rigidity.
These tests may include:
- blood tests, which can help your doctor check for muscle damage and the presence of certain autoimmune disorders that can cause rigidity
- MRI and CT scans, which can reveal any bone abnormalities that may be causing pinched nerves
- an electromyogram, which can help your doctor evaluate how well the muscles and nerves are working
- an ultrasound, which can help your doctor find tears and inflammation in muscle fibers
The main goal of treatment is to encourage the muscles to relax. The specific treatment used for muscle rigidity can vary depending on the cause.
Home remedies are usually effective in treating muscle rigidity caused by minor injuries, stress, or overuse. They can include the following:
- Applying a warm compress or heating pad to the affected muscle to help relax rigid muscles.
- Gently stretching your stiff muscle to help relax it.
- Avoiding strenuous activity that may trigger the muscle to become rigid again.
- Encouraging the muscles to relax using massage, yoga, or tai chi.
You’ll need medical treatment for any severe injuries or underlying health conditions that may be causing your muscle rigidity. Treatment will first address the condition or injury and then the muscle rigidity.
Depending on the specific cause of your muscle rigidity, medical treatment may involve surgery, medications, and physical therapy. You and your doctor can discuss which treatments would be best for you.