Psoriatic arthritis (PsA) is a chronic inflammatory condition that can cause muscle pain and weakness. You might find it difficult to move around and exercise, which could result in muscle loss.

If you live with psoriatic arthritis you may often experience muscle pain and weakness. There are several reasons for this, and we’ll explore the contributing factors in this section.

Immobility

PsA causes joint pain and stiffness. You might have limited mobility in your spine, arms, and legs, which can lead to decreased physical activity.

People with PsA often spend long periods sitting or lying in bed if their disease is not well managed. Over time, this can make your muscles weaker.

Inflammation

Another reason for muscle weakness and pain in people with PsA may be chronic inflammation.

Doctors measure levels of inflammation with blood markers such as C-reactive protein. High levels of this protein have been associated with smaller muscle size.

Inflammatory proteins in the blood can stimulate protein breakdown in the body and reduce protein production in the muscles. This leads to muscle wasting and decreased skeletal muscle mass and strength.

Obesity

Obesity can also contribute to inflammation.

Body fat increases the production of inflammatory markers in the blood, such as tumor necrosis factor (TNF), interleukin-6, and CRP. High levels of these are associated with psoriasis, psoriatic arthritis, and more severe arthritis symptoms.

Obesity is more common in people with PsA — up to 45% of people with PsA also have obesity.

A high body weight can cause worsening PsA symptoms. Extra weight increases joint stress and can increase musculoskeletal pain and injury. The higher levels of inflammation from obesity can also make some PsA medications, like TNF blockers, less effective.

Even after inflammation is managed, about 20% of people still have body pains. Some of this pain is thought to be caused by problems in pain signals from the nervous system.

Chronic low-grade or intense episodes of inflammation turn up the “volume” of nerve signals from the central nervous system. This can make you more sensitive to pain.

Pain can also be worse in women. A 2019 study found that women were two to three times more likely to have increased widespread pain.

Decreased muscle mass or muscle wasting (sarcopenia) can occur due to aging or immobility.

Muscle wasting can also be caused by nutritional deficiencies, chronic inflammation, and reduced physical activity. People with PsA who have chronic pain are less likely to do weight-bearing exercises and are more likely to be sedentary, which can lead to muscle wasting.

Loss of lean muscle mass can lead to weakness and disability. Some studies have demonstrated muscle loss from psoriatic arthritis.

In a 2020 study using MRI scans, hand muscle volume was found to be significantly decreased with age for people with psoriatic arthritis. The decrease in hand muscle volume was twice that in men than women among people with PsA.

Psoriatic arthritis is a musculoskeletal disease that can involve the joints, spine, or ligaments/tendons.

The musculoskeletal pain can present in four ways:

  • Axial arthritis: This is arthritis of the spine.
  • Peripheral arthritis: This is arthritis of the joints of the arms and legs.
  • Dactylitis: This causes swollen fingers or toes.
  • Enthesitis: This is inflammation of the site where a ligament or tendon inserts into a bone — these can include the Achilles tendon of the ankle, the elbows, heels, hips, knees, or shoulders.

Inflammatory back pain from psoriatic arthritis has the following characteristics:

  • It’s worse with inactivity.
  • It’s worse when rising in the morning, or it wakes you up in the middle of the night.
  • It improves with activity, worse with rest.
  • It occurs gradually.
  • It’s chronic (lasting more than 3 months).

Once the inflammation from the psoriatic arthritis is managed, you can introduce exercise. Physical activity has been shown to improve muscle strength and reduce pain.

Try low impact exercises such as swimming, walking, tai chi, yoga, and Pilates to help stretch your muscles and prevent stiffness. Talking with your doctor before trying high impact exercise is a good idea.

One 2018 study showed that resistant exercises using machine leg extension and a triceps machine, as well as free weights, reduced pain, improved daily function, and improved muscle strength.

Your doctor may refer you to physical therapy or occupational therapy. Massage therapy and acupuncture might be helpful for some people.

Applying heat and alternating with ice to the muscles may be soothing.

Fibromyalgia is a chronic pain condition that can coexist with rheumatic diseases, including PsA. Symptoms of fibromyalgia include:

  • widespread musculoskeletal pain
  • fatigue and problems with sleep
  • brain fog, or difficulty paying attention and concentrating
  • depression or anxiety
  • burning, numbness, or tingling sensation in the arms and legs
  • migraine attacks, headaches, or pelvic pain

In one study, 38.3% of participants with PsA also had fibromyalgia. Pain, tenderness, and fatigue were found to be increased in people with combined PsA and fibromyalgia, as compared to the PsA-only group and the fibromyalgia-only group.

Fibromyalgia is a clinical diagnosis. There’s no diagnostic blood test or X-ray. Your doctor may want to do additional tests to rule out other conditions.

Early treatment with medication can help manage PsA inflammation and reduce pain, muscle pain, and stiffness.

These medications include:

  • Nonsteroidal anti-inflammatory drugs (NSAIDs): These reduce pain and inflammation. They’re available over the counter or by prescription and include ibuprofen, naproxen, diclofenac, and meloxicam.
  • Disease-modifying antirheumatic drugs (DMARDs): Examples include methotrexate, leflunomide, and sulfasalazine. Your doctor might also prescribe targeted synthetic DMARDs such as tofacitinib (Xeljanz).
  • Biologics: These drugs are made from living cells and target cytokines or inflammatory proteins such as TNF IL-17, IL-12/23, IL-23, and CTLA4-Ig.
  • Apremilast (Otezla): This oral medication is commonly used to treat psoriasis and psoriatic arthritis.

If you receive a diagnosis of fibromyalgia and PsA, treatment for fibromyalgia includes medications such as anticonvulsants, antidepressants, muscle relaxants, and sleep aides.

Lifestyle changes for fibromyalgia include good sleep hygiene, low impact aerobic exercise, stress reduction through meditation, journaling, tai chi, yoga, and cognitive behavioral therapy.

Good nutrition and physical activity are essential for managing your psoriatic arthritis muscle pain.

It’s also important to eat enough protein. The recommended dietary allowance (RDA) for protein intake in most adults is 0.8 g per kg of body weight per day.

The National Psoriasis Foundation recommends a Mediterranean diet. Make sure your diet includes:

  • whole grains (quinoa, brown rice, whole grain bread)
  • extra virgin olive oil as the main cooking oil
  • low sugar fruits such as berries, apples, and pears (at least three servings daily)
  • fish or seafood, particularly fatty fish such as wild salmon, mackerel, and sardines
  • tree nuts and seeds, such as almonds and walnuts, which are high in omega-3 (at least three times weekly)
  • legumes such as beans and lentils (at least three servings weekly)
  • at least two servings of vegetables daily
  • very little or no sugar and white flour products

Dr. Margaret Li is an ABMS board certified physician with experience in internal medicine and rheumatology. She is a practicing physician at NYU-Langone Medical Center in New York City. She completed a 2-year fellowship in integrative medicine at the University of Arizona and has a special interest in treating the whole person through mind-body medicine as well as nutrition and lifestyle changes.