What causes muscle weakness?

True weakness means a muscle cannot produce its usual force, such as difficulty climbing stairs, lifting an arm, gripping, or rising from a chair. Pain can also make movement feel weak, so the distinction matters. A pinched nerve in the neck, called Cervical Radiculopathy, may affect an arm with pain or altered sensation. A Rotator Cuff Tear can reduce shoulder strength. Polymyalgia Rheumatica may make the shoulders and hips feel weak because of pain and stiffness. Sarcopenia and Vitamin D Deficiency are other possible contributors, alongside illness, medication effects, and prolonged inactivity.

Note when weakness began, which movements are affected, and whether it is on one side or both. Keep gently active within your limits, eat regularly, and avoid pushing through sudden loss of strength. A clinician may examine nerves and muscles and review medicines or blood tests. Strength Training Rehabilitation can rebuild capacity when deconditioning is involved; Vitamin D Supplementation is appropriate only when a clinician identifies a need.

Arrange an assessment for unexplained, persistent, progressive, or function-limiting weakness. Seek emergency help for sudden weakness of the face, arm, or leg; trouble speaking, breathing, or swallowing; new severe headache; or weakness after a significant injury.

Ask whether the problem is true weakness or pain-limited movement, which nerves or muscles may be involved, and whether testing or supervised rehabilitation is needed.