Joint and muscle pain are common health complaints. According to the Merck Manuals website, muscle pain occurs when muscle fibers are affected by an injury, autoimmune reaction and decreased blood flow or infection, and almost all joint injuries produce a stiff, aching pain. Joint and muscle pain may be the only symptom associated with a musculoskeletal injury, or it may be accompanied by other symptoms, including stiffness, decreased range of motion and swelling and inflammation.
Stiffness
Joint and muscle pain is often accompanied by stiffness in one or both structures. According to the U.S. National Library of Medicine and the National Institutes of Health, or NIH, rheumatoid arthritis is an autoimmune disorder that causes both stiffness and pain in the joints. The Cure Research website states that there are numerous possible causes of joint stiffness, including the following: osteoarthritis, inactivity, joint injury, normal aging, certain muscle and neurological disorders and medical conditions, such as ankylosing spondylitis, which lead to fusion of the spinal joints.
Muscle stiffness may be caused by vigorous physical activity following a prolonged period of sedentary living. A more severe form of muscle stiffness, among elite athletes and weekend warriors alike, is delayed onset muscle soreness, or DOMS. DOMS is characterized by pain and stiffness in the muscle for 24 to 72 hours post-exercise. The Cure Research website states that certain medical conditions can cause muscle stiffness, including myotonic dystrophy, Rocky Mountain spotted fever, spastic disorders and tetanus.
Decreased Joint Range of Motion
A common symptom associated with joint and muscle pain is decreased range of motion, although pain does not have to be present for a person to experience a reduced range of motion in one or more joints or body segments. According to the NIH, range of motion refers to the distance and direction of a joint's movement. Reduced range of motion means that a specific joint or body segment cannot be moved through its full, dynamic range of motion. The NIH states that joint range of motion may be limited by a mechanical problem within the joint, such as a free-floating piece of cartilage in the knee joint, along with tissue swelling around the joint, muscle stiffness or pain. Other possible causes of decreased joint range of motion include medical conditions that prevent a joint from fully extending, causing contracture deformities and an inability to move the involved body part or joint past a fixed position. Scar tissue from injuries or surgery may also be painful and limit a joint's range of motion.
Swelling & Inflammation
Swelling and inflammation--due to traumatic soft tissue injury and certain medical conditions--can affect joint and muscles, causing pain or discomfort and limiting active range of motion in the affected joint or body segment. According to the Cleveland Clinic--one of the top four hospitals in the United States--inflammation is a process in which a person's white blood cells and other chemicals protect her from infection and foreign substances. Swelling around injured tissues occurs after a sprain or strain injury, as a response to soft tissue damage. Excessive swelling and inflammation, along with the pain that typically accompanies these types of injuries, reduces a person's active range of motion. The Cleveland Clinic states that the following medical conditions may cause joint inflammation: rheumatoid arthritis, shoulder tendinitis or bursitis, gouty arthritis and polymyalgia rheumatica.
