Synovial joints offer the widest range of motion for your body, making them an essential part of exercise. These joints provide lubrication and cushioning to bones and tissues as you exercise. In return, exercising has the potential to maintain synovial joint health.
Synovial Joint Features
Synovial joints feature a synovial cavity surrounded by a synovial membrane that is filled with with fluid, which nourishes the articular cartilage. Bones encased in this type of joint are covered in hyalin cartilage, a substance that provides cushioning between the bones. Synovial membrane cells secrete substances called hyaluronan and lubricin into the synovial fluid to increase hyalin cartilage density and elasticity. Synovial fluid also helps protect your body from infection and inflammation.
Movement of Synovial Joints
Exercise requires the use of almost all six types of synovial joints. Ball and socket joints -- like the hip and shoulder -- provide the greatest range of motion while your fingers, toes and elbows are hinge joints and move in two directions. Pivot joints are found between bones like the radius and ulna in the forearm, with one bone rotating around the other. Your wrist contains condyloid or ellipsoidal joints -- where the contact surface of one bone is concave and the other is convex, allowing the joint to move in a circle. Saddle joints -- found in your thumb -- have similar range of motion to condyloid joints, but are shaped like a saddle. Your acromioclavicular joint, which is part of your shoulder, is an example of a gliding joint.
Joints During Exercise
Common forms of exercise like walking, running, biking and swimming use a variety of synovial joints. Your knee plays a major role in bipedal motion; it is necessary for the flexion and extension of your leg. Your feet contain condyloid and hinge joints that absorb impact and transfer motion. During a tennis match your shoulder blade and collarbone glide together while your elbow hinges to power your serve and ground strokes. Your hips are in almost constant motion, with the ball and socket joint rotating to keep you upright or help you sit, twist or move laterally. Exercising regularly can help keep your joints in working order.
Exercise and Synovial Fluid
Exercising may help increase the protective power of synovial fluid, and may potentially help manage arthritis and osteoarthritis. These diseases are characterized by a breakdown of joint cartilage as well as decreases in synovial fluid and increases in inflammatory substances. An article in "Arthritis Research & Therapy" in July 2010 examined the effects of exercise on women with osteoarthritis of the knee. The study found that women who exercised experienced increases in anti-inflammatory substances in their synovial fluid. In comparison, the non-exercising group did not experience these effects. If you have arthritis or osteoarthritis, talk to your doctor before beginning an exercise program.