A tendon is tissue that attaches muscle to bone. It is flexible, tough and fibrous and is designed to withstand tension. Tendinitis, also called tendonitis, is a condition whereby tendons become inflamed, irritated or suffer microscopic tears. In many cases the cause is unknown, but when it can be identified, the condition usually happens due to overuse and or overload. With overuse, a particular motion is repeated too often. Examples include the repeated gripping and swinging of a tennis racquet, or repeated gripping and twisting of a screwdriver. Overload occurs when the level of a certain activity, such as weightlifting, is increased too quickly. These methods of injury can also trigger protective reflexes in the fascia wrapped around the tendon itself and or other structures intimately connected with the tendon (arteries, veins, nerves, bone, for example). Symptoms of tendinitis usually occur at the point where the tendon attaches to a bone and they typically include pain that is often described as a dull ache, especially when moving the affected limb or joint. It is also often described as tenderness and/or mild swelling in the area of pain. Sometimes the pain with activity can be quite severe. Common areas affected by tendinitis include the shoulder (rotator cuff tendinitis), elbow (golfers elbow or tennis elbow), knee (jumpers knee), wrist/thumb (de Quervain’s disease), and the achilles tendon.