Tendons, or sinews, connect muscle to bone. The bones in a person's skeleton enable him or her to walk, run, jump, roll, lift, carry, drop, and do other important physical activities. Without the connection between the muscles and bones that are responsible for controlling these actions, it would be impossible for the body to move in the way it does. Since tendons are important for body movements, it is important to keep them strong, healthy, and free from harm.
The composition of tendons is much like gelatin, but harder and not as elastic. They are made of special cells called tenocytes, water, and fibrous collagen proteins. Millions of these collagen proteins weave together to form the strong strand of flexible tissue. Tendons grow into the bone and form a tough mineralized connection. This connection creates a permanent bond that is extremely tough to break.
Despite their incredible strength, tendons can be damaged if overstrained or improperly cared for. Overuse can cause the collagen fibers to form small tears, a condition called tendinitis. Damage most often occurs in the knee, ankle, shoulder, wrist, bicep, calf, and back of the heel, which is called the Achilles tendon. This tendon is named after the mythological figure, Achilles, who was killed when an arrow struck him in the back of his heel. The Achilles tendon connects the heel to the back of the calf, and since it is used so frequently, it is one of the most commonly damaged.
Tendons cannot easily heal from damage, which makes medical intervention necessary when one is injured. If they are damaged, anti-inflammatory drugs are used to bring the swelling down. Complete rest for a long period of time is generally mandatory. If one tears completely, surgical intervention is necessary to reconnect the tissue to the bone.
Strength training can help ensure that the tendons remain tough and less susceptible to damage. As a person ages, this tissue also ages, and excess weight and activity can slowly weaken them over time.