Tendon a decrease in the average thickness of the collagen fiber bundles comprising the tendon. In humans, an experiment in which people were subjected to a simulated micro-gravity environment found that tendon stiffness decreased significantly, even when subjects were required to perform restiveness exercises. These effects have implications in areas ranging from treatment of bedridden patients to the design of more effective exercises for astronauts. The tendons in the foot are highly complex and intricate. Therefore, the healing process for a broken tendon is long and painful. Most people who do not receive medical attention within the first 48 hours of
Achilles tendon tend to attach closer to the midline. Vibration of the tendon without vision has a major impact on postural orientation. Vibration of the tendon causes movement backwards and the illusion of a forward body tilt in standing subjects. This is because vibrations stimulate muscle spindles in the calf muscles. The muscle spindles alert the brain that the body is moving forward, so the central nervous system compensates by moving the body backwards. Inflammation of the Achilles tendon is called Achilles tendinitis. Achilles tendinosis is the soreness or stiffness of the tendon, particularly worse when exercising, and generally due to overuse.