Achilles Tendonitis is a condition of irritation and inflammation of the large tendon in the back of the ankle. It is a common problem often experienced by sports men, particularly distance runners. Individuals who suffer from Achilles Tendonitis often complain that their first steps out of bed in the morning are extremely painful. Another common complaint is pain after steps are taken after long periods of sitting. Achilles Tendonitis is a condition of irritation and inflammation of the large tendon in the back of the ankle. It is a common problem often experienced by sports men, particularly distance runners. Individuals who suffer from Achilles Tendonitis often complain that their first steps out of bed in the morning are extremely painful. Another common complaint is pain after steps are taken after long periods of sitting.