There are many detrimental effects of sitting in addition to the physical inactivity itself, which has links to obesity, diabetes and so on.
For example, when standing, the spine has a characteristic ‘s’ shape whereas sitting curves the spine into a ‘c’ shape, which compresses the discs between the vertebrae and can increase the risk of back injury.
Hip and knee flexor muscles may shorten with too much sitting, which reduces the range of motion of those joints.
Muscle inactivity can result in pooling of blood in the legs, which can lead to varicose veins and increases the risk of deep-vein thrombosis.
Reduced lymphatic drainage leads to swelling at the extremities, puffiness in the eyes and face, and fatigue headaches.
In prolonged sitting, internal organ function is impaired.
Bowel mobility is reduced and your digestion is not as efficient, while reduced diaphragm movement can cut lung capacity after as little as an hour.
A simple way of reducing the risks from sitting is to stand up and move at least every half an hour and to take daily exercise.