The pathway of these signals has been extensively studied in cell culture, in animal studies and in humans. The dominant arm of tennis players is much larger and stronger than the non-dominant arm. Exercise programmes can increase bone mass at all ages. Osteoporosis leads to fractures of the spine, the wrist and the hips. It thereby causes acute and chronic pain and can lead to invalidation.
Osteoporosis is the most common metabolic bone disease in the industrialised world .
It used to be a women's disease, but it is now just as much a disease of men. As explained above, the skeleton behaves like a mechanostat - and as the physical demands decrease with adaptation to the modern lifestyle, so the mechanostat will react, and bone mass and strength will decrease to a very low level. Summary Bones are living structures which undergo dynamic changes throughout life. The four different bone cells each play a role concerning bone turnover. The balance in this turnover is determined by hormonal factors and mechanical usage.