Many people believed that the bone is static and inert, but this idea is incorrect. The organic and mineral components of the bone matrix are continually being recycled and renewed through a process called remodeling.
This process goes underway throughout life as a part of normal bone maintenance. Bone remodeling plays a key factor in the activities of osteocytes, osteoblasts, and osteoclasts. In the adult stage, osteocytes continually remove and replace the surrounding calcium salts. However, osteoclasts and osteoblasts also remain active even after the epiphyseal plates have closed.
For the most part, their activities have a balance. As one osteon forms through the activity of osteoblasts, another is destroyed by osteoclasts. In young adults, approximately one fifth of the adult skeleton is demolished and rebuilt or replaced each year. The turnover and recycling of minerals give each bone the ability to adapt to new stresses. The mechanism that controls the internal organization and structure is osteoblasts. Whenever a bone is stressed, the mineral crystals generate electrical fields.
Osteoblasts are attracted to electrical fields and begin producing bone once in the area. Bones are adaptable and their shapes reflect applied forces. Heavily stressed bones become thicker and stronger, while bones not exposed to ordinary stresses deteriorate. Therefore, it is important to exercise daily to maintain normal bone structure.