Pilates, Exercise, & Osteoporosis (Part 2)

II. Definition of Osteoporosis

Basically, osteoporosis means porous bones. In the Greek it translates as “passages through bones.” (This makes perfect sense if you look at the images of osteoporotic bone as opposed to normal bone.) Osteoporosis is a silent disease in that there is no physical sensation associated with it. Some people experience back, neck, or joint pain with fractures, but most do not. Even so, Americans experience 1.5 million osteoporotic fractures per year.

Throughout our lives our bones constantly change. This process is actually called bone remodeling, where old bone is resorbed into the body with the help of cells called osteoclasts at the same time that new bone is being laid down by osteoblasts. The human skeleton reaches its maximum bone mass (amount of bone tissue) and density (how tightly it is packed) around ages 20-30, after which bone removal begins to occur faster than bone production.

Bone density is measured by comparison to that of this healthy young adult; this is called a T-Score. Normal Bone Density is defined by the World Health Organization as density within -1 standard deviation (SD) of the 20-30 year old norm (10-15% bone loss). Osteopenia, or low bone density, is defined as within -1 to -2.5 SD (15-25% bone loss). Osteoporosis is defined as lower than -2.5 SD (over 25% bone loss). You may also have heard of a Z-Score, which is a comparison to the average bone density of individuals in your age group. Primary osteoporosis is caused by either a natural estrogen deficiency or age; secondary osteoporosis is caused by certain medical conditions (see box). Osteopenia should be treated like osteoporosis in terms of preventing future loss. Once you have been diagnosed with osteoporosis, you have a documented severe and established loss of bone.

Note here that while bone density testing is typically done at several sites such as the hip, wrist, or spine, these findings should be generalized to your entire skeletal system. Many clients have told me that I shouldn’t worry about their spines because their osteoporosis was only in their hip--WRONG! If you are losing bone you should be worried, period.