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Christine

September 9, 2007

Some facts about Osteoporosis

We've all heard about Osteoporosis, mostly via tv commercials for such pharmaceutical products as Boniva ® and Actonel ®. Many of us also have known elderly people, even had grandparents or parents who have suffered a broken hip or wrist. Usually, such injuries are attributed to the inevitable "brittle bones" that are associated with aging. What is often not discussed is the frightening fact that mortality rates in the first year following a broken hip are around 25% among older patients, and among those who live, another 20% will need assisted living with a year of the fracture.

It is important that we all become educated about this disease and about ways to minimize risk in developing it, especially for those who fall into the higher-risk categories. Certainly, the weight-lifting and weight-bearing workouts we do at the gym are extremely important in reducing our risk of developing Osteoporosis, along with other healthy lifestyle choices.

This week, I have pulled out excerpts from an article about Osteoporosis that was the feature story in the August/September issue of the American Council on Exercise's "Certification News". The following quoted text is from:
"Osteoporosis Health: A Review for Fitness Professionals." By Namju Lee, PH.D, Boyeon Kim, M.S. and Len Kravitz, PH.D.

Who is at most risk for the disease?

Small-boned, caucasian and asian women are at most risk. Interestingly, it is becoming more clear that genetics play a large role in one's likelihood of developing OP. The ACE Certified News story states that recent "studies have suggested that 70 percent to 85 percent of the variance in bone mass density might be genetic."
Factors such as one's bone size, gender, race and age can't be changed. However, many lifestyle factors can contribute to the risk of developing osteoporosis and these can be modified. These higher-risk lifestyle factors would include: physical inactivity, smoking, excessive alcohol consumption, and inadequate vitamin and mineral intake and/or absorption.

In order to understand osteoporosis, it is important (and quite interesting I might add) to understand the ways that our bones are constantly transforming. Though we often might think of bones as being these hard, tough structures in our bodies, they are living tissue that constantly maintains itself in relationship to external stresses and internal needs, just like all of our bodies' tissues.

When we are young, our bones go through a process called "modeling", in which they grow in length and width via specialized cells called Osteoblasts, which are responsible for bone formation. Once we stop growing, the bones continue a process referred to as "Remodeling", in which older tissue and minerals are removed by specialized bone-removing cells called Osteoclasts, and replaced by tissue created by Osteoblasts. This fine balance between destruction and construction is mediated and carried out in response to mechanical loading and availability of minerals (mostly calcium) and is affected by reproductive hormones.

It makes sense then, that if the bones are not being loaded on a regular basis, that the osteoblasts will not be as active in creating new tissue, since it seems that it isn't needed. This creates an unbalanced situation in which more tissue is being destroyed and not replaced. This leads to lower bone density. As more mechanical and functional demands are placed on the skeleton, the bone adapts, making the osteoblasts produce more new bone tissue in the wake of the osteoclasts' destruction of old tissue and thus remodels itself in a process known as "Wolff's Law (Pearson & Lieberman, 2004) "

Given this knowledge, the role exercise plays in keeping bones strong is easy to understand. Higher- intensity weight-bearing exercises such as running and jumping, lifting heavier weights all provide the high-level stimulus that forces those osteoblasts to keep producing new bone material.

What is the full exercise and bone health relationship? ie, what exactly do you have to do at the gym to increase your bone density and reduce your risk of osteoporosis? We'll discuss this in more depth next week, so be sure to visit SWAC Fitness Info next week!

Past SWAC Fitness Info Articles