Bone Mineral Density in Women Runners
There are lots of unanswered questions in osteoporosis research. What is the best way to measure bone mineral density (BMD)? How exactly does the disease develop? Does it affect all bones the same way? Does weight-bearing exercise only improve BMD in certain bones? What kind of exercise is best to improve BMD? Does training too hard actually make bones weaker?
These authors tackled some of these questions. They studied BMD in 49 white female distance runners. All the women were serious about running. The researchers measured BMD in 10 different places in the women's legs, arms, hip, ribs, and spine. This is many more measurements than are usually made in osteoporosis studies. Results showed that the runners had much higher BMD in the bones of the leg. This supports the theory that exercise improves BMD in the bones it works. The bones in the upper body had much lower BMD measurements.
The researchers looked at how BMD related to the women's training programs. Women who ran longer distances had higher BMD. However, women who had been running for many years had lower BMD, especially in the upper body.
The researchers also studied the way BMD related to diet. The amount of calcium taken seemed to have different effects depending on the bone. They saw little benefit of calcium in the hip, which is where BMD is often measured. Calcium did seem to be related to higher BMD in the legs.
Taking all these results together, the authors question if building bone in the legs means that the body can't build bone as well in other areas. It is an important question, especially for women athletes. The authors note that lifting weights for the upper body might help runners increase BMD in the upper body. More research is needed--and another question has been added to the study of osteoporosis.
References: Alan M. Nevill, et al. Does Lower-Body BMD Develop at the Expense of Upper-Body BMD in Female Runners? In Medicine & Science in Sports & Exercise. October 2003. Vol. 35. No. 10. Pp. 1733-1739.
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