Mark, and others interested in the osteoporosis/exercise discussion,

My apologies for taking a while to respond to your comments.

You say:

To my knowledge, there are in fact no
>well-designed (randomised controlled, longitudinal) studies published for
>exercise intervention in a sample of individuals classified as having

I agree that the majority of exercise intervention trials have tended to
exclude osteoporotic individuals and that this is problematic for the
wholesale application of results. A few papers, however, such as Ayalon et
al., Arch Phys Med Rehab 68(5): 280-83, 1987; Dilsen et al., Clin Rheumatol
8 (Suppl 2): 70-5, 1989; and Simkin et al., Calcif Tiss Int 40:59-63, 1987,
have reported findings specifically from osteoporotic cohorts. Although
these trials were relatively short term (5-6 months), each reported a
beneficial effect of exercise on BMD. One problem in this area is that it
is often difficult to tell whether some or all of the subjects in a study
were osteoporotic because it was not specifically stated. For example, the
subjects in a study by Krolner et al. (Clinical Science, 64: 541-546, 1983)
may have been at least osteopenic as they were recruited from women treated
for previous Colle's fractures, but they were not described as such.

A paper which addresses the question of the safety of exercising
osteoporotic patients (Chow et al., Int J Rehabil Res 12[1]:49-56, 1989)
describes a Toronto program aimed to prevent bone loss in osteoporotic
patients. They reported improvements in bone mass (and other indices of
well-being and health) after one year of exercise with no incidence of
fracture. Unfortunately, I have only been able to get the abstract of this
paper so I have not been able to critique it in full. Along the same lines
of exercise and fracture risk, the Tromso study (Joakimsen et al., 1998,
13[7]:1149-1157) concluded that physically active people, 45 yrs or older,
suffered fewer low-energy fractures in the weight bearing skeleton than
sedentary people.

Just to clarify a point from my last post, I would not recommend HIGH
impact activities for osteoporotic individuals. I should probably have
used the term "weight bearing" rather than "impact" to avoid the
implication that sudden, large magnitude loads are non-injurious to an
osteoporotic skeleton, which, of course, they can be. Further, Joakimsen
et al. (1998) found that it was not necessary to perform vigorous, high
intensity activity to invoke the protective effect of exercise against
fracture risk.

I want to also include a disclaimer that, as do the vast majority of
reports in this area, the above cited studies contain a number of design
and methodological flaws. Pristine design and methodology of human
exercise intervention trials is an important goal, but has clearly been
very difficult to achieve.

All the best,

Belinda Beck, Ph. D.
Stanford University
Musculoskeletal Research Lab
Veterans Affairs Medical Center, Menlo Park
795 Willow Road, Bldg. 301
Menlo Park, CA 94025
U. S. A.
Phone: (650) 493 5000 x22336
Fax: (650) 617 2606

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