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Mark Forwood
07-09-1998, 10:28 AM
Dear Belinda,

While I agreed with much of the information you provided concerning the
adaptive responses of bone, I would like to urge a certain amount of caution
in extrapolating these data, and the data from exercise in young or aging
individuals, to "exercise for osteoporosis". For example, you note
>
>... that there is a large
>body of literature available regarding the effects of exercise loading on
>bone, particularly osteoporotic bone.

Unfortunately, this is not the case. 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
osteoporosis. (I would be happy to hear from you that there some of these
now published). There is a large number of studies published for exercise
effects on bone in various populations, including aged individuals, and some
in which the subjects are classified as having osteopenia (eg Nelson et al,
1994). Even in these, the number of studies with a robust design is
remarkably small. Then when considering attempts to determine optimal
physical activities or training volumes for effecting a positive bone
adaptation, the studies simply have not been done.

Participants in most studies are usually "healthy" men, pre or
post-menopausal women selected according to various exclusion criteria. In
addition, women with significant chronic disease or medications known to
affect bone density may also be excluded (eg Kerr et al., 1996). Of
importance is the fact that subjects excluded from studies for a criterion
such as low bone mass are among a very well defined group of patients who
are often referred for bone density assessment. These subjects then seek
advice for the appropriate type and quantity of exercise. Yet it is this
population for which the least information is available from the literature.

One must remember that osteoporosis is not synonymous with osteopenia or
age-related bone loss. At present, clinical criteria are based on WHO
recommendations that a bone density 2.5 standard deviations or more below
the young adult mean in the same sex at the same site is indicative of
osteoporosis. The general definition also emphasises the point that under
these conditions there is "enhanced bone fragility and a CONSEQUENT INCREASE
IN FRACTURE RISK". To advocate a "general" recommendation to start
exercising, particularly including "impact" loading in this population,
without considering the individual circumstances, is quite unwise. They are
at greater risk of fracture! The most recent WHO Guidelines for Preclinical
Evaluation and Clinical Trials in Osteoporosis makes the point strongly that
there may be hazards, associated with prescriptive exercise in osteoporotic
subjects; and a regrettable dearth of reporting adverse events in the
publications in this area.

Your comments about avoiding certain exercises that involve dynamic
abdominal training or vertebral flexion are important and relevant. The
goals for exercise in subjects with osteoporosis should include increased
muscle strength and endurance, improved balance and stability, increased
mobility and quality of life, reduction of pain, improvement of posture -
all of which largely reduce the propensity to fall. The types of exercise
that may be useful initially would include "some" well-supervised resistance
exercises (the resistance might come from rubber tubing as much as from
weights), low-impact physical activity, water exercise or hydrotherapy. The
exercise program would be advanced based on individual characteristics and
improvement. Placing a weight on the shoulders of a patient with
osteoporosis for the performance of squats would concern me greatly.
Alternatives such as seated leg press would be far more appropriate, but
these are just examples. Other types of exercises to avoid would be those
that involve twisting (eg golf swing), and those which are abrupt or
explosive in nature.

I have not addressed some of the concerns in the original message from
Justin, but felt that the application of principles from "general" exercise
studies to the population with osteoporosis needs to be undertaken with
gretaer caution. There is a real danger of adverse events (fracture) in this
group.

Best wishes

Mark Forwood


>
__________________________________________________ __________________
Mark R. Forwood PhD Tel: (07) 3365 2818
Anatomical Sciences Fax: (07) 3365 1299
The University of Queensland International +61 7 3365 1299
Brisbane Q 4072 Email: m.forwood@mailbox.uq.edu.au
AUSTRALIA
WWW: http://www.uq.edu.au/anatomy/StaffInterests/forwoo_m.html

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