Dear all,

I have noticed a number of articles on the "stone age diet" (aka the
paleolithic diet) on the web lately. These mainly talk about how little
magnesium (too little seafood!) and too much sodium chloride and coffee
in our diet might cause many of our modern ailments (everything from
acne to osteoporosis some sites claim).

The other day I saw a claim on some of these sites that might be of
interest to those involved in biomechanics. The authors' contention is
that a sedentary life reduces the mineralization of our bones.
Apparently ambulatory exercises that cause high impact stresses on the
leg bones (such as walking and jogging) increase the production of
calcitonin and thus increase the deposition of calcium in the bones and
enlarge their cross sectional area (and possibly their bone density).
Hence many sports (such as cycling and swimming) and bench-based
gymnasium exercise are not quite so beneficial because they are not as
likely to cause calcitonin production.

The article ("Factors that Inhibit Calcium Absorption" by Ron Hoggan &
Don Wiss) quotes a textbook (Tortora and Grabowski, "Principles of
Anatomy & Physiology", Harper Collins, N.Y., 1996) but no journal
references for this particular topic.

Cut out tiring, expensive gymnasium exercises and do more cheap
do-it-yourself walks (and eat more fish); this sounds almost too good to
be true!

Does anyone know if there has been any good new research on the topic of
high impact exercises, calcitonin secretion and bone strength published
recently?

By the way the idea that high impact exercises are particularly good
might lie behind the various leg stamping and hand slapping training
exercises of the sumo wrestlers; has anyone been evaluating their
skeletal effects lately?

Regards,

David McFarlane
Ergonomist, WorkCover NSW

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