Robert Ames wrote:
> Now to respond to the queries about longevity, I'll cite three
> studies. There are several other studies done in Finland on related
> subjects. I have to say that I've only read the first of these, and
> that was some time ago. Nevertheless the abstracts are clear
> enough. I wonder why no one else was able to find them. You did
> at least search Medline before asking, didn't you?
Thanks. I seem to have been too dumb to think of entering "weight"
and "lift*" as separate words rather than as "weightlift*".
I don't agree that the abstracts are clear, though. The topic under
discussion is rate of aging, not longevity; mean life expectancy and
amount of hospital care are much poorer indicators of the rate of aging
than the maximum life span, which the first abstract says was the same
in all groups. I also don't think one can extrapolate very much from
the BMI result in the last article: it says that power-sports athletes
have high BMI but low heart disease, whereas high BMI is bad for heart
disease in general, so it says that the power-sports athletes were
somehow protected from their high BMI.
Coming back to your original point, though -- that weightlifters have
high longevity but low mitochondrial density -- there is a complication.
In comparing weightlifters with endurance athletes one must also take
into account the changed surface-to-volume ratio. Bigger organisms
have a lower specific metabolic rate and consequent lower mitochondrial
density, assuming equal energy output on tasks other than thermogenesis.
I haven't found the result you mentioned that calcium toxicity reduces
mitochondrial density; I'd be interested to know how the alternative
interpretation I've just described was eliminated.
Aubrey de Grey