I have seen concern on this list that aerobic exercise, by producing
oxidative stress, could actually *decrease* longevity if taken to extremes.
I have two comments on this:
1) This notion is not supported by epidemeological data. In studies of the
death risk of distance runners, for example, number of miles run per day
correlated with likelihood of surviving the study. Since the average
distance runner is well exceeding 30 minutes of cardio exercise per day,
this supports the notion that even large amounts of aerobic exercise
increase rather than decrease longevity.
Also note that several studies on CR in rats have found that
a) Exercise does not offset the benefits of CR by producing increased
oxidative stress; and
b) The effects of exercise and CR are not additive in rats; and
c) Exercising rats tend to outlive CR rats
References: McCarter (97), Holloszy (97), Holloszy (98)
(See especially the McCarter paper which shows exercising rats outliving CR
rats.)
2) The 9 November Nature Insight section on ageing engages in some
speculation on the need for acute oxidative stress to build up oxidative
stress resistance. In particular it theories that one mechanism via which
exercise extends mean longevity is by producing an oxidative stress on
cells that builds a resistance to future oxidative stresses.
To support this notion, the Nature review article cites papers
demonstrating a correlation between "conditioning stresses" (heat and
radiation) and increased mean longevity in C. Elegans and Drosophila.
References: Nature 11/9/00 - "Oxidants, oxidative stress, and the biology
of ageing"; Lithgow (95), Johnson (98)
mez
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