[Homestead] Exercise does no damn good... for some
mmcharry at springnet1.com
Sat Dec 4 01:19:52 EST 2004
Just to keep us all honest, stories like this are published.
Genes are likely a lot more involved than we know at this time.
Some people are 'immune' to exercise
10:45 02 December 04
Public-health campaigns regularly plug exercise as a sure-fire way to avoid
an early grave. But that message may be too simplistic. For an unhappy few,
even quite strenuous exercise may have no effect on their fitness or their
risk of developing diseases like diabetes.
"There is astounding variation in the response to exercise. The vast
majority will benefit in some way, but there will be a minority who will not
benefit at all," says Claude Bouchard of Louisiana State University in Baton
At the Australian Health and Medical Research Congress in Sydney, Australia,
last week Bouchard reported the results of a study assessing the role of
genes in fitness and health changes in response to exercise.
In the study, 742 people from 213 families were put through a strict 20-week
endurance training program. The volunteers had not taken regular physical
activity for the previous six months. Exercise on stationary bikes was
gradually increased so that by the last six weeks the volunteers were
exercising for 50 minutes three times a week at 75% of the maximum output
they were capable of before the study.
Previous reports indicated that there are huge variations in "trainability"
between subjects. For example, the team found that training improved maximum
oxygen consumption, a measure of a person's ability to perform work, by 17%
But the most trainable volunteers gained over 40%, and the least trainable
showed no improvement at all. Similar patterns were seen with cardiac
output, blood pressure, heart rate and other markers of fitness.
Bouchard reported that the impact of training on insulin sensitivity - a
marker of risk for diabetes and heart disease - also varied. It improved in
58% of the volunteers following exercise, but in 42% it showed no
improvement or, in a few cases, may have got worse.
"It's negative, but it's true. Some people slog away and don't get any
improvement," says Kathryn North of the Institute of Neuromuscular Research
at the Children's Hospital at Westmead in Sydney, Australia.
In the eight volunteers who showed the largest improvement in insulin
sensitivity, 51 genes were expressed in muscles at double the levels of the
eight people who showed the least improvement, and 74 genes were expressed
at half the level. Many of these genes were a surprise to the researchers
because they have not previously been linked to exercise.
"We need to recognise that although on average exercise may have clear
benefits, it may not work for everyone," says Mark Hargreaves of Deakin
University in Melbourne, Australia. "Some people may do better to change
Rachel Nowak, Sydney
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