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2010-06-01 10:21:36
By LAURAN NEERGAARD, AP Medical Writer Lauran Neergaard, Ap Medical Writer
WASHINGTON Ten minutes of brisk exercise triggers metabolic changes that last
at least an hour. The unfair news for panting newbies: The more fit you are,
the more benefits you just might be getting.
We all know that exercise and a good diet are important for health, protecting
against heart disease and diabetes, among other conditions. But what exactly
causes the health improvement from working up a sweat or from eating, say, more
olive oil than saturated fat? And are some people biologically predisposed to
get more benefit than others?
They're among questions that metabolic profiling, a new field called
metabolomics, aims to answer in hopes of one day optimizing those benefits or
finding patterns that may signal risk for disease and new ways to treat it.
"We're only beginning to catalog the metabolic variability between people,"
says Dr. Robert Gerszten of Massachusetts General Hospital, whose team just
took a step toward that goal.
The researchers measured biochemical changes in the blood of a variety of
people: the healthy middle-aged, some who became short of breath with exertion,
and marathon runners.
First, in 70 healthy people put on a treadmill, the team found more than 20
metabolites that change during exercise, naturally produced compounds involved
in burning calories and fat and improving blood-sugar control. Some weren't
known until now to be involved with exercise. Some revved up during exercise,
like those involved in processing fat. Others involved with cellular stress
decreased with exercise.
Those are pretty wonky findings, a first step in a complex field. But they back
today's health advice that even brief bouts of activity are good.
"Ten minutes of exercise has at least an hour of effects on your body," says
Gerszten, who found some of the metabolic changes that began after 10 minutes
on the treadmill still were measurable 60 minutes after people cooled down.
Your heart rate rapidly drops back to normal when you quit moving, usually in
10 minutes or so. So finding lingering biochemical changes offers what Gerszten
calls "tantalizing evidence" of how exercise may be building up longer-term
benefits.
Back to the blood. Thinner people had greater increases in a metabolite named
niacinamide, a nutrient byproduct that's involved in blood-sugar control, the
team from Mass General and the Broad Institute of MIT and Harvard reported last
week in the journal Science Translational Medicine.
Checking a metabolite of fat breakdown, the team found people who were more fit
as measured by oxygen intake during exercise appeared to be burning more
fat than the less fit, or than people with shortness of breath, a possible
symptom of heart disease.
The extremely fit 25 Boston Marathon runners had ten-fold increases in that
metabolite after the race. Still other differences in metabolites allowed the
researchers to tell which runners had finished in under four hours and which
weren't as speedy.
"We have a chemical snapshot of what the more fit person looks like. Now we
have to see if making someone's metabolism look like that snapshot, whether or
not that's going to improve their performance," says Gerszten, whose ultimate
goal is better cardiac care.
Don't expect a pill ever to substitute for a workout the new work shows how
complicated the body's response to exercise is, says metabolomics researcher
Dr. Debbie Muoio of Duke University Medical Center.
But scientists are hunting nutritional compounds that might help tweak
metabolic processes in specific ways. For example, Muoio discovered the muscles
of diabetic animals lack enough of a metabolite named carnitine, and that
feeding them more improved their control of blood sugar. Now, Muoio is
beginning a pilot study in 25 older adults with pre-diabetes to see if
carnitine supplements might work similarly in people who lack enough.
Next up: With University of Vermont researchers, she's testing how metabolic
changes correlate with health measures in a study of people who alternate
between a carefully controlled Mediterranean diet and higher-fat diets.
"The longterm hope is you could use this in making our way toward personalized
medicine," Muoio says.