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Bed
Rest Study Can Help on Earth and in Space Starting in two weeks, 50
healthy men aged 30 to 55 will be paid $5,000 each to spend 28
days in bed, just lolling around, not even allowed out of bed to
go to the bathroom. The unusual study, to be done
at Tufts-New England Medical Center in Boston, is designed to
document just how debilitating bedrest is for muscles and bones
– and to see whether resistance training with springs and
pulleys, along with special protein supplements, can reverse this
downward slide. The implications are huge –
and not just for NASA, which is funding the study to find ways to
protect astronauts’ muscles and bones on long space flights,
such as those planned to Mars. In past space flights, astronauts
have lost one-third of their muscle strength and the equivalent of
four years of bone loss on earth after one month of
weightlessness. Bedrest is the best model earth-bound scientists
have for studying weightlessness. But the Tufts findings may be
even more useful on earth. Many medical conditions, including
high-risk pregnancies, congestive heart failure and some surgical
procedures, send people to bed for prolonged periods.
Some nursing home patients virtually live in bed. And some
people with chronic fatigue syndrome or fibromyalgia put
themselves to bed for long periods, though this may be the worst
thing they could do. Bluntly put, prolonged bedrest
can be a medical disaster - that’s why hospitals insist that
patients get up and move around, even after major surgery. Human
bodies evolved in sync with the gravitational pull of the earth.
Without that force to pull against, muscles and bones get weak
with stunning rapidity as the rate of muscle protein synthesis
drops. “If you’re healthy, you
can tolerate a week without trouble, but after that, you start to
see large losses of muscles and bone,” says Dr. Ronenn Roubenoff,
the leader of the study and an associate professor of medicine and
nutrition at Tufts. Among other things, bedrest
triggers inflammatory cytokines, natural chemicals with names like
TNF, IL-1 and IL-6, that tell muscles to export amino acids to the
liver so the body can make the antibodies and white blood cells to
fight disease. “We are built to sacrifice protein from muscle,
in times of stress, to boost the immune system,” says Roubenoff.
“We’re designed to get better relatively quickly or drop
dead.” Cytokines are the reason people lousy when they get the flu, says Dr. Jeremy Walston, a geriatrician at Johns Hopkins Bayview Medical Center in Baltimore, MD. “People feel malaise and weakness. That’s due to the impact [of cytokines] on muscle.” Without the pull of gravity, a
growth factor called IGF-1 is markedly reduced, further weakening
muscles. Calcium leaches out of bones, winding up in the kidneys,
where it can cause kidney stones. Bedrest also leads to bedsores,
which can lead to deadly infections. Circulation in the legs
slows, too, potentially triggering blood clots. Inactivity
triggers constipation, too. Moreover, it takes only a few days of bedrest to cause insulin resistance, which can lead to diabetes, notes Bob Wolfe, a professor of surgery at the University of Texas Medical Branch in Galveston. Lung function deteriorates with prolonged rest, too, says Dr. Michael Keane, director of the intensive care at the David Geffen School of Medicine at UCLA. Indeed, in the landmark Dallas
Bed Rest and Training Study, researchers put five healthy college
men to bed for three weeks in 1966 and measured their muscle loss
and other factors. When allowed to get up and exercise again, the
men recovered. Thirty years later, the researchers tested the same
men again. The results were stunning: The three weeks of bedrest
the men experienced in their 20s “had a more profound effect on
physical work capacity than did three decades of aging.” And it’s not just sick people who spend long periods in bed. Dr. Alan De Cherney, professor
of obstetrics and gynecology at the David Geffen School of
Medicine at UCLA, says that some women with high risk pregnancies
are put to bed for as long as 20 weeks. Bedrest is often
prescribed for women carrying triplets, those with a weak cervix,
those in premature labor and those with bleeding problems. “Bedrest is torture,” says
Candace Hurley, a 49-year old mother of two boys in Laguna Beach,
CA who spent 24 weeks in bed during her two pregnancies and
founded the Sidelines National Support Network (www.sidelines.org). Moral support is crucial, she
says. “We let these
moms tell us how scared, bored, frustrated they are. We say,
‘Yup, I know, it’s really, really bad..[but] you are doing the
best thing you can for your baby before it’s born.” Unfortunately,
“nobody knows” whether that’s really true, says De
Cherney of UCLA. “The theory is that if you stay off your feet,
there is less pressure on the cervix, so you’re less likely to
deliver …I have no idea if it’s effective. But I wouldn’t
take a chance, so I would prescribe it if [a pregnancy] is too
high risk.” “There is very little firm
evidence” on the benefits of bedrest, agrees Dr. Jodi Abbott, a
maternal-fetal medicine specialist at Beth Israel Deaconess
Medical Center in Boston. But it’s hard to find out for sure
because women don’t want to be in a study that would involve
bedrest for some and not for others. The good news is that a
little, judicious exercise in bed can minimize the dangers. Dr. Christopher Cooper, an
exercise physiologist at the David Geffen School of Medicine at
UCLA, says that his data show that even frail, geriatric patients
can exercise in bed, which lowers the risk of incontinence. (This
often occurs in people who get so weak from bedrest they can’t
get out of bed.) You have to use common sense, of course. Don’t exercise in bed if you have a fever. But you can try to sit up several times a day. Stay away from sugar - you’re already at risk of insulin resistance just from lying around. Try high-protein supplements instead. (For more information on the Tufts study, you may call 1 800 738 7555 or visit www.hnrc.tufts.edu and look for the study inquiry form.) Judy
Foreman is a Lecturer on Medicine at Harvard Medical School. Her
column appears every other week. Past columns are available on www.myhealthsense.com.
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