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 up 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 bed rest 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 missions, 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. Bed rest 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 bed rest 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," said Dr. Ronenn Roubenoff, the leader of the study and an associate professor of medicine and nutrition at Tufts.
Among other things, bed rest 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. People who've experienced the weakness and malaise of the flu have experienced the power of cytokines.
"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."
Without the pull of gravity, a growth factor called IGF-1 is markedly reduced, further weakening muscles. Calcium leeches out of bones, winding up in the kidneys, where it can cause kidney stones. Bed rest also leads to bedsores, which can lead to deadly infections. Circulation in the legs slows, too, potentially triggering blood clots. And inactivity triggers constipation and reduces lung function.
Moreover, it takes only a few days of bed rest to cause insulin resistance, which can lead to diabetes, noted Dr. Bob Wolfe, a professor of surgery at the University of Texas Medical Branch in Galveston.
In the landmark Dallas Bed Rest and Training Study in 1966, researchers put five healthy college men to bed for three weeks and measured their muscle loss and other factors. When allowed to get up and exercise again, the men recovered. Thirty years later, researchers tested the same men again. The results were stunning: The three weeks of bed rest the men experienced in their 20s "had a more profound effect on physical work capacity than did three decades of aging," a 2001 study concluded.
And it's not just sick people who spend long periods in bed.
Bed rest -- sometimes for as long as 20 weeks -- is often prescribed for women carrying triplets, those with a weak cervix, those in premature labor, and those with bleeding problems.
"Bed rest is torture," said Candace Hurley, a 49-year-old mother of two boys in Laguna Beach, Calif., 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 said. "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, said Dr. Alan De Cherney, a professor of obstetrics and gynecology at the David Geffen School of Medicine at 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 bed rest, agreed 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 bed rest for some and not for others.
The good news is that a little judicious exercise in bed -- with your doctor's permission -- can minimize the dangers. Leg and arm lifts can help.
Dr. Christopher Cooper, an exercise physiologist at the David Geffen School of Medicine at UCLA, said that his data show even frail, geriatric patients can exercise in bed to lower their risk of incontinence, a common side effect of weakness from bed rest.
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, which is still recruiting subjects, call 1-800-738-7555 or visit www.hnrc.tufts.edu and look for the study inquiry form.
Judy Foreman is a freelance columnist who can be contacted at foreman@globe.com. 
