TOULOUSE, France — Laurence Theil lounges around in bed, with attendants to massage her back and bring her breakfast on a tray.
But it isn’t exactly a life of leisure; the French nurse has spent 50 straight days confined to bed for space research.
She is not allowed to stand or sit up — a 24-hour surveillance camera ensures that. She showers lying down and even jogs in bed, strapped into a vertical treadmill that makes her feel as if she’s running up a wall.
“Running while you’re on your back takes some getting used to,” said Miss Theil, 36, one of 24 Europeans who volunteered to boldly go where few women have gone before — to bed for 60 days.
The joint study by the European Space Agency, the French space agency CNES, the Canadian Space Agency and NASA is expected to fill in unknowns about protecting female astronauts from the side effects of weightlessness.
Twelve women completed the study six months ago, and the rest completed their participation Thursday at a hilltop research center overlooking the red tile roofs of Toulouse, in southwest France.
In that time, they lounged day and night, in comfy T-shirts and pajamas, on hospital beds tilted so their feet were 6 degrees higher than their heads, provoking a physical reaction akin to weightlessness.
In space, as in the off-kilter beds, fluids shift to the upper body, which can make the face swell, disrupt digestion and bring on vertigo.
In microgravity, the magic of floating makes up for it.
“Human beings become halfway between a fish and a bird,” said Roberto Vittori, a European Space Agency astronaut who visited the clinic to cheer volunteers on.
But it also means that the lower body starts wasting away. At first, astronauts lose up to 3 percent of muscle mass a week in parts of their legs, and bone mass in segments of their lower bodies drops about 2 percent in a month, said Dr. Peter Jost, project manager for the study.
Bed-rest studies are frequent in space study, and testing nutritional supplements and exercise routines is important to keep astronauts fit for longer missions. A manned trip to Mars, for example, would expose astronauts to reduced or zero gravity for up to three years. When they land on the red planet, they have to be strong enough to work.
Few of the studies have focused on women, however, because most astronauts are men, Dr. Jost said. Today, however, one in five NASA astronauts is a woman.
“We know there are subtle differences, but we don’t know which, and to what extent,” Dr. Jost said.
One question is how much exercise women need to best avoid loss of bone mass, given that strenuous workouts can modify women’s complex hormonal and menstrual systems.
In the first group of bed-rest volunteers, all lost bone mass at first, but after six months, they are back to normal, said Dr. Arnaud Beck, the coordinator in charge of medical ethics.
Past research from short-term missions had suggested that female astronauts are more susceptible to dizziness after returning home. But that did not prove true during tests in Toulouse. One possibility is that the difference might fade or disappear during long-term missions.
Volunteers from across Europe are paid $17,500 each to give constant blood samples, submit to electrocardiograms and take tests for bone density and muscle strength. Their urine is stored and analyzed. The women receive counseling and will have checkups for three years.
Anne Bouchet, 36, a translator, is used to putting her body to the test by hiking in the French Alps. She signed up to test the opposite: extreme idleness.
“I thought it would be interesting to live confined for a long period, without moving at all,” said Miss Bouchet in a phone interview, because face-to-face interviews are prohibited.
Miss Theil, whose part in the experiment ended Thursday, said she feels in good shape and has even lost some flab on her legs.