You might want to take your dumbbells with you on your next spaceflight.
During space missions lasting six months or more, astronauts may experience bone loss equivalent to 20 years of aging.One year of Earth’s gravitational recovery rebuild about half of lost bone strengththe researchers reported on June 30 in Scientific Reports.
Bones “are a living organ,” says Leigh Gabel, an exercise scientist at the University of Calgary in Canada. “They’re vibrant and active, and they’re constantly remodeling.” But without gravity, bones lose strength.
Gabel and her colleagues tracked 17 astronauts, 14 men and three women, with an average age of 47, who spent four to seven months in space. The team used high-resolution peripheral quantitative computed tomography (HR-pQCT), which can measure 3-D bone microstructure at a scale of 61 microns, thinner than the thickness of a human hair, to image and image the bone structure of the lower leg tibia. The radius of the lower arm. The team took these images at four time points — before spaceflight, when astronauts returned from space, and then six months and a year later — and used them to calculate bone strength and density.
Astronauts who spent less than six months in space were able to regain their pre-flight bone strength after a year back in Earth’s gravity. But those who spent longer in space experienced permanent bone loss in their shin or tibia, the equivalent of a decade of aging. They had little loss of lower arm bone or radius, possibly because those bones weren’t load-bearing, Gabel said.
Calgary exercise scientist Steven Boyd said increasing weightlifting in space could help reduce bone loss. “A bunch of struts and beams are held together to give your bone overall strength,” Boyd said. “Those struts or beams are what we lose in spaceflight.” Once these microscopic tissues, called trabeculae, are gone, they can’t be rebuilt, but the remaining tissue can be strengthened. The researchers found that the remaining bone thickened as it returned to Earth’s gravity.
Laurence Vico, a physiologist at the University of Saint-Etienne in France, who was not involved in the study, said: “As spaceflight increases, we can expect greater bone loss and possibly There’s a bigger recovery problem.” That’s especially worrisome considering that A manned future mission to, say, Mars will last at least two years (SN: 7/15/20). Space agencies should also consider other bone health measures, she added, such as nutritionto reduce bone resorption and increase bone formation (SN: March 8, 2005). “It’s probably a mix of countermeasures that we have to find,” Vico said.
Gabel, Boyd and their colleagues hope to gain insight into the effects of spending more than seven months in space on bone. They are part of a planned NASA project to study the effects of a year in space on more than a dozen body systems. “We really want people to hit a plateau where they stop losing bone after a while,” Boyd said.