For missions lasting six months or more, exposing astronauts to the microgravity of space causes them to lose bone mass equivalent to two decades of aging. And only half of the lost bone recovers after a year back on Earth, leaving them with a decade of age in their bone structure, the researchers wrote in a study published June 30 in the journal Scientific Reports (opens in a new tab). Bones, like muscles, are always growing and have evolved to remodel under constant mechanical stress caused by the earth gravity. And, like muscles, if weight-bearing bones aren’t used — such as during a long, low-gravity period in space — they can weaken irreversibly. “We found that weight-bearing bones were partially recovered in most astronauts one year after spaceflight,” said lead author Leigh Gabel, assistant professor of kinesiology at the University of Calgary in Canada. he said in a statement. “This suggests that permanent bone loss due to spaceflight is about the same as age-related bone loss on Earth in a decade.” Researchers evaluated the bones of 17 astronauts left behind on the International Space Station (ISS). The astronauts — 14 men and three women — had an average age of 47. Their stays on the ISS ranged from four to seven months. To track the wear and tear of the astronauts’ bones, the researchers scanned specific areas of the astronauts’ bodies—such as the wrists, ankles, and shins—before they traveled to the ISS and upon their return. The scientists then performed two follow-up scans six and 12 months after the astronauts returned to solid ground. The scans were taken using a technique called high-resolution peripheral quantitative computed tomography (HR-pQCT), which creates three-dimensional images of human bone structure at scales finer than the width of a human hair. Using these scans, the researchers discovered the mineral content and bone density of the astronauts – key indicators of how susceptible bones are to fracture. The results showed that, of the 17 astronauts, 16 had not regained their pre-space shin strength after a year of recovery. Additionally, after the recovery year, the eight astronauts who spent more than six months in space had tibia bones that had experienced the equivalent of a decade of aging and could support 75 pounds (334 Newtons) less force than they could before their space missions. . . In contrast, the bones of the lower arms (radii) of the spaceships had almost completely deteriorated, probably because these bones cannot bear the weight. Bones can be roughly divided into two layers: cortical and trabecular. The cortical part of the bone represents about 80% of a person’s bone mass and is the outer axis of the bone that gives it its shape. The remaining 20% of bone mass is made up of the trabecular component, which is the trellis-like structure of tiny beams and struts that reinforce the cortical bone from within. When people lose bone density, some of this trabecular meshwork disappears, reducing the strength of the bones and making them much more vulnerable to fracture. “We have seen that many of these connections are lost during spaceflight, and so it is very likely that although new bone is formed after returning to Earth, the body’s ability to replace these missing rods is very unlikely,” Steven stated. Boyd, professor of radiology at Cumming School of Medicine in Calgary, Canada, told Live Science. Previous research had predicted that, on a three-year round trip to Mars, 33% of astronauts would return at risk of osteoporosis, a progressive condition that sees the holes and gaps in the bone’s honeycomb grow, making it more prone to breaking . And it’s not just bones that wear out in low gravity. Previous studies have also shown that muscles, eyes, brains, hearts, spines, and even cells can be damaged by prolonged exposure to space—all of which present unique challenges for long-duration spaceflight. The silver lining from the new study is that in-flight deadlift training delivered by the ISS’s Advanced Resistive Exercise Device (ARED) slowed the rate of bone loss and enhanced recovery — meaning that specific training programs, equipment and Targeted nutrition could be vital to keeping astronauts fit on long journeys, such as a future three-year round-trip mission to Mars. “Since tight quarters will be a limiting factor for future exploration-class missions, exercise equipment should be optimized for a smaller footprint,” the scientists wrote in the study. “Resistance training (especially deadlifts and other lower-body exercises) will remain a mainstay in mitigating bone loss; however, adding a figure-jumping exercise to the track may prevent further bone loss.” and reduce daily exercise time.” The scientists are now planning a follow-up study to investigate the effects that traveling for more than seven months has on bones. This research is planned as part of a NASA project to study the long-term effects of space on more than a dozen vital parts of the human body. “Those who spent more time in space lost more bone. So it would be reasonable to assume that spending even more time in space might mean further bone loss,” Boyd said. “This is obviously a concern for missions that may last years (e.g. to Mars). But, what we don’t know is whether the human body reaches a bone loss plateau at some point. It doesn’t seem likely that the bones will” was melting” completely, but we do not know at what level of bone loss equilibrium can be achieved.” Beyond helping astronauts stay healthy on long flights, the research also offers insights into how to help them adapt to another shock to their systems: their return to Earth. “Just as the body must adapt to spaceflight at the start of a mission, it must also re-adapt to Earth’s gravity field at the end,” Robert Thirsk, a former University of Calgary chancellor and astronaut, said in the statement. “Fatigue, dizziness and imbalance were immediate challenges for me upon my return. Bones and muscles take the longest time to recover after spaceflight. But within a day of landing, I felt comfortable as an Earthling again. .” Originally published in Live Science.
