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Astronauts can temporarily take 2 inches in height, but suffer from muscle loss and back pain
Several countermeasures involving exercise can help relieve pain and muscle loss
A six-month stay on the International Space Station can be a pain in the back for astronauts. Although they can temporarily take up to 2 inches in height, this effect is accompanied by a weakening of the muscles that support the spine, according to a new study.
Astronauts have been reporting back pain since the late 1980s, when space missions became longer. Their medical flight data show that more than half of U.S. astronauts have reported back pain, particularly in the lower back. Up to 28% indicated that it was moderate to severe pain, sometimes lasting their entire mission.
Things do not get better when they return to Earth’s gravity. In the first year after their mission, astronauts have a 4.3 times higher risk of a herniated disc.
“It’s a kind of persistent problem that has been a significant problem for cause for concern,” said Dr. Douglas Chang, first author of the new study and associate professor of orthopedic surgery and head of physical medicine and rehabilitation services at the University of California San. Diego Health. “So this study is the first to take it from just an epidemiological description and look at the possible mechanisms of what goes on with the backs of astronauts.”
Much attention has been focused on intervertebral discs, the spongy shock absorbers that sit between our vertebrae, as the culprit for the back problems that astronauts face. But the new study contradicts that mindset. In this research, funded by NASA, Chang’s team observed little or no changes in the disks, their height, or swelling.
What they observed in six astronauts who spent four to seven months on the ISS was a huge degeneration and atrophy of the supporting muscles of the lumbar spine, Chang said. These muscles are the ones that help us stay upright, walk and move our upper extremities in an environment like Earth, while protecting discs and ligaments from strain or injury.
In microgravity, the torso lengthens, most likely due to spinal relief, where the spinal curvature becomes flat. Astronauts also do not use muscle tone in the lower back because they do not bend or use the lower back to move, as on Earth, Chang said. This is where the pain and stiffness occur, as if the astronauts were in a body cast for six months.
MRI scans before and after the missions revealed that the astronauts experienced a 19% decrease in these muscles during their flight. “Even after six weeks of training and recovery here on Earth, they only get about 68% of their losses recovered,” Chang explained.
Chang and his team consider this a serious problem for long-term manned missions, especially when considering a trip to Mars that could take eight or nine months just to reach the red planet. That trip, and the astronauts ‘potential time spent in Mars’ gravity – 38% of the Earth’s surface gravity – creates the potential for muscle atrophy and deconditioning.
The team’s future research will also look at reported neck problems, where there may be even more incidences of muscle atrophy and a slower recovery period. They also hope to collaborate with another university on ultrasound of the spine on board to look at what happens to astronauts while they are on the space station.
Because no one likes back pain and muscle loss, Chang suggested countermeasures to be added to the already two-three-hour workout that astronauts have on the space station every day. Although their exercise machines focus on a number of issues, including cardiovascular and skeletal health, the team believes that space travelers should also include a core strengthening program focused on the spine.
In addition to the “fetal tuck” position that astronauts use in micro-gravity to stretch their lower back or relieve back pain, Chang suggested yoga. But he knows it’s easier said than done.
“A lot of yoga depends on the effects of gravity, like a dog downward, where a stretch through the buttocks, calf muscles, neck and shoulders is possible due to gravity. When you remove it, you may not have the same benefit.”
All machines on the space station must also be designed in terms of weight, size and even the reverberations they could produce at the station.
Chang and the other scientists brainstormed with a virtual reality team about various training programs that would allow astronauts to invite friends, family or even Twitter followers to participate in a virtual training, making the daily repetition of their training more fun and more competitive.
One of Chang’s teammates has felt this pain personally. Dr. Scott Parazynski is the only astronaut to top Mount Everest. He experienced a disc herniation after returning from the ISS to Earth. Less than a year later, when he tried to climb Everest for the first time, he had to be flown away. After a rehabilitation process, he finally reached the summit. Now he is talking to current astronauts about how they can contribute to studies on their health in microgravity.
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Keeping astronauts healthy and well is the least they can do, Chang said.
“When a crew comes back, they say on one side of the space station that they see this beautiful blue planet,” he said. “Everything they love about them is on this fragile little planet. And they look out the other window and just see the infinity stretch out into the darkness, and they come back with a different sense of themselves and their place in the universe. .
“They are all committed to advancing space knowledge and taking step-by-step steps in every way they can for the next crew.”