(CNN)A six-month stay on the International Space Station can be a pain in the back for astronauts. While they can temporarily gain 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 reported back pain since the late 1980s as space missions grew longer. Their aeromedical data shows that more than half of US astronauts have reported back pain, particularly in the lower back. Up to 28% said the pain was moderate to severe, sometimes lasting for the duration of their use.
Things don’t improve when they return to Earth’s gravity. Astronauts are 4.3 times more likely to have a herniated disc in the first year after their mission.
“It’s kind of an ongoing problem that’s a cause for concern,” said Dr. Douglas Chang, first author of the new study and associate professor of orthopedic surgery and chief of the Physical Medicine and Rehabilitation Service at the University of California San Diego Health. “So this study is the first to start from a purely epidemiological description and look at the possible mechanisms for what’s going on with astronauts’ backs.”
Like in a body cast
Much attention has been given to the 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 thinking. In this NASA-funded research, Chang’s team observed little to no changes in the discs, their height, or swelling.
What they observed in six astronauts who spent four to seven months on the ISS was tremendous degeneration and atrophy of the supporting muscles in the lumbar (lower) spine, Chang said. These muscles 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 unloading where the spinal curvature flattens. Astronauts also don’t use muscle tone in their lower back because they don’t bend over or use their lower back to move like they do on Earth, Chang said. This is where pain and stiffness appear, similar to when the astronauts were in a cast for six months.
MRI scans before and after the missions showed that the astronauts experienced a 19% decrease in these muscles during their flight. “Even after six weeks of training and reconditioning here on Earth, they’re only recovering about 68% of their losses,” Chang explained.
Chang and his team see this as a serious problem for long-term human missions, especially considering a trip to Mars that could take eight or nine months just to reach the red planet. That journey and the potential time the astronauts will spend in the gravity of Mars — 38% of Earth’s surface gravity — creates the potential for muscle atrophy and deconditioning.
The team’s future research will also address reported neck problems, which may be even more likely to result in muscle wasting and a slower recovery time. They also hope to work with another university to do onboard spinal ultrasounds to see what happens to astronauts while they’re on the space station.
Yoga in space?
Since no one likes back pain and muscle atrophy, Chang suggested countermeasures to add to the already two to three hour training astronauts have every day on the space station. Though their exercise equipment focuses on a range of issues, including cardiovascular and skeletal health, the team believes space travelers also need to incorporate a core-strengthening program that focuses on the spine.
In addition to the “fetal tuck” position, which astronauts use in microgravity to stretch their lower back or relieve back pain, Chang suggested yoga. But he knows that’s easier said than done.
“A large part of yoga depends on the effects of gravity, such as B. Downward-Facing Dog, allowing gravity to stretch through the hamstrings, calf muscles, neck, and shoulders. If you remove these, you may not get the same benefit.”
All of the machines on the space station must also be designed with weight, size, and even the reverberations they might create on the station in mind.
Chang and the other researchers brainstormed with a virtual reality team different exercise programs that would allow astronauts to invite friends, family, or even Twitter followers to a virtual workout, making repeating their workout every day more fun and competitive .
One of Chang’s teammates felt that pain personally. dr Scott Parazynski is the only astronaut to climb Mount Everest. He suffered a herniated disc after returning to Earth from the ISS. Less than a year later, when he first attempted to climb Everest, he had to be airlifted. After a rehabilitation process, he finally reached the summit. Now he talks to actual astronauts about how they can contribute to studies of their health in microgravity.
Keeping the astronauts healthy and fit is the least they can do, Chang said.
“When a crew comes back, they say they see this beautiful blue planet on one side of the space station,” he said. “Everything they hold dear is on this fragile little planet. And they look out the other window and they just see infinity stretching into the blackness and they come back with a different sense of themselves and their place in the universe.
“They are all eager to expand space knowledge and incremental progress in every way possible for the next crew.”
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