Astronauts can temporarily grow 2 inches in height, but suffer from muscle loss and back pain
More countermeasures with exercise can help reduce pain and muscle loss
A six-month stay on the International Space Station can be a back pain for astronauts. While they can temporarily increase up to 2 inches in height, that effect is associated with a weakening of the muscles that support the spine, according to a new study.
In 1994, astronaut Mark Lee had his height measured by fellow astronaut Jerry Linenger as part of a back pain study.
Astronauts have been reporting back pain since the late 1980s, when space missions got longer. Their flight medical records show that more than half of American astronauts have reported back pain, especially in their lower back. Up to 28% indicated it was moderate to severe pain, sometimes for the duration of their mission.
Things don’t improve when they return to Earth’s gravity. In the first year after their mission, astronauts have a 4.3 times higher risk of a hernia.
“It’s kind of an ongoing problem that’s a major problem and cause for concern,” Dr. Douglas Chang, lead author of the new study and associate professor of orthopedic surgery and chief of physical medicine and rehabilitation services at the University of California at San Francisco. Diego Health. “So this study is the first to take it out of an epidemiological description and look at the possible mechanisms for what’s going on with the astronauts’ backs.”
Much attention has been paid to intervertebral discs, the spongy shock absorbers that sit between our vertebrae, as the culprit for the back problems astronauts face. But the new study goes against that notion. In this study, funded by NASA, Chang’s team observed little to no changes in the discs, their height or swelling.
What they did see in six astronauts who spent four to seven months on the ISS was massive degeneration and atrophy of the supporting muscles in the lumbar (lower) spine, Chang said. These muscles are the ones that help us stay upright, walk, and move our upper limbs in an environment like the Earth, while protecting discs and ligaments from strain or injury.
In microgravity, the trunk lengthens, most likely due to the unloading of the spine, which flattens the curvature of the spine. Astronauts also don’t use the muscle tension in their lower backs because they don’t bend over or use their lower backs to move, like they do on Earth, Chang said. This is where the pain and stiffening occur, just like 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 only recover about 68% of their losses,” explains Chang.
Chang and his team consider this a serious problem for long-term manned missions, especially if they are considering a trip to Mars that could take eight or nine months to reach the Red Planet. That journey and the potential time the astronauts spent in Martian gravity — 38% of Earth’s gravity — creates the potential for muscle atrophy and deconditioning.
The team’s future research will also look at reported neck problems, which can lead to even more muscle atrophy and a slower recovery period. They also hope to partner with another university to take onboard spinal ultrasounds to see what happens to astronauts while on the space station.
Since no one likes back pain and muscle loss, Chang suggested countermeasures that should be added to the already two to three-hour workout astronauts have every day on the space station. While their fitness machines target a range of issues, including cardiovascular and skeletal health, the team believes space travelers should also include a core-strengthening program that targets the spine.
In addition to the “fetal tuck” position that astronauts use in microgravity to stretch their lower backs or relieve back pain, Chang suggested yoga. But he knows that’s easier said than done.
“A lot of yoga relies on the effects of gravity, like downward dog, where a stretch through the hamstring, calf muscles, back of the neck and shoulders is possible because of gravity. If you remove that, you may not have the same benefit.”
All machines on the space station must also be designed with regard to weight, size and even the reverberation they can produce on the station.
Scott Parazynski, who has walked in space seven times, helped build the space station in 2007.
Chang and the other researchers brainstormed with a virtual reality team about various exercise programs that astronauts could invite friends, family or even Twitter followers to join a virtual workout, making the daily repetition of their workouts more fun and competitive.
One of Chang’s teammates has personally felt this pain. dr. Scott Parazynski is the only astronaut to climb Mount Everest. He suffered a hernia after returning from the ISS to Earth. Less than a year later, when he attempted to climb Everest for the first time, he had to be lifted off the ground. After a rehabilitation process, he finally made it to the top. Now he speaks with current astronauts about the ways they can contribute to studies of their health in microgravity.
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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 just see infinity stretching out into the darkness, and they come back with a different sense of themselves and their place in the universe.
“They’re all committed to increasing knowledge of space and making incremental steps forward for the next crew in every possible way.”