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Astronauts can temporarily gain 2 inches tall but experience muscle loss and back pain
More countermeasures involving exercise may help relieve pain and muscle loss
A six-month stay on the International Space Station may be a backache for astronauts. While they may temporarily reach a height of 2 inches, this effect is accompanied by weakening of the muscles supporting the spine, according to the New study.
Astronauts have reported back pain since the late 1980s, when spaceflight grew longer. Medical data from their flights shows that more than half of American astronauts report back pain, especially in the lower back. Up to 28% indicated that the pain was moderate to severe, sometimes as long as their task.
Things don’t get any better when you return to Earth’s gravity. In the first year after their mission, astronauts were 4.3 times more likely to have a herniated disc.
Douglas Chang, first author of the new study and associate professor of orthopedics and chief of physical medicine and rehabilitation services at UCSD Health told UCSD. “So this study is the first to take it from just an epidemiological description and look at the potential mechanisms of what happens with the emergence of astronauts.”
Much attention has been focused on the intervertebral discs, the spongy shock absorbers between our vertebrae, as the cause of the back problems astronauts face. But the new study contradicts this thinking. In this research, which was funded by NASA, Zhang’s team noticed few changes in the discs, their elevation, or their swelling.
What they observed in six astronauts who spent four to seven months on the International Space Station was massive deterioration and atrophy of the supporting muscles in the lumbar (lower) spine, Chang said. These muscles are what help us stay erect, walk and move our upper limbs in an environment like the ground, while protecting our discs and ligaments from strain or injury.
In microgravity, the torso lengthens, likely due to spinal unloading, as the curvature of the spine is flattened. Zhang said astronauts also don’t use muscle tone in their lower backs because they don’t bend or use their lower back for movement, as they would on Earth. This is where the pain and stiffness occurs, as if the astronauts had been in a body 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 regeneration here, they only recover 68% of their losses,” Zhang explained.
Zhang and his team consider this a serious problem for long-range manned missions, especially when considering a trip to Mars that could take just eight or nine months to reach the Red Planet. This flight, and the potential time astronauts spend in Mars’ gravity – 38% of the surface gravity on Earth – creates the potential for muscle atrophy and loss of conditioning.
The team’s future research will also look at reported neck problems, as there could be more cases of muscle atrophy and a slower recovery period. They also hope to partner with another university in the field of spinal ultrasound, to look at what happens to astronauts while on the space station.
Since no one likes back pain and muscle loss, Zhang suggested countermeasures that should be added to the two to three hours of exercise astronauts practice daily on the space station. Although their exercise machines focus on a range of issues including cardiovascular and skeletal health, the team believes that space travelers also need to include a core strengthening program focused on the spine.
In addition to the “fetal bend” pose that astronauts use in microgravity to stretch the lower back or relieve back pain, Zhang suggested yoga. But he knows it’s easier said than done.
“A lot of yoga is based on the effects of gravity, like downward dog, where stretching through the hamstrings, calf muscles, back of the neck and shoulders is possible due to gravity. When you remove that, you may not get the same benefit.”
Any machines on the space station must also be designed for weight, size, and even the bounces they can produce on the station.
Zhang and the other researchers brainstormed with the VR team about different exercise programs that would enable astronauts to invite friends, family, or even Twitter followers to join them in a virtual exercise, making the daily repetition of their exercises more fun and competitive.
One of his teammates felt this pain personally. Dr. Scott Paraczynski He is the only astronaut to reach the summit of Mount Everest. He suffered a herniated disc after returning from the International Space Station to Earth. Less than a year later, when he attempted to climb Everest the first time, he had to be airlifted. After the rehabilitation process, he finally reached the top. Now, he’s talking to current astronauts about ways they can contribute to studies about their health in microgravity.
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Chang said keeping the astronauts healthy and fit is the least they can do.
“When a crew returns, they say on one side of the space station, they see this beautiful blue planet,” he said. “Everything they hold dear is on this fragile little planet. And they look out the other window and see only infinity stretching into blackness, and they come back with a different sense of themselves and their place in the universe.
“They are all committed to enhancing space knowledge and taking incremental steps forward in whatever way possible for the next crew.”