Astronauts have reported back pain since the late 1980s, when space missions have lengthened. Their flight medical data shows that more than half of American astronauts reported back pain, especially in the lower back. As many as 28% said it was moderate to severe pain, sometimes lasting throughout their mission.
Things don’t 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 disk.
“It’s a kind of persistent problem that is a serious concern,” said Dr. Douglas Chang, first author of a 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 be based solely on an epidemiological description and examines the possible mechanisms of what is happening in the backs of astronauts.”
Much attention has been focused on the intervertebral discs, the spongy shock absorbers that sit between our vertebrae, as if to blame the backs facing the astronauts. But the new study contradicts this idea. In this NASA-funded research, Chang’s team observed little or 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 a huge degeneration and atrophy of the supporting muscles in the lumbar spine, Chang said. These muscles help us stay upright, walk and move our upper limbs in an environment like Earth, while protecting discs and ligaments from stress or injury.
In microgravity, the torso lengthens, most likely due to the unloading of the spine, in which the curvature of the spine flattens. 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. There is pain and stiffness, as if the astronauts had been cast in the body for six months.
MRI scans before and after missions revealed that astronauts saw a 19% drop in these muscles during the flight. “Even after six weeks of training and reconditioning, they only recover 68% of their losses here on one Earth,” Chang explained.
Chang and his team see this as a serious problem for long-term manned missions, especially when considering a trip to Mars that could take eight or nine months to reach the Red Planet. This journey and the potential time astronauts spent in Martian gravity – 38% of the surface gravity on Earth – creates the potential for muscle atrophy and deconditioning.
Future research by the team will also focus on reported neck problems, where even more muscle atrophies and a slower recovery period may occur. They also hope to connect with another university for an ultrasound of the spine during the flight and see what happens to the astronauts when they are on the space station.
Yoga in space?
Because no one likes back pain and muscle loss, Chang suggested countermeasures that should be added to the two- to three-hour exercises astronauts have every day on the space station. Although their exercise machines focus on a number of issues, including cardiovascular and skeletal health, the team believes that space travelers must also include a core strengthening program focused on the spine.
In addition to the “fetal engagement” position, astronauts use microgravity to stretch the 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 influence of gravity, like a dog down, where it is possible to stretch over the hamstring, calf muscles, back of the neck and shoulders due to gravity. When you remove it, you may not have the same advantage. ”
Any machines on the space station must also be designed with the weight, size and even reverberations they could produce on the station in mind.
Chang and other scientists have debated with the virtual reality team about various exercise programs that would allow astronauts to invite friends, family or even Twitter followers to join them in a virtual exercise, making daily repetitions of their exercises more fun and competitive.
Keeping astronauts healthy and fit is the least they can do, Chang said.
“When the crew returns, they will say on one side of the space station that they see this beautiful blue planet,” he said. “Everything dear to them is on this fragile little planet. And they look out of the second window and only see infinity stretching into the darkness, and return with a different sense of self and their place in the universe.
“Everyone is committed to deepening their knowledge of space and to stepping forward in any way possible for the next crew.”