Astronauts have been reporting back pain since the late 1980s as space missions lengthened. Medical data from their flights show that more than half of US astronauts have reported back pain, especially in the lower back. Up to 28% indicated that it was moderate to severe pain, sometimes lasting throughout their mission.
The situation does not improve when they return to Earth’s gravity. In the first year after the flight, astronauts have a 4.3 times higher risk of disc herniation.
“It’s kind of an ongoing problem that has been serious and worrisome,” the doctor said. Douglas Chang, the first author of the new study, is an associate professor of orthopedic surgery and director of the Physical Medicine and Rehabilitation Service at the University of California, San Diego Public Health. “Thus, this study is the first to rely solely on the epidemiological description and look at possible mechanisms for what happens to astronauts’ backs.”
A lot of attention has been given to intervertebral discs, spongy shock absorbers located between our vertebrae, as the culprit behind back problems experienced by astronauts. But a new study contradicts that thinking. In this NASA-funded study, Chang’s team saw little to no change in disc height or swelling.
In six astronauts who spent four to seven months on the ISS, Chang said they did experience massive degeneration and atrophy of the supporting muscles in the lumbar (lower) spine. It is these muscles 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 unloading of the spine, which flattens the curvature of the spine. Astronauts also don’t use lower back muscle tone, Chang says, because they don’t bend over and use their lower back to move like they do on Earth. This is where the pain and stiffness comes in, as if the astronauts had been in a cast for six months.
Pre- and post-mission MRI scans showed that astronauts lost 19% of these muscles during the flight. “Even after six weeks of training and recovery here on Earth alone, they only recover about 68% of their losses,” Chang explained.
Chang and his team see this as a major problem for long-term manned missions, especially when it comes to Mars, which can take eight or nine months just to reach the Red Planet. This journey and the potential time spent by astronauts in Martian gravity – 38% of Earth’s surface gravity – creates the potential for muscle atrophy and deterioration.
The team’s future research will also look at reports of problems with the neck, where there may be even more cases of muscle atrophy and a slower recovery period. They also hope to collaborate with another university on in-flight spinal ultrasound to see what happens to astronauts while they’re on the space station.
Yoga in space?
Since no one likes back pain and muscle loss, Chang suggested countermeasures to add to the already two to three hour workout that astronauts do on the space station every day. While their machines focus on a range of issues, including cardiovascular and skeletal health, the team believes space travelers should also include a spine-focused core strengthening program.
In addition to the “rolled fetus” position that astronauts use in 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 relies on the effects of gravity, such as the downward dog where gravity can stretch the hamstring, calf muscles, back of the neck and shoulders. . ”
Any machines on the space station would also need to be sized for the weight, size, and even the reverb they might produce on the station.
Chang and other researchers brainstormed with the VR team about different exercise programs that would allow astronauts to invite friends, family, or even Twitter followers to join them for a virtual workout, making daily repetitions of their workouts more fun and competitive.
Keeping astronauts healthy and fit is the least they can do, Chang says.
“When the team comes back, they say they see this beautiful blue planet from 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 going into darkness, and come back with a different sense of themselves and their place in the universe.
“They are all committed to expanding space knowledge and are taking incremental steps forward in any way possible for the next crew.”