Going to space is a real pain in the back
Astronaut Scott Kelly grew taller in space 01:56
Story highlights
- Astronauts can temporarily gain 2 inches in height but suffer muscle loss and back pain
- More countermeasures involving exercise may help mitigate pain and muscle loss
(CNN)A six-month stay on the International SpaceStation can be a pain in the back for astronauts. Whilethey may gain up to 2 inches in height temporarily, thateffect is accompanied by a weakening of the musclessupporting 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 study on back pain.
Astronauts have been reporting back pain since the late 1980s, when space missions grewlonger. Their flight medical data show that more than half of US astronauts have reported backpain, especially in their lower backs. Up to 28% indicated that it was moderate to severe pain,sometimes lasting the duration of their mission.
Things don’t improve when they return to Earth’sgravity. In the first year after their mission, astronautshave a 4.3 times higher risk of a herniated disc.
“It’s sort of an ongoing problem that has been asignificant one with cause for concern,” said Dr.Douglas Chang, first author of the new study andassociate professor of orthopedic surgery and chief ofphysical medicine and rehabilitation service atUniversity of California San Diego Health. “So this studyis the first to take it from just an epidemiologicaldescription and look at the possible mechanisms for what is going on with the astronauts’backs.”
Like being in a body cast
Much attention has been focused on intervertebral discs, the spongy shock absorbers that sitbetween our vertebrae, as the culprit for the back issues that astronauts face. But the new studyruns counter to that thinking. In this research, funded by NASA, Chang’s team observed little tono changes in the discs, their height or swelling.
What they did observe in six astronauts who spent fourto seven months on the ISS was a tremendousdegeneration and atrophying of the supportingmusculature in the lumbar (lower) spine, Chang said.These muscles are the ones that help us stay upright,walk and move our upper extremities in anenvironment like Earth, while protecting discs andligaments from strain or injury.
In microgravity, the torso lengthens, most likely due tospinal unloading, in which the spinal curvature flattens.Astronauts also aren’t using the muscle tone in their lower backs because they aren’t bendingover or using their lower backs to move, like on Earth, Chang said. This is where the pain andstiffening occurs, much like if the astronauts were in a body cast for six months.
MRI scans before and after the missions revealed thatthe astronauts experienced a 19% decrease in thesemuscles during their flight. “Even after six weeks oftraining and reconditioning here one Earth, they areonly getting about 68% of their losses restored,” Changexplained.
Chang and his team consider this a serious issue forlong-term manned missions, especially whenconsidering a trip to Mars that could take eight or ninemonths just to reach the Red Planet. That trip, and theastronauts’ potential time spent in Martian gravity — 38% of the surface gravity on Earth –creates the potential for muscle atrophy and deconditioning.
The team’s future research will also look at reported neck issues, where there can be even moreoccurrences of muscle atrophy and a slower recovery period. They are also hoping to partnerwith another university on inflight ultrasounds of the spine, to look at what happens to astronautswhile they are on the space station.
Yoga in space?
Because nobody likes back pain and muscle loss, Chang suggested countermeasures thatshould be added to the already two- to three-hour workout astronauts have on the space stationeach day. Though their exercise machines focus on a range of issues including cardiovascularand skeletal health, the team believes that space travelers also need to include a core-strenghtening program focused on the spine.
In addition to the “fetal tuck” position astronauts use inmicrogravity to stretch their lower back or alleviateback pain, Chang suggested yoga. But he knows thatis easier said than done.
“A lot of yoga depends on the effects of gravity, likedownward dog, where a stretch through the hamstring,calf muscles, back of the neck and shoulders arepossible because of gravity. When you remove that,you may not have the same benefit.”
Any machines on the space station also have to be designed with regards to weight, size andeven the reverberations they could produce on the station.
Scott Parazynski, who walked in space seven times, assisted with construction on the space station in 2007.
Chang and the other researchers brainstormed with a virtual reality team about differentexercise programs that would enable astronauts to invite friends, family or even Twitter followersto join them in a virtual workout, making the daily repetition of their workouts more fun andcompetitive.
One of Chang’s teammates has felt this pain personally. Dr. Scott Parazynski is the onlyastronaut to summit Mount Everest. He experienced a herniated disc after returning from the ISSto Earth. Less than a year later, when he attempted to climb Everest the first time, he had to beairlifted off. After a rehabilitation process, he eventually made the summit. Now, he speaks tocurrent astronauts about the ways they can contribute to studies about their health inmicrogravity.
Keeping the astronauts healthy and fit is the least theycan do, Chang said.
“When a crew comes back, they say on one side ofthe space station, they see this beautiful blue planet,”he said. “Everything they hold dear to them is on thisfragile little planet. And they look out the other windowand just see infinity stretching off into the blackness, and they come back with a different senseof themselves and their place in the universe.
“All of them are committed to furthering space knowledge and making incremental stepsforward in any way they can for the next crew.”
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