Astronauts may temporarily gain 2 inches of height, but experience muscle loss and back discomfort
Exercise and other countermeasures may be helpful in reducing pain and muscle loss
Astronauts can experience back pain after a six-month stay at the International Space Station. According to a recent study, astronauts may temporarily gain 2 inches of height, but this is accompanied with a weakening in the muscles that support the spine.
Since the end of 1980s when space missions became longer, astronauts have reported back pain. The flight medical data shows that more than 50% of US astronauts reported back pain. This was most common in the lower back. Up to 28% of astronauts reported moderate to severe back pain. This pain could last the entire mission.
The situation does not improve once they return to Earth gravity. Astronauts are at a higher risk for a herniated disk in the first year following their mission.
It's an ongoing issue that is a cause for concern, said Dr. Douglas Chang. He is the first author of this new study. He is also associate professor of orthopaedic surgery and chief of Physical Medicine and Rehabilitation Service at University of California San Diego Health. This is the first study to look beyond an epidemiological description of what's happening with astronauts' spines.
The intervertebral disks, those spongy, shock-absorbing discs that are located between our vertebrae and the spine, have been blamed for many of the back problems astronauts experience. The new study contradicts this belief. Chang's research team, funded by NASA observed that the discs did not change in size, height, or swelling.
Chang stated that they observed a degeneration and atrophying in the supporting musculature of the lumbar spine (lower). These muscles help us to stay upright, walk, and move our upper limbs in an environment such as Earth. They also protect discs and ligaments.
In microgravity the torso lengthens. This is most likely because of spinal unloading. The spinal curve flattens. Chang explained that astronauts are also not using the muscles in their lowerbacks, because they don't bend over or use their lowerbacks to move like on Earth. The stiffness and pain are felt in this area, just like when astronauts wear a cast for 6 months.
MRI scans conducted before and after missions showed that astronauts had experienced a 19% reduction in their muscles. Chang explained that even after six weeks of training on Earth and reconditioning, only 68% of the astronauts' losses are restored.
Chang and his team believe this is a major issue for long-term missions that involve manned astronauts, especially if you consider a trip to Mars which could take up to nine months to get to the Red Planet. This trip and the astronauts’ potential time in Martian gravity (38%) - which is 38% the Earth's surface gravity - can lead to muscle atrophy and deconditioning.
Future research by the team will focus on neck problems, as there are more instances of muscle atrophy in this area and a longer recovery time. They also hope to partner with another University on inflight ultrasonics of the spinal cord, to see what happens to astronauts on the space station.
Chang proposed countermeasures to be added to the astronauts' daily workout of two to three hours on the station. The team's exercise machines are designed to address a variety of health issues, including cardiovascular and skeletal. However, they believe that astronauts should also include a spine-strengthening program.
Chang also suggested yoga, in addition to the "fetal-tuck" position that astronauts use to stretch or relieve back pain. He knows it is not easy to do.
Gravity is a key factor in many yoga poses, such as downward dog. This pose allows for a stretch of the hamstrings, calf muscle, neck, and shoulders. You may not get the same benefits if you remove gravity.
The weight, size, and reverberations that machines could create on the space station must also be considered when designing them.
Chang and other researchers brainstormed ideas with a virtual-reality team on different workout programs that astronauts could use to invite their friends, family, or Twitter followers to join in a virtual workout. This would make the daily repetitions of their workouts fun and competitive.
Chang's teammate has experienced this pain first-hand. Scott Parazynski, a doctor from the University of Colorado, is the only astronaut who has climbed Mount Everest. After returning to Earth from the ISS, he suffered a herniated disk. He had to be airlifted from Everest less than a year after he first attempted the climb. He eventually reached the summit after a long rehabilitation process. He now speaks to astronauts to discuss how they can help studies on their health in microgravity.
Chang stated that keeping the astronauts fit and healthy is the minimum they can do.
He said: "When the crew returns, they will say that on one side of space station they can see this beautiful blue world." "Everything that they cherish is on this little fragile planet." They look out of the window, see the infinity that stretches into the darkness and come back to a new sense of their own self and place in the universe.
All of them are dedicated to advancing space knowledge, and taking incremental steps in any way possible for the next crew.