A six-month stay on the International Space Station can be a pain in the back for astronauts. While they may gain up to 2 inches in height temporarily, that effect is accompanied by a weakening of the muscles supporting 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 grew longer. Their flight medical data show that more than half of US astronauts have reported back pain, 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’s gravity. In the first year after their mission, astronauts have a 4.3 times higher risk of a herniated disc.
“It’s sort of an ongoing problem that has been a significant one with cause for concern,” said Dr. Douglas Chang, first author of the new study and associate professor of orthopedic surgery and chief of physical medicine and rehabilitation service at University of California San Diego Health. “So this study is the first to take it from just an epidemiological description 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 sit between our vertebrae, as the culprit for the back issues that astronauts face. But the new study runs counter to that thinking. In this research, funded by NASA, Chang’s team observed little to no changes in the discs, their height or swelling.