Approximately 52 percent of space travelers report some form of back pain in the first 2–5 days of space travel, according to a study of 722 space flights. The condition is dubbed “space adaptation back pain,” and while most cases were mild, the pain felt was enough to hinder astronauts’ abilities to complete tasks.
Another study found that military helicopter pilots and crewmembers who experience fluctuating gravitational forces are almost three times more likely to develop lumbar (lower back) disc herniation compared to the general population. Astronauts are more than four times as likely to herniate a disc, according to a 2010 NASA study.
Radostin Penchev, MD, resident physician at the Johns Hopkins Hospital, says the high prevalence of back pain among these groups is understandable because the human spine is built to support our bodies under the gravitational forces experienced on Earth. One prominent feature is the spinal curvature—an S-shaped bend in the spine that allows it to resist gravity, remain flexible, and absorb weight and impact. However, in microgravity, this curve is reduced.
Resistance exercises such as isometrics, squats, lunges, and bench pressing have been a mainstay of back pain prevention in space travelers, and space stations are equipped with exercise machines and other resistance training tools. Specialized suits that provide spinal resistance similar to that experienced under Earth’s gravity have also been used. These suits combined with exercise regimens relieved space adaptation back pain in 85 percent of subjects.
Researchers at Johns Hopkins Medicine published a new report in the September 2021 issue of Anesthesiology that predicts further study among astronauts of these methods—including specialized suits and certain exercises—may provide insights for treating back pain in the estimated 80 percent of Earth-bound people who experience some form of it over their lifetimes.
Other methods to prevent back pain among astronauts mentioned by the researchers include massage, nutritional supplementation to increase vitamin D and caloric intake, neuromuscular electrical stimulation, and negative pressure devices, all paired with resistance exercise.
The full article in Anesthesiology is available online at https://doi.org/10.1097/ALN.0000000000003812.