Spines in Space: three questions for Douglas Chang
Douglas Chang, MD, PhD, chief of Physical Medicine and Rehabilitation at UC San Diego Health System is working on a three year project with NASA to study how weightlessness affects the spines of astronauts. Chang and his colleague, Alan Hargens, PhD, use an upright MRI system to image the spines of International Space Station astronauts, before and after their 6 month-long missions.
Question: What led you to the idea to study the spines of astronauts?
Answer: We were intrigued by the numbers of astronauts who have complained about back pain (68 percent report low back pain during short duration space flights, varying in duration from 14 percent to 100 percent of the flight). The more we thought about it, the more we realized that the extreme environment of space could tell us unique things about the spine that would be helpful to all of us back on Earth.
Q: Inversion equipment and inversion therapies are popularly sold to consumers as healthy options for the spine. The claims are that “anti-gravity” reduces stress and increases blood flow. What are your studies showing about what really happens to the spine when gravity is absent?
A: The spinal disks, like our bones, seem to benefit from daily cyclic loads and weight-bearing activity.
The musculoskeletal system senses and adapts to physical loads. To remain strong, our muscles, bones, ligaments and disks need to be exercised.
I can’t see how an inversion table would result in any beneficial effects lasting more than several minutes (when one goes upright again).
Q: What has surprised you the most about how the spine behaves in a weightless environment?
A: I was surprised to learn that astronauts gain 5 cm in height because of straightening of the spine and swelling of the intervertebral disks!