APRIL 2, 2025
Astronauts may seem superhuman, but most deal with a problem all too familiar to many on Earth: crippling low back pain. In fact, nearly 80% of astronauts experience back pain during their missions, and one-third continue to suffer from chronic pain after returning to Earth, according to a systematic review (J Pain Res 2024;17:4103-4139).
“I was truly shocked when we saw this incredibly high percentage of astronauts experiencing back pain, especially since most of them lack preexisting
Astronauts may seem superhuman, but most deal with a problem all too familiar to many on Earth: crippling low back pain. In fact, nearly 80% of astronauts experience back pain during their missions, and one-third continue to suffer from chronic pain after returning to Earth, according to a systematic review (J Pain Res 2024;17:4103-4139).
“I was truly shocked when we saw this incredibly high percentage of astronauts experiencing back pain, especially since most of them lack preexisting complications or known health issues,” said Guillermo Ceniza-Bordallo, PhD, a postdoctoral researcher at the University Complutense of Madrid, and lead author of the study.
The high prevalence of low back pain can be traced to the unique challenges of living in space. Exposure to microgravity reduces disc compressive loading, causes a loss of spinal curvature and lengthens the vertebral column, leading to a dramatic shift in the spine. As Richard Scheuring, DO, a NASA flight surgeon, explained, the spine elongates, and the muscles that support it essentially turn off.
“These muscles fire while the astronauts engage in daily exercise routines, like dead lifts and squats, but these exercises only account for about an hour and a half of their 24-hour day,” Scheuring said. “The rest of the day, they’re off-loaded and are going to start atrophying—kind of like how your muscles would be really small after your limb is in a cast for weeks.”
This lack of muscle activity likely contributes to the significant deterioration of the lumbar multifidus, especially in the L4-L5 and L5-S1 segments, according to the study. These areas have a high nerve density and are already vulnerable to degenerative changes and disc disease in the general population due to their role in bearing weight and stress, according to Charles Argoff, MD, a neurologist at Albany Medical Center, in New York, who specializes in pain management, and a member of the Pain Medicine News editorial advisory board.
“In space, the absence of muscle engagement, especially in the lower spine, might accelerate the degeneration of the L4-L5 and L5-S1 segments, which are already vulnerable to wear and tear under normal gravity, and lead to this high occurrence of back pain,” Argoff said.
Adding to the problem, astronauts are three times more likely to suffer from lumbar disc herniation than the general population (Aviat Space Environ Med 2010;81[6]:566-574). One contributing factor is the loss of hydration in the intervertebral discs due to the absence of gravity, according to Ceniza-Bordallo.
Disc degeneration begins naturally around 20 years of age as water content decreases in the intervertebral discs. “Over time, this leads to disc desiccation and the growth of new bone, which can crowd nerve roots or narrow spinal canals, sometimes causing pain without noticeable symptoms,” Argoff said. “Many people have these issues without knowing it.”
However, the challenge is determining whether space travel accelerates this degeneration or whether it is simply part of the natural aging process. Prior to 2023, Scheuring screened astronauts for spine issues only if they reported pain, limiting assessments of preexisting pathology. Now, all U.S. astronauts undergo pre- and post-flight spine MRI to better monitor their spinal health.
“Almost everybody, if you get an MRI, is going to have some type of radiographic abnormality, and that thing you find might not correlate with pain, and your ability to do your job may not be impaired whatsoever,” Scheuring said. “It’s frustrating with MRI and healthy otherwise asymptomatic people, because the honest answer is we don’t know what these subtle abnormalities mean. There was a big pushback on us getting MRIs in astronauts for so long because I as a flight surgeon have to certify them before the medical board. If we find a condition, I have to explain it and justify why the astronaut should be cleared to fly in space.”
To manage “space adaptation back pain,” which occurs within the first 24 to 72 hours in space, astronauts use a NadaChair (Nada Concepts)—a wearable chair with a seat and backrest that allows astronauts to position their knees close to their chest. Describing the device as similar to “a camping chair that puts you in a fetal position,” Scheuring said it may relieve tension on the anterior longitudinal ligament, which stretches out early in spaceflight and contributes to back pain.
Scheuring also administers low-dose muscle relaxants like lorazepam and anti-inflammatory medication, along with recommending stretching and flexion and extension exercises. NASA’s Astronaut Strength, Conditioning and Rehabilitation group is designing targeted conditioning programs for before, during and after space missions to prevent back pain.
“[On the International Space Station], the astronauts are using existing equipment like the T2 treadmill and the CEVIS [Cycle Ergometer with Vibration Isolation and Stabilization System, Danish Aerospace Co.] cycling machine, but our athletic trainers and physical therapists are, I would say, MacGyvering some uses of different things to try to activate those multifidus muscles or the other core stabilizing muscles that we’ve never done before,” Scheuring said. “Ideally I’d like to introduce a new exercise like a stair stepper so [astronauts] also get some metabolic and cardiovascular benefit.”
However, relieving back pain caused by multifidus atrophy remains a challenge, as there are limited options for addressing chronic back pain linked to muscle deterioration in microgravity.
One promising approach for combating multifidus atrophy and related back pain is neuromodulation. Argoff pointed to ReActiv8 (Mainstay Medical), an implantable neurostimulation system that restores motor control by overriding multifidus inhibition.
“Multifidus muscle restorative stimulation is one of the hottest treatments for lower back pain,” he said. “There is a recent five-year outcome study published on ReActiv8, and the outcome is amazing—it’s effective at relieving back pain, it’s safe and it’s FDA approved.”
Scheuring echoed cautious optimism, emphasizing the need for an approach that is feasible, cost-effective and comfortable for astronauts.
“[ReActiv8] sounds interesting, and if this device can cause those otherwise sleeping motor neurons to fire and the neuromuscular junction to kick off and keeps multifidus going, that would be awesome,” Scheuring said. “But anything that we would use would have to go through rigorous evaluations to ensure it doesn’t disrupt the spacecraft’s other systems, like the avionics or electronics.”
Of note, microgravity is not just a challenge for space travelers; this research can enhance our understanding of muscle loss and chronic pain here on Earth, especially in patients who suffer from muscle degeneration from extended bed rest.
“Microgravity is essentially a model for long-term immobilization,” Ceniza-Bordallo said. “The mechanisms that cause pain in astronauts might help explain chronic pain in patients at rest for long periods of time.”
By unraveling the mysteries of spinal health in astronauts, researchers could bring us closer to a future where fewer people suffer from back pain—no rocket required.
—Anna Tsioulias
