Why a lot of astronauts have chronic pain after coming back from space

By Gwyn Wright via SWNS

Astronauts can grow three inches during space missions - leaving them with chronic back pain, reveals a new study.

Weightlessness allows their spines to straighten, making them 'grow' but when back on earth gravity crunches it back which can leave them in debilitating pain.

The spinal curvature, an S-shaped bend that helps the spine resist gravity, stays flexible and absorbs weight and impact.

However, it flattens out in space and MRI scans found astronauts had a smaller curve in their spine on their return.

Experts from Johns Hopkins University in the United States, analyzed existing studies, for their new research.

Dr. Radostin Penchev resident physician at The Johns Hopkins Hospital, said: "Humans can 'grow' up to three inches in space as the spine adapts to microgravity.

"If reduced gravity allows this curvature to straighten, this could not only be a cause of acute pain in astronauts, but it could also affect the stability of their spine when they return to Earth."

The researchers say 80 percent of space travelers got back pain at some point after touching down to Earth.

Most of the time it disappears on its own, but astronauts are at higher risk of sciatica - a type of back pain that can radiate into your legs.

The research team, whose analysis was published in the journal Anaesthesiology, said the stress and vibration trauma of riding in a rocket and changes to astronauts' diets while in space could also be causing pain.

Astronauts have often hit the gym in a bid to stop it with resistance exercises, such as isometrics, squats, lunges and bench pressing as a mainstay of back pain prevention.

Space stations are now equipped with exercise machines and other resistance training tools.

Resistance suits can alleviate back pain in 85 percent of sufferers when combined with regular exercise.

They help activate muscle groups from the shoulders to hips, but some say they are uncomfortable as it feels like they have a rubber band across their upper body.

Massages, vitamin D and calorie supplements, electrical muscle stimulation and negative pressure devices can also help if combined with exercise, the researchers believe.

Professor Steven Cohen, of Johns Hopkins University, said: "Insight into back pain in space travelers may provide useful information to treat back pain in other people.

"With growing numbers of humans venturing into space, experts predict an increase in the number of people experiencing the physical toll of such travel, including highly common forms of back pain."

Dr. Penchev added: “Science fiction has popularized the spinning space station that uses centrifugal force to mimic gravity but a more realistic and perhaps better alternative are specialized suits that provide spinal resistance similar to that experienced under Earth’s gravity."

Just over half (52 percent) of astronauts end up with some form of back pain two to five days after returning to Earth, according to a 2012 study that analyzed 722 space flights.

The condition, dubbed 'space adaptation back pain,' can make it harder to complete daily tasks although most cases are mild.

Astronauts are more than four times more likely to herniate a disc, NASA found in 2010 and the risk is even higher in the first year after they return to Earth.

A separate study of military helicopter pilots and crew from the University of Innsbruck in Austria found almost half of those who experienced fluctuating gravity reported lower back pain.

Pilots were almost three times as likely to develop lower back disc herniation, an injury to soft connective cushioning in the spine.