Back pain in outer space

High radiation levels, nausea and loss of appetite, lower back pain and a shrinking heart muscle. Space travel isn’t all it’s cracked up to be.

Despite the setbacks suffered by Virgin Galactic in the last few years, there are still more than 500 customers who have reserved their place to venture into space with Sir Richard Branson.

It’s likely they are happily imagining unexplored planets, curved earth vistas and somersaults in mid-air.

It’s doubtful they’ve contemplated losing bone density and muscle mass, being exposed to high radiation levels, and vomiting. They may also not have considered that the heart muscle shrinks, faces swell as fluids migrate from the legs to the head, and some will return to Earth up to eight centimetres taller because their spinal discs have expanded.

Space adaptation syndrome is experienced by more than half of all space travellers, as the body’s systems struggle to adapt to the loss of gravity.

Call the physio

One symptom in particular, lower back pain, has been targeted by a European Space Agency study and ACU physiotherapist Professor Julie Hides.

Professor Hides was invited to participate in the study after developing a lower back rehabilitation program, which used ultrasound imaging to teach people how to contract hard-to-reach muscles.

“You would think that no gravity and no load on your spine would be a good thing, but in actual fact microgravity is quite bad for your back,” she said.

“On Earth, when we go to bed and take the load off our backs, our spinal discs absorb fluid, and we’re slightly taller when we get up in the morning. During the day, on Earth, gravity loads our spine and pushes fluid out of the discs. In space, where there is never any load, the discs continue to absorb fluid and the curve in the spine flattens out.

“This means that not only are astronauts up to eight centimetres taller when they come back to Earth, but their spines are really vulnerable when they are suddenly forced to handle a normal load again, and many astronauts go on to experience chronic back pain.”

Back to bed

Two prolonged bed-rest studies were carried out in a Berlin hospital to take a closer look at what happens to muscles when the body has no gravitational axial loading over a long period of time.

“Traditionally, space research has focused on muscles of the lower limb, not muscles of the trunk and pelvis. This is because the muscle system in this region is complex,” Professor Hides said. “The pelvis alone has 97 muscles attached to it.

“The study returned some of the results we had expected, such as deterioration of the muscles which control the curve of your back and hold you up against gravity, but there were a few surprises in there as well.

“Most people would expect that lying in bed for a long time, or floating around in space, would cause all your muscles to waste, but we discovered that some in fact got larger.

“The hip flexors and abdominal muscles actually increased in size — which is extremely important for us to consider when devising appropriate and specific rehabilitation programs for astronauts and people who are unwell and incapacitated, and spend prolonged periods of time in bed.

“The other thing that struck me was how quickly the changes happened — in as little as two weeks.”

To infinity and beyond

“As space agencies prepare for extended duration missions, for example to Mars, it is difficult to predict the extent of the effects that prolonged exposure to microgravity will have on astronauts,” said Professor Hides.

“However we can look to Earth for some of the answers. The physiological changes seen in astronauts when they return from space are similar to changes often seen by physiotherapists in people with lower back pain, muscle wasting diseases, elite athletes, and critically ill patients in intensive care.”

Testing a solution

Professor Hides worked with European Space Agency physiotherapist Gunda Lambrecht to develop a program which is now used to prepare astronauts for space flight, inform the exercises they should be doing while at the International Space Station, and recondition them when they return.

“When these astronauts return to Earth, they need to relearn to feel the position of their spines. They need to reload their spines appropriately and safely.

“It was however sometimes quite difficult to obtain concrete data on what problems astronauts have when they return. If they thought their low back pain could possibly hinder their return to space, then I don’t think they would tell you about it.

“Back pain and all, they absolutely love what they do.”

Learn more about studying physiotherapy at ACU.