ACU (Australian Catholic University)

ACU Alum

Issue 1, Spring 2011

Back pain in outer space

Back pain_THUMB

High radiation levels, nausea and loss of appetite, lower back pain and a shrinking heart muscle. Alisse Grafitti talks to physiotherapist Professor Julie Hides, and discovers that space travel isn't all it's cracked up to be.

So far more than 390 Virgin Galactic 'astronauts' have paid their $20,000 deposits and signed up to venture into space with Richard Branson.

It's likely they're 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, or 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 centimeters taller because their spinal discs have expanded.

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

One symptom in particular, lower back pain, is now being targeted by a European Space Agency study and Australian Catholic University (ACU) physiotherapist Professor Julie Hides.

Professor Hides was invited to participate in the study after publishing her PhD  and papers on low back pain, and developing a 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 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 centimeters taller when they come back to Earth, but their spines are vulnerable when they are suddenly forced to handle load again, and many astronauts go on to experience chronic back pain."

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.

The participants spent 60 days lying with their head tilted down six degrees, and weren't allowed to get up at all - even to eat or go to the bathroom.

"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 in space, would cause all your muscles to waste, but we discovered that some in fact got larger.

"The deep hip flexors and abdominal muscles actually increased in size - which is extremely important for us to consider when devising a rehabilitation program 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."

Professor Hides worked with European Space Agency physiotherapist Gunda Lambrecht to develop a program which taught the bed rest subject s to contract the specific back muscles which atrophy without gravity - and build up endurance. This is part of the program now used by Gunda to rehabilitate the astronauts when they return to Earth.

"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 safety," she said.

We can learn a lot from space research and apply it here on Earth, Professor Hides said.

"Healthy load on Earth is a good concept for people to understand," she said. "If your spine is properly aligned and your muscles are working well, this keeps the tissues healthy. However sitting in front of a computer for 10 hours a day with poor posture may be just as bad for the back muscles as being in space."

While the Berlin studies were carried out on civilians, Professor Hides is still working with Gunda Lambrecht and the European Space Agency to develop the program, and hopefully do some direct research with astronauts. The next planned experiment is a parabolic flight, where humans can experience up to 20 seconds of weightlessness.  

"It's quite hard to get concrete data on what problems astronauts have when they return," she said. "If they thought their answer could hinder their return to space, then they just wouldn't tell you."

"Back pain and all, they absolutely love what they do."

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