If you’re looking for a bit of extra height then going into space will help you get taller but you pay a price: on-going back pain.

New research was born from past astronauts complaining of back pain after lengthy stays at the International Space Station (ISS). Some are still complaining of back ache after space travel undergone in the 1980s.

To find out why, a team of researchers led by Dr. Douglas Chang of University of California San Diego, examined six NASA astronauts before and after their stints in space. Before launch, each had an MRI scan to determine body composition and then another MRI once they returned back to Earth. The results showed each one actually grew around a couple of inches but lost muscle mass in the process of which never returned.

It’s thought the height gain is due to the straightening of the spine because gravity isn’t there to push it down like it does on Earth. This would be an advantage but the problem comes when the muscle mass around the spine disappears and once back home, the spine has less support when is comes to alignment and core movement.

“These findings run counter to the current scientific thinking about the effects of microgravity on disc swelling,” said Chang. “Further studies will be needed to clarify the effects on disc height, and determine whether they contribute to the increase in body height during space missions, and to the increased risk of herniated discs. However, it’s information like this that could provide helpful information needed to support longer space missions, such as a manned mission to Mars.”

The advantage of this study is that more can be done to prevent astronauts from losing this vital muscle mass through core-strengthening exercises such as yoga that can be carried out before travel and while in space.

Details of the study can be found in the journal Spine.