Fast Fact: At least 10 million people suffer from bone loss (or osteoporosis) in the United States.
Traveling through space for months on end is not all fun and games. It requires intense mental and physical endurance, which can only be achieved through long hours of difficult training. In terms of physical side effects, the parts of an astronaut's body that suffer the most from living in space are the bones. In fact, space travelers can lose (on average) one to two per cent of their bone mass every month. Recovery can take up to two or even three years!
When astronauts return to Earth, their bodies have to readjust to the added weight of gravity. They may even suffer severe fractures because their bones have lost so much density and have become very fragile. But the health outlook for space travelers is not entirely bleak. Methods are being developed to help slow and possibly even prevent bone loss during space travel.Fast Fact: Postmenopausal women are especially prone to osteoporosis, but they're not alone. Most people, including men, contract the disease as they age.
One of the most popular strategies currently in use involves special weight bearing exercise equipment. “Treadmill Kinematics” (or Biomechanical Analysis of Treadmill Exercise) is an experiment being undertaken by NASA on the International Space Station (ISS) to determine the ideal conditions for maintaining good health and healthy bones in space. According to NASA, the data gathered may also “provide researchers with a better understanding of how exercise speed and external loads affect forces experienced by the joints and muscles on Earth.” The treadmills on the ISS allow astronauts to be securely attached so they can practice weight bearing exercises like walking, jogging, and running. This helps simulate the environment on Earth and can delay, if not completely prevent, severe bone loss.
In another exciting experiment, space researchers are currently testing the use of bisphosphonates, a class of drugs already used to treat osteoporosis (bone loss) in older adults. For example, in 2011 and 2012, about seven astronauts participated in a research study where they exercised while taking bisphosphonates and vitamin D supplements. The results are being compared to the level of bone loss experienced by astronauts who used exercise alone as a preventative measure. So far, it looks like bisphosphonate treatments do have a positive effect.Fast Fact: Thinning bone mass also triggers a rise in calcium levels in the blood, which increases the risk of kidney stones.
In another fascinating experiment, a team of astronauts recently sent a group of six mice into space, where genetic therapy was used to cause three of them to produce extra pleiotrophin (PTN), a protein that is known to help bone development. The results have been very positive: the mice with extra PTN lost only three per cent of their spine volume, compared to a 41.5 per cent decrease in the untreated mice.
So even if space travel comes with some health risks, researchers are actively exploring ways of reducing or even eliminating the risk of bone density loss among astronauts. And who knows? They might even find a cure for osteoporosis along the way!