A Space Walk may look like fun but it does little to keep an astronaut in shape. Without having to work against the force of gravity, muscles and bones become weaker rather than stronger. We’ve all been told that weight bearing and resistance exercises are the best activities for developing strong bones and muscles. So what happens if you just spend your days floating around?
Studies at NASA have found that crew members of the International Space Station lost about 15 percent of their muscle mass and 20 to 30 percent of muscle performance during a six month stay aboard the lab. The before and after in an astronaut is the equivalent of comparing a 20 year old to an 80 year old. Muscle loss recovers after return to earth; bone loss can be permanent which is why it is so important to exercise in space. If man ever has the capability to take journeys of several years, it will be critical that he keep his skeleton in good shape so that he can walk at his destination.
We all know how old people shrink with age the opposite is true in zero gravity. As the spinal column expands without the compression of earth’s pull, you grow taller by 5 to 8 cm. However, that causes problems as well such as backache and nerve problems. Without gravitational forces, the body senses no need to maintain the skeleton and the body absorbs bone tissue leading not only to bone loss but also to high calcium levels which can cause kidney stones. Blood volume drops as well and many astronauts develop anemia. Without having to exert itself to pump blood, the heart also shrinks and weakens.
Exercise! That’s the answer. So astronauts spend hours a day doing just that. While it doesn’t stop bone loss, it does maintain muscle tone and helps astronauts maintain a sense of well-being. Maintaining muscle also helps astronauts to do chores inside and outside of the space capsule. Astronauts strap themselves to treadmills and run. They also use Ergometers, machines similar to a bicycle without wheels in which the resistance can be adjusted by changing the pedal’s pressure. There are also rowing Ergometers. Astronauts divide their exercise time between intensity training and resistance training much the same as an athlete on earth interspersing running long distances with weight lifting.
It isn’t just bones and muscles that suffer in zero gravity. Although everyone who experiences the wonderful floating sensation is eager to go back again, there are still some unpleasant problems. The subtle vestibular organs inside the inner ear give us balance. Pressure sensors in our body allow us to know the position of our body. Take that away and the result is “Space Adaptation Syndrome” defined by astronauts as “a fancy term for throwing up.” When astronauts return to earth, the re-adjustment is painful as they re-gain their balance and their muscles. It’s also hard for them to remember they can’t just let go of a cup or plate in the air without gravitational results.
The International Space Station has a gym with an Advanced Resistance Exercise Device that NASA delivered in November, 2008. The gym also has bungee-like resistance bands. Without exercise, astronauts would lose as much body function as someone spending 60-90 days in bed. If you’ve ever spent even a week in bed with an illness, you know how weak you are. The good news is that the new gym and the astronauts’ dedication to staying fit is making a difference. NASA is continuing to carry out studies to improve exercise regimens in the hopes that future astronauts will suffer even less debilitating physical effects on their journeys into space.
