Astronauts Test Glenn Exercise Harnesses

Imagine that you want to exercise on a treadmill. You step onto the machine and select your desired speed. As the belt starts moving, you start walking and eventually running. Your feet rhythmically hit the belt, and you get a nice workout.

In space, it isn't that simple.

For astronauts living in space, like those who reside on the International Space Station, getting a good workout is equally -- and in some ways even more important -- than for earthbound people.

"Crew members exercise for a host of important reasons. There's a psychological benefit to exercise, and crew members work out to combat spaceflight deconditioning -- to help fend off the bone loss that they experience in microgravity and to help maintain muscle strength and cardiovascular endurance. All of these things are adversely affected by long-duration space flight," says Gail Perusek, Manager for Exercise Physiology and Countermeasures Project at NASA's Glenn Research Center.