While in orbit, it is extremely important for the Shuttle crew members to get at least 15 minutes of exercise a day. This is because the <a href="Glossary">microgravity</a> environment of space affects the <a href="text">human body</a> in many different ways.
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A special exercise ergometer is stowed on the mid-deck. The astronauts fix it to the floor or wall and then attach themselves to it with a harness and bungee cords. They adjust the tension, then pedal in place. The more the tension of the bungee cords, the more difficult the exercise.