How do astronauts keep healthy?

How do t he Int ernat ional Space St at ion (ISS) ast ronaut s keep f it ? And what happens, if t hey get ill?
Inside the ISS, the astronauts orbit Earth in a state of weightlessness, and if their stay lasts for weeks or months, keeping fit is a specific challenge. The human body is used to the gravity on Earth, and without this effect, muscles and

bones will weaken fast. After just six months in space, up to 15 % of the muscle mass and up to 10 % of the bone mass will disappear. Consequently, special exercise equipment is required aboard the station. The astronauts exercise in at least three different ways, using treadmills, exercise bikes, and a versatile exercise bench, which can be utilised to strengthen several different groups of muscles. Although astronauts on long missions exercise two hours a day, they will still lose muscle and bone mass, but not as much as without exercise.
If an astronaut is very unlucky and needs medical treatment, at least one of the astronauts on every mission ISS will have

high-level first aid and medication training as the “flight doctor”. Moreover, the space station is stocked with many types of medication, equipment for infection testing of saliva and blood, plus a heart defibrillator. A sophisticated ISS monitoring system keeps an eye on the quality of the air and sounds the alarm if toxic gasses or unhealthy microbes are detected. And as a matter of standard procedure, the staff tests the water quality and whether there are bacteria on any surfaces inside the station. In the longer term, the astronauts’ health may be affected by cosmic radiation, which can cause a slightly increased risk of developing cancer and damage to the nervous system.