You were trapped on the space station in a weightless environment for 3 months. The exercise equipment was not working the entire time. When you are rescued and return to Earth, you collapse to the ground and pass out.
Space is a weightless environment, meaning that gravity is much weaker in space rather than on Earth. As a result, the muscular and skeletal system do not have to work as hard or as much, which can quickly lead to muscle or bone deterioration. This causes an inability to support themselves because the muscles and bones are weaker. The cardiovascular system is also weakened so breathing and heart rate is not as strong as it was on Earth. In particular, the amount of cardiac muscle lost in space can cause a person to pass out upon return to Earth. This is due to a reduced cardiac output in space. The cardiac output in space is reduced because low gravity is keeping blood in the legs and returning less blood to the heart. When an astronaut returns to Earth, cardiac output increases but due to the weakened heart muscle, the heart cannot pump enough blood, leading to the astronaut to faint. A lack of exercise in space severely impacts the muscular, skeletal, cardiovascular, and respiratory systems. It is imperative that astronauts exercise in space.