The problem of muscle loss is a well known and researched area in space medicine, but this study is the first to include specific analysis of muscle cells on long-duration missions. Fitts and his team collected tiny samples of calf muscle tissue from nine US and Russian astronauts, 45 days before launch and again on the day of return from a six month mission onboard the International Space Station (ISS). Sample analyses results confirmed just how much muscles atrophy in zero gravity takes place, with according to Fitts, a decline of more than 40% in the capacity for physical work.
Crew members on board the ISS take part in a program of daily exercise, typically devoting up to 2 hours of their day for preparation and exercise time, either pedalling a stationary bike, jogging on a treadmill while held down by a harness, or using resistance devices. A once a day exercise session, however, no matter how intense, cannot compensate for the fact that whilst in Space their bodies are not having to work against the force of gravity.
From the day that we are born, here on Earth, we grow and function in a world where every movement we make requires our physiology to battle against gravity – and thus, our muscles develop and are maintained. Obviously, a lot depends on how active an individual is as to how well maintained those muscles are – are you a fitness god or a couch potato?
But the point is that astronauts on the ISS live in a virtually gravity free world. This has physiological effects and consequences which need to be addressed if a manned trip to Mars is ever to be a realistic option.