In honour of British astronaut Tim Peake’s space walk this Friday, we thought it would be fitting to talk a little bit about the training that astronauts undergo while in space and beyond!

Although weightlessness might not seem tough on the body, it plays havoc with our musculoskeletal system (e.g. bones, joints, muscles) along with various other aspects of our physiology. Our bodies are pretty cool (biased party speaking here). They constantly adapt and change based on the stresses and strains that we place on it. So you can imagine if we place our body in an environment without any outside physical stressors, our body will adapt, even though it may not be advantageous in the future. Because gravity, even though we don’t really pay much mind to it, is a stressor that our body has to deal with day in and day out. Then, on top of gravity, we have activity and exercise that forces further adaptation which we’ve talked about in a previous blog

If we don’t have these stressors, our body looks at all that dense bone and muscle tissue as a waste of resources and begins to downsize. This wouldn’t seem like a big deal while you’re in space, but oh boy would you feel it when you got back to earth. That’s why astronauts at the International Space Station (ISS) have to spend at least two hours per day performing a mixture of resistance and cardiovascular training. You can see more about it in a great segment done by Canadian astronaut Chris Hadfield during his recent stint at the ISS.

Although two hours per day may seem like a lot of exercise, it’s still not enough to prepare them for the challenge of gravity. Recent studies done on astronauts returning from space show that even with this rigorous training program bone density still decreases at a rate upwards of 1% per month spent in space. This is why on their return from the ISS, astronauts take part in an intensive 45 day rehabilitation training program on site which includes hours of physical rehab along with various medical tests, followed by ongoing strength and conditioning for months afterwards to reach pre-flight levels of fitness. To learn more about the physiological effects of space and importance of exercise you can check out these pages from NASA and the CSA.

Hopefully this gives you a brief glimpse into a day in the life of an astronaut and shows you that it’s not all weightless somersaults, but takes some serious hard work. Stay Agile Tim!