I think we can all agree that space travel is very cool. Astronauts are like real world superheroes. The selection process to be an astronaut and the preparation for space travel is extremely rigorous. One thing we don’t think about when considering these brave spacemen and woman are there bones. Protracted time in space has several physiological challenges, among them being reduction in the strength or density of your bones due to microgravity (reduced gravitational pull). You have likely heard of osteoporosis, which is a low bone density which leaves you susceptible to fractures. We routinely screen certain groups for this condition and offer different types of medication for treatment. A typical patient with osteoporosis is usually female and postmenopausal. However, reduced bone density is a real concern for all space travelers. This is a concern for all sexes and ages of astronauts.
Why does space travel cause reduction in bone density? The bones are formed through processes that build them and break them down. This is called bone remodeling. These two process work in tandem to maintain healthy bones. When exposed to reduced gravitational pull, like when in space, there is an alteration in the careful balance of the bone remodeling system with the net result being bone breakdown. It is said that for every 1 month in space, there is a ~1% reduction in done density (NASA.gov).
This accelerated bone density reduction is a significant concern for astronauts. As a result, there are many things to consider before takeoff. First, it is important to maintain adequate levels of calcium and vitamin D through supplementation. Second, there is exercise. There are treadmills and exercise bicycles in space for the astronauts to utilize. Lastly, there are medications for the management of osteoporosis. All these things are part of the management of accelerated bone loss in space.
Let’s bring things back down to earth for a moment. If you can believe it, osteoporosis management is the same for astronauts as it is for us earthlings. A combination of appropriate vitamin supplementation, weight bearing exercise and medications are key to maintain healthy bones.