Project 440246

Physical activity is essential for bone health. Everyday activities, like walking, dancing and other forms of exercise force our bodies to work against gravity to carry our body weight, making our skeleton stronger. When we are less active, our bones get weaker. This can pose a serious health risk for elderly individuals who are less mobile, patients confined to their beds for long periods of time, and for astronauts in space who spend most of their time floating. Astronauts typically launch to the International Space Station for 6-month missions at a time. Average loss over 6-months is similar to what we would expect to see over two decades on Earth. The purpose of this study is to understand the time-course of bone loss in space. Astronauts will participate in either 2-, 6- or 12-month space missions. Astronauts will undergo high resolution bone imaging on their leg and forearm before and after spaceflight to investigate how long it takes for bone loss to stabilize in space. Results will help us understand the risks and feasibility of longer-duration spaceflights in the future (e.g., to Mars) and how to ensure astronauts remain healthy on long-duration missions. The applicability of this research extends beyond long-term spaceflight, since bone loss due to spaceflight is an accelerated model for bone loss due to immobilization, aging, or decreased physical activity on Earth. Findings from this project will be used to understand the time-course of bone loss on Earth, such as bone loss in individuals with spinal cord injuries and individuals who are immobilized. This research will also be used to identify individuals who are predisposed to bone loss and lead to individualized treatment strategies in terrestrial and spaceflight populations. The first phase of this project was recently completed (N=17 astronauts), and this next exciting phase is part of an international effort by NASA to study the effects of the human body on long-duration missions in space.