Effects of Space Travel on Human Bones, How does space affect the bones? Does space travel cause bone loss? Why do astronauts have bone loss in space?
The study of bone loss among 17 astronauts aboard the International Space Station provides a better understanding of space travel's effects on the body. It also provides steps to mitigate them.
New data was gathered on bone loss in astronauts due to space microgravity and how bone mineral density can be recovered on Earth. The research involved 14 male astronauts and three females, averaging 47 years, who spent four to seven months in space. On average, they were there for about five months.
One year later, the astronauts returned to Earth with an average 2.1% decrease in bone mineral density at their tibia (one of the lower leg bones) and 1.3% less bone strength. Nine astronauts lost bone mineral density for good and never got it back. This happened because of their time in space.
We know that astronauts experience bone loss during long-duration spaceflight. The novelty of this study is that it followed astronauts for one year after they returned from spaceflight to see if and how their bones recovered, "Leigh Gabel, a University of Calgary exercise scientist, said.
Gabel stated that astronauts suffered significant bone loss over six-month spaceflights. This loss is similar to what we see in older adults over two decades. They only recovered half of that loss after a year on Earth.
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Space weight is insufficient to support bone mass, so bones normally weight-bearing on Earth don't carry as much weight in space. Gabel said that space agencies must develop countermeasures like exercise and nutrition to stop bone loss.
Spaceflight causes delicate bone structures to thin, and bone rods eventually become disconnected from one another. Gabel stated that astronauts can strengthen and thicken their bones once they return to Earth. However, any bony connections lost in space cannot be repaired.
In the last seven years, the astronauts from the study have flown on the space station. Although they did not reveal their nationalities, the astronauts were from NASA, Canada, the European Space Agency, and Japan's Aerospace Exploration Agency.
Space travel presents many challenges for the human body. This is why space agencies must be concerned as they plan future explorations. NASA plans to send astronauts to the moon in 2025, the earliest date for such a mission. This could be a prelude to future missions to Mars or a longer-term presence on the lunar surface.
Gabel said microgravity can affect many body parts, such as bones and muscles.
The cardiovascular system is also subject to many changes. Astronauts feel fluid shifts that cause more blood to pool in their upper bodies, even though gravity isn't pulling blood towards their feet. This can harm vision and the cardiovascular system.
Gabel stated that radiation is also a concern for astronauts. The further they travel from Earth, the more exposed they are to the sun's radiation. This increases their cancer risk.
According to the study, more extended space missions were associated with more bone loss and lower chances of recovering bone afterward. Resistance training on the space station was critical in preventing muscle and bone loss. The chances of regaining bone after a mission were higher for astronauts who did more deadlifts than on Earth.
Gabel stated that there is still much to learn about microgravity's effects on human health, especially on more extended space missions than six months. "We hope bone loss will plateau on longer missions, and people will stop losing bones." But we don't know.
