Introduction
Sunita Williams is back!
She has spent close to 9 long months aboard the ISS- which is a long time by Earth standards, but even longer by space standards! This is because space has NO gravity- which means the way our bodies function change drastically.
How Do Astronauts Prevent Bone Loss In Space?
With no gravity to hold them down, or provide resistance and weight for the bones and muscles, astronauts literally do not need to put any effort in moving around- they just tend to randomly zoom or float around to their destination.
Since they are not using their muscles and bones in the normal way, they can suffer from accelerated bone mass and muscle loss. Thankfully though, the two astronauts in question had to embark on a space walk where they had to get some repairs done, but otherwise, with them being cooped up in the ISS where space is at a massive premium, it does beg the question- how are they staying strong and healthy? How are their bones and muscles working normally?
In a recent interview that one of the astronauts gave (she is the well known Sunita Williams)- she joked that she had almost forgotten how to walk around, as floating about has been the norm for the last 235 days.
Why Do Astronauts Lose Bone Mass In Space?
The earth has gravity, which is continuously acting on us- even if we don’t consciously feel it. This means the muscles of the lower half of the body and the back are in constant use- working hard to keep us upright. This is how we maintain our posture all day- while sitting, standing, eating, walking, running, jogging or whatever else we may be doing.
But, since there is no gravity in space, there is no need to use any effort at all- with respect to moving around or staying upright. With muscles and bones- it is literally ‘use it or lose it’.
When you keep using your muscles and bones in the right way, your body keeps making new bone cells, while also relegating resources for continuous maintenance and breaking down as needed.
But, in microgravity, the breaking down or resorption rate is higher than the formation of new bone- resulting in a net loss in bone density.
Astronauts lose almost 1-2% of their bone mass every month due to atrophy. If it continues unabated, it can lead to brittle bones and fractures, along with other issues like osteoporosis (which are normally associated with aging and normal wear and tear or tissue).
To check for changes in bone densitometry values closely, NASA has a Human Health and Performance Directorate’s Bone and Mineral Laboratory- where astronauts need to get dual energy X-ray absorptiometry- (DXA) before and after a stint in space.
Muscles also show less expression of growth and metabolism related genes when astronauts are in space.
Ways Astronauts Stay Healthy In Space
Weight bearing and resistance are the two primary factors that determine how strong and functional bones and muscles will be. Since both of them are virtually absent in space, astronauts find it really hard to exercise.
This is why they are asked to follow a highly specific set of exercises and workouts- for over 2 hours everyday. Most of us hate the idea of working out everyday, let alone a couple hours. The non-existent conditions and poor motivation can make life worse for astronauts- which is why they work out using VR goggles to make things more interesting.
Astronauts use a treadmill called TVIS which allows them to work out with small amounts of gravitational resistance, along with a well designed tether that keeps them on the machine- mimicking gravity. Another component they need to include everyday is weightlifting- which is done with the help of the Advanced Resistive Exercise Device (ARED). Some studies want to check the difference between astronauts who use and don’t use the treadmill everyday, and instead exercise without any equipment.
Conclusion
Astronauts undergo a very rigorous pre-flight training regimen, just like athletes do. When they continue to work out for two hours or more everyday, and eat well - they can limit the side effects of microgravity on bone loss, muscle strain and other factors. Myostatin inhibitors are certain specialised drugs used to treat osteoporosis on earth and scientists are trying to figure out if they will be good for astronauts in space. All of this research is being done in an effort to help them recover soon and prevent debilitating muscle atrophy and brittle bones from affecting them long term, once they are home.
FAQs
1.How do astronauts protect their bone health while in space?
Astronauts need to exercise 15 hours a week (2.5 hours, 6 days), while also eating foods rich in vitamin D and calcium. To help them combat microgravity related tissue loss, they also take bisphosphonates - to help them increase bone mass and reduce the chance of developing brittle bones. They also get bone densitometry scans done regularly - before and after a mission and once every 3 years afterwards, even if they have not flown to space.
2. How much bone loss do astronauts experience in space?
They lose about 1-2% of bone mass every month- which is mostly pronounced in the hip, spine and knees-mall regions that help you maintain posture.
3. What exercises do astronauts do to maintain bone health in space?
They do aerobic exercises, run on a treadmill with a tether, lift weights, do spacewalks, use stationary bikes, etc.
4. Do astronauts take calcium supplements in space?
Astronauts consume about 1000-1200 mg calcium per day, along with Vitamin D supplements. They also need to drink plenty of water to ensure they don’t get kidney stones.
5. How do astronauts' bones adapt after long-duration space missions?
Their bones demineralise - meaning lose their capacity to bear weight, causing brittle bones and leaving them more susceptible to fractures, muscular atrophy and osteoporosis.
