Getting in Shape to Go into Space

Astronauts have to be the fittest and healthiest they can be in order to endure the challenges they face in space. But the requirements don't stop there. Space travellers also have to maintain a vigorous exercise regime while in space. Research from previous missions has shown that astronauts can lose up to 20 percent of their muscle mass during a space flight of just 5 to 11 days, a process known as muscle atrophy.

This muscle loss is due to the weightless environment that the space travellers live in on the International Space Station. While on Earth, our bodies are constantly fighting against the force of gravity to hold us upright. Known as the anti-gravity muscles, our calves, back ,and neck muscles contract constantly in order to keep us standing up with correct posture.

When in space, there is no force acting against these muscles to keep them as strong as they are needed. This means that they become weak, and although astronauts can regain this muscle once back on Earth, it can put them at a severe risk of injury when they come home.

Not only are astronauts injury-prone once back in Earth's gravitational field, but there also appears to be a marked decrease in astronauts' bone mass during their stays on the ISS. This is because the astronauts have no impact or forces going through their legs as they walk and run, like we all do on Earth (and which in normal situations strengthen our bones through "load-bearing exercise.")

Considering the detrimental effects of prolonged weightlessness, astronauts working at the ISS are now required to wear what is known as the Lower Extremity Monitoring Suit (LEMS), a tight fitting garment that has 20 sensors built into it to monitor the electrical activity of the muscles, bones and joints in the lower body. By requiring the suit to be worn during exercise, researchers are able to determine which exercises work best for maintaining bone density and muscle strength in astronauts. The results are also being used in ongoing research for the prevention and treatment of osteoporosis, a condition that sees bone density become significantly reduced, particularly in elderly people.

As space is limited on the station for large, bulky exercise equipment, there are just three devices that the astronauts use in order to work their muscles on board the space station. They are all lightweight and portable as every kilogram of equipment taken into space can cost thousands of dollars in fuel. The first is known as the Resistive Exercise Device (RED), which can be used for weight-training exercises and provides a constant resistance against the astronauts' muscles. In this way, the device can replicate the effects of gravity and prevent muscle atrophy. The second device is the Cycle Ergometer with Vibration Isolation and Stabilization (CEVIS) and is similar to the cycling machines you'll find at your local gym. It's bolted to the floor, and the astronauts strap their feet and waist to the device to stop them from floating away. The final device is a type of free-floating treadmill, which is designed to prevent bone loss.

In order to prevent muscle atrophy and loss of bone density to dangerous levels, astronauts perform special exercises for 2.5 hours every day while on board a space flight.

However, exercise isn't the only problem that astronauts face. It is vitally important that they also maintain a good diet while on board, with enough vitamins and minerals to replace those they won't be able to get from fresh produce. All the meals eaten by the crews are prepared on Earth and specially formulated to meet the requirements for each individual. This can mean planning their menus nine months in advance of the flight. The key is to keep it creative, according to NASA's food specialists at the Space Food Systems Laboratory at the Johnson Space Center. Otherwise, astronauts can suffer from "meal boredom," which can suppress their appetites. Although weightless, the astronauts need the same number of calories as they do on the ground, and much of their nutrition comes from dehydrated meals or nuts, cookies, and granola bars. Other problems astronauts might face during their travels include motion sickness, disorientation, and lack of coordination, which they can tackle with medication and by using virtual reality simulators prior to their flight to help them adapt to a weightless environment.

Despite all these challenges, most astronauts nowadays come back to Earth relatively unscathed, thanks to extensive research conducted during previous missions on the effects that living in space can have on the human body. However, still lacking are means to tackle these problems for extended missions. This remaining hurdle, along with the increased levels of ionizing radiation that astronauts are exposed to from the Sun and cosmic rays, means that any manned-mission to Mars is out of the question, at least in the near future.

Image Credit: NASA (via Wikimedia Commons)