For an astronaut living on the international space station is like being Superman every day, flying to their breakfast, work and even the bathroom. But floating around in zero gravity can have some serious consequences for the human body, including the weakening of bones. In fact, studies by NASA have shown that space travellers can lose 1 to 2 percent of their bone mass each month on average.
One way that astronauts have been fighting bone loss is through strength training. So shuttle Endeavour is delivering an advanced Resistive Exercise Device to the international space station.
The advanced Resistive Exercise Device, aRED for short, functions like a weight machine in a gym on Earth, except it has no conventional weights. Instead, it has vacuum cylinders – canisters with air that have had a vacuum applied – that provide concentric workloads up to 272kg. The device works somewhat like a bicycle pump, only in reverse, said Mark Guilliams, a NASA trainer. For example, if you are squatting, the vacuum gets pulled out as you stand up, and when you squat back down, the vacuum pulls the bar back to the normal position. Between the vacuum cans and the bar, there are small flywheels that spin in opposite directions, creating an artificial gravity when someone lifts the bar.
Astronauts can do upper and lower-body exercises, such as squats, dead lift, heel raises, bicep curls and bench press on the device.
The machine is huge and looks like something out of the movie Transformers. Compared to the old mechanism on the space station, a very limited rubber band contraption, aRED will allow for more effective exercises to be performed and reduce the boredom of the old device.
As astronaut’s workout about two hours a day, it will be in constant use. They also have a treadmill and an exercise bike.
Exercising in zero gravity is very different to exercising on earth. On earth running in gravity means that your whole body weight pounds against the pavement. On the treadmill on the space station the astronauts have to use bungees to hold them down onto the running bed. Therefore the downward load is very much reduced resulting in muscle and bone loss.
Astronauts have lost up to 16% body mass in 152 days off the planet but now they can reduce that too less than 4% by daily workouts.
The other difference is the type of muscles used. On earth you tend to use the larger muscle groups of the legs, but in space it’s the smaller muscles of the hands, arms and upper body. That’s why you see astronauts walking unsteadily off the shuttle after they return from space, because their legs have not had their normal use.
Combating bone loss is one of the challenges that the space program has, especially given the goal of a mission to Mars.
An ongoing study is measuring how much astronauts who stay on board the international space station eat and exercise. The experiment will determine what kinds of dietary supplements astronauts should take in addition to the food they eat, and also the appropriate level and type of exercise they should get.
NASA is making some good strides in figuring out how to keep people healthy on a six- to nine-month trip to Mars, although experts are still a long way away from figuring out the bone loss issue for a round-trip journey of about two years.