A Simon Fraser University professor is hoping to find out more about the final frontier with an ongoing International Space Station project.
Professor of biomedical physiology and kinesiology (BPK), and director of SFU Aerospace Physiology Laboratory Dr. Andrew Blaber is the principal investigator for CARDIOBREATH – an acronym as well as a title – that involves using smart shirt, or Bio Monitor, technology to monitor how space affects astronauts over long periods of time.
Human bodies are best suited to life on Earth, he noted, and when astronauts travel to space and live in a weightless environment, their cardiorespiratory systems adapt – sometimes in ways that can affect their health. Fluids that circulate in their bodies decrease in volume, for example, which means their blood pressure is lower than on Earth.
How does space impact the human body?
"What we're really interested in is how our physiology changes while weightless – your body is a beautiful machine, it adapts to different situations, but it takes some time to adapt in some ways compared to others," Blaber said. "When a human enters space and you remove that gravitational influence on the body, there are a large number of changes which occur."
On Earth, humans spend much of the time standing or sitting, with gravity pulling most of the blood towards our legs or rear, but there's only so much blood in the body, and if there's not enough blood getting to the head, someone can faint due to lack of oxygen, Blaber explained, and while the human body has developed mechanisms to help counter such things, it's different on Earth than it is in space.
Researchers can study some of these effects in animals, but human beings are the only animals that spend much of their time with their heads high above their feet, "so most of our blood is below our heart."
"If you look at a dog, 70 per cent of the blood is above the heart, ... but then what about a giraffe?"
The difference is, giraffes' legs are thin-skinned, but very tough and stiff, unlike humans, whose skin is quite stretchy.
"We took that and turned it into an anti-G suit," Blaber continued, explaining that, when in space, the anti-G suit means there are inflated bladders around the abdomen and legs that squeeze them – making them more stiff, like a giraffe's legs – so blood doesn't accumulate.
"When (astronauts) become weightless, the blood doesn't go in the legs anymore – it goes upwards. ... When you see pictures of astronauts on the station or previous missions, their faces are always a little bit more puffy, more rounded. That's because there's more blood in the upper part of the body than we're used to seeing, because it's not accumulating in the abdomen and lower legs."
That also causes change, because astronaut's kidneys start to work more to remove blood, because humans are not supposed to have that much blood up there, Blaber said, and it also increases pressure in the brain, "which we now think might be causing changes to the structure of the eye."
A certain syndrome can happen when the optic nerve swells, he said.
"Then it bends, and then the back of the eyes flatten, and you get folds in the back of the eye. ... It could be something that may end up being permanent if it lasted for a long time," said Blaber. "Like many things that we're finding in astronauts, it doesn't happen to everyone. ... That's an ongoing issue astronauts are concerned about... that's one of the issues – and it may resolve when they come back or it may not."
That's why there are so many ongoing research programs, to help find out why there are differences from one person to the next, he said.
"If we can understand that, we could probably help people who have a problem."
CARDIOBREATH and how it works
Supported by the Canadian Space Agency, CARDIOBREATH looks at what can be done to protect astronauts' blood pressure regulation, by examining how astronauts' cardiovascular and respiratory systems interact with their blood pressure control during missions on the International Space Station.
Blaber, who helped develop the technology for the ongoing experiment, said the multi-system approach helps he and other researchers collect important data, with the goal of keeping crews healthier in space and upon return.
Researchers are working to understand more about how astronauts' cardiorespiratory systems decondition when they are in microgravity. To examine this, researchers use the Bio-Monitor, a Canadian-made smart shirt system designed to monitor astronauts' vital signs in space.
"Most things get worse the longer you stay in flight, but we don't know the trajectory – does it happen really quickly at the beginning then slowly over time, or is it creeping along?" Blaber said. "We don't have answers to those questions, and that's why NASA no has astronauts that stay up for a year. ... They're looking at different lengths of time. I think some of the astronauts coming back this time will have been up for a year."
With their experiment, Blaber said researchers are trying to understand how each individual system changes within the body, and how that might be altered by removing gravity.
"It's the only situation where we can remove gravity in an experiment. For thousands of years, anything we've done to understand what happens to a human has involved gravity," he said. "When you do an experiment and want to understand how something works, it's good if you can remove it, and then add it again, so you can see the one variable you're removing."
When scientists don't have the option of removing gravity, they will often conduct bed rest studies on people who are in bed for long periods of time, to try and duplicate weightlessness as best as possible.
"We can do things like look at people in bed for long periods of time and say, 'OK we removed gravity from the vertical axis,' but it's still acting through the chest in the other direction, but it does seem to mimic some of the changes in space because of the lack of mobility and lack of blood volume movements," said Blaber. "So from the cardiovascular, muscle and bone standpoint, it's quite a good analog to space flight, but for other things not really, because we haven't removed gravity completely."
Humans on Earth don't necessarily realize that every time they stand and walk, their muscles are being activated not only to walk, but also to counteract the fact that they don't want to fall on the floor, and that maintains muscle mass and tone, he noted.
"Astronauts lose bone mass and they lose muscle mass, which means they have atrophy of muscles – including cardiac muscle and skeletal muscle. Their arteries respond differently – they get stiffer. Some (astronauts) tend to have changes in response to sugars, so there's some pre-diabetic conditions that can occur over a long period, even though the average astronaut is required to do a number of hours of exercise every day to try maintain their cardiovascular system."
Blaber said scientists are still working on improving exercise programs and also, hope to compares data from male and female astronauts to shed light on whether their cardiorespiratory systems adapt to space flight in different ways throughout the experiment.
Body mechanics: Earth vs. space
When astronauts wear the Bio Monitor, researchers are able to look at a number of systems simultaneously, Blaber said.
"It measures the ECG per heart rate, so we can get cardio function. It also measures blood pressure, so we can look at blood pressure regulation. ... It also measures breathing rate and volume and blood pressure and heart rate."
Astronauts who participate have their cardiovascular and respiratory systems tested multiple times after a set amount of exercise on the ground before the flight and after the flight; they complete the same exercise multiple times in space, while also wearing the Bio Monitor. They will also collect measurements for a few minutes during rest periods before and after the exercise session; there's also a stand segment, and a float portion of the test in space.
Researchers will compare the results they get on Earth with the results obtained in space.
"We're looking at those dynamics – not just how the breathing changes, heart rate, and blood pressure, but we're looking at the dynamics between those two systems," Blaber said. "On one side, we have the mechanics of breathing and the mechanics of the heart affecting the neural reflex which controls the heart, so we have a mechanical effect which then drives the reflex, which is neural. Then, when you exhale, you squeeze the heart."
When astronauts have been in space for awhile, the nervous system side of things tends to decrease.
"So when they come back, when their blood pressure drops, they don't respond as strongly as they did before they left, and hat's one reason why they faint," he said. "We don't understand why the nervous side is reduced. It could be a number of reasons – that's why we're trying to tease it out."
Scientists started looking at muscle activity when people are standing and found that quite a significant proportion of that muscle activity wasn't for posture – it was for blood pressure regulation, Blaber added.
"In the stand portion (of the experiment), we actually measure their sway and their muscle activity. In bed rest, we found that when a muscle contracts in the leg, regardless of before they went into bed or after, out of bed, it caused a similar change in blood pressure afterwards as before, but the nervous system response was dramatically reduced.
"Something in bed rest or we think in (space) flight, is dampening the (nervous system) signal – like turning down the volume on your radio... we're trying to figure it out. Now we've added the third system – the muscle system."
Blaber said studying heart function, lung function and their mechanics, as well as the leg muscles before, during and after exercise on Earth and in space all helps scientists collect the data they need for their research.
Future of the final frontier
As Blaber and others continue to explore the impact of space flight on human bodies, more and more people will be conducting space flight missions, he said.
"We have now more private industry. ... They're a a select few and they have to have money and so on, but it does mean that the pool of people who will be flying (into space) may not fit the elite category of fitness and training, and so the question is, what are the risks?"
More people in space also means it will provide more opportunities for researchers to get more science and to understand human physiology in those conditions, especially in people who haven't gone through the rigorous selection process that space agencies require.
"If we got to the moon and eventually to Mars, it's going to take longer and (people will) spend more time in either zero or a lower-G environment. We still don't understand whether one-sixth on the moon or one-third on Mars would be good enough to maintain that ... that's up for debate. We may have to design exercises on the moon and Mars to compensate."
As space travel increases, researchers need to focus more on understanding how to increase safety and reduce risks for those who are making the journey, Blaber said.
"It's going to happen. We need to prepare for that eventuality."
A lot of what scientists see happening in astronauts is similar to aging, he said, and why they're collecting data on astronauts who repeatedly participate in space flight, as they are able to recondition and get most of the loss of muscle and bone back, when they return to Earth.
"The inactivity and immobility ... often looks like what we see in older people," said Blaber.
"If we follow one person, then we get a repeated measure that will allow us to hone in on the cellular molecular mechanisms involved in these changes, and that would help with rehabilitation in patients who are hospitalized in bed for a long time ... maintain their systems as they get older aging in place at home."
