Astronauts experience decrease in blood vessel function during spaceflight, study finds

May 9, 2017
Astronauts aboard the International Space Station experience decreased physical fitness because of a decrease in the way oxygen moves through the body, according to a Kansas State University kinesiology study. Credit: NASA

Astronauts aboard the International Space Station have decreased physical fitness because of a decrease in the way oxygen moves through the body, according to a Kansas State University kinesiology study.

Carl Ade, assistant professor of exercise physiology, and collaborators partnered with the Johnson Space Center to find that astronauts' exercise capacity decreases between 30 and 50 percent in long-duration spaceflight because the heart and small blood vessels are not as effective at transporting to the working muscle.

"It is a dramatic decrease," Ade said. "When your cardiovascular function decreases, your aerobic exercise capacity goes down. You can't perform physically challenging activities anymore. While earlier studies suggest that this happens because of changes in heart function, our data suggests that there are some things happening at the level of the heart, but also at the level of the microcirculation within capillaries."

In addition to improving astronaut health and providing valuable information for future long-duration spaceflights, the research also can help Earth-bound clinical patients with heart failure, Ade said.

The NASA-funded research appears in the Journal of Applied Physiology in the publication "Decreases in maximal oxygen uptake following long-duration spaceflight: Role of convective and diffusive O2 transport mechanisms." The journal also featured the research in a recent podcast.

Other Kansas State University researchers involved include Thomas Barstow, professor of kinesiology, and Ryan Broxterman, 2015 doctoral graduate in physiology and postdoctoral fellow at the University of Utah. Alan Moore, associate professor of health and kinesiology at Lamar University, also contributed.

Carl Ade, Kansas State University assistant professor of exercise physiology, and collaborators have found that astronauts' exercise capacity decreases in long-duration spaceflight because the heart and small blood vessels are not as effective at transporting oxygen. Credit: Kansas State University

While in outer space or on the International Space Station, astronauts have to perform many physically demanding tasks, from the simpler task of opening a capsule door to potentially more intense future planetary tasks such as helping a fallen crew member. Just as important is making sure astronauts can perform life-saving tasks when they return to gravity—tasks that could include an emergency landing on Earth or performing extravehicular activities on the surface of Mars, Ade said.

For the study, the researchers used Johnson Space Center data on nine male and female astronauts who spent about six months aboard the International Space Station. The data included exercise measurements before and after their time in outer space.

The astronauts performed a stationary bike exercise test several months before they launched to the International Space Station. The researchers established the astronauts' exercise capacity through measurements—such as oxygen uptake, cardiac output, hemoglobin concentration and arterial saturation—that illustrate how effectively the body transports oxygen to the muscle mitochondria. Within a couple of days of returning to earth, the astronauts performed the same stationary bike exercise test to determine changes in aerobic .

By comparing the two sets of data, the researchers saw a 30 to 50 percent decrease in maximal oxygen uptake. Maximal oxygen uptake is the maximum rate of oxygen that is consumed during exercise and shows the cardiorespiratory health of a person. The researchers attribute this decrease to the way that microgravity changes the interaction between blood vessel capillaries and red blood cells, but say that more research is needed to understand what is happening in the capillaries.

"This decrease is related to not only health, but performance," Ade said. "If we can understand why is going down, that allows us to come up with targeted interventions, whether that be or pharmacological interventions. This important new information can help these and prevent any adverse performance changes in their job."

While the research is key to planning for future long-duration spaceflights, such as journeys to Mars or deep , it also can help understand blood vessel function in older patients or patients with heart failure.

"We have seen similar situations happen with heart failure and with aging," Ade said. "If we can better understand what is happening in the astronaut and how to prevent it, then we might be able to do the exact same thing in a patient who is older or who has ."

Explore further: Resolving to stay fit in space and on Earth

More information: C. J. Ade et al, Decreases in maximal oxygen uptake following long-duration spaceflight: Role of convective and diffusive Otransport mechanisms, Journal of Applied Physiology (2017). DOI: 10.1152/japplphysiol.00280.2016

Related Stories

Resolving to stay fit in space and on Earth

February 23, 2015

In February, our attention turns to romantic matters of the heart. As American Heart Month, this month is also a time to focus on heart health and a perfect excuse to start working out to improve your physical fitness. Astronauts ...

Image: Testing astronauts' lung health

April 21, 2017

The stellar views from the International Space Station are not the only things to take an astronaut's breath away: devices like this are measuring astronauts' breath to determine the health of their lungs. ESA astronaut ...

Five things that happen to your body in space

January 18, 2016

Tim Peake is the first official British astronaut to walk in space. The former Army Air Corps officer has spent a month in space, after blasting off on a Russian Soyuz rocket to the International Space Station on December ...

Exercise has benefits, even when it's done in space

March 22, 2012

Astronauts have been taking part in short spaceflight missions since 1961. They have only recently begun to spend significantly longer times in space, with missions extending for months, since the days of the Russian Mir ...

Recommended for you

Recurring martian streaks: flowing sand, not water?

November 20, 2017

Dark features on Mars previously considered evidence for subsurface flowing of water are interpreted by new research as granular flows, where grains of sand and dust slip downhill to make dark streaks, rather than the ground ...

Image: Hubble's cosmic search for a missing arm

November 20, 2017

This new picture of the week, taken by the NASA/ESA Hubble Space Telescope, shows the dwarf galaxy NGC 4625, located about 30 million light-years away in the constellation of Canes Venatici (The Hunting Dogs). The image, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.