Good News for Astronauts: Arteries Remain Normal Years After Long-duration Spaceflight

Rockville, Md. (July 24, 2025)—The structure and function of astronauts’ arteries appear to remain stable and free of disease for as long as five years after they’ve returned from the International Space Station (ISS), according to a new study published in the Journal of Applied Physiology. The paper has been chosen as an APSselect article for July. 

Studies have shown changes in astronauts’ bodies after spaceflight, including in the eyes, muscles and bones. In the short-term, adaptations in the human cardiovascular system in microgravity include less blood circulating throughout the body, a decreased ability to physically exert themselves, and dizziness or lightheadedness when standing after returning to Earth. But the evidence is less clear about the long-term effects of long-duration spaceflight on a person’s body.

The new study, which involved 13 NASA astronaut volunteers, aimed to shed more light on these long-term effects. In their late 30s to late 50s when they began their ISS missions, the astronauts spent between four months to nearly a year in space. Researchers studied ultrasound images of the volunteers’ carotid and brachial arteries (located in the neck and arm, respectively) before launch, during spaceflight, one week after return to Earth and up to three times in the five years after landing. In addition, the research team also reviewed the astronauts’ medical data in those five years after landing and compared them to data collected before flight.

Key findings of this study included:

• Higher levels of most markers of inflammation and oxidated stress observed in blood and urine samples during spaceflight resolved within one week after landing.
• No observed increased carotid artery thickening or stiffness. These increases are hallmarks of future cardiovascular disease.
• Brachial artery vasodilation, a subclinical marker of cardiovascular disease that measures the health of blood vessels, remained stable over time.
• Total cholesterol and glucose levels rose moderately over seven years of observation but hemoglobin A1C did not, suggesting that heart disease and diabetes risks did not rise as a result of spaceflight.

Using the medical data in a risk estimation tool developed for the general population that predicts developing heart disease within the next 10 years, the researchers found that risk increased from 2.6% to 4.6% from before spaceflight to five years after landing. However, calculated risk increased only by an additional 0.5% when using an estimation tool developed from a population with similar health characteristics to astronauts.

The astronauts self-reported that they maintained an active lifestyle after their mission, including those who retired from the astronaut corps. Notably, the researchers explained that natural aging of the astronauts accounted for most of the increase in predicted risk.

“[W]e report that most indices of arterial structure and function in ISS astronauts were not different than preflight and that there were no signs, symptoms, or diagnoses of cardiovascular disease during the first [five years] after returning to Earth from long-duration spaceflight,” the researchers wrote. “Thus, [the cardiovascular system of] astronauts appear resilient to the stressors of spaceflight.”

Read the full article, “Arterial Structure and Function in the Years after Long-duration Spaceflight.” It is highlighted as one of this month’s “best of the best” as part of the American Physiological Society’s APSselect program. Read this month’s selected research articles.   

NOTE TO JOURNALISTS: To schedule an interview with a member of the research team, please contact APS Media Relations or call 301.634.7314. Find more research highlights in our Newsroom.   

Physiology is a broad area of scientific inquiry that focuses on how molecules, cells, tissues and organs function in health and disease. The American Physiological Society connects a global, multidisciplinary community of more than 10,000 biomedical scientists and educators as part of its mission to advance scientific discovery, understand life and improve health. The Society drives collaboration and spotlights scientific discoveries through its 16 scholarly journals and programming that support researchers and educators in their work.