September 17, 2026Circulation
Impact of Prolonged Spaceflight on Cardiac Structure and Function: An Exploratory Longitudinal Observational Study
Key result
Prolonged spaceflight linked to ~17% greater LV longitudinal strain magnitude early in-flight versus preflight.
- P=0.006
- n=13
Why the study?
Does prolonged spaceflight alter cardiac structure and function in astronauts compared to preflight Earth gravity?
Key Points
- To track changes in cardiac structure and function during long-duration spaceflight and compare them to responses across varying gravitational loads, including simulated Martian gravity.
- Prospective, within-subject, repeated-measures observational study of 13 astronauts (9 male, mean age 49±4 years) aboard the International Space Station with a median flight duration of 164 days (interquartile range, 126 to 169 days).
- Serial echocardiography performed preflight (supine, upright tilt, and 22° tilt for 0.38 G Martian simulation), in-flight at microgravity (0 G), and postflight to evaluate chamber volumes and myocardial deformation mechanics.
- Significant reductions occurred in left ventricular end-diastolic volume, stroke volume, and myocardial deformation measures between preflight supine rest and early in-flight measurements at 14 days.
- Early in-flight changes mirrored preflight upright Earth posture, accompanied by increased left ventricular longitudinal strain magnitude (-14.5%±1.79% vs. -16.9%±2.03%; P=0.006) and decreased global circumferential strain (-26.09%±1.76% vs. -23.3%±3.22%; P=0.016).
- Over ~6 months in space, left ventricular volumes stabilized toward preflight supine baselines, and exposure to simulated Martian gravity (0.38 G) produced no greater hemodynamic load or stress than standing upright on Earth.
Study Design
Type
Observational (n=13)
Structured PICO
Does prolonged spaceflight alter cardiac structure and function in astronauts compared to preflight Earth gravity?
P
Population
13 astronauts (mean age 49, 31% female) evaluated for cardiac structural and functional changes during a median 164 days of spaceflight.
E
Exposure
Long-duration spaceflight (median 164 days) and simulated Martian gravity (22° tilt; 0.38 G).
C
Comparator
Preflight supine rest and upright tilt at specific gravitational loads on Earth.
O
Outcome
Changes in cardiac structure and function (echocardiographic variables including left ventricular end-diastolic volume, stroke volume, and myocardial deformation).surrogate
Main Result
Absolute Event Rate: -16.9% vs -14.5%
p-value: p=0.006
Prolonged spaceflight up to 6 months causes transient initial changes in cardiac volumes and mechanics that stabilize during flight and return to baseline upon return to Earth, suggesting orthostatic intolerance on Mars may be unlikely with appropriate countermeasures.
Limitations
- Small exploratory study
- small exploratory study
Key expert perspectives
Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“Our previous studies had demonstrated that the heart atrophies in both bed rest and in space – it becomes smaller and stiffer – and we were concerned that could be a problem over long-duration spaceflight, especially for missions to Mars. Our findings suggest that the exercise countermeasures we already have in place are enough to keep the heart in good working order for Mars' gravitational loads”
Implication
Cardiac adaptations to 6-month spaceflight stay within Earth postural norms with exercise; leaves open effects in non-astronauts or longer missions.
Abstract
BACKGROUND: Gravitational gradients, ranging from the surface of the Earth (1 G) to the microgravity of spaceflight (0 G), including intermediate gravitational fields such as those on Mars (⅜ G), directly affect cardiovascular hemodynamics. We sought to track changes in cardiac structure and function over the course of long-duration spaceflight and compare them with responses to specific gravitational loads measured preflight and postflight in a uniquely simulated Martian gravitational load. METHODS: We performed a prospective, within-subject, repeated-measures observational study of astronauts during flights to the International Space Station, with acquisition of echocardiographic variables during preflight supine rest and upright tilt at specific gravitational loads, including simulated Martian gravity (22° tilt; 0.38 G). Data were subsequently acquired during spaceflight onboard the International Space Station, upon landing on Earth, and after landing during exposure to simulated Martian gravity. Offline analyses of echocardiographic images were performed according to standardized methods, including myocardial deformation measurements. RESULTS: Thirteen astronauts (9 male) with a mean age of 49±4 years were included. The median spaceflight duration was 164 days (interquartile range, 126 to 169 days; median absolute deviation, 21 days). Significant reductions occurred in left ventricular (LV) end-diastolic volume, stroke volume, and myocardial deformation measures from preflight supine to early in-flight (14 days) measures in microgravity. These early in-flight values were similar in magnitude to those observed in the preflight upright Earth posture, with the exception of an increase in LV longitudinal strain magnitude (−14.5%±1.79% versus −16.9%±2.03%; P =0.006) and a reduction in LV global circumferential strain (−26.09%±1.76% versus −23.3%±3.22%; P =0.016). Throughout the subsequent duration of spaceflight, LV end-diastolic volume and LV stroke volume increased toward preflight supine values. After ≈6 months in space, when astronauts were exposed to simulated Martian gravity (⅜ G), no volumetric or hemodynamic measure evinced greater load or hemodynamic stress than upright posture on Earth before flight. CONCLUSIONS: In this small exploratory study, initial changes in LV chamber volumes, myocardial mechanics, cardiac output, and stroke volume with transition from Earth’s gravitational loads to microgravity were transient and stabilized during flight. Given current countermeasures, prolonged spaceflight of up to 6 months does not result in large changes in cardiac structure or function within the context of normal posture variations on Earth. These adaptations generally return to baseline upon return to Earth, with no large changes in cardiac volumes or function relative to the upright posture on Earth in a simulated Martian gravity landing, suggesting that orthostatic intolerance may be unlikely to occur on Mars after a 6-month transport with appropriate exercise countermeasures.
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Cite This Study
Appadurai et al. (2026) conducted an observational in Healthy astronauts (n=13). Prolonged spaceflight vs. Preflight Earth gravitational loads was evaluated on LV longitudinal strain magnitude (early in-flight vs preflight upright) (p=0.006). Prolonged spaceflight resulted in transient changes in cardiac mechanics, including an increase in LV longitudinal strain magnitude early in-flight compared to preflight upright posture (-16.9% vs -14.5%; P=0.006).