Exercise Protected Astronauts' Hearts in Six-Month Space Study — SkimNews
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- Circulation study of 13 astronauts who performed onboard echocardiograms during six months in space found initial changes in heart structure and function stabilized over time and returned to normal after returning to Earth, with exercise regimens credited for the protection.
- Benjamin Levine, NASA's consulting cardiologist and director of the Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Dallas, said the most novel finding was that after returning to Earth and being exposed to 3/8 gravity (Mars-like), no astronaut had a cardiovascular response more stressed than upright posture on Earth before launch.
- Astronauts learned to perform their own echocardiograms in space via real-time remote guidance from ground-based sonographers — 'you can't fly a sonographer into space' — producing research-quality imaging that went beyond the blood pressure and heart rate measures used in prior work.
- NASA's planned 2035 Mars mission requires two six-month microgravity journeys sandwiching 18 months on the red planet, and Levine noted that NASA exercise scientists are currently designing fitness hardware for the smaller Mars-bound vehicle, balancing mass, volume, and power constraints.
- Ground-based bed rest studies showed that deconditioning causes the heart to shrink, atrophy, and become functionally stiffer, and that exercising while in bed completely eliminates those changes — the conceptual foundation for the in-flight countermeasure approach.
- Approximately 75% of left ventricular muscle mass responds to changes in physical activity, illustrating the cardiac plasticity that allowed astronauts' hearts to adapt to and recover from microgravity.
Why it matters: A planned 2035 Mars mission demands two six-month microgravity voyages bookending 18 months on the planet, and this Circulation study provides the first direct echocardiographic evidence that structured exercise preserves cardiac structure across that timeline — including simulated Martian gravity. Levine flagged a caveat: astronauts who can't exercise (e.g., after injury) might land more compromised, a real risk given that cardiovascular events are the most likely cause of any catastrophic in-flight medical emergency.
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