Exercise Counters Cardiac Mars Risk

A Circulation study of 13 International Space Station astronauts shows disciplined in‑flight endurance and resistance training largely restored cardiac filling and output lost in early microgravity and that crews tolerated a 22° tilt‑table test approximating Martian gravity. The result suggests cardiac deconditioning may be manageable for year‑long Mars missions if robust exercise protocols and monitoring are maintained. — If reproducible, this empirical result reduces one medical barrier to human Mars missions and shifts policy debate toward implementing, funding, and regulating effective in‑flight exercise, monitoring, and return‑to‑gravity care.