Improving VO₂ max—the body’s ability to use oxygen during exercise—has been consistently linked to longer life and lower risk of heart disease. This benefit shows up across all ages, but the size of the benefit can depend on age, baseline fitness, and health status. Research shows that even modest improvements of 1–2 METs (a standard unit to measure aerobic capacity) can significantly reduce the risk of dying early or developing cardiovascular problems.

In middle-aged adults (40–59 years), large studies from the Cooper Institute and meta-analyses in JAMA have shown that each 1-MET increase in VO₂ max is associated with about a 10–15% reduction in all-cause mortality. That means if a person improves their aerobic fitness by just 2–3 METs, their risk of dying from any cause drops by roughly 20–25%. This is why the table shows a strong reduction in mortality for the 40s and 50s age groups with fitness gains.

In older adults (60–69 years), the benefit becomes even more striking. Because the baseline risk of cardiovascular disease is higher, gains in VO₂ max are tied to disproportionately larger reductions in death from heart disease. For example, Finnish cohort data show that a ~2-MET increase in aerobic fitness is linked with nearly a 20% lower risk of cardiac death in this age group. In people over 70, the focus shifts slightly: rather than pushing to very high heart rates, the emphasis is on safe training, adding strength and balance, and maintaining functional independence. Clinical studies in patients with heart failure (like the HF-ACTION trial) show that exercise programs that improve VO₂ max lead to 15–20% fewer hospitalizations and better ability to stay independent.

Taken together, these findings explain the “Impact on Longevity” column in your table. The numbers are not guesses—they are drawn from decades of large studies, systematic reviews, and clinical trials showing that better aerobic fitness translates directly into longer life, fewer cardiac events, and less time spent in the hospital.

Exercise training for patients with heart failure with mildly reduced ejection fraction (HFmrEF) is recommended based on extrapolation from robust evidence in heart failure with reduced (HFrEF) and preserved ejection fraction (HFpEF). The American College of Cardiology, American Heart Association, and Heart Failure Society of America recommend structured, supervised aerobic and resistance exercise training to improve functional status, exercise performance, and quality of life in these populations, with similar benefits anticipated in HFmrEF.[7]

The guideline rationale is grounded in randomized controlled trials and meta-analyses showing that moderate-intensity aerobic exercise (e.g., targeting 150 minutes per week) improves peak oxygen consumption, exercise duration, and health-related quality of life, and may reduce heart failure hospitalizations. High-intensity interval training (HIIT) and resistance training are also supported for their roles in enhancing maximal oxygen uptake, muscle strength, and exercise tolerance, without evidence of adverse cardiac remodeling. The societies emphasize that exercise should be avoided in patients with acute decompensated heart failure or unstable ischemia, and that supervised programs are preferred for safety and efficacy.[7]