In 1,651 Norwegian coronary artery disease patients (21% women, mean age 61) followed across 7,880 person-years of cardiac rehabilitation, peak oxygen uptake measured via treadmill CPET emerged as a powerful graded predictor of major adverse cardiovascular events (MACE — encompassing all-cause mortality, acute coronary syndrome, stroke, and heart failure). Each 1 mL·kg⁻¹·min⁻¹ increment in VO2peak corresponded to a 7% lower MACE hazard in men (HR 0.93) and 5% in women (HR 0.95). Patients in the top cardiorespiratory fitness quartile faced a 55% lower MACE risk versus the lowest quartile — a clinically enormous gradient. The study also generated sex- and diagnosis-specific reference tables, noting VO2peak declines of 2.5 mL·kg⁻¹·min⁻¹ per decade in men and 1.7 in women.
This confirms — in a real-world secondary-prevention cohort — what exercise physiologists have long argued: cardiorespiratory fitness is not merely a lifestyle marker but an actionable prognostic variable that belongs in clinical cardiovascular risk stratification alongside cholesterol and blood pressure. The sex-specific reference data fill a genuine gap; prior normative tables were largely derived from healthier populations. Practically, this reinforces that improving VO2peak through structured aerobic exercise after a cardiac event is a modifiable target, not just a reflection of disease severity. Limitations include the retrospective, observational design (no causal inference), a predominantly male cohort limiting female-specific precision, and a Norwegian ethnic homogeneity that may restrict global generalizability. Overall, a confirmatory yet clinically useful contribution.