In 2018, a study published in JAMA Network Open followed 122,007 patients who underwent treadmill testing and tracked their mortality over a median follow-up period. The findings were striking. Adults with elite cardiorespiratory fitness had an 80 percent lower all-cause mortality rate compared to those in the lowest fitness group. The association between fitness and survival was stronger than the associations observed for hypertension, diabetes, smoking, or end-stage renal disease. Cardiorespiratory fitness was, in practical terms, the most powerful predictor of survival in the entire dataset.
What VO2 Max Actually Measures
VO2 max is the maximum volume of oxygen the body can consume per minute per kilogram of body weight during maximal exercise. It reflects the combined efficiency of the heart's pumping capacity, the lungs' gas exchange capacity, the blood's oxygen carrying capacity, and the muscles' ability to extract and use oxygen. A higher VO2 max means a more efficient cardiovascular and metabolic system. It declines naturally with age, at approximately 10 percent per decade from the mid-twenties, but the rate of decline is substantially slower in people who train regularly.
The Dose-Response Relationship
A meta-analysis published in JAMA in 2009, covering over 33,000 participants, found that each 1 MET increase in cardiorespiratory fitness was associated with a 13 percent reduction in all-cause mortality and a 15 percent reduction in cardiovascular mortality. The relationship held across age, sex, and baseline health status. The benefit of increasing from low to moderate fitness was larger than the benefit of increasing from moderate to high fitness, meaning the biggest gains come from addressing the lowest end.
How to Improve VO2 Max After 40
- Zone 2 training: steady-state aerobic work at 60 to 70 percent of maximum heart rate, performed for 45 to 60 minutes, 3 to 4 times per week, is the most evidence-based foundation for VO2 max improvement
- High-intensity interval training: 4 to 6 intervals of 3 to 4 minutes at 90 to 95 percent maximum heart rate produce acute VO2 max improvements superior to moderate steady-state work when used 1 to 2 times per week
- Consistency over intensity: VO2 max responds to training volume accumulated over months; two weeks of hard training does not offset six months of inactivity
- Combination training: resistance training combined with aerobic training produces greater VO2 max improvements than aerobic training alone, via cardiac output improvements
Sources
- Mandsager, K., et al. (2018). Association of cardiorespiratory fitness with long-term mortality among adults undergoing exercise treadmill testing. JAMA Network Open, 1(6), e183605.
- Kodama, S., et al. (2009). Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women. JAMA, 301(19), 2024-2035.
- Myers, J., et al. (2002). Exercise capacity and mortality among men referred for exercise testing. New England Journal of Medicine, 346(11), 793-801.