# Why VO2 max matters so much after forty
There is one number that can tell a doctor more about the length of your life than cholesterol, blood pressure, or blood sugar levels. It's not some secret metric from the latest fitness gadget – it's called VO2 max, and scientists consider it one of the most powerful predictors of health and longevity that modern medicine knows. Especially after forty, it becomes a number that each of us should pay attention to.
Most people have never heard of VO2 max, or know it only as a mysterious value displayed on a smartwatch. Yet it's an indicator that in recent years has fundamentally transformed the perspective of sports medicine and preventive cardiology on how to measure a person's health – not just their performance.
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What exactly VO2 max means and why it matters
VO2 max, or maximum oxygen consumption, expresses how many millilitres of oxygen your body can process per minute per kilogram of body weight at maximum exertion. Simply put: it's a measure of how efficiently your cardiovascular system, lungs, and muscles work together during physical activity. The higher the number, the better your body supplies tissues with oxygen – and the more resistant it is to a whole range of diseases.
This indicator is measured in laboratories during a so-called cardiopulmonary exercise test – the patient runs or cycles on a bike with a mask on their face, while instruments monitor the composition of exhaled air. The result is a precise number that experts call the "gold standard" of cardiorespiratory health. Modern sports trackers and smartwatches can estimate VO2 max even without a laboratory test, though with less precision.
But why does this particular number predict lifespan? Research published in the prestigious journal JAMA Network Open followed more than 120,000 patients over nearly ten years and found that people with low VO2 max had a significantly higher risk of premature death – regardless of age, sex, or the presence of cardiovascular disease. Low cardiorespiratory fitness proved to be a stronger predictor of mortality than smoking, diabetes, or high blood pressure.
In other words: if you want to know how long and how well you will live, VO2 max will tell you more than most standard preventive examinations.
Forty as a turning point
The human body undergoes gradual changes throughout life, but it is after the age of forty that processes begin which are particularly important from the perspective of VO2 max. Maximum oxygen consumption naturally declines – by approximately 10% every ten years in people who are not physically active, according to experts. The heart pumps less blood at maximum exertion, muscles use oxygen less efficiently, and the lungs gradually lose some of their capacity.
This is where the crucial question arises: is this decline inevitable, or can it be slowed?
The scientific answer is unequivocal – and encouraging. Regular aerobic exercise can dramatically slow the natural decline in VO2 max, and in some cases can even increase the value after forty, fifty, or sixty. Research repeatedly shows that physically active people in their forties and fifties have VO2 max levels comparable to the average sedentary thirty-year-old. Biology is therefore not destiny – it is more of a challenge.
Let's consider a concrete example. Markéta, a forty-five-year-old accountant from Brno, began running regularly after years of sedentary work. At first she could barely manage five minutes at a stretch, but after a year of training she completed her first half-marathon. At a preventive check-up with a sports physician, she discovered that her VO2 max had increased by nearly 20% over twelve months. The doctor told her that metabolically she had "rejuvenated" by approximately eight years. Markéta's story is not exceptional – similar results are documented in studies around the world.
How to improve VO2 max and what lifestyle has to do with it
When it comes to training, the most effective method for increasing VO2 max is high-intensity interval training, known as HIIT. It consists of short, very intense bouts of movement alternated with rest or low-intensity effort. Research shows that even two to three such sessions per week can increase VO2 max more significantly than the same amount of slow endurance running. At the same time, regular moderate-intensity aerobic activity – brisk walking, cycling, swimming – also yields demonstrable results, particularly for people starting from scratch.
As physician and longevity expert Peter Attia noted in his book Outlive: "Cardiorespiratory fitness is one of the most powerful tools we have for extending a healthy life – and it is completely free."
But physical activity is only one piece of the puzzle. VO2 max does not function in isolation – it is closely linked to overall lifestyle, nutrition, sleep, and stress levels. A body that is chronically fatigued, poorly nourished, or permanently under stress cannot fully benefit from even the best training plan.
Sleep plays a surprisingly large role in this regard. During deep sleep, key regenerative processes occur – muscle fibres are repaired, hormones are regulated, and the body prepares for the next physical exertion. People who sleep fewer than six hours per night demonstrably have lower VO2 max than those who sleep seven to eight hours, even with the same training volume.
Nutrition is another pillar. A diet rich in antioxidants, healthy fats, and sufficient protein supports muscle recovery and reduces inflammatory processes in the body, which naturally hinder cardiorespiratory performance. Shifting towards a more plant-based diet, reducing industrially processed foods, and ensuring adequate intake of magnesium, zinc, and vitamin D are steps that have a direct impact on how efficiently the body works with oxygen. This is not about any trendy diet – these are fundamental principles confirmed by decades of research.
Interestingly, even seemingly unrelated factors – such as the quality of air in which a person lives, or the degree of exposure to natural environments – have a measurable influence on cardiorespiratory health. People living in areas with high air pollution have on average lower VO2 max, while regular time spent in nature and clean air acts as a natural support for both lungs and heart.
Stress, and especially its chronic form, is one of the most underestimated enemies of VO2 max. Cortisol, the primary stress hormone, at chronically elevated levels damages the heart muscle, raises blood pressure, and impairs the body's ability to use oxygen efficiently. Meditation, yoga, time in nature, or simply regular moments of calm are not just fashionable trends – they are physiologically justified tools for protecting cardiorespiratory fitness.
One less-discussed aspect is also worth mentioning: social bonds and a sense of purpose in life have a demonstrable influence on physical health, including VO2 max. Research in the field of psychoneuroimmunology shows that people with strong interpersonal relationships and a clear sense of life's meaning have lower levels of inflammation, better hormonal balance, and overall higher cardiorespiratory fitness. Longevity is not just a matter of genetics and a training plan – it is the complex result of how we live.
As for specific recommendations for those who want to improve or at least maintain their VO2 max after forty, science points to several key areas:
- Aerobic exercise for at least 150 minutes per week at moderate intensity, ideally supplemented by 1–2 interval sessions
- Strength training twice a week, which supports muscle mass and metabolism
- Quality sleep of 7–8 hours as the foundation of recovery
- An anti-inflammatory diet rich in vegetables, healthy fats, and quality protein
- Stress management through meditation, exercise in nature, or other relaxation techniques
It is important to perceive these elements not as isolated tasks, but as parts of a single whole. The body functions as a system, and cardiorespiratory fitness is the result of how well this entire system functions together.
Forty tends to be the age at which people first begin to ask questions about their own mortality – about what lies ahead, how long they will remain healthy and vital. VO2 max provides surprisingly concrete and scientifically grounded answers to these questions. It is not a magic number or a guarantee of immortality, but it is one of the best indicators available for understanding how our body is truly doing – and what we can do about it.
The most valuable aspect of the entire VO2 max story is the fact that this number can be changed. Unlike genetic makeup or past health complications, cardiorespiratory fitness is largely in each of our own hands. It is not necessary to become a marathon runner or spend hours in the gym. It is enough to start moving, eat well, sleep sufficiently, and pay attention to what the body truly needs. The results will then manifest not only in the number on a sports tracker, but above all in the quality of every day that follows.
