VO2max: the fitness number that predicts your lifespan better than smoking

Your fitness level says more than your medical chart

If you had to guess which single measurement best predicts how long you'll live, you'd probably think of blood pressure, cholesterol or your smoking history. The largest study on fitness and mortality to date points somewhere else: cardiorespiratory fitness, roughly how well your heart, lungs and muscles take up and use oxygen during exercise. That one number explains more about your odds of survival than almost any classic risk factor, and unlike your birth year or your genes, it's something you can build.

What cardiorespiratory fitness actually measures

Cardiorespiratory fitness, often expressed as VO2max, measures how much oxygen your body can take up and use at maximum effort. The higher that number, the more efficiently your heart pumps blood, the better your lungs take up oxygen, and the more effectively your muscles convert that oxygen into energy. A lab test with a breathing mask gives the most precise figure, but a treadmill test to exhaustion (the method most studies use) already gives a solid, usable picture.

What the largest study to date shows

Researchers at the Cleveland Clinic followed 122,007 patients who underwent an exercise stress test, for a median of 8.4 years. During that time, 13,637 of them died. People in the fittest group (the top 2.3%) had a mortality risk 80% lower than the least fit group. People who scored below average had a 41% higher mortality risk, a figure in the same range as smoking (41% higher risk) and diabetes (40% higher risk), and even higher than existing coronary heart disease (29% higher risk). Low fitness turned out to be at least as dangerous as several of the risk factors healthcare has traditionally focused on most.

No ceiling, and recent research confirms the pattern

What made this study stand out further: there was no ceiling. The fitter the participants were, the lower their mortality risk kept falling, even in the highest performance groups. That contradicts an old assumption that extreme amounts of training would become harmful at some point. More recent research (2024-2025) confirms that picture: every one-unit improvement in fitness (1 MET) was associated with 11.6% lower all-cause mortality, 16.1% lower cardiovascular mortality and 14% lower cancer mortality. Even among athletes with extremely high training volumes, researchers found no increased mortality risk over ten years of follow-up. Training intensity played a bigger role than training volume.

How to build your fitness effectively

The good news: VO2max is one of the most trainable traits there is, at any age. The combination that works best in research is a mix of easy, longer efforts and occasional real hard ones, exactly the principle behind polarized training, where roughly 80% of your training time stays low-intensity and 20% is hard to very hard. Strength training contributes indirectly by making your muscles more efficient at using oxygen, as we wrote earlier about strength training for endurance athletes. And if you're short on time: even twenty minutes of focused training already gives your fitness a measurable boost.

How HealthyDNA turns this into a concrete plan

Improving your fitness works best when you know where you're starting from and why your body responds the way it does. That's why we bring DNA analysis, blood testing, nutrition and coaching together:

• Blood testing — in partnership with Clinica Montgo in Denia, we map out how your cardiovascular system, blood sugar regulation and recovery stand today, as a baseline to track progress objectively.
• DNA analysis — gives insight into your predisposition for endurance and recovery, so your training build-up matches what your body already brings to the table.
• Coaching — turns that information into a training rhythm that fits your life, with someone reviewing and adjusting alongside you instead of a schedule you have to push through alone.

Curious how your fitness compares to your mortality risk, and what you can concretely do about it? Get in touch or read more about the DNA analysis and blood testing.

You can quit smoking. You can't change your genes. Your fitness, you can, and of the three, that might be the strongest lever you hold yourself.

This article is general information and does not replace medical advice.