Doctor Claims VO2 Max Predicts Longevity Better Than Anything Else. The Problem? Most Research Never Tests It

A recent debate has emerged in the health optimization space, and it’s making waves among fitness enthusiasts and longevity seekers alike.

The question centers on whether VO2 max—a specific measure of maximum oxygen uptake—is really the gold standard metric for predicting longevity, or if we’ve been conflating it with the broader concept of cardiorespiratory fitness.

Dr. Eric Topol recently challenged claims made by longevity expert Dr. Peter Attia, pointing out that most studies don’t actually measure VO2 max directly.

What follows is a nuanced discussion that reveals why chasing a single number might be missing the bigger picture.

The Critical Distinction Between VO2 Max and Cardiorespiratory Fitness

These aren’t interchangeable terms, despite how they’re often used in popular health discourse.

VO2 max and cardiorespiratory fitness are distinctly different. And most of the longevity studies that Dr. Attia has cited, they don’t actually ever measure VO2 max.

VO2 max represents a precise measurement of maximum oxygen uptake. Getting an accurate reading typically requires a maximal effort test using specialized equipment called a metabolic cart.

Cardiorespiratory fitness, on the other hand, casts a much wider net. In large-scale research studies, it’s usually assessed through estimated treadmill tests where participants exercise until they reach their tolerance limit.

These tests measure metabolic equivalents (METs) at peak effort—not true VO2 max. Researchers can also use submaximal tests or even questionnaires to gauge fitness levels.

The Percentile Problem

In his book Outlive and throughout his podcast appearances, Dr. Attia has provided specific VO2 max percentile targets broken down by age and sex. He’s called VO2 max “the single most powerful marker for longevity.”

He’s probably directionally correct. The controversy emerges because the underlying research he references doesn’t actually measure what he’s telling people to optimize.

Take the frequently cited 2022 study published in JAMA Network Open. It assessed exercise capacity using METs from stress tests, then mapped those performance numbers onto VO2 max percentiles. Another landmark 1989 JAMA study used treadmill time—again, a performance-based metric rather than direct VO2 max measurement.

Why Optimizers Love Concrete Numbers (And Why That’s Problematic)

Folks like Dr. Attia, quote unquote optimizers, are very interested in discrete and concrete metrics that they can aim to optimize.

There’s an economic principle at play here—Goodhart’s Law. Once a measure becomes a target, it often ceases to be a good measure.

VO2 max tells us something valuable about cardiorespiratory fitness, particularly regarding central adaptations like cardiac function. But it reveals less about peripheral determinants of performance—factors happening at the muscular level that also contribute significantly to overall fitness and health.

Collapsing all of cardiorespiratory fitness into this single metric creates tunnel vision. It’s shortsighted given that the evidence base draws from actual performance measures, not lab-controlled VO2 max tests.

The Case for Performance-Based Benchmarks

Nobody’s arguing against the value of cardiorespiratory fitness for longevity. The relationship is clear and likely causal—being more aerobically fit improves both lifespan and healthspan.

The real question: Do we need to obsess over VO2 max percentiles, or should we focus on performance improvements?

Maybe why don’t we just pay attention to performance and we don’t need to use this very particular metric.

Picking a standardized benchmark test and improving it over time is a reasonable approach. If your chosen performance measure shows consistent improvement, your cardiorespiratory fitness—including VO2 max—is likely improving along with various health outcomes.

The Strength Training Analogy

Consider how this plays out in resistance training. Strength clearly correlates with health outcomes.

Imagine deciding that grip strength will be your sole metric. You orient all training protocols around improving that one measure. Would you be healthier than doing nothing? Absolutely. But are you missing valuable training adaptations by ignoring other strength modalities? Also yes.

Someone else might choose the 5-rep max back squat as their singular focus. Both approaches improve strength and health, but both also deprioritize other valuable aspects of training.

Having metrics is great, but collapsing everything down into that one metric and making that the primary outcome of interest to potentially the exclusion of other valuable aspects might be where some people could improve the way they go about this.

The Protocol Trap

When people fixate on optimizing VO2 max specifically, they often seek out particular interval training protocols shown in studies to maximize that metric. This can lead to deprioritizing other forms of aerobic training that build cardiorespiratory fitness through different pathways.

Zone 2 training, long slow distance work, tempo runs, and various other modalities all contribute to overall fitness. They might not spike VO2 max as dramatically as certain high-intensity protocols, but they develop crucial adaptations nonetheless.

The Semantic Versus Practical Debate

Is the criticism of Dr. Attia’s recommendations mostly semantic? Perhaps partially.

Having concrete targets provides something valuable that’s missing from standard exercise guidelines: a monitoring framework. Exercise works better when it demonstrably improves your fitness, not just when you complete recommended weekly minutes.

It’s not just like do the guidelines, double the guidelines. It’s like yeah, but do it in a way that makes you stronger, that improves your cardiorespiratory fitness.

Dr. Attia could have chosen any performance benchmark—a 20-minute cycling time trial, specific power output thresholds, or running pace metrics. He selected VO2 max percentiles, which correlate well with exercise tolerance tests anyway.

The error might be in precision rather than direction. If the complaint is that specific percentile thresholds aren’t as evidence-based as presented, that’s a fair science communication critique. But what’s the actual harm if people improve their fitness pursuing these targets?

A More Comprehensive Approach

The solution doesn’t require abandoning metrics entirely. It means adopting a broader measurement strategy.

Organizations like Barbell Medicine recommend tracking VO2 max alongside field tests across different modalities. This prevents the tunnel vision that comes from singular focus.

We don’t hamstring people by saying you just got to get your V2 max up and anything else that doesn’t directly raise your V2 max is useless. We’re just like look we want to improve your cardiorespiratory fitness.

Multiple benchmarks allow you to monitor progress across the full spectrum of cardiorespiratory adaptations. They ensure your training program actually works for you, not just theoretically.

What This Means for Your Training

The takeaway isn’t to abandon VO2 max testing or stop caring about the metric. It’s valuable information, particularly if you have access to accurate testing.

Instead, consider these principles:

• Recognize that cardiorespiratory fitness encompasses more than VO2 max alone
• Use multiple performance benchmarks to track progress
• Don’t abandon training modalities just because they don’t maximally spike VO2 max
• Focus on sustained improvement across various fitness domains
• Remember that the correlation between exercise tolerance tests and actual VO2 max is strong

The relationship between cardiorespiratory fitness and longevity remains robust regardless of which specific metric you emphasize. Being aerobically fit matters immensely for healthspan and lifespan.

The debate ultimately centers on optimization culture’s tendency to reduce complex biological systems to single numbers. While metrics provide useful targets and motivation, fitness itself remains the true goal—measurable through various lenses, developed through diverse training methods, and beneficial across multiple physiological systems.

Choose benchmarks that resonate with you. Track them consistently. Improve them progressively. And don’t lose sight of the forest while counting the trees.