The Single Greatest Predictor of Lifespan

What if I told you about a lifestyle choice that not only outshines the most nutritious diet but also serves as a more precise predictor of longevity than the impact of smoking? Intriguing, isn’t it? Dive deeper with me as we uncover the compelling evidence behind this remarkable health insight.

The metric we are about to delve into is called VO2Max. 

VO2Max stands as the most accurate metric known for predicting whether a person will die in the next 10 years. It outperforms other predictors such as diabetes, smoking, high blood pressure, and cholesterol levels in forecasting the risk of death, highlighting its exceptional role in predicting longevity.

What Exactly is VO2Max?

Simply put, VO2Max is the ultimate test of your body’s ability to consume oxygen. It is measured during peak exercise and is expressed as milliliters of oxygen used in one minute per kilogram of body weight. Essentially, it’s a direct reflection of your cardiovascular fitness. The higher your VO2Max, the more oxygen your body can use, and the better your overall endurance and fitness.

Think of VO2Max as the capacity of your body’s engine. Just like a car with a larger engine can go faster and longer, a person with a higher VO2Max can perform more intense physical activities for a longer duration. This metric isn’t just for elite athletes. It’s a crucial indicator for anyone interested in their health as we are about to discover.

Interestingly, VO2Max is not static – it can be improved with the right kind of training. Targeted exercise can boost your score, not just extending your lifespan but also your health span!

For example, the more aerobically fit you are, the more energy you will have in whatever you enjoy doing, even if your favorite activity is shopping.

Now, you might be wondering: How can we trust the reliability of VO2Max as a predictor of mortality? And how exactly does VO2Max foretell our chances of death? These are crucial questions, and the answers lie in a blend of scientific research and real-world evidence that we will explore next.

The Compelling Link Between High VO2Max and Reduced Mortality Risk

A 2018 JAMA study, which followed over 120,000 individuals with an average age of 53, made a significant impact regarding cardiovascular fitness and mortality. The study revealed that higher VO2Max, as measured using treadmill tests, was associated with lower mortality rates across the board. The fittest individuals, those with the highest VO2Max, exhibited the lowest mortality rates by a remarkable margin.

When compared with the risks of smoking, the data becomes even more compelling. Smoking increases the risk of all-cause mortality by 40%, a hazard ratio (HR) of 1.40. In stark contrast, individuals with a VO2Max below the average for their age and sex – specifically between the 25th and 50th percentiles – face a risk of all-cause mortality that is double that of those in the top quartile (75th to 97.6th percentiles). This places poor cardiorespiratory fitness as a greater relative risk factor for death than smoking.

The study’s findings are further intensified at the lower end of the fitness spectrum. Individuals in the bottom quartile of VO2Max for their age group are nearly four times more likely to die than those in the top quartile. The risk increases to five times more likely to die when compared to those with elite-level fitness (top 2.3 percent of VO2Max). Moreover, improving one’s fitness from the bottom 25 percent to the 25th to 50th percentile effectively cuts the risk of death by nearly half.

These findings were confirmed by a much larger 2022 study published in the Journal of the American College of Cardiology. This study examined data from 750,000 U.S. veterans aged 30 to 95, a completely different population, and yet found that the least fit 20 percent of the studied population had a 4.09 times greater risk of dying than those in the top 2 percent of their age and sex category. Even individuals with moderate fitness (40th to 60th percentile) were at more than double the risk of all-cause mortality compared to the fittest individuals.

“Being unfit carried a greater risk than any of the cardiac risk factors examined”, the authors concluded.

The table above is from the 2022 study mentioned before. This chart shows us how different health conditions compare with fitness levels in terms of relative risk. For instance, someone with chronic kidney disease has a roughly 49% higher chance of dying at any moment than someone without this condition. Now let’s see how the least fit group compares to the extremely fit (top 2%). If you are among the least fit individuals, your risk of dying at any moment is 309% higher than someone who is considered extremely fit. The table also indicates that as fitness levels improve, the risk of dying decreases significantly across the board.

Similarly, the 2018 JAMA study reinforces this finding, indicating that individuals with the lowest fitness levels have a 5.04 hazard ratio or a staggering 404% or increased risk of mortality compared to their elite counterparts. These numbers make it clear that maintaining a higher level of fitness can significantly decrease the risk of premature death.

I would like to add that it’s crucial to note that the benchmark here is set against elite athletes, a standard that might seem daunting. However, it’s important not to be discouraged by this comparison. The primary goal should be to transition out of the low fitness category, a feat achievable for almost all individuals.

Remarkably, reaching an above-average or a high fitness level can also lead to substantial reductions in mortality risk. As we can see from the same chart, indicating that moving into these higher fitness categories can decrease mortality risks by an impressive 64% being in the average compared to low group and 76% being in the high vs low group. This significant reduction in risk highlights that while elite fitness levels are commendable, substantial life-extending advantages are attainable through more moderate improvements in physical fitness.

To finish off this section here is another chart below, showing the survival rate of people compared to different fitness groups.

As we can see after 10 years, almost 1 in 4 or 27% of people did not survive from the low fitness group.

Upon understanding these correlations, there is one more crucial question that needs to be asked: How do we know if this correlation is also causal? Meaning, how do we know if one variable is directly influencing the other, or if their relationship is mere coincidence, influenced by external factors, or due to a third variable?

An example of correlation without causation can be seen in the relationship between ice cream sales and drowning incidents. During summer months, ice cream sales tend to increase. Simultaneously, there is also an increase in drowning incidents. While these two variables show a positive correlation, one does not cause the other. Instead, the common factor influencing both is the hot weather – more people buy ice cream to cool down and more people go swimming, which unfortunately increases the risk of drowning incidents. Here, the season (summer) acts as a confounding variable that affects both ice cream sales and drowning rates, creating a correlation without direct causation between the two.

The Evidence for Establishing Causation Beyond Correlation

Acknowledging the almost certain presence of confounders in observational studies, as previously discussed, it becomes crucial to discern when a correlation actually implies causation. However, by applying five of Bradford Hill’s specific criteria (explore the Bradford Hill criteria and their role in establishing causation here) we uncover strong evidence of a probable causal link. This approach not only mitigates potential biases but also significantly strengthens our confidence in the causal interpretation.

  1. Magnitude of Effect Size – The effect size observed in these studies is very large. Its extremely rare to find correlations with this magnitude of doubling, quadrupling, and even higher risks of mortality among those with lower VO2Max levels.
  1. Consistency Across Studies – The data are consistent and reproducible across many studies of disparate populations. 
  1. Dose-Response Relationship – There is a dose-dependent response (the fitter you are, the longer you live). This relationship is evident in these studies. As VO2Max increases, the risk of mortality decreases.
  1. Biological Plausibility – There is great biologic plausibility to this effect, via the known mechanisms of action of exercise on lifespan and health span.
  1. Support from Experimental Data – Virtually all experimental data on exercise in humans suggest that it supports improved health. As the authors of the JAMA study concluded, “Cardiorespiratory fitness is inversely associated with long-term mortality with no observed upper limit of benefit. Extremely high aerobic fitness was associated with the greatest survival.”

Despite these findings, a common question arises: “I know someone fit who died early and was healthy, so why should this even matter to me?”

I would like to discuss that statement in the next section.

Probability vs Luck

It’s not uncommon to hear skepticism regarding the importance of fitness, especially when anecdotes surface about fit individuals who unfortunately passed away early. Such instances can create doubt, making one wonder, “If they were so fit and still met an untimely end, why should I bother striving for elite fitness?” To address this, let’s consider a relatable analogy and delve into the tangible benefits of striving towards higher fitness levels.

The Seatbelt Analogy

Virtually everyone has been in a car and understands the concept of using a seatbelt for safety. Seatbelts reduce the chance of fatality by 40-50% for drivers and front seat passengers, and by about 25% for those in the rear. Similarly, maintaining a VO2Max above the lowest 50% decreases your risk of early mortality comparably to how a seatbelt reduces the risk of severe injury or death in a car accident.

How would you feel driving never buckled up?

Just as a seatbelt significantly reduces your risk of severe injury in a car accident, elite or high fitness greatly lowers your risk of chronic diseases and early mortality.

The Poker Analogy

Let’s consider another analogy, poker: Imagine you’re playing poker. You have a hand of aces, which is statistically the best starting hand in Texas Hold’em. Now, does having aces guarantee a win? No, because poker is a game of probability, not certainty. However, if you consistently start with aces, your chances of winning over many games increase significantly.

A high VO2Max is like holding aces at the start of each day – a powerful advantage in the ongoing game of life and longevity.

Addressing “What if I’m the exception?” 

The “What if I’m the exception” mindset is a dangerous gamble. It’s like choosing not to wear a seatbelt because you believe you’ll be lucky enough to avoid an accident or survive it unscathed. Or to irrationally believe that, due to sheer luck, you can win as often with weak hands as you can with strong ones in poker. The reality is, you don’t know if you’ll be the exception or not. However, what you can be sure of is that improving your fitness, similar to the routine use of a seatbelt or consistently being dealt a pair of aces every game, substantially increases your chances of a prolonged life, as robustly demonstrated in the earlier evidence.

You really have the control to make the odds work in your favor, it’s in your hands!

Can We Compare Exercise to Drugs and Medical Interventions?

Just as you might be amazed by the extraordinary influence of cardiorespiratory fitness on longevity by now, you’ll be equally captivated by the impact of exercise in combating age-related diseases. Exercise, a simple yet potent tool, stands shoulder to shoulder with, and sometimes surpasses, various medications in warding off ailments like heart disease, stroke, and diabetes. Stanford researcher John Ioannidis put this bold claim to the test, comparing the effects of exercise against various drug interventions in clinical trials. The results were astounding – exercise interventions often equaled or outdid pharmaceuticals in reducing mortality from diseases like coronary heart disease, diabetes, and stroke. And what’s more exhilarating? No prescription needed for exercise.

Delving deeper, exercise acts akin to a pharmaceutical marvel, inducing the release of cytokines from our muscles. These drug-like chemicals journey throughout the body, including the brain, enhancing the health of every organ. Indeed, exercise affects every other organ in our body.

By now, you might be curious about your own VO2Max. You’re probably also wondering where you stand on the fitness scale and what exercises can boost your VO2Max.

Ideally, measuring VO2Max involves a laboratory setting with specialized equipment. However, not everyone has access to such facilities. 

Thankfully, there are several reliable and free alternatives available for accurately estimating your VO2Max.

Accurately Estimating VO2Max Outside the Lab: The Efficacy of the Cooper Test

Ten-year survival measured from middle age (50s). Based on the 2018 JAMA study

The Cooper Test, conceptualized by Dr. Kenneth Cooper, is a 12-minute run designed to gauge cardiorespiratory fitness. Its high correlation with VO2Max laboratory tests positions it as the most reliable self-test for VO2Max. Since 1968, The Cooper Institute has conducted this test on tens of thousands of participants, establishing fitness performance standards still in use today in military, law enforcement, and professional sports sectors.

To perform the test all you have to do is go on a treadmill (at 1% incline) or outside and run for 12 minutes, record the distance with a smart watch, on a track or on the treadmill and see where you fit!

12 Minute Run Test For Women (KM)

12 Minute Run Test For Men (KM)

You can gain an insight into your fitness level and areas for improvement to enhance survival rates. For instance, a 52-year-old woman covering 1.6 kilometers in 12 minutes would find her score linked to a 77% survival rate over ten years, If she trains for 6-12 weeks and increases her distance by just 0.2 kilometers, her survival rate could rise to 93.5% and an enormous 64% lower chance of death from any cause compared to where she was.

The next concern that comes to mind is “It probably takes too much time and effort to get there”

How Much Time and Effort Does It Take to Improve Your Fitness?

Improving your fitness and VO2Max is achievable with a well-structured training plan, potentially requiring just a few hours per week. This plan could include only 1 or 2 challenging workouts per week, with the rest being light to moderate activities, like brisk walking, tailored to your fitness level. Given sufficient time, this approach will likely lead most individuals towards the upper brackets of VO2Max.

If you need any help or questions, feel free to contact me here!

Can I Get to the Top 2% If I’m Not an Athlete?

In your 20s, 30s and even 40’s the chance of boosting your VO2Max and making it to the top 2% is at its peak. This period represents a prime opportunity for cardiorespiratory development, where your body is most responsive to intense training. Focusing on high-intensity workouts during these years can significantly elevate your VO2Max, establishing a high benchmark for later years. It’s an ideal time to leverage your physiological potential to achieve elite fitness levels.

However, for those beyond their 40s and 50s, the prospects of improving VO2Max are still very promising. Many studies have demonstrated that individuals well into their later years can make significant enhancements in their VO2Max. While the path to reaching elite levels may be more challenging with age, it is by no means unattainable. Consistent and tailored exercise regimens can lead to meaningful increases in VO2Max.

A Few Final Words

My final message, and perhaps the most crucial takeaway from this article, is to elevate yourself out of the low fitness category. Remember, your VO2Max is not just a number, it is a crucial indicator of your overall health and a strong predictor of mortality. Being in the lower fitness levels is not merely a matter of lesser physical capability, it significantly increases your risk of health complications and early death. This should be a compelling reason to prioritize improving your cardiorespiratory fitness.

The studies highlighted in this article clearly show that the benefits of enhancing your fitness have no observed upper limit. This is a powerful incentive to continually strive for higher levels of fitness, no matter where you currently stand. Whether you’re young, with the potential to reach elite fitness levels, or older, with the capability for meaningful progress, the opportunity for improvement is always present. Each step you take towards increasing your VO2Max translates into a step away from the risks associated with low fitness levels, leading you towards a longer, healthier life.


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