If you can live without a bike for a couple of weeks, you might not live long at all (on VO2 max).
11 January 2024
I believe this post will remain one of the most important on this blog for a long time.
In the previous post, I presented extensive evidence that overall muscle strength, as reflected in the biomarker “grip strength,” statistically extends a healthy lifespan.
However, an even more significant factor [Strasser B & Burtscher M 2018]—perhaps the most important one we can influence—is cardiorespiratory fitness, best represented by the biomarker “maximum oxygen consumption” (VO2 max).
Writing this post led me into a deep dive into scientific literature and days of reflection. Ultimately, I arrived at several conclusions that challenge some common perceptions about VO2 max. If the text seems too complex, at least read the conclusions.
In the previous post, I presented extensive evidence that overall muscle strength, as reflected in the biomarker “grip strength,” statistically extends a healthy lifespan.
However, an even more significant factor [Strasser B & Burtscher M 2018]—perhaps the most important one we can influence—is cardiorespiratory fitness, best represented by the biomarker “maximum oxygen consumption” (VO2 max).
Writing this post led me into a deep dive into scientific literature and days of reflection. Ultimately, I arrived at several conclusions that challenge some common perceptions about VO2 max. If the text seems too complex, at least read the conclusions.
1. VO2 Max Studies and Their Limitations
Although VO2 max is much harder to measure than grip strength, there are millions of person-years [Mandsager K et al. 2018] of cohort studies linking high VO2 max to reduced mortality from all causes, including cancer and chronic diseases [Imboden M et al. 2018], regardless of gender or race [Harber M et al. 2017].
Same as grip strength, VO2 max is a predictor of the future—just one measurement in middle age showing low levels can identify the risk of cardiovascular death [Berry J et al. 2011].
Unfortunately, these studies are limited by the complexity of data collection: non-athletes rarely perform more than one VO2 max test in their lifetime, and regular data from athletes are rarely published—possibly because it could provide valuable insights to competitors.
One high-quality study involved repeated VO2 max measurements in the same individuals over several years [Laukkanen J et al. 2016]. It showed that increasing VO2 max by 1 ml/kg/min (around 2% for an active person) reduces the risk of all-cause mortality by 9%. (That’s huge!)
That’s the first evidence suggesting that it’s not only important to achieve high VO2 max once but also to maintain or even improve it throughout life. More on this later, but first, let’s cover the basics.
Conclusion: Achieving high VO2 max is great; maintaining it is even better.
Although VO2 max is much harder to measure than grip strength, there are millions of person-years [Mandsager K et al. 2018] of cohort studies linking high VO2 max to reduced mortality from all causes, including cancer and chronic diseases [Imboden M et al. 2018], regardless of gender or race [Harber M et al. 2017].
Same as grip strength, VO2 max is a predictor of the future—just one measurement in middle age showing low levels can identify the risk of cardiovascular death [Berry J et al. 2011].
Unfortunately, these studies are limited by the complexity of data collection: non-athletes rarely perform more than one VO2 max test in their lifetime, and regular data from athletes are rarely published—possibly because it could provide valuable insights to competitors.
One high-quality study involved repeated VO2 max measurements in the same individuals over several years [Laukkanen J et al. 2016]. It showed that increasing VO2 max by 1 ml/kg/min (around 2% for an active person) reduces the risk of all-cause mortality by 9%. (That’s huge!)
That’s the first evidence suggesting that it’s not only important to achieve high VO2 max once but also to maintain or even improve it throughout life. More on this later, but first, let’s cover the basics.
Conclusion: Achieving high VO2 max is great; maintaining it is even better.
2. VO2 Max Is About the Heart, Lungs, Blood, and Muscles
VO2 max reflects the coordinated functioning of several systems in the body. For the body to consume maximum oxygen per unit of time:
VO2 max reflects the coordinated functioning of several systems in the body. For the body to consume maximum oxygen per unit of time:
- Well-developed respiratory muscles must deliver a large volume of air to capacious lungs.
- The lungs must efficiently extract oxygen from the air and enrich the blood with it.
- Blood, rich in oxygen-carrying hemoglobin and sufficient in volume, must be rapidly pumped by a well-developed heart through a network of vessels into trained muscles with a high number of mitochondria.
- Mitochondria must effectively utilize oxygen to produce energy, generating carbon dioxide as a by-product, which the body then swiftly needs to expel to complete the cycle.
3. The Key to Increasing VO2 Max Is Heart Capacity
If any of the links in the cardiovascular-respiratory-muscular chain is weak, achieving a high VO2 max is impossible. However, the primary limiting factor for VO2 max [Bassett D & Howley E 2000; Ogawa T et al. 1992] is the maximum cardiac output (stroke volume × maximum heart rate).
Only specific exceptions exist where VO2 max is limited by respiration, blood vessels, or muscles [Taylor B & Johnson B 2010; Smith J et al. 2017].
While maximum heart rate is barely trainable [Zavorsky G 2000] and naturally declines after age 25—reducing VO2 max by roughly 10% per decade [Pimentel A et al. 2003]—a critically low VO2 max eventually limits daily activity [Myers J et al. 2002], and later, basal metabolism [Burtscher M 2012], leading to natural death in the absence of specific diseases.
In essence, “dying of old age” often means dying from critically low VO2 max.
The higher your VO2 max in youth, the longer it takes to reach critical levels in old age. Therefore, increasing VO2 max by enhancing stroke volume can extend healthy lifespan. While VO2 max can be improved at any age [Bacon A et al. 2013], the earlier you start, the better [Berry J et al. 20112, Cumming G 1975].
Conclusion: Take care of your bike since it’s new, and your VO2 max since you’re young.
If any of the links in the cardiovascular-respiratory-muscular chain is weak, achieving a high VO2 max is impossible. However, the primary limiting factor for VO2 max [Bassett D & Howley E 2000; Ogawa T et al. 1992] is the maximum cardiac output (stroke volume × maximum heart rate).
Only specific exceptions exist where VO2 max is limited by respiration, blood vessels, or muscles [Taylor B & Johnson B 2010; Smith J et al. 2017].
While maximum heart rate is barely trainable [Zavorsky G 2000] and naturally declines after age 25—reducing VO2 max by roughly 10% per decade [Pimentel A et al. 2003]—a critically low VO2 max eventually limits daily activity [Myers J et al. 2002], and later, basal metabolism [Burtscher M 2012], leading to natural death in the absence of specific diseases.
In essence, “dying of old age” often means dying from critically low VO2 max.
The higher your VO2 max in youth, the longer it takes to reach critical levels in old age. Therefore, increasing VO2 max by enhancing stroke volume can extend healthy lifespan. While VO2 max can be improved at any age [Bacon A et al. 2013], the earlier you start, the better [Berry J et al. 20112, Cumming G 1975].
Conclusion: Take care of your bike since it’s new, and your VO2 max since you’re young.
4. VO2 Max Is Limited by Genetics, But Not Crucially
Unlike FTP—a cycling metric largely influenced by lactate levels in the muscles (and more impactful on performance than health or longevity)—VO2 max is more strongly influenced by genetics.
Some people win the genetic lottery and achieve high VO2 max even without targeted training [Martino M et al. 2002]. Such individuals appear to reach these levels simply by living an active lifestyle. Studies on rodents confirm this, showing that genetically predisposed rats live significantly longer than those bred for poor cardiovascular adaptation, with the former having higher VO2 max despite identical conditions (with the lack of training) [Koch L et al. 2011].
True, parental lifespan is a key predictor of longevity, regardless of training or other lifestyle factors [Brandts L et al. 2021]. This gives rise to arguments like, “My great-grandfather smoked and drank his whole life and lived to 100.” While this doesn’t mean smoking and alcohol don’t shorten life (especially the healthy part of it), some people are simply born lucky.
However, I have good news here. While it was long believed in sports science that VO2 max has a strict genetic limit—one you can’t surpass no matter how hard you train—this has been disproven by numerous studies [Williams C et al. 2017].
Conclusion: Genetics can sure help with VO2 max, but it’s unlikely to hold you back.
Unlike FTP—a cycling metric largely influenced by lactate levels in the muscles (and more impactful on performance than health or longevity)—VO2 max is more strongly influenced by genetics.
Some people win the genetic lottery and achieve high VO2 max even without targeted training [Martino M et al. 2002]. Such individuals appear to reach these levels simply by living an active lifestyle. Studies on rodents confirm this, showing that genetically predisposed rats live significantly longer than those bred for poor cardiovascular adaptation, with the former having higher VO2 max despite identical conditions (with the lack of training) [Koch L et al. 2011].
True, parental lifespan is a key predictor of longevity, regardless of training or other lifestyle factors [Brandts L et al. 2021]. This gives rise to arguments like, “My great-grandfather smoked and drank his whole life and lived to 100.” While this doesn’t mean smoking and alcohol don’t shorten life (especially the healthy part of it), some people are simply born lucky.
However, I have good news here. While it was long believed in sports science that VO2 max has a strict genetic limit—one you can’t surpass no matter how hard you train—this has been disproven by numerous studies [Williams C et al. 2017].
Conclusion: Genetics can sure help with VO2 max, but it’s unlikely to hold you back.
5. VO2 Max for Running vs. Cycling—What’s the Difference?
Most studies measure VO2 max during running (on a treadmill), but there is extensive and consistent data from the second measurement method—cycling ergometers (indoor trainers or stationary bikes) [Clausen J et al. 2018].
These two measurement methods reveal some interesting findings. For triathletes, who train both running and cycling, treadmill VO2 max is a few percentage points higher than cycling VO2 max [Price S et al. 2021].
When runners, swimmers, and cyclists are tested using both methods, the first two groups show similar results (with runners having the largest difference), but cyclists achieve slightly higher VO2 max on the bike compared to the treadmill [Marko D et al. 2021].
At that, the highest recorded VO2 max in history—97 ml/kg/min—belongs to a cyclist, Oscar Svendsen. Runners, by comparison, have never surpassed 92 ml/kg/min and generally rank lower than cyclists in VO2 max records.
Cross-country skiers, however, rival cyclists. Yet skiing is seasonal—limited to winter. Ski rollers are an option, but they come with specific drawbacks and limitations. Perhaps the solution is seasonal: cycling in summer and skiing in winter?
Based on the data, running and cycling VO2 max levels are trained differently. This aligns with practical experience: stopping cycling training in winter or skiing training in summer can lead to partial detraining.
However, cycling offers year-round training possibilities. Depending on the climate and personal preferences, you can either continue outdoor rides in winter or switch to indoor trainers.
Conclusion: Cycling is arguably the best way to train VO2 max.
Most studies measure VO2 max during running (on a treadmill), but there is extensive and consistent data from the second measurement method—cycling ergometers (indoor trainers or stationary bikes) [Clausen J et al. 2018].
These two measurement methods reveal some interesting findings. For triathletes, who train both running and cycling, treadmill VO2 max is a few percentage points higher than cycling VO2 max [Price S et al. 2021].
When runners, swimmers, and cyclists are tested using both methods, the first two groups show similar results (with runners having the largest difference), but cyclists achieve slightly higher VO2 max on the bike compared to the treadmill [Marko D et al. 2021].
At that, the highest recorded VO2 max in history—97 ml/kg/min—belongs to a cyclist, Oscar Svendsen. Runners, by comparison, have never surpassed 92 ml/kg/min and generally rank lower than cyclists in VO2 max records.
Cross-country skiers, however, rival cyclists. Yet skiing is seasonal—limited to winter. Ski rollers are an option, but they come with specific drawbacks and limitations. Perhaps the solution is seasonal: cycling in summer and skiing in winter?
Based on the data, running and cycling VO2 max levels are trained differently. This aligns with practical experience: stopping cycling training in winter or skiing training in summer can lead to partial detraining.
However, cycling offers year-round training possibilities. Depending on the climate and personal preferences, you can either continue outdoor rides in winter or switch to indoor trainers.
Conclusion: Cycling is arguably the best way to train VO2 max.
6. Training VO2 Max Can Be Tough, But There’s a Solution
The fact that cyclists perform better on cycling ergometers and runners on treadmills confirms the principle of sports specialization: you train for what you aim to achieve. For cyclists, this means training on a bike, where sprints develop short-term power, and endurance rides build stamina.
So, how should we train to improve VO2 max?
As mentioned earlier, VO2 max is primarily constrained by cardiac output (maximum blood flow) [Bassett D & Howley E 20002; Ogawa T et al. 19922]. With training, cardiac output at submaximal loads doesn’t change much. Instead, heart rate decreases at a given intensity while stroke volume increases, keeping output steady [Evans L 1985].
However, maximum cardiac output does improve: maximum heart rate stays constant, but stroke volume increases. This drives the rise in VO2 max, assuming the respiratory, vascular, and muscular systems develop harmoniously alongside the heart, which it usually happens [Taylor B & Johnson B 20102; Smith J et al. 20172].
According to the principle of progressive overload, “It never gets easier; you just go faster.” To train VO2 max, you periodically need to reach a heart rate at which the maximum cardiac output surpasses your previous limits as stroke volume increases, meaning nearly maximum heart rate.
Classic sports literature describes this as intervals of 3–8 minutes in Zone 5 (VO2 max zone) according to Coggan’s system—90–100% of maximum heart rate or 106–120% of FTP. Unfortunately, these intervals are notoriously painful.
Here’s some good news: high-quality evidence (meta-analyses of randomized controlled trials) shows that even 30-second sprints can significantly improve VO2 max [Sloth M et al. 2013]. This supports the idea that periodically hitting near-max heart rate is what matters most.
Modern training literature (e.g., TrainingPeaks, TrainerRoad) suggests additional methods, such as short intervals under a minute or the “hard start” technique: ramping up heart rate near maximum and then reducing power while maintaining the same heart rate.
While interval training can be grueling, it doesn’t have to be unbearable. For example, in our cycling club, we hold Thursday rides where we warm up together, then push each other with sprints and climbs—not at full effort, but just enough to hit VO2 max levels. Routes vary to add unpredictability and fun competition. It works—we love our Thursday rides!
Conclusion: VO2 max training doesn’t have to be punishing—it can even be enjoyable.
The fact that cyclists perform better on cycling ergometers and runners on treadmills confirms the principle of sports specialization: you train for what you aim to achieve. For cyclists, this means training on a bike, where sprints develop short-term power, and endurance rides build stamina.
So, how should we train to improve VO2 max?
As mentioned earlier, VO2 max is primarily constrained by cardiac output (maximum blood flow) [Bassett D & Howley E 20002; Ogawa T et al. 19922]. With training, cardiac output at submaximal loads doesn’t change much. Instead, heart rate decreases at a given intensity while stroke volume increases, keeping output steady [Evans L 1985].
However, maximum cardiac output does improve: maximum heart rate stays constant, but stroke volume increases. This drives the rise in VO2 max, assuming the respiratory, vascular, and muscular systems develop harmoniously alongside the heart, which it usually happens [Taylor B & Johnson B 20102; Smith J et al. 20172].
According to the principle of progressive overload, “It never gets easier; you just go faster.” To train VO2 max, you periodically need to reach a heart rate at which the maximum cardiac output surpasses your previous limits as stroke volume increases, meaning nearly maximum heart rate.
Classic sports literature describes this as intervals of 3–8 minutes in Zone 5 (VO2 max zone) according to Coggan’s system—90–100% of maximum heart rate or 106–120% of FTP. Unfortunately, these intervals are notoriously painful.
Here’s some good news: high-quality evidence (meta-analyses of randomized controlled trials) shows that even 30-second sprints can significantly improve VO2 max [Sloth M et al. 2013]. This supports the idea that periodically hitting near-max heart rate is what matters most.
Modern training literature (e.g., TrainingPeaks, TrainerRoad) suggests additional methods, such as short intervals under a minute or the “hard start” technique: ramping up heart rate near maximum and then reducing power while maintaining the same heart rate.
While interval training can be grueling, it doesn’t have to be unbearable. For example, in our cycling club, we hold Thursday rides where we warm up together, then push each other with sprints and climbs—not at full effort, but just enough to hit VO2 max levels. Routes vary to add unpredictability and fun competition. It works—we love our Thursday rides!
Conclusion: VO2 max training doesn’t have to be punishing—it can even be enjoyable.
7. More VO2 Max Training Isn’t Always Better
The listed cohort studies suggest that the benefits of a high VO2 max have no upper limit—the higher, the better. However, population studies show a U-shaped curve for all-cause mortality relative to training intensity: mortality initially decreases as intensity rises but increases again when training becomes excessive [Arem H et al. 2015; Lee DC et al. 2014; Schnohr P et al. 2015].
Cohort studies have stronger evidence than population studies, but this stark difference between studies of cardiorespiratory fitness (outcome-focused) and training intensity (process-focused) likely reflects real physiological causes rather than mere methodological differences.
Two explanations stand out:
Overtraining limits VO2 max potential, explaining the contradiction between cohort and population studies.
Conclusion: More than three VO2 max sessions per week is too much.
The listed cohort studies suggest that the benefits of a high VO2 max have no upper limit—the higher, the better. However, population studies show a U-shaped curve for all-cause mortality relative to training intensity: mortality initially decreases as intensity rises but increases again when training becomes excessive [Arem H et al. 2015; Lee DC et al. 2014; Schnohr P et al. 2015].
Cohort studies have stronger evidence than population studies, but this stark difference between studies of cardiorespiratory fitness (outcome-focused) and training intensity (process-focused) likely reflects real physiological causes rather than mere methodological differences.
Two explanations stand out:
- Genetics: As we already know, some individuals achieve high VO2 max with relatively little training [Martino M et al. 20022]. In other words, it’s possible that the high VO2 max observed in cohort studies isn’t necessarily tied to high training intensity. However, it’s statistically unlikely that these studies exclusively included individuals with exceptional genetic predispositions.
- Recovery: Numerous studies [Barnett A 2006] and sports literature emphasize the importance of proper recovery between sessions. Physiological adaptation—where fitness improves—occurs during rest. Training VO2 max requires 36–48 hours of recovery according to TrainingPeaks.
Overtraining limits VO2 max potential, explaining the contradiction between cohort and population studies.
Conclusion: More than three VO2 max sessions per week is too much.
8. Consistency Matters More Than Volume
Now for the bad news: VO2 max declines quickly without training. Negative effects begin after just 10 days of inactivity.
Significant reductions occur after 14 days, caused by decreased cardiac output and blood volume [Neufer P 1989]. VO2 max drops by 6% after 4 weeks [Coyle E et al. 1985], 19% after 9 weeks [Ready A & Quinney H 1982], and 20–25% after 11 weeks.
To illustrate, consider the well-documented VO2 max progression of cyclist Oscar Svendsen:
Conclusion: Training VO2 max steadily over years is better than going all-out and burning out.
Now for the bad news: VO2 max declines quickly without training. Negative effects begin after just 10 days of inactivity.
Significant reductions occur after 14 days, caused by decreased cardiac output and blood volume [Neufer P 1989]. VO2 max drops by 6% after 4 weeks [Coyle E et al. 1985], 19% after 9 weeks [Ready A & Quinney H 1982], and 20–25% after 11 weeks.
To illustrate, consider the well-documented VO2 max progression of cyclist Oscar Svendsen:
- Starting point: 75 ml/kg/min (already exceptional).
- 6 months later: 83; 1 year later: 88.
- World record (2 years later): 97 ml/kg/min. For obvious reasons, there were doubts about the accuracy of the equipment and so on, but everything was thoroughly checked and rechecked—the result is valid.
- After 15 months of no training — due to the athlete’s burnout — 77 ml/kg/min, losing nearly all gains from 30 months of intense training, which aligns with the negative trends described in the scientific literature mentioned above.
Conclusion: Training VO2 max steadily over years is better than going all-out and burning out.
Conclusions
— Achieving and maintaining high VO2 max at any age is one of the best-known ways to ensure a healthy, long life.
— Genetics won’t fundamentally hinder progress—VO2 max is highly trainable, despite the outdated beliefs.
— Year-round cycling is likely the best way to sustain high VO2 max.
— While VO2 max training can be tough, it doesn’t have to be painful—it can even be enjoyable.
— Aim to push your heart rate near maximum at least weekly, but no more than three times per week.
— If your goal is health and longevity rather than athletic performance, focus on finding sustainable ways to train over the long term.
— Achieving and maintaining high VO2 max at any age is one of the best-known ways to ensure a healthy, long life.
— Genetics won’t fundamentally hinder progress—VO2 max is highly trainable, despite the outdated beliefs.
— Year-round cycling is likely the best way to sustain high VO2 max.
— While VO2 max training can be tough, it doesn’t have to be painful—it can even be enjoyable.
— Aim to push your heart rate near maximum at least weekly, but no more than three times per week.
— If your goal is health and longevity rather than athletic performance, focus on finding sustainable ways to train over the long term.
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