“VO2 max can be improved, on average, by only 5-15%, even with intensive training. It is clear, then, that the average person can train as much as he or she likes yet never achieve a VO2 max anywhere near that of elite athletes.” – Tim Noakes (Lore of Running)
Since my first exercise physiology undergrad classes, some 25 years ago, I have been taught the above “truth.” That is, that one of the most important physiological attributes for endurance athletes—VO2 max—is largely fixed, largely genetic, and if you don’t like your own number, “blame your parents.”
But just how true is this widely held belief?
Putting aside the sedentary twin studies and the short-term papers, if we turn to the real world and look at the observations of an exercise physiologist whose primary job was testing athletes—often the same athletes over multi-year time frames—how does the belief that VO2 max is largely untrainable stack up? If we watch real athletes over extended periods of time, what kind of gains are we likely to see? That is the perspective and those are the answers I hope to provide in this post.
Understanding VO2 Max in Team Sports
First, a quick recap on what VO2 max is and why it’s important. VO2 max, or the maximal oxygen uptake, is the total amount of oxygen that your muscles can extract from your blood per minute. It represents the overall strength of the aerobic system and is the product of oxygen delivery (from the heart and lungs) and oxygen uptake (from the muscles).
VO2 max is an important metric for endurance athletes because when energy is generated aerobically (in the presence of oxygen), the by-product of glycolysis (sugar burning) can actually be used to create even more energy (via the Krebs cycle) rather than “hanging around” in the muscle and contributing to acidosis and subsequent fatigue. While energy generation might be a little slower than anaerobic processes, it can take an athlete a whole lot further for a given amount of fuel. Hence, its importance to endurance events.
While VO2 max is an important metric for endurance athletes, it also plays an important role in the between-effort recovery in most team sports, says @alan_couzens. Click To TweetHowever, even in “intermittent events” like most team sports, it plays an important role in the between-effort recovery. Even if the critical moments in a given event are anaerobically dominant, a strong aerobic system and all that comes with it (development of the “lactate gobbling” type 1 fibers, increased capillarization within the muscle to allow faster transport of the “good stuff” in and the “bad stuff” out) gives the athlete the ability to recover quickly between these crucial efforts, facilitating more of them within the game. The same principle is even more true in training, where the ability to recover quickly between specific training bouts ultimately allows more quality training within the program.
With the above in mind, it should come as no surprise then that the best endurance athletes in the world have very high VO2 max values. Even athletes from sports not typically considered “endurance” sports still exhibit relatively high numbers, as shown in the table below.
Now, back to our depressing revelation: There’s only 5-15% potential improvement. Not a whole lot of wiggle room there. If you come into the lab and I test you as having a VO2 max of 50 ml/kg/min, the best you can hope for with “all the training in the world” is an improvement to ~57 ml/kg/min. With world-class males typically scoring 75-85 ml/kg/min and world-class females scoring 65-75 ml/kg/min, an improvement from 50 to 57 isn’t going to put you in sight of winning most local races, let alone validate your dream of winning a big one!
And, indeed, there was some science to back up this “rule of thumb.” A study that looked at VO2 max values in twins1concluded that genetic factors explained 72-74% of the difference in VO2 max and, even when “sports participation” was factored in, genetic factors continued to explain between 57% and 63% of the variance in VO2 max. Presumably, studies like this formed the basis of the belief that VO2 max was largely genetic and could only be increased by a small amount through training.
My first VO2 max test during my exercise physiology undergrad yielded a VO2 max of 62 ml/kg/min. Not bad, but not great either, especially for someone who had spent the better part of the previous decade following the black line up and down the pool. It seemed to line up well with my experience of never quite having that quality to make it to that next level. That 62 ml/kg/min “well trained” would put my life range from untrained to trained in the 53-62 ml/kg/min ballpark, dooming me to a life of middle-of-the-pack athletics. And the story gets even more depressing…
Many years after my first VO2 max test, we set up an exercise physiology lab here in Boulder, Colorado, and I got my hands on a fresh, new metabolic cart. So, of course, I had to put it through its paces. This time around I tested at 49 ml/kg/min! I was hardly what I would call untrained at the time—still competing recreationally in triathlon. Nor was I old enough that age should have a large impact, and yet my VO2 max had already shifted downwards by ~20%! Rather than drowning my sorrows, such a shift had me asking: If my VO2 max can change so significantly, beyond what I had learned was the “norm” in my studies, could it change the other way?
Fortunately, I wasn’t just an exercise physiologist. A big part of my “second job” as an endurance coach was to try and have a positive impact on the VO2 max of the athletes I worked with. This meant that, over long periods of time—years, in many cases—I was performing repeated testing on the same athlete, while carefully monitoring and quantifying the training load, and seeing how this VO2 max value shifted in response to the training. And (spoiler alert) the shifts that I witnessed were far greater than the 5-15% that I had been taught to expect!
One particular case study of an athlete that went WAY beyond that 5-15% improvement in VO2 max comes to mind…
The Case Study: Why Real-World Testing Matters
I started working with a youngish, middle-of-the-pack athlete with some big goals. He had come from a history of rotating through a number of intensity-based programs and was frustrated at the plateau despite “working as hard as I could.” In more detail, the programs typically involved focused periods of 3-4 months before the key event, which would begin with high-intensity (threshold and “VO2”) trainer intervals and progressively extend to a few specific long rides/runs before the event. After the event, he would take a couple of months off/unstructured to mentally recover from the high-intensity training and then begin the cycle again. As a part of the initial assessment, we got the athlete into the lab for a full workup including a VO2 max test. The result? A fairly modest 53 ml/kg/min.
Again, knowing what we “know,” we might say to him (or at least be thinking), here is a guy who, as someone preparing for repeated Ironman triathlon events, is clearly not untrained. So, with a trained VO2 max of 53 ml/kg/min, his long-term goal of qualifying for the Ironman World Championship might be overly ambitious, at best. For comparative purposes, most male athletes in that age group who I have coached and who have achieved that level are closer to 65-70 ml/kg/min. Even at the low end, this would represent an improvement of 22% in VO2 max (from an already trained state)! Perhaps it was my duty to send this guy on his way? Or at the very least, let him know “not gonna happen, champ.” Well, fortunately, we didn’t take that route…
Over the course of the next three years, this athlete shifted his VO2 max from 53 to 74 ml/kg/min: An increase of 40% from a very middle-of-the-pack number to an elite level! And, in the process, he achieved his goal of qualifying for the Ironman World Championship.
Figure 2 shows the progression in VO2 max values for this athlete over each year of training…
So, how did we accomplish such a large change (above and beyond that suggested by the literature)?
While the majority of the short-term literature that has looked at interventions to increase VO2 max has focused on the impact of high-intensity training (so-called “VO2 max intervals”), we took a different approach. In this case, the bulk of the athlete’s training was in and around the aerobic threshold (the first lactate turnpoint—i.e., at lactate levels of 1-2 mmol/L). A LONG way from VO2 max.
My basis for using low-intensity, high-volume training as a potent stimulus for large changes in VO2 max is the observed relationship between training volume and cardiac stroke volume. Click To TweetMy rationale for using low-intensity, high-volume training as a potent stimulus for large changes in VO2 max comes from the observed relationship between training volume and cardiac stroke volume, one of the most important and modifiable factors in VO2 max. In a large EKG study of athletes’ heart morphology, Berbalk discovered a strong, almost linear, relationship between training volume and total heart volume,2as shown in figure 3.
That is, the total volume of the athletes’ hearts, scaled not with the intensity of training, but with the average weekly volume! This makes good physiological sense, since we know that for the majority of people, stroke volume reaches its maximum limit at relatively low intensities of training (~40-60% VO2 max).3However, as the Berbalk data suggests, it takes a whole lot of beats to make these significant changes!
Additionally, there are positive peripheral adaptations that are favored by LSD (“long, slow, distance”) work. Harms and Hickson concluded that changes in mitochondrial content within the aerobic fibers largely scaled with the number of contractions rather than the intensity of effort.4Since mitochondria represent the oxygen processing “factories” within the muscle, more available mitochondria means more potential oxygen extraction from each beat.
This emphasis on low-intensity aerobic training represented a marked departure from what the athlete had done prior to working with me. One of the most interesting aspects of the current wave of technology and data collection for me, as a coach, is that I learn a lot about what other coaches are doing purely from the logs that the athlete brings with them. In this case, he had been doing a lot of threshold and VO2 max training. You can see the clear difference in relative proportions of the annual training intensity distribution in figure 4 from his year prior to working with me (year 0) to his highest fitness in year 3.
Prior to working with me, the athlete did very little work below 80% max heart rate. Most of the work he did in this range was restricted to just warming up for the “main event.” We made a large shift in this training emphasis by adding a lot more easy aerobic work (~65-80% max heart rate) and a lot less high-intensity work (~85-100% max heart rate). Paradoxically, less “VO2 work” resulted in a significant boost to the athlete’s VO2 max!
While the athlete didn’t have VO2 data from before beginning his high-intensity program, his recollection was that his power numbers on the bike improved quickly but then plateaued and then stayed “stuck” at that point following each build. This pattern of stagnation with athletes who focus on high-intensity (traditional “VO2 max”) training is a common one.
This is not to say that traditional VO2 max intervals (3-5 mins @ 95-100% max heart rate ~1:1 recovery) are useless; merely that they are the proverbial icing on the top rather than the cake itself. Athletes can certainly reach a point with pure aerobic training where they are so efficient that they are no longer able to max out their aerobic power. This is indicated by an inability to reach a VO2 “plateau” during a test where, despite increased work, VO2 stabilizes. When an athlete fails to get to this plateau, a small dose of VO2 max intervals can be very effective in eking out those last few ml/kg/min. However, in this case, this form of training represents the move from 70 to 74 ml/kg/min, *not* the move from 53 to 70. That shift was made with “bread and butter” aerobic work!
Athletes who focus on high-intensity (traditional “VO2 max”) training often see a pattern of stagnation, says @alan_couzens. Click To TweetThe above distribution has some important implications in the training of athletes for anaerobic sports. Traditional VO2 max intervals tend to run counter to a speed/power athlete’s objectives of maximal rates of power production: i.e., they favor lactate tolerance over lactate production in the type II fibers—endurance over speed. By focusing the aerobic development on the other end of the intensity spectrum, it allows the speed/power athlete to keep the adaptations of those type II fibers very specific to the task at hand, while further developing the aerobic abilities of those type I “recovery fibers,” which, frankly, aren’t of much help to you in the rapid power generation game anyhow.
I’ve been fortunate to train with some very high-level sprint cyclists and this is their approach—the endurance work is very easy, and the fast work is very fast. This “polarization” of the training is likely of the most value to those athletes who wish to develop their ability to quickly generate energy anaerobically but also quickly recover from these efforts aerobically.
Is This Level of VO2 Max Improvement Typical?
I would have to say that this 40% improvement represents one of the largest jumps I have seen, and it’s not typical. However, in my experience, jumps far greater than the 5-15% cited in the literature, with sustained aerobic training, are routine.
In fact, when I model the average response to training across the entire group that I have VO2 and long-term training data for, I see an average shift from 54 to 67 ml/kg/min (a change of 24%) when a long-term, high-volume training plan is undertaken.
Conversely, when a short-term, high-intensity training plan is undertaken, the model shows a maximal increase (in 4-6 weeks) to only 63 ml/kg/min (16%).
So, while a 40% increase in VO2 max may not be considered “typical,” after my experience testing and observing athletes over the past 10+ years, I would have to consider a ~25% increase in VO2 max to be very typical given the right training over a sufficient period of time (the two items missing from those initial studies that suggested high genetic limitations).
Maximize Your Athlete’s Talents
In summary, given the crucial role that the aerobic system plays not only in providing energy for the vast majority of sports, but also in accelerating the recovery from anaerobic bouts, all athletes should pay proper attention to its development. Obviously, at a very high level of priority for endurance sports, but also to a larger extent than is commonly acknowledged for “anaerobic sports,” where a base level of aerobic development plays a large role in the overall work capacity of the athlete.
Whatever the sport, given the appropriate training over a sufficiently long period, VO2 mx is a very trainable quality, says @alan_couzens. Click To TweetI hope that my experience in facilitating change will bolster the confidence of all coaches to make effective change in this domain. My years of testing and tweaking to develop this quality have led me to conclude that, whatever the sport, given the appropriate training over a sufficiently long period of time, VO2 max is a very trainable quality.
References
1. Fagard, R., Bielen, E. and Amery, A. “Heritability of aerobic power and anaerobic energy generation during exercise.” Journal of Applied Physiology. 1991; 70(1): 357-362.
2. Berbalk, A. “Echokardiographische Studie zum Sportherz bei Ausdauerathleten” in: Zeitschrift fur Angewandte Trainingswissenschaft. 1997; 4: 34-64. Aachen: Meyer & Meyer
3. Åstrand, Per-Olof, Cuddy, T. Edward, Saltin, Bengt and Stenberg, Jesper. “Cardiac output during submaximal and maximal work.” Journal of Applied Physiology. 1964; 19(2): 268-274.
4. Harms, S.J. and Hickson, R.C. “Skeletal muscle mitochondria and myoglobin, endurance, and intensity of training.” Journal of Applied Physiology. 1983; 54(3): 798-802.
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Your subject s vo2 probably improved not because of stroke volume but because you created more mitochondria. They are the guys consuming the oxygen. The more you have the higher your vo2max can go 🙂
Well said!!!
There’s ample evidence showing that in trained humans, oxygen delivery (in exercise with large muscle mass) is the limiting factor for VO2max, not oxygen extraction. So, cardiac output and the O2 transportation capacity of blood set the upper limit in healthy, active people. There is an abundance of mitochondria in skeletal muscle that may play a role in e.g. substrate metabolism, but they do not limit VO2max. This is why blood manipulation acutely affects VO2max (an increase in blood volume increases stroke volume via the Frank-Starling mechanism). Any training-induced changes in VO2max are attributable to changes in cardiac output, either through changes in heart dimensions or blood volume. For a review, see e.g. Lundby et al. 2017 (https://www.ncbi.nlm.nih.gov/pubmed/27888580) . There’s a remarkable linear correlation between VO2max and cardiac output, whereas there’s no correlation between mitochondrial volume and VO2max in trained individuals (e.g. Gifford et al. 2016). Again, mitochondria are important for other reasons, but their capacity to use oxygen does not limit VO2max in running or cycling.
Interesting.Thank you for the insight. Does this mean that I could raise my blood volume by increasing muscle mass through strength training, thereby increasing VO2 max?
Ridiculous sweeping generalisation. You need an awful lot of inefficient fast twitch fibres in order to hit VO2max, especially in a legs-only sport. Be careful of conflating sport-specific VO2peak with maximal cardiac output VO2max.
The original published study relied on echocardiogram data to accurately measure left ventricular volume! So the data shows that ventricular volume improves as a function of steady aerobic training volumes. Mitochondrial density was not measured in the original article as far as I could see, although increased mitochondrial density is another major change that accompanies suitable aerobic volumes of training.
Thank you so much! Im moderately trained and my VO2 max is around 53 from an out-of-shape 40. After reading your article, I feel confident that I can hit that 60 mark.
Hi Alan, interesting article. I had a look at study number 2 (by Berbalk), but couldn’t find the training volume vs cardiac volume. Can you please point to the section in the article where the data is from? Thanks
Hi Alan, your article was very thought provoking for myself as an athlete and as a coach. The development of the athlete in your article raised the following question in my mind. With the concept of ‘training years’ in mind, could it have been possible for this athlete to have reached his impressive potential sooner if he had had a more active adolescence and clocked up those many thousands of beats required to develop his cardiac volume across his whole life rather than the three years of structured training that he undertook with yourself?
If improvement to VO2max is mainly about stroke volume, with some contribution from an increase in red blood cells, I assume that cross-training could provide some of the additional training volume because stroke volume is all about the heart regardless of where and how the oxygen is used. Is this true?
For figure 3 it seems as if “Cardiac Volume” should be where “Mean training Volume”, and the vice versa.
It would interesting to see whether the variance in stroke volume and hence vo2max is related to the volume of training performed at the intensity where maximal stroke volume occurs – for example in some individuals stroke volume continually increases as intensity increases and does not plateau at low percentages of vo2max. Response to training may also be effected to fibre type phenotype – after all if you have a high pro dominance of type II fibres – LSD training may not recruit these fibres and hence no training effect or no increase in mitochondrial volume. Jan Olbrecht hinted that response to HIIT may be influenced by anaerobic capacity (maximal glycolysis flux – VLaMax) with athletes with low VLaMax not responding well to lots of high intensity or training in the heavy zone. I found a very similar experience when a did a tour of Mexico riding at very low intensities – 50-60% of max hr – when I came back I did my best power numbers in years and as I have done similar high volumes in the past but at higher intensity – only the low intensity volume could explain my changes
How changed weight of your example athlete? Because in VO2max there is important variable which is weight.
Hi!
A very interesting case study! More interesting still would be to hear if this wasn’t an isolated case. Have you seen similar approvements of VO2 max exceeding 20-25% among your other athletes as well?
Hi, when was this study published? all the best!
I have not had a lab test, but the Vo2Max figures from my Garmin watch (though not totally accurate) are still very interesting. I am 57 years old. I was once, long ago, a school athlete when in my teens, running 400m, 800m and 1500m track, but for decades now I have let myself go. In my April 2020 I took up running again to get fit during Covid 19 lockdown in the UK. My Garmin Fenix 5 gave me a Vo2Max of 36 in April, which is about average for my age group.
I gradually built up both quantity and intensity of training and have started following Garmin’s 10K training plan. My weekly mileage is still modest.
Today (November 2020) Garmin gives me a Vo2Max of 47 which it claims is in the top 10% for my age group. That would give a 30% improvement in just 7 months. Based on my running times, I still don’t feel particularly fit. I am still very slow compared to where I was in my teens or twenties. I expect there is still a lot of room for improvement.
I used the Coopers 12 minute test and got a result very similar to the VO2 max score my Garmin watch calculated.
My experience is that the Coopers test is quite accurate.
I have seen numerous improvements such as the best you mention in the 40% range even with elite level athletes. I think when you put the right training stimulus with the data you can see positive change. Oh and sedentary individuals or novice athletes have even more to gain. It’s all about the correct stimulus for training and controlling the negative impact of the stress.
But Andy how do know the 40% improvement all came from HIIT? How much of that 40% came from none HIIT exercise?
As with all things there’s the law of diminishing returns otherwise you’d keep improving to a Vo2 max of 500 and you’d be faster than a speeding bullet
Hi,
Im 15.3years old cyclist, I started cycling about 3 years ago but I started training properly about 1year ago , and my VO2max is 69ml/kg/min. I did that im december, about 3 weeks after I started training again for the new season, so I had offseason,rest, then trained for3 weeks and did my test.
I was just wondering if any coach or scientist could tell me is my vo2max high or low or mid pack.
*I struggle a lot with spirometry and always get really bad results in that tests although Im not untrained.
And also my test 2 year ago was 59 but didn’t train really properly and muh at that time
Someone else pointed this out but all the VO2 max numbers used are relative to athlete weight. I’m wondering what the contribution changing the athletes body composition over a three year period had on that number. Is the 5-15% “truth” actually accurate for absolute VO2 max (in units of ml/min) in the athletes you’ve trained? I would guess in your study the athletes are all pretty lean to start but adding an additional 10 hours a week of fat burning zone 2 work would probably change body composition somewhat. For an extreme example imagine an obese 300 lb man who lost 150 lbs over the course of 3 years with diet/exercise. He could realize a 100% increase in VO2 max when measured in ml/kg/min.
If Volume is king, then why set “LSD” limits on this?
If 60 minutes at 80% is great for Vo2Max, then 60 minutes at 85% is even better, 88% better again.
Given finite time and the requirement to participate in sport specific training, athletes should be maximising their Vo2 training time with the highest intensity training they can sustain for the session.
p.s. Hickson et al. found over 40% average increase in VO2 Max in 10 weeks, from high-intensity training.
https://journals.physiology.org/doi/abs/10.1152/jappl.1977.42.3.372
In 1977.
I.e., before Cousins was born.
I think they set LSD limits because they’re maximizing for different constraints. When time is the constraint, yeah maybe your best bet is to compensate with intensity.
But if you’re a pro and time is not the constraint but recovery is, I think it’s different.
This makes a lot of sense. Why did I believe the notion that you could get fit by just a little high intensity exercise instead of the long slog of long moderate exercise. It was a garbage theory all along, I should have known better but I wanted to believe it.
Let’s put your findings another way to make it clearer. The bulk of a person’s improved fitness will always come from long periods of moderate exercise but it’s subject to diminishing returns. Eventually you will reach the point where no improvement will come no matter how much more you exercise. It’s at that point you can’t squeeze another 15% from HIIT. That shouldn’t fool you that HIIT is anything more than what you say is the icing on the cake.
It makes sense. HIIT can improve you by 15%. but from what starting point level of fitness? That’s the key. Obviously it’s better to engage in HIIT at a high level of fitness gained from moderate exercise rather than from a couch potato level. As you pointed out you can drop drastically with no exercise at all very quickly so you can do the opposite with moderate exercise before you ever get to engage in HIIT
I think the theory of HIIT was a case of throwing the baby out with the bath water.
So the science definitely makes sense, but my question is the number of hours riding at that lower intensity that’s required to make a significant improvement in VO2 max. Between work and family commitments I’m only able to average about 10 hours/week. For those of us with limited time, does it make more sense to focus on a polarized or HIIT protocol, or is there a way to effectively incorporate LSD training to improve VO2 max over time? For example, could I focus on lower intensity/longer distances during the winter (Nov-April here in Minnesota) then start adding intensity for the 6 week leading into the first spring criteriums?
Thank you a great read and interesting as I trying different ways to increase my v02max.
Would longish brisk walking / walking with a weighted vest have the equivalent effect to zone 1?