The gold standard to measure your VO2 max is going to be in a laboratory with a metabolic cart. You can get this stuff in various equations. You can use any of your fitness technologies.
I will strongly encourage you though that if you care about this number, if it's possible, and it may not be, spend a couple of hundred dollars and get this actually tested in the laboratory. The data are quite clear, at this point. I have not yet seen really any standard over the counter fitness technology that gets an accurate number of your VO2 max when the number gets high and particularly for people who are already fairly fit.
If you're VO2 max is really low, it might give you a decent number. But for folks that are kind of moderate to highly trained, it's just really challenging to get an appropriate estimate from a watch or a ring or things like that. Perhaps, those will improve in the future.
In fact, I quite expect them to. But as of now, the margin of error is a little bit too high for me to be comfortable with when you care about accuracy. If you're trying to just get a global sense, they're fine.
In fact, if you want to do that, you can use any number of absolutely free estimate equations. Examples of this would include something like a two-minute step test where you would take your heart rate, step up and down on a very small box, say 12 inches or so. You do that continuously for two minutes and then measure your heart rate at the end.
You can enter that score into an equation and get an estimate of your VO2 max. Those are scientifically validated methodologies. The 12-minute test ends up being something like a mile and a half run.
So you could simply, in fact, you could do this if you'd like, as well. Run a mile and a half as fast as you can. Take that time.
Enter it into equation and get an estimate. If you have that time as well as your heart rate, you can enter it in as well and get a more accurate picture. And so again, all of these are close.
We call these sub-maximal estimates because they are that, they're not the direct measure. So I would encourage you, again, if at all possible to actually go into a laboratory and get this measured. In addition, if you do something like that, you can get a bunch of other metrics you can't get with some of these estimated equations, like what percentage of fat versus carbohydrate you're using, your anaerobic and lactate thresholds, your maximum ventilation so how much total air you can bring in and out, and a bunch of other stuff that we talked about on the show and we'll get into in a second.
Again, if you don't have access to any of that, that's fine. Use any of those other free or extremely low cost options and you'll get yourself pretty close. Our next "I" is interpretation.
So sticking with heart rate and VO2 max, as I mentioned a little bit earlier, resting heart rate will go down as you improve fitness, but your maximum heart rate will not really change. In fact, if anything, it will be reduced because you're a little bit older. And so to state it one more time, there's no real association between highly fit people and their maximum heart rate, and unfit people.
So it's not a metric that we should be overly concerned about of, you know, where is your maximum heart rate. It is relevant to, again, your stroke volume, but the heart rate itself is not going to tell you that much. So not something to be concerned about.
Your resting heart rate though, or your heart rate at any given intensity is very important. So if you're going to be running, say at a standard pace, say seven miles per hour and your heart rate at seven miles per hour was 150 beats per minute and now a couple of months later, your heart rate at the exact same speed is now 115 beats per minute. That would represent a significant improvement in cardiovascular fitness.
Stroke volume would be much higher. And because of that, that allows your heart rate to come down. Resting heart rate is a similar story.
I'm giving you a little bit of context here. And the reason this is top of mind is because there's a hummingbird that lives in my backyard and my wife and kids look at it every single day and they get so excited. They call her mom's little helper.
They named it Squirt, actually. And so they get really excited when this little hummingbird is flying back there 'cause it's super fast. Hummingbirds have a resting heart rate of something like 1200 beats per minute.
It's absolutely insane. So you're talking about putting an order of magnitude on top of almost a human maximum heart rate. You contrast that to a larger animal like a giraffe, an elephant or a blue whale and you're talking about a heart rate of something like five to six beats per minute.
And so humans, of course, are somewhere in between. If you were technically to Google this, you might see something like a normal resting heart rate is 60 to 100 beats per minute. I'm here to tell you, I cannot fathom a situation in which somebody's resting heart rate is over 80 beats per minute and they are healthy.
And I absolutely would not think that that would happen to somebody who's performing at their maximum. In fact, I even will tell you, this is off the record, this is not the science, this is me and my professional opinion. Even a resting a heart rate of 60 or so, particularly in a man is.
. . That's catching my eye.
I would like to see most folks probably in the forties to fifties, somewhere in the range. Again, you might be fine at 60, but getting a much above 60 is quite a bit high. I also personally tell you, I've worked with plenty of athletes, specifically in this case, several UFC fighters whose resting heart rates were in the low forties, if not high thirties.
So 37, 38, 40, things like this. And so that's the lowest I have personally seen. That said, there are classic stories of plenty of endurance athletes.
You're talking about elite cyclists and cross country skiers and marathon runners and such who are in the low thirties. Lowest I'm aware of is the legendary cyclist, Miguel Indurain, having a resting heart rate of 28 beats per minute. As far as I can tell, that's the lowest ever reported in the scientific literature.
Though please, if you've seen any lower, let me know. I'm sure there are plenty of stories of anecdotes of people in personal training records and stuff who think they're lower. But if you've ever seen anything verified scientifically, I would love to see that.
Interpreting your VO2 max is more interesting in my opinion 'cause there's a lot of components to it. And so in order to truly understand this, let's talk about how we calculate VO2 max to begin with. The easiest way in my opinion is to think about VO2 max equals your cardiac output multiplied by what's called your AVO2 difference.
Now, as I've stated, cardiac output is simply your stroke volume multiplied by your heart rate. So if we were to combine this entire thing, we would say your heart rate multiplied by your stroke volume, which says, okay, how much blood am I getting out per pump? How many pumps am I getting?
And I multiply that by what's called your AVO2 difference. Now the A stands for arterial, V stands for venous, and the O2 is oxygen. So what literally this means is what's the difference in oxygen concentrations between the arterial side and the venous side?
Remember, arteries generally go away from your heart, which means they're going to exercising tissue, and veins come back. And so what we're really looking at is saying, okay, how much blood, how much oxygen's in the blood when it leaves the heart, this is going to be the highest concentration of oxygen possible, and how much is in the blood when it comes back having passed through muscle? This then directly tells you how much oxygen your tissue extracted in the process.
So to give you some numbers here, to make this easy, these are not accurate, just representing the math here. If you had a hundred molecules of oxygen that left your heart and went into your quadriceps, and then once it's gone through the capillaries that surround all the muscles and tissues and fibers in your quadriceps and it went in as a hundred and then it came back out the other side and went back to the heart and lungs to be re-oxygenated, well, if it went in at a hundred and came out as 75, the difference between the arterial and the venous side is a hundred minus 75, which would give you a score of 25. Now what that means, and again, I'm using those round numbers to make this simple.
You've extracted now 25% of the oxygen that came in your system. You only got 25% of it out. That's not a very good score.
You want that number, because it's a multiplier, to be as high as possible. So if a hundred goes in, I don't want 75 coming out, I want zero coming out. Let's say maybe you got 10 out.
So now a hundred went in, 10 came out. You extracted 90% of the oxygen that was available to you and got to bring it into muscle and use it for everything we talked about earlier. And so now your AVO2 difference is 90, much higher than 25.
So we get to multiply that by our cardiac output, which brings our VO2 max even higher. The easiest way to think about VO2 max is to use what's called the thick equation. VO2 max, according to the thick equation is your heart rate, in other words, how many beats per minute, multiplied by your stroke volume, how much blood coming out per pump, multiplied by what's called your AVO2 difference.
To be perfectly honest with you, the AVO2 difference numbers are difficult to convey over audio only. So I'm going to spend most of our time on the other side of the equation. When it comes time to interpreting your VO2 max numbers, there's a lot of charts and papers you can use.
We'll provide some of those in the show notes for you. I want to give you some numbers though to give you rough context. Typically, we think about VO2 max in what's called a relative term.
Now scientists and people that are more advanced in this field might like to use the absolute versions. Depending on the scenario, that might make more sense. But for now, let's just stick to the relative.
What that means is how many milliliters of oxygen are you using per kilogram of body weight per minute? So you'll see them expressed as things like your VO2 max is 50 milliliters per kilogram per minute. So 50 milliliters of oxygen per kilogram of body weight per minute.
You can kind of think about VO2 max almost on a scale of zero to 100. And so the average person that would kind of say, walk out of my classroom somewhat moderately trained, male or female, that's you know, in the neighborhood of 170 pounds or 70 kilos, something like that, is probably going to have a VO2 max around, you know, 35 to 45 milliliters per kilogram per minute. Something in that range.
If you fall below 18 milliliters per kilogram per minute, you're probably crossing below the threshold of what we call independence. For women, that's about 15 or 16, which means it's very difficult to live independently and by yourself because your fitness is so low going through basic activities of daily living become challenging. So what I'd like to share with you is not only the normative values, but also the highest we've ever seen in terms of VO2 max, cardiac output and stroke volume.
Now there's so much data on VO2 max, we can actually break this down by age and by sex, in really specific numbers. So if you know your exact age, you can go ahead and look these up in these charts. But I'll give you a couple again just to give you a ballpark.
Let's say you were a female between 40 and 49-years-old and your VO2 max was 28. That would put you as what we consider to be below average. If you wanted to go from below average to average, you'd have to go into the 32 to 36 milliliters per kilogram range.
If you wanted to go all the way to elite, tell me what's the best ever, you'd be needing to surpass the mark of 47 milliliters per kilogram per minute. Any of you that are maybe older, let's go ahead and jump way down. Let's say you are 71-years-old, again, talking about a 71-year-old female here.
Below 18, you know, you're still above that line of independence, but it would still be considered low. You would really want to be looking at something like 22 to 24 to be considered above average and then really over 36 to be considered elite. Now I know my friend, Peter Attia, likes to tell people he wants them to be considered elite in at least the decade before their actual age, if not two decades before.
And that's a phenomenal way to think about it. So just as that example, if you were that incredibly ambitious and vigorous 71-year-old, elite for you would be 36 milliliters per kilogram per minute. The decade before, again 60 to 69, that would be 40.
But if you wanted to be that extra person to get that double gold stamp from Peter, you'd want to be above 46. So the difference was going from 36 to 46 would give you that elite category for two decades younger than you. For the men, it's a similar story.
You just add a little bit of the numbers to it. So a male who is say between 50 and 59-years-old, above average would be 36 to 40 milliliters per kilogram per minute. And you'd need to be above 50 to be considered elite at that age.
Now, in my personal opinion, I kind of like to say there's no excuse to be under 50 unless you're over 50, meaning you have no reason to be having a VO2 max of lower than 50 unless you're over 50-years-old. And even then, 50 to 60, I don't want you anywhere near below 50. So that's a nice number to go after.
We'll also talk about in a second how changeable that is and how much it responds to various types of training. And so it's going to give you a little bit of hope. You have some room to move there and it will respond to your training.
And so there's some light at the end of the tunnel. If you're looking at those numbers and you've had a VO2 max done recently and you're thinking, "Oh my gosh, I am way below what Andy said there," that's fine. You still have within your capabilities to change that.
