Image source: Garmin

Tracking VO2 max with wearables. Why is it important? How to properly measure.

In the past only the preserve of high-end sports watches, VO2 max has made its way to a many popular 24/7 activity trackers, smartwatches and other devices. Here’s everything you need to know about this metric.

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So what exactly is VO2 max?
Why should I improve my VO2 max?
How do I improve my VO2 max?
Tracking VO2 max with wearables
How to improve the accuracy of your VO2 max reading

So what exactly is VO2 max?

VO2 max is a measurement of how well your body uses oxygen when you’re working out at your hardest. It reflects the aerobic physical fitness of the individual, and is an important determinant of their endurance capacity during prolonged exercise. Put simply, the higher your VO2 max, the more fit you are. Results vary, of course, depending on fitness level, sex, age and genetics – the older you are the lower your VO2 max is estimated to be. Men also typically tend to have higher VO2 max than women.

The name is derived from V – volume, O2 – oxygen, max – maximum. It’s expressed either as an absolute rate in litres of oxygen per minute (L/min) or as a relative rate in (for example) millilitres of oxygen per kilogram of body mass per minute (e.g., mL/(kg·min)). You are likely to find the latter expression on your fitness tracker or sports watch.

Essential reading: Top 10 GPS watches for running and training

Traditional measurements of VO2 max involve running on a treadmill or stationary bike. Exercise intensity is progressively increased while a mask attached to your face measures ventilation and oxygen and carbon dioxide concentration of the inhaled and exhaled air. VO2 max is reached when oxygen consumption remains at a steady state despite an increase in workload, i.e. when you are exhausted.

Tracking your VO2 Max with wearables. Why is it important?
Image source: Firstbeat

Anyone who’s ever had their VO2 max tested in a traditional lab setting can tell you that it’s not the most pleasurable experience. Thankfully, this can now be done with less effort and discomfort. The results aren’t going to be as accurate as those you’d get from a laboratory test, but they represent pretty decent estimates.

Activity trackers start off by combining resting heart rate, age, gender, weight, and other personal information to arrive at an initial value. For a more precise score, wearables use the relationship between pace and heart rate during your runs. This is because individuals with higher VO2 max have a lower heart rate while running at the same pace compared to individuals with lower VO2 max.

This requires you to run for at least 10 minutes. Typically, it is required that you do this with a device that also tracks GPS. You may need to go on several runs that are at least 10 minutes for a more precise score. It is believed that this method can achieve 95% accuracy compared to lab tests. When measuring, you also need to make sure that you run on flat terrains, as your score may be distorted if you are running uphill or downhill.

Why should I improve my VO2 max?

There are many reasons to improve your VO2 max. When you improve your fitness you’ll feel better and less stressed and daily life gets much easier. You’ll also perform better in a variety of sports, particularly endurance activities such as running and cycling.

Another benefit is that you’ll turn back the clock. Okay you won’t get any younger, but regular exercise and keeping your Vo2 max at high levels will protect you from many effects of aging. This is according to a recent study published by the Department of Sport Science, Medical Section, University of Innsbruck, Austria.

VO2 max has been shown by this study to be a strong and independent predictor of all-cause and disease-specific mortality. So while exercise training has not been proven to extend a genetically fixed lifespan, it may add years to your life. What’s more it has been shown to give the years you are here more life.

The charts below illustrate this best. The first shows how average VO2 max values of lifelong endurance athletes decline with age. The top line is for male subjects, the one in the middle for female and the bottom line is the control group of sedentary subjects (the average Joe).

Where are you on this scale? Hopefully closer to trained than sedentary individuals!

A high Vo2Max adds many healthy years to your life one study says

The second chart is the all-important one. This shows the physical fitness of individuals until their death. The top line is for trained VO2 max people, the other one is for sedentary individuals. The dotted line shows where the cut-off point resides between independent and dependent living.

As you can see, the study found that having a high VO2 max adds years of assisted-free living. For a person that makes it to their mid-90s, it can add about 20 healthy life years. Instead of becoming dependent in your mid 70s, you can be independent well into your 90s.

A high Vo2Max adds many healthy years to your life one study says

All of this makes interesting reading and illustrates the importance of keeping fit as you age, particularly during midlife. The study concludes:

“As yet, it is not possible to extend the genetically fixed lifespan with regular exercise training, but the chance to reach the later end of natural lifespan increases with higher physical fitness in midlife, where targeted preventative efforts may be launched. CRF (VO2 max) is the strongest independent predictor of future life expectancy in both healthy and cardiorespiratory-diseased individuals.”

How do I improve by VO2 max?

If your score is not as high as you would like it to be, don’t despair. There are things you can do to improve it. Improving your VO2 max is not easy but it can be done with regular training and persistence.

Not surprisingly, the best ways to improve your score involve exercise and healthy weight loss. Fitbit says, increased exercise may help you bump your score by up to 20% over a period of two to three months.

This can be done with both aerobic and anerobic exerciseInterval training is particularly effective at improving your fitness. It involves a series of high intensity exercise workouts interspersed with rest or relief periods. Or even more simply put, you run, cycle or row fast for a bit, then slow down for a bit. This is also a get-fit-quick scheme that works brilliantly well at burning fat.

Essential reading: Torch fat quickly with interval training: a beginners guide

Additionally, healthy weight loss (primarily by lowering your body fat percentage) can contribute to an increase in your cardio fitness score. On the other hand, unhealthy weight loss (lowering your muscle mass) can have a negative effect on your score.

Here’s a great little video from Firstbeat explaining VO2 max.

Tracking VO2 max with wearables

There are plenty of sports and runners’ watches to choose from if you’re looking to monitor your VO2 max. Generally, the more you use your wearable, the more reliable your VO2 max measurements will become. Here’s our pick of GPS watches for running and training. It is more convenient to purchase a device with built-in GPS as this is typically required in order to obtain a measurement.

Having said that, you can buy watches and fitness trackers that do not have built-in GPS, but have the capacity to link to your smartphone and obtain a signal from there. Of course, that means you’ll need to carry your smartphone with you during the run.

The Apple Watch has recently added VO2 max as a metric but pretty much any Garmin sports watch will do. The same applies to Suunto, Polar, Huawei, Withings, Samsung and other popular brands. You can check out our list of the best health and fitness wearables on this link.

But the list doesn’t end there. You don’t need to spend an arm and a leg for something that tracks VO2 max. There are other wearables, such as Fitbit, that use their own proprietary measurements. This includes some of their 24/7 fitness trackers. Excluding fully fledged sports watches, a few of the more popular devices that dish out VO2 max values can be seen below.

Fitbit Charge 2 and above

Fitbit users take to forums to complain about Charge 3 blank screen issue
Image source: Fitbit

Fitbit Charge is pretty much a smartwatch disguised as a fitness tracker. It is our recommended device for the average person who does the occasional run or cycle here and there.

The fourth and fifth generation trackers slap on built-in GPS. This means you can monitor your outdoor exercise with detailed stats and a map without your smartphone. Earlier generations only have Connected GPS. This means they need to tap into your smartphone for a satellite signal.

The device also offers 24/7 activity and sleep monitoring, Multi-Sport tracking and basic smartphone notifications. Plus there are a few features that tap into your hear-rate readings. Cardio Fitness Level gives you a snapshot of your fitness level using a personalized Cardio Fitness Score, which is based on your VO2 max. It also shows how you compare to those of the same age and gender, and ranges from poor to excellent.


Fitbit Inspire range

Fitbit Inspire HR vs Charge 3: which is best?
Image source: Fitbit

The Inspire range does not come with anything revolutionary. Rather, it repackages Fitbit’s existing technology into a more modern form-factor, and makes it affordable to the masses. In a sense, the activity band sits somewhere between the Alta HR and Charge 3.

The device is a good option for those starting to track their fitness as it covers the basics without overloading you with data. The only sensor that is missing is an altimeter for counting floors, but this will not be a dealbreaker to most. This means it spits out info on steps, distance, active minutes, sleep, heart rate and calories burned. Just like on Charge 3, you also get VO2 max and Cardio Fitness Level.

If you want something that is low key but more fancy looking, there’s Fitbit Luxe. It is more aesthetically pleasing and slaps on a AMOLED display. Luxe also has a metal housing made of polished stainless steel. This can be paired with various straps including some special edition ones.


Fitbit Versa & Sense range

Tracking your Vo2 Max with wearables. Why is it important?
Image source: Fitbit

Versa comes with most of the sensors you’ll find on Ionic, but with its rounded edges, polished look and more compact form factor, it looks much better. Quite rightly, the company has realised that form is just as important as function.

When it comes to features, this is a water-proof smartwatch that puts fitness first. It includes everything you need for 24/7 activity tracking, along with capturing real-time stats on more than 20 different types of sports. And you are able to keep tabs on all this in real-time on the gorgeous hi-res touchscreen. Admittedly there is the lack of built-in GPS on the earlier editions but that has been rectified since generation 3.

The other option is to go for Fitbit Sense. The device looks like Versa 3 but packs a whole lot more. In fact, it is Fitbit’s most feature smartwatch to date.


Garmin Vivosmart 4

Garmin Vivosport or Vivosmart 4: activity tracker matchup
Image source: Garmin

Vivosmart 4 builds on the popular Vivosmart 3 fitness tracker. In additional to all the usual fitness tracking smarts, the fourth generation device comes with a SpO2 sensor and it will keep tabs on your body’s energy reserves.

The oxygen saturation feature measures your oxygen levels at night, allowing you to better understand your sleep quality. Body Battery energy monitoring uses a combination of stress, heart rate variability (HRV), sleep and activity data to let you know when to push hard, when to rest.

Thanks to Garmin Elevate wrist heart rate technology, you still get 24/7 heart rate monitoring, and the wearable automatically tracks activity including steps, floors climbed, calories burned, intensity minutes, sleep and more. It also features smart notifications to keep you connected while on the go.

Amazon | Garmin*

Garmin Vivoactive 4 and Venu range

Image source: Garmin

The Vivoactive range is Garmin’s answer to the all purpose sports smartwatch. The most recent fourth generation comes in a choice of size options, including Venu – a more pricey edition with an AMOLED display.

You get the full range of features such as VO2 max and a comparison to those your age and gender. Plus there’s PulseOx and respiration rate in addition to all the usual fitness tracking stats.

With GPS onboard, the thing comes with multiple sports profiles, including new ones for snowboarding, cardio, yoga, elliptical and stair stepper. There’s storage for music, too, along with NFC for payments on the go.

Amazon | Garmin*

How to improve the accuracy of your VO2 max reading

If you think your VO2 max does not align with the effort you are putting in, there are some things you can do. In fact, this is a common occurrence. Scan forums and Reddit and you’ll see people complaining about this very thing every day. Generally, sports watches have become pretty good at estimating your VO2 max as indicated by this study.

Here are some things you should be aware of to ensure your readings are accurate. Go through this and make sure you have ticked all the boxes.

Setup your watch in the right way. VO2 max does not only depend on your performance statistics. Make sure you have entered your correct age, gender, weight and height. And be honest about it! Better yet, link up a smart scale to your account – no cheating allowed there!

There are tests you can do to calculate Max heart rate. They typically involve short hill spring repeats and require that you go all out. You might feel like you’re going to pass out by the end!

Another option is to use the lactate threshold tests. Some devices, such as Garmin watches, support this. Polar has a good article on how to calculate your Max heart rate for running.

If you use a strap with HRV, some sports watches can auto detect your Max heart rate and adjust accordingly. Garmin watches send out notifications when lactate threshold changes.

Use an external heart rate chest strap or armband. As good as wrist-based heart rate monitors have become, they are not yet on par with accuracy that you get from these types of devices. And an accurate reading of your heart rate is absolutely essential in your VO2 max calculations. Most arm and chest straps will also deliver heart rate variability (HRV) information – which is a measurable way of calculating the fatigue of your body.

It depends on conditions. Running uphill will give you a better performance score and the opposite is the case when running downhill. For a most accurate VO2 max estimate, run on flat terrain. Other things that can negatively impact your reading include surface (grass is more difficult to run in), running into the wind, rain, cold weather and more. Having said that, some of the newer watches do account for heat and elevation changes.

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Marko Maslakovic

Marko founded Gadgets & Wearables in 2014, having worked for more than 15 years in the City of London’s financial district. Since then, he has led the company’s charge to become a leading information source on health and fitness gadgets and wearables.

One thought on “Tracking VO2 max with wearables. Why is it important? How to properly measure.

  • What’s the cheapest fitness/sports watch with Vo2 max released from at least 2018?


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