VO2MAX ON YOUR GARMIN: How do watches estimate VO2max?!

[@joyridaz]

The best way to lower your vo2max is running hills in the summer heat! At least on my forerunner 235 which doesn’t do altitude or temp...

[@BuggatiWeryon]

Sounds pretty contradictory :D Run that high effort, only to get your Vo2 max decreased doesn't sound very appealing :D

[@lechprotean]

@@BuggatiWeryon he's just referring to the limitations of how the Garmin estimation is limited to extrapolating from HR. As your HR increases with heat (normal thing) - Garmin incorrectly interpolates this to a lower estimated vo2max.

[@levbobrov1398]

My personal experience with Garmin temperature measurements: I don't know where they get those values, but they are not based on reality. They would be much better off just getting it from some local (based on location) weather station.

[@phl0w666]

@@levbobrov1398 Temperature is measured by the barometric altimeter (which are thermometers as well). Since Garmin puts the altimeter (little hole) on the back of the case, it measures first and foremost your skin temperature.

[@iannewey]

Lower?

[@robcarter8957]

useful video, thanks. it was hurting my brain not to understand how accurate/inaccurate garmin vo2 estimates are. and why mine, despite exercising every day, has gone down quite a lot over the past couple of months.

[@kingtoffolon]

100%. Applying 80/20 feel like I am fitter but due to less tempo type workouts VO2 is not improving as dramatically.

[@Trihope]

Seems like that would make it more accurate maybe. I’m just thinking from the perspective of it being able to gauge different systems.

[@EJD2012]

Interesting that you are so positive about this value. Mine is 51 .... and has been 51 for the last 10 years (or something like that). During this period I got injured. At start I ran half marathons (best 1h 37 min), and trained 70 k/week. My knees got bad, I needed to stop training and gained nearly 15 kg. Started slowly again after two years of recovery. Was suprised my VO2 still was 51. Did run occasionally (but cycled a lot). VO2 max stayed at 51. Only after 8 years it went to 49. Then I lost the 15 kg, and started running a bit more often. It got back to 51.... As I just got 60 years old, this is supposed to be pretty good - which is the only reason I still look at the number, as it clearly does not tell me anything.

[@NJSportScience]

I mentioned this on another comment but keep in mind improved performance/fitness doesn’t not directly result in increased VO2max. Running economy improvements reduce the oxygen cost of a particular intensity therefore VO2max might be stable when pace goes up. Your training style may also be a stimulus more focused around improving your fractional utilization of VO2max and therefore your VO2max again doesn’t change but you can hold a higher % of it for longer. Finally as you get older seeing the number remain the same is a positive because you’re delaying the rate of decline with age. Unlikely it would rise significantly.

[@Fishermensbiblestudy]

What if gender changes often?

[@thickseed]

😄

[@colettedagny-4972]

That is normal.

[@JamieHines]

it's almost like this video Read My mind. I was just analyzing mine the last couple days and wondering how accurate the Garmin VO2 max was. outstanding video I appreciate your time and the data.

[@NJSportScience]

Thanks Jamie! Any other topics you’d like to hear about?

[@usainvanrudisha1649]

As an 800m runner I think Garmin reads my V02 max as lower than it is (60 vo2 max, 52s 400m and 1:56 800m) Most of my sessions are interval training with a big focus on speed, and generally I rest for longer than I run. My heart rate is high but my overall pace per km is slow, causing Garmin to underestimate.

[@zacsborntorunrunningadvent3441]

1:56 800m awesome!

[@danielson9144]

1'56" it's very good...but it isn't VO2 Max effort...(it's more anaerobic...).

[@NJSportScience]

That’s a great 800m time, it’s definitely above vVO2max but still a high aerobic contribution. Very typical of garmin to underestimate in these circumstances.

[@evangossell1980]

Video starts at 4:20

[@chriswright9096]

One thing that's worth pointing out; Garmin has no idea of the terrain! In the winter I run on straight flat pavement. In the summer I move to trail running; quite technical trails on difficult terrain. Garmin sees me running slower with a higher heart rate and reduces my VO2max even though I'm much fitter in the summer.

[@NJSportScience]

Chris Wright can also get a similar effect if all you do is top end aerobic power work but minimal volume/long slow (my training usually). A great point you raise here.

[@stevemurray710]

We'll I'd hope the Garmin watches that have a barometric altimeter can make adjustments for climbs. Maybe your watch doesn't have the altimeter.

[@chriswright9096]

@@stevemurray710 Yes, my watch has an altimeter. But I'm talking about gnarly trails with rocks and roots, mud, twists and turns. The pace is naturally slower for the given effort. Garmin can't possibly know this and clearly interprets the slower pace and higher heart rate as a decline in VO2max. Fair enough (its a fitness watch not a miracle). But good to be aware of the limitations of the technology.

[@phl0w666]

That's why you should use the trail running profile/app if your route is anything but flat on a hard surface. The trail profile has no impact on vo2max. And no, even the models with barometric altimeter don't take elevation gain into account, only temperature in the latest x45/6 series.

[@Claus3000]

@@phl0w666 This! I always use the trail running-profile on trails and mountain runs. 👍😊

[@danieljames1]

Always great, clear, detailed, informative and educational content. Thank you for this and other vids. Much appreciated!!

[@fabianverolme]

Interesting. I'm a young guy with a Garmin vo2 max of 75. Mine keeps increasing when I'm training after a hard ride the day before. In the last 3 weeks it went up 4 points. I'm not taking it very seriously but it's a good indicator of my fitness and where I'm standing

[@NJSportScience]

That’s the best way to look at it. The general trend over time, day by day change doesn’t give you much value

[@kuntkoalition]

Showing where to review in Garmin connect was helpful in addition to the explanation. Thank you @njsportscience! 🙏

[@TK-nc3ou]

For me this is rather straightforward - the faster I run with a lowe HR vo2 goes up... I train mostly aerobically - in Zone2.

[@tommyigonzales]

Nice video! A technical note: Within individual, the HR-to-VO2 relationship will be overestimated if HR is measured prior to achieving a steady-state value (for example, as may occur during an incremental exercise test where work rate is increased in a linear fashion). This is particularly important when prescribing exercise intensities at a percentage of VO2max.

[@lopey66]

from an elite running coach Australian Dick Telford, a simple rule was to run at the pace where you could not talk, that was considered your VO2 Max

[@NJSportScience]

Luis Lopez I see the thought process. Might be a useful tool similar to an RPE scale in a practical setting, but like anything estimating need to understand there will be a fair amount of variance in the outcome using that method.

[@lopey66]

@@NJSportScience this was general practice before we had HRM, I have been doing ironmans for 33 years, this is a sample of my power/hr mapping data strava.lopeys.com/mapdata.php , I am already playing with CDA aerodynamics with a velocomp Aeropod to measure live CDA, vo2 is one of the variables in performance. check twitter.com/DickTelford/status/1002541270521114624

[@PhiyackYuh]

@@lopey66 the theory and application 20-30 years ago still applies up to this date when it comes endurance training. The keep it simple stupid rules will always trump anything fancy that all these exercise scientist or ep try to regurgitate. If you are a pro then go with all the testing and all the taking blood samples whilst in the lab. For your average punter enjoying the sport and do it as a hobby it is not necessary and its overkill. Hobby does not bring money to the table plus if you are in tuned with your body, consistency is the key. The problem with age groupers is they think they are a pro when in reality they have no self awareness and some are plain delusional thinking they are hot pooh because they simply do a triathlon. If you know you know.

[@chrisgleesonx]

I'm 28. I do weight training and long runs. I would consider myself fairly fit i can comfortably cover a half marathon on any given day and the watch keeps telling me my fitness age is 39. Its beyond frustrating 😂

[@onzeit1822]

That's weird. At what pace and HR do you run 10km (or 1/4 marathon)? I'm 29, did only climbing, strenght training and very little cardio in the last years and it tells me my fitness age is 20.

[@TheShumoby]

It's weird I don't even workout much. I'm in my mid-40s and m vo2max is 42

[@davetravis3342]

A video on estimating maximum heart rate ( & heart rate zones) would be useful

[@NJSportScience]

Dave Travis just finished recording on this topic, thanks for a great question. Video will be uploaded shortly!

[@belliiahmed]

You can easily do this video in just 2-4 Minutes and be useful and informative and entertaining to watch

[@zapkvr]

Agreed, far too much drivel. Shocking presentation. Loves the sound of his own voice

[@JuanderBoyMusic]

Yep, I couldn't finish it... On to the next.

[@PK7..]

In the nicest way possible, agreed

[@MJCampu]

Very good video, congrats. What I do not understand is how oxygen consumption is correlated with heart rate. I'm pretty sure two bodies can have the same heart rate but one utilises more oxygen while the other is simply uncapable. That is just a gut feeling although I guess there must also be a correlation behind it. Diving through the actual equations that Garmin uses to estimate the value would be useful, if they were public.

[@logiconabstractions6596]

For practical and reasonnably accurate way to estimate vo2max, the Cooper test is interesting. It correlates the distance ran in 12 minutes with r value of 0.9 or 0.95. Probably better with regular runners at least somewhat used to that intensity and are able to do closer to maximal effort. And it's a fun running challenge too, say if you're with a local running club.

[@NJSportScience]

Not a bad field test as you say for trained runners. It’s highly sensitive to pacing strategy optimization though. In theory it’s a 12min max effort but different pacing strategies will suit different individuals and therefore we end up with some skewed data. A good starting point but obviously be aware of the variation you might run into with those who aren’t as good at pacing accurately.

[@logiconabstractions6596]

@@NJSportScience Good caveats, and yes an R=0.95 or whatever does mean some stuff won't fit as well. That being said, I don't know if pacing should really be an issue here. This should be run on flat (or ideally track as formula fitting are based on data collected on track). I'm fairly certain the best possible performance fort this would be even splits. When running a race, things are different, e.g. there's the psychological aspects but also the very practical aspect of sticking to the lead pack for aerodynamical purposes. For that kind of test however, those considerations are removed. That's an interesting question in itself however. I'd be curious to see if some runners may set a PB they can't never break with even splits using negative (or positive for that matter) splits. My intuition is that if you're running a TT by yourself, even split is always going to be faster. Simply a matter of efficiency - if your 1000m time is say 2:55 (so 35s/200m), then running say the last two 200m @32s is going to make those last 2 laps significantly more demanding, in a way that the +1sec /200m for the first 600m cannot make up. E.g. close to your limit, increasing your pace isn't a linear increase in demand on your body.... closer to exponentially harder.

[@NJSportScience]

First time doing the test. How do I know what even split is? Regardless of being in a race or not, you’ve just described pacing. Knowing what an even split is, is a pacing strategy. I’d also be interested to know when the 12min run paper was published given how closely aligned a 1.8-2km TT is with very accurate vVO2max. Most would finish this somewhere between 6-8mins.

[@whycantiremainanonymous8091]

Here's a funny story: I ran a half-marathon race yesterday. I improved my personal best by almost three minutes (and that old PB was set on a treadmill; it was well over five minutes faster than any time I ran outdoors in the past). For this feat, my Garmin watch "rewarded" me with downgrading my VO₂max by 1½...

[@NJSportScience]

Classic garmin hahaha

[@jimoconnor8597]

I just use mine as trend data. Anecdotal with your fitness. At 57, mine sits around 51 but our 100F+ (37+C) summer temps seem to decrease it as HR is always higher than normal. Conversely, fitness is far improved after the summer months of 50-60mpw work.

[@NJSportScience]

Jim O'Connor and that’s how it should be used as in the video. Trend data over time to maybe see peaks and lows or highlight a major issue in training or even with the device.

[@jimoconnor8597]

@@NJSportScience Thanks again for some good videos and information. Watch data is great but knowing the limits is important. So many runners use it as absolute fact. LOL

[@JonathanHebert]

I don't take the garmin vo2max data like it is the real vo2max. But it is a real good baseline/tools to measure if I am progressing or not. My setup Garmin Tactix Delta with HRM Pro on my runs.

[@NJSportScience]

Absolutely it’s just a guide for how things might be going. Going and getting a test in a lab is the way to go if you want the real deal.

[@MyPaulclark]

Great explanation of the Garmin stats. Ive got a test on Monday and my V02 max has been improving over the last 6 months. Just watched your other video on training to improve. Im currently doing the 30/30 and 2 by 2 sessions and long zone 2 rides. And im getting improvements every week. Im 53 80kg got a FTP of 288 and currently V02 of 70. It will be interesting to see what the test results say compared to Garmin.

[@marianneoelund2940]

Please let us know your test result. I'm also curious about power at VO2 max. Thanks in advance.

[@MyPaulclark]

@@marianneoelund2940 my V02 came in at 62. Off of the 70 Garmin predicted. FTP 298 which Garmin was close to. The Garmin 1030 plus is good for a guide and training zones

[@16kcostello]

I’ve noticed the last few weeks as it has gotten hotter my vo2 has dropped by two points I have anemia and wonder if that plus the heat plays that big of an impact. I always feel super sluggish in the summer and feel fastest and strongest in early spring/ winter though I am doing more consistent training in summer

[@peterko8932]

309/5000 This video leaves the interested watcher with many questions: Since VO2 is directly proportional to HR, this also applies to VO2max and HRmax. And if HRmax depends on age only, this is valid for VO2max too? So how can VO2max additionally depend on the fitness level and what role do HR and speed (GPS) play?

[@NJSportScience]

Peter Kötzing because HRmax doesn’t depends on age. Estimated max in a generic equation. Just saying age as a sole factor influencing HRmax is naive, as HRmax is dependent on age, genetics, fitness level, stroke volume etc. VO2max depends on fitness level because a key adaptation from aerobic training is an increase in mitochondria size/surface area/density which allows greater oxygen use at the muscle site. This is then why elite athletes have such high VO2max values. If age was the only influence on VO2max, every person of the same age has the same value, which is means professional athletes and chronically ill stroke patients would have the same VO2max, which we know is just not true. HR will change for fitter individuals because an adaptation from training here is the increased left ventricle size and wall thickness, allowing the heart to pump more blood per beat (stroke volume). This means cardiac output (blood pumped per minute) for a given intensity likely stays the same but with more blood coming out per beat, HR doesn’t need to be as high. Speed/Pace is also proportional to all acute responses including HR and Vo2max. As exercise intensity increases HR must increase to supply Oxygen to the working muscles, and then use more oxygen to create enough useable energy, therefore our ability to take in, transport and use oxygen increases with intensity, this is VO2 and the highest value obtainable for an individual is the VO2 peak/max.

[@peterko8932]

@@NJSportScience You are missing the point : Garmin does use the "220 - age" proxy in it's watches plus the Firstbeat algorithm and this is totally different from what you tried to explain.

[@NJSportScience]

Peter Kötzing the first question you asked didn’t mention either of these so if I’ve misinterpreted that, the wording is why. Yes they use firstbeat/220-age, how this relates to VO2max though is the firstbeat algorithm adjusts based on fitness as I’m sure your aware. This is why you get threshold HR updates either positive or negative and HR zones adjust. VO2max is different because there is no age based formula otherwise you’d end up with say 120-age (example only, this doesn’t actually exist). For the reasons in my previous response, VO2max will vary based on a number of factors , including HR and then based on those physiological responses plus pace information the algorithm estimates VO2max. So it’s not a derivative of HRmax estimated from 220-age. Where some confusion you may be having is that HR and VO2 are proportional, estimating HRmax however has minimal bearing on estimating VO2max when that’s the only factor being used.

[@antonovsyannikov7404]

@@peterko8932 You can change maxHR if you turn on it on settings and do a maxHR test yourself either than relie on 220-age formula. So you are the one missing the point. Good luck with testing your maxHR. many videos on how to do it.

[@peterko8932]

​@@antonovsyannikov7404 Seems you don't understand the question here and I bet you haven't even fully read/digested the thread. Nowadays every elementary school student knows how to test HRmax and entering it into the watch is a no-brainer. But Garmin claims to estimate the fitness level via VO2max w/o manipulating the HRmax - which from my view totally makes sense - but @Nick Jankovskis video completely fails to elaborate on that. If you know better, then please speak up!

[@Ruck.Norris]

Bruh, u can sleep 12+hours in deep sleep? Thats fkn amazing.

[@MattD86]

No. No one can.

[@68cristian]

excellent explanation. thanks heaps mate !

[@NJSportScience]

Glad it was useful!

[@winty2721]

What number do you need to go from green to blue on the colour scale please I’m right between the two 🙏

[@barnesandrewc711]

Great information, I do a mix of intensity. And the more metrix ,help accuracy, I'd guess.

[@gungnir3926]

I have a cheap Vivosmart 4. My vo2 max hovers around 37. Which is utter bs. I'm 29 male 188 cm 90 kilo. My resting heartrate is only 50, my cooper time is 2800m which is elite, and I don't even train running often, mostly bike commute, I follow Brian Johnsons doet and exercise but without large caloric deficit and pills.

[@healingenso7923]

I claim the prize for the lowest VO2max of commenters here, with 30. It's not so much the scoring that concerns me as the somewhat negative interpretation by Garmin of "Poor", which appears at odds with most other assessments. 60yo 36.5 BMI, Type 2 Diabetes and recovering from a spinal injury for several years. My endurance has increased well. But I need more intensity now. I may never go paragliding again and I will certainly never go rock climbing again. I just hope I can get some high altitude trekking done. I don't take my Garmin data too seriously, until I see the same trend over longer periods. It's about enjoying the outdoors for me, not competition.

[@NJSportScience]

A relative VO2max of 30 is not bad given the other factors you mentioned. I’ve seen clinical assessments of

[@healingenso7923]

@@NJSportScience - Thanks. I try to focus on what I can do today rather than at 30yo. The weight is coming down and I have seen a clear improvement in fitness over the last year. I do love my Garmin Fenix 7S (AKA bargain basement personal trainer) and the data it provides - I'm now increasing intensity, instead of duration and seeing good results there.

[@josephaugustinerhodenhiser1353]

Love the Michigan gear 💛💙

[@NJSportScience]

Go Blue!

[@chrishollyryan]

In my experience, one of the biggest variables is temperature. Outdoor bike/runs in the summer will skew your value downwards as I don’t think there’s any compensation for HR increase due to the heat. In any case, it’s the trend that matters - are you improving or not...

[@Amongus-mf3ho]

Some garmin watches factor that in because the have thermometers built in. My forerunner 645 has one

[@chrishollyryan]

They measure the temperature but I’m not sure it gets factored into the VO2 max calculation (it doesn’t seem to be anyway based on my experience with my Fenix 5).

[@hrishikeshbyby393]

Color map( not imo) Heartrate monitor and accuracy Vivo 2max Map accuracy Training schedule Speed and powerload Battery capacity I want this much list in one watch which watch is best plz suggest???

[@atomicdemise]

hey, very straight forward and good video; no unnecessary frills. I got a really strange circumstance going on right now with my Garmin connect ap, where ever since I replaced my FR45 with a Fēnix 5x+ that my V02 is dropping down significantly from 46 to 42 now, even though I feel myself getting stronger and better at running, going longer distances faster etc. can anyone tell me why is this BS happening? also I noticed I didn't have a "productive/ maintenance/ unproductive" data bar until I got the Fenix5x+ (&yes, all my personal info is correct)

[@NJSportScience]

Thanks for watching. I haven’t had this issue myself but maybe someone else in the comments here has that can help??

[@diegom2157]

Thank you Nick

[@certified_5135]

Why does my VO2 max never update after the first input. It has been on the same VO2 max and is not updating recent runs . Any info would be helpful. Thanks

[@king-qi2ks]

Maybe because your vo2 max isn’t getting better?

[@certified_5135]

Actually there was a problem in the settings .. thx anyways idiot.

[@aalmarzouqi1]

THANKS ... WELL DONE

[@Trihope]

So, I naturally built like a sprinter with a lot of fast twitch muscle and built like a sprinter. I started endurance sports about 11 years ago. I’ve noticed that if I put my fastest 5k pace in a race predictor, it predicts a lot faster marathon than I can possibly run. If I put my marathon PR in the calculator it predicts my 5k as a lot slower. I’ve interpreted this as a need to build my aerobic engine and have been doing all low HR training. Is this the best approach for me? My first marathon was 4:54, but I was able to get it down to 3:31 before I started MAF training. I want to get to sub 3. My 5k PR IS 21:10. Thoughts? I’m going to start incorporating some speed work and tempo runs leading up to a half marathon in about 6 weeks. I’ve noticed my VO2 on my Garmin has been going up lately, but it predicts times that seem way out of reach. That’s how I ended up on your video and kind of confused right now.

[@NJSportScience]

Great question, the low end is important but your fundamental problem is this: 5k PB = approx 4:15 pace 3hr Marathon = approx 4:15 pace This is a better view of the data than your pace predictor theory. Essentially it’s impossible to run the same pace for a flat out 5km and Marathon so the key focus should be on increasing your upper end of the engine (ie Vo2max) specifically your velocity/pace at Vo2max. In my experience those who run sub 3hr marathons have a VO2max pace of around 3:30min/km and a 5km TT pace of at least 3:40-3:45min/km. Not always but largely true. In 6 weeks, if your 5km PB was recently done, unfortunately you’re very unlikely to break 3hrs. Long term you’d want the focus to be on aerobic power and Vo2max. Get as aerobically fit as possible at the top end to have the ability to run 4:15 pace at a much lower % of max making it more realistically sustainable for a marathon like effort.

[@BobBob-uv9fq]

Mine is coming in at 44 ,,,,I’m 55 putting me at a fitness age of 25 : I wish ,,,,getting pnna vo2 max test done next week to get clarity ,,,I would be happy maybe at vo2 44//. I love my training no matter ,,,,,,,

[@BleakVision]

7:30 Yeah sure, er, my slow pace runs are at 4:30/km pace. Of course they are.

[@ndk4]

BleakVision for pro runners that is not surprising.. around 3min/km pace is about their half marathon pr pace. But for not so pro, i doubt that....

[@NJSportScience]

Pulled a number from the top of my head based on athletes I was working with at the time of recording. Personally I sit about 5:00min/km for my slow runs but yes elite guys will run at 3:45 for their slow runs with ease, not uncommon for half marathon pace to be very low 3:00 nudging into 2’s in min/km

[@williamchase5698]

I thought I had more to do with volume than heart rate. The research I've been looking at now is showing low intensity high volume increases VO2 max just as much if not more than high intensity

[@NJSportScience]

Typically until about 60ml/kg/min, low intensity high volume can be effective on it’s own on average. Most will find prior to reaching that point, low intensity in isolation becomes not as effective as using a mixed approach that incorporates both high and lower intensity training. Volume will play into the garmin algorithm as a tool given it’s an estimation and a contributor. This video is more looking at how a watch could estimate the value reasonably well based on a few simple correlations such as HR and oxygen consumption for varying intensities.

[@ItsCyclonic]

When I run everyday, my V02 Max is always 48. That’s pretty good, but I want it to increase.

[@matthiaskettner6686]

My Garmin watch told me, my VO2Max was 57. A ramp test in the university hospital for sports medicine showed, it is 70. So all those estimated stats have to be taken not too seriously.

[@NJSportScience]

Matthias Kettner it’s an estimation, as per a previous reply it will never be compeltely accurate for more than about 2/3 of the population. Even then you’ll still get variance. Best way to get the number is to get actually tested like you’ve done.

[@trepidati0n533]

@@NJSportScience You also need to consider that formal VO2 max tests are not perfect either. The protocol, the current state of the equipment, how you feel that day, etc can all affect the report VO2 max value. The three times, all different locations, I've had my VO2 max tested and asked for their calibration certs...they didn't have them or were out of date...and these were universities. So what is a better model for measuring an indirect value of performance (e.g. We do not train VO2 max, we train our muscle to use your more oxygen which increases use of oxygen)...a one time test space out every 4 months...or continuous estimation? I think people are just stuck on the number and not the progression of the number. Does it make a person feel better compared to others? Seems like a pretty expensive odd thing to get hung up on.

[@kidsafe]

I have my HR zones and weight entered correctly and FirstBeat estimates my VO2max at 69-73 depending on fluctuations in weight/recovery/fitness. I’ve always been suspicious of that number as I have a very low LTHR and HRmax...I bet the algorithm is less accurate for people who fall well off the bell curve.

[@NJSportScience]

yoog correct. The bell curve fits about 66-67% of the whole population. This doesn’t account for specific subsets of that population (ie athletes, training history etc.). As in the video use it as a general trend to see it go up or down or plateau over time. Get tested if you want the actual number, but great point you raise.

[@vasjadover8575]

Thanks, well said

[@NJSportScience]

Vasja Dover great to hear you liked the video!

[@voltagefrogmatthias2375]

Great, thank you!!

[@pi3dpi3dvisualisaties2]

I have my doubts about the accuracy of my score, I have a VO2mac (cycling) of 69 (top 1% of my age and gender). Thing is: I don't train and my fitness level is reasonable but not great. Could there something wrong with the way the measure it or is there something wrong with me?

[@NJSportScience]

As with any calculation, there will be error from a number of sources. Depends largely on the type of training you do and what plays on the algorithm the best. I wouldn’t stress over it too much.

[@Northwindbreeze]

Absolutely! Before the garmin hacking, my vo2max was almost 50. As I train more and perform much better than last year, my vo2max after the hacking has been around 35 lol c'mon, I am not especial but 35! I can ride at my threshold for a good 30min and just feel the legs, not the lungs

[@TheReneepruitt]

Mine is wrong! Has to be. I run now, I lift, I hike and no lung issues and blood pressure low and no health issues. I am 52 my garmin says my age is 77 according to my VO2 max! How can I fix it ?

[@whiz57]

Have you talked about accuracy with a Garmin watch? My watch estimates my VO2max as 45, but I just did a Bruce protocol test and only got a 35.5. I was rather surprised.

[@NJSportScience]

I can do a follow up video on what I see garmin present vs lab test data which is a bit anecdotal but we’ve compared Garmin to lab test results a bunch so worth sharing what we’ve found. I’m not a huge fan of the bruce protocol, largely because of the really steep gradient’s it gets to, not usually a true reflection of your ability given running mechanics change for that steep an incline.

[@whiz57]

@@NJSportScience I'm not a fan either. Only training for it as a fire dept I'd like to join requires you to get a 42 on it to get an offer of employment. Rather weird

[@NJSportScience]

I can understand the applicability then to fire fighter work, sometimes frustrating when you have to train for a test.

[@whiz57]

@@NJSportScience Been a firefighter for 5 years, that test definitely won't determine if you can keep up on the fire ground.

[@NJSportScience]

You’d obviously know it best but I can understand why they’d choose that over a higher speed/flat protocol.

[@TheRugbyClubHQ]

Does the heat change vo2max?

[@NJSportScience]

You’re ability to produce a certain level of oxygen consumption isn’t necessarily altered. What will occur is a great reliance in your ability to thermoregulate (maintain core body temp via sweating etc.) and ultimately may negatively impact your ability to express your oxygen uptake compared to “normal” temperatures. If you’re able to thermoregulate effectively then really it won’t have much influence in a short bout of activity. The influence largely comes as a result of inability to effectively cool the body which would typically occur more so after long exposure to high heat.

[@TheRugbyClubHQ]

@@NJSportScience makes sense, now work in a hot country and my vo2 Max has gone from very high level to average.

[@jonathanbower7081]

"R value" - do you mean R squared? or is "R value" a thing i don't know about?

[@NJSportScience]

Sorry yes, R squared value.

[@brandonlarose4767]

Good Job!

[@Alf_4]

I was surprised to find out they don't use the pulse oximeter as an additional factor in calculating VO2max

[@IAmRetail]

What's the most accurate heart rate strap on the market?

[@scubandre1]

Why my Vo2max is a lot higher (47) when i use a separate HRM compare to the integrated HRM on my Garmin watch? (38)

[@lityeah1568]

the satellites in my local area dont really measure correctly all the time so im running what i believe is 6.30 miles but its saying im doing a 8.45. I know this isnt related to the video but is there a reason that my gps measures my route way shorter and at less speed in winter as oppose to summer. I know the speed could be explained due to lack of fitness but i know what a 8.45 mile feels like and im running way faster than that

[@NJSportScience]

I’m speculating a bit here but possibly in winter you’ve got a greater likelihood of interference with satellite connection due to cloud cover etc. plus also the orientation of the earth is slightly different compared to summer so this might be a reason for the difference. That other part is ensuring your watch is updated with the latest firmware etc and allowing it the full amount of time to connect to satellite before you start running. Basic troubleshooting here but sometimes can work well.

[@lityeah1568]

@@NJSportScience haha i never really deal with the waiting for satellites i just turn it on and go, i suppose i know the distance of my route so its not too bad but yeah it can be a hassle some timea

[@KevinSanchez-vq3mh]

Great video, very informative! Do you think the Garmin 245 analytics (ie. vo2 max measure, heart rate etc.) will be reliable for a sport like CrossFit where it would be tracking not only during runs but also tracking during slow lifts, faster paced metabolic conditioning and gymnastic style workouts? Thanks again for the video, much appreciated.

[@NJSportScience]

You won’t get VO2max without Heart rate AND pace being recorded so crossfit/gymnastics for the most part won’t benefit. Only your conditioning work (ie running, cycling etc). The 245 being at the base end of the spectrum is a solid watch if you want basic HR data and pace etc for running, I don’t see you needing more than that. Even then you might consider a more fitness tracker style device (ie apple watch, fitbit etc) rather than GPS watch unless you plan to get into running more.

[@marianneoelund2940]

If you consistently exercise without venturing near your true VO2 max, then the Garmin algorithm needs to extrapolate the HR-vs-VO2 curve, and somehow decide what your max HR is, without an opportunity to actually measure it. Many older athletes have a HR that significantly exceeds the "220 minus age" rule, so wouldn't that cause large inaccuracies for them?

[@NJSportScience]

I find the same trend but in the opposite direction given my personal training is largely high intensity lower volumes. So I’d tend to agree a good variety of sessions is a good way to improve the accuracy.

[@mhendraherviawan9120]

I know my Garmin vo2max, now what ?how to crate training plan based on vo2max

[@rinohunter6190]

How’s Australia?, still cray cray?

[@markjonesvlogs563]

Good vid. Thanks mate

[@rweaver8140]

I’m wondering how it works if you are walking or running/walking I’ve had a garmin for about six months it started me with a vmax 10 years older then I am(60) now it is at 80. Not sure if I’m about to die or if this thing is confused

[@maipes]

Either that or you need a swift trip to a & e 😂

[@flyoverstateresident2890]

Go Bucks!

[@stephengarrett8167]

If you set your Maximum Heart Rate too low, does if affect your VO2 Max number?

[@NJSportScience]

Possibly, I typically don’t change it and allow the watch to self adjust max Hr so would be something to play around with, possibly it could based on it changing the relationship with HR/Pace/VO2.

[@harlychandra5987]

@@NJSportScience So does it mean that the lower I set my Maximum Heart Rate, then the higher VO2Max I could get?

[@inagopro-gi2sb]

Hello, If I train with stryd work out app on my garmin for running and zwift for circling. Can my garmin calculen my vo2 max. Or I need to use garmin ( treadmill or circling indoors)?

[@mikephilpot]

Do you have to run to increase your VO2 max? For example ... can I increase it by using a stationary bike or mini trampoline?

[@NJSportScience]

You can improve it relative to the VO2max of that mode of activity. Pretty difficult to increase say a running VO2max by only cycling (you may see a small gain if your a very untrained athlete) but training specific to that sport you can increase it definitely. Haven’t tested mini trampoline though..haha

[@benhanzen2732]

Hi, thanks for the video! Would you have an explanation / opinion on the gap between the "bike VO2max" and the "run VO2max" that Garmin calculates? (systematic 5 to 8 points difference between the two) Thanks!

[@NJSportScience]

Benoit Hanzen Not uncommon and usually will come down to the accuracy of your power meter OR if you are way stronger on one discipline over another. Have a look at my video on what the difference should be bike vs run, not necessarily garmin based but more the general principles of differing statistics between the two: kzbin.info/www/bejne/oaClmpmtbb6Vg8U

[@benhanzen2732]

@@NJSportScience thanks, will check it;)

[@vcthegreek]

There are a lot of things Garmin should improve. First of all, its security due to the ransomware. But, seriously, I agree that the measurement is pretty accurate, but it usually doesn't take into account a ton of factors. When I do interval training, it always increases my vo2max by 1 or 2, while there is a small drop at my long run. Also, it doesn't take into account the terrain and the altitude difference. And most importantly, my vo2max was 61 in the winter and it is 59 right now in the summer, while I feel I am in better shape than winter. Temperature obviously is not a factor for Garmin and all my training sessions here in Greece are between 32 and sometimes 37 degrees of celcius.

[@verbon47]

if you want complete accuracy, go to the doctor and take a vo2 max test. these watches are usually useless.

[@BobBob-uv9fq]

U can c how close vo2 is ,there are race predictions on garmin ,,,,so guess that if their close to what your getting then think the vo2 is probably close ?

[@NJSportScience]

In my experience, more often than not the Garmin race predictors are way off. Depends how you train (similar to the errors in VO2max estimate) but also the dynamic impact of running economy plays a bit of a role in determining what your VO2max might be. In short, where possible get in and test VO2max in a lab if you really want to know what it is.

[@swaky5138]

Been wondering this ever since I got my Garmin, thanks for the info! I'll be 40 in September and my VO2 max is reading 60. I usually hit a 10 mile run every morning. Also nice hoodie! I happen to live in Michigan.

[@NJSportScience]

Go Blue!

[@TheTheThewillow]

So it great, but if you on that level you will understand 🎉

[@chronophagocytosis]

Just a minor style detail that's only relevant to the few people who are interested in statistical analysis. The scatter plot of heart rate vs. VO2 has the dots connected with lines, which can imply a connection of some sort. Normally when you're showing a correlation between two variables through linear regression, you wouldn't connect the dots, because adjacent points might not be measured right after one another. I don't know if that's actually the case with this data, but normally you would avoid giving that impression by simply using isolated dots instead. BTW one more thing about correlation coefficients: if your R²=0.9999999999 it's phenomenally good, but still not absolutely impossible. However if R²=1 it means you've messed something up really badly in your analysis, and you should have a look at the data and calculations before publishing your results. Most likely there's an obvious mistake like plotting X against itself rather than X against Y. But it's a great video anyway. I didn't mean to nitpick about every little thing, because I really found the rest of the explanation beneficial. Thanks!

[@MsAlexalexalexalex]

I’m still a little confused… I have a really high vo2max for my current level of training (I stopped training for a long time), current vo2max 56 (33yo male 177cm). As Garmin uses pace to estimate power, could this be simply because I have a relatively efficient gait, so power is overestimated?

[@NJSportScience]

Possibly, it can’t measure your economy (oxygen cost of an intensity) so if your technique was really good in the lab you’d see lower oxygen consumption for the same speed. So yes it could very well be overestimating.

[@MsAlexalexalexalex]

@@NJSportScience Thanks! I'll take the vo2max value with a grain of salt. Maybe one day I'll measure it in an activity I'm terrible at to see how it goes!

[@christophsproehnle2114]

Great clip! What`s the song in the end?

[@olivergobow9634]

Thanks for the vid. Really profound explanation. What irritates me a little about my Garmin is that it totally ignores elevation when calculating VO2max. I mean it measures altitude, right? So why doesn‘t it play any role in the Vo2max algorithm? Even if Vo2max may not be a 100% precise, it‘s better than pretending going steeply upward with 170bpm is just like running slowly on completely flat surface with an unexplicably hight hr.

[@cranker100]

I assume it's because factoring in elevation would be too complicated (think smooth asphalt vs rocky uneven terrain at similar grades). When you select "trail run" on a Garmin watch instead of "run", Garmin will not include that activity when calculating VO2 max. So if I know there will be a reasonable amount of climbing during my run (even if just short hill repeats), I select "trail run" as the activity type.

[@olivergobow9634]

Oh thanks. Actually didn‘t consider this option. Just installed it as a favourite and will use it in the future.

[@phl0w666]

If FirstBeat's whitepapers can be believed, they actually do factor that in. Not on a run-by-run basis though, but they compare runs on similar routes and effort over time and leave "odd" ones out, so to speak. Otherwise your VO2Max would fluctuate much, much more if they used every single run's absolute value.

[@thecolinranger]

The problem I have is getting my Garmin device to record my vo2max it only gives me a figure every now and then when I ride every day.

[@kylieney4306]

NIce, great video and straight forward answer. I have been in the lab and noticed that temperature plays a huge role in HR and plays with my VO2 max..Is that common? Also, during a taper my VO2 max will go up quite a bit due to lower HR and fitness level. Thanks again, and I am curious about temperature and altitude in accordance with my VO2 max readings. Thanks again!

[@NJSportScience]

Temperature is only an issue when thermoregulation is challenged. If you can’t maintain core temp during activity then you start to get impacts on things like VO2max etc. typically though heat won’t impact VO2max as much as it impacts HR, given HR is more directly linked in with temperature regulation. Altitude you can expect to see VO2max drop. Change the atmospheric conditions and (oversimplified) oxygen availability, you’re going to get a negative response.

[@kylieney4306]

@@NJSportScience Hey Nick, thanks for the response. I actually was thinking long term training. I just did 2 weeks at altitude and now back in the heat of Arizona. A lot of my coaches tell me that training in heat is synonymous with training at altitude, but I see different results. Did a threshold test set today running off the bike and HR was significantly lower at my 16:10 5k pace at 149. It felt a lot easier too. I am 53, but an ex pro athlete and olympian. I'm also currently working with swim teams and trying to gain VO2 with hypoxic work with lowering oxygen intake through stroke snorkels and closing the hole a bit each week. I think swim training has lessened science wise then other sports I'm involved in. I am a true believer in the 80/20 rule, just trying to figure a way to bring that to the pool without boring my swimmers.

[@NJSportScience]

Heat and altitude have very different adaptation effects physiologically. Both increase difficulty/RPE in the short term but the response is different. It’s two different environments so you’re spot on to expect a different result. I tend to agree that swimming isn’t maybe as advanced as say cycling is but definitely getting there. The complexity is in the water, as simple as it is, it makes it so much harder to develop useable and useful technology compared to a sport like cycling to track, monitor and assess performance. The hypoxia piece is interesting, I’m a bit mixed on my opinion there. I can understand the argument for shorter distance events, not so much for longer but would have to read more into it to be completely honest. I like the experimental nature to try different things and assess the results

[@stevebelzer4758]

Wow - your RATE of speaking is SUPER fast how much Expresso did you have before the upload This makes presentation of science based data a little tough on your audience Rewatch your video -it sounds like it’s being played at 2x speed Wow

[@NJSportScience]

Watch it on half speed then

[@jamesbailey5008]

Why don't they do it outside of swim bike run.. rowing please..

[@shredpow]

Go Wolverines!

[@NJSportScience]

Go Blue!!

[@KazzArie]

I understand the correlation between rhr and vo2max but what I don’t understand is how it goes from hr to the value. My wife’s measured rhr was in the high 50s and was given a vo2max of 54 or so. My rhr is in the mid 50s but my vo2max is in the low 60s. Wouldn’t this imply a higher rhr for a relatively non-precision instrument would calculate a higher vo2max with a higher rhr? Surely an athletic person with low rhr is the healthier individual…

[@NJSportScience]

The correlation has nothing to do with RHR… Your right, generally speaking lower RHR is a sign if a fitter individual, but resting HR alone has effectively zero relationship to VO2max. Might be an indicator but not correlated. RHR is also regulated by a number of other factors other than just “fitness”. The correlation I talk about is with your HR during activity. Increase exercise intensity = increase in oxygen supply = increase in heart rate. Similarly, increase in intensity = increase in oxygen use (VO2). Can’t have this without the supply, therefore as HR increases with intensity so to does oxygen consumption. It’s the relationship DURING EXERCISE (emphasis on this) that correlates VO2 and HR

[@KazzArie]

@@NJSportScience hey, I appreciate the reply! My polar strap app says to do the fitness test lying down and rested a couple minutes. Makes me wonder if it’s detecting more than just hr, but maybe more precise electrical signals in p, q, r, s waves 🤷🏼‍♂️ It does make me interested in eventually getting a more precise test. Not sure what result I was expecting to see, to be honest. For illustration, my wife is 40, relatively inactive so her score makes sense. I’m 38, row 50k/week. I wonder what it would indicate if I tested during an active session 🤔

[@jesperjongman4319]

''A slow run, like a 4 min per kilometer''. Lol

[@NJSportScience]

Must of had a few super fast athletes in that week so my examples were a bit skewed 😂

[@anagamin6793]

Im trying zone 2 running or HR monitoring run it seems VO2 max declines !

[@NJSportScience]

Sounds like you need to top up the top end with some aerobic power work near VO2max. This is why polarised training is super effective, targets the same awesome aerobic adaptations by doing Long slow Z2 and HIIT. The combination of both when executed correctly is how VO2max boosts up, particularly plays into the Garmin algorithms well also.

[@patlau2utube]

Good video. Thanks. I would like to know if true VO2Max will be affected by heat? My Garmin VO2Max has been dropping since summer come in.

[@NJSportScience]

patlau2utube VO2max shouldn’t be impacted by heat. What would be impacted is your heart rate. Warmer conditions require the body to work harder at cooling down, therefore HR increases to help pump more blood to the skin surface allowing heat to release through sweating etc. You could then be running at the same pace with a higher heart rate. Nothing has physiologically changed, garmin likely now “thinks” you’re not as fit because it only sees higher HR/slower pace.

[@patlau2utube]

@@NJSportScienceSince Garmin watch can sense temperature (e.g. Forerunner 935, or with Garmin Tempe sensor), wouldn't it be possible to somehow compensate the increase of HR due to heat and obtain a more realistic VO2max?

[@NJSportScience]

patlau2utube not saying it can’t be done, I just doubt the algorithm factors that information in because not all devices have a temperature reading. If I were to test you in the lab and actually measure oxygen consumption rather than just estimate it temperature wouldn’t change what VO2max you had, just likely a higher HR. That’s why it wouldn’t make much sense to have temperature in the algorithm anyway. But we’re left with this flaw where you possibly have a higher HR for same pace which can be misinterpreted. As in the video, estimate only, unless you get your VO2 actually assessed you’ll never have a 100% accurate reading from something that misses the fundamental step in the measurement (actually measuring your oxygen consumption directly)

[@Peter-wn3nm]

@@NJSportScience on the Garmin Forerunner 945 - there is heat adaptation % - but the major fault of it is - it doesn't consider humidity. Due to this - training or racing in hot & humid conditions results in lot lower VO2 MAX - I would guess? I noticed that running in - lets say in 30C & 85-90% humidity vs 30C & 5-10% humidity - the pace is very different, and also how the HR reacts to cooling down. Any experience with this & how accurate the VO2 MAX would be due to these conditions?

[@NJSportScience]

Peter that pretty much sums up what I would reply anyway. Slower pace for higher HR would typically underestimate because it thinks your not as fit, mainly because not all watches have the heat metrics so it likely doesn’t factor this i to the algorithm.

[@deepfriedoprah]

What is the vo2 max setting in user settings, should I adjust it and how?

[@NJSportScience]

That allows you to manually adjust your VO2max which could be done after obtaining a lab test result. I otherwise wouldn’t adjust it.

[@deepfriedoprah]

@@NJSportScience Thanks!!!

[@Peter-pv4yb]

In the winter time, I used to run in temps around 15 deg. Now it has gone up to 30-34 and my Fenix 6 started downgrading my VO2 max big time. Doesn't it factor temperature into the calculation?

[@stevemurray710]

DCrainmaker KZbin fenix 6 what's new indicated the 6 does some adjustments for temperature and altitude. Check the video from August 2019.

[@phl0w666]

It does, but for whatever reason the Fenix6/x45 line looks at the temp (via weather widget) in the morning, when temps are naturally much lower, and doesn't let you take another snapshot of what temps are when you actually start your activity - in short: useless feature.

[@johannesrk2003]

04:05

[@chocol8milkman750]

Is that a Canadian hockey jersey? Aren't you Australian? Hi from Canada though! I also really enjoy this video. Good stuff!!!

[@NJSportScience]

chocol8milkman yes it is. Love watching ice hockey and have a few jersey’s in my collection.

[@FedericoCzerwinski]

Haha First thing I noticed was the (Eric lindros?) jersey, but then we he started talking I thought...”wait a minute...this guys Aussie”

[@NJSportScience]

Federico Czerwinski haha nah crosby canada/penguins jerseys and a Melbourne Ice jersey (yes we have a hockey league)

[@FedericoCzerwinski]

@@NJSportScience I know we've got hockey! I'm from Sydney, and play a local hockey League here. Great vid btw! Thanks

[@jeffpeterson8197]

Go Blue!

[@shamohit13]

Where I struggle with my Garmin - I’ve gotten faster in my runs, swims, and on the bike over the past year, to the point where there are measurable improvements in pace at the same heart rate, and the top end Z5 speeds as well. My Garmin, strangely, shows me a flat out constant line (with two drops in the middle for a few weeks) over the last twelve months. Just checked all data on weight and height (gender is correct! :-)), and still can’t make sense of this. Any ideas?

[@NJSportScience]

Mohit S homestly reset the watch and do any updates you need to do. Sometimes that will fix it. Alternatively check your HR data, has that changed or not really? The algorithm is just estimating VO2 remember so if your HR is similar it may not be picking up a difference.

[@rhyspect]

I do all of my running & cycling off road, would this affect it guessing my vo2 max as my pace will be lower?

[@NJSportScience]

rhyspect likely it would unless you had a power meter to then quantify the output in a way that is an absolute measure rather than pace/speed which is heavily impacted by the terrain.

[@paulbuxtom5120]

It’s inaccurate for me as it predicted my 5 k at 26 min even though I can do 21-22mon

[@AreFarmen]

Thanks for the explanation. I've been using a forerunner 245 for about 3 weeks now and the watch say I have a VO2 max of 48. I find that strange because I just started running and run a 3K in about 20 minutes with a average heartrate at about 150 bpm. This is with no altitude and probably my best run in these weeks. So basically I do 3 runs each week and 3 strength sessions at age 40.. 6/7 days training a week. Do the strengttraining give me a higher VO2 max rating maybe? The forerunner says I can do a 5K in 24:01 witch is laughable.. maybe I could do it in 35--40 minutes.

[@NJSportScience]

Having a VO2max of between 35-45 is typical of a fairly healthy member of the general population so this will likely only increase as you begin to run more and more. As for Garmin's race predictor, i find it useless also, usually underestimates by a long way and gets worse as the distance increases. The strength training won't really give you a VO2 improvement, however it depends on what you are doing. If you are following more of a HIIT style session in the gym (i.e. high intensity, circuit-type or max reps for time like training) then it is possible to get a bit of an aerobic adaptation and improve VO2max however not something that will continue to increase the number for very long. The running will be the main contributor. If you are doing max strength/power work with lots of rest between sets and focus on quality lifts then unlikely this will be causing VO2 increases. Thanks for watching!!

[@AreFarmen]

What i wondered was if the strength sessions made the watch overestimate my VO2 max, not that it actually increased my V02 max :). Thanks for answering my question! Maybe my V02 max at 48 isnt far too high then. Will keep running to see if I can increase it! :)

[@NJSportScience]

@@AreFarmen I would think unlikely that the strength sessions are contributing but if you're reasonably healthy and fit 48 seems pretty reasonable. Glad I could help.

[@jsf8145]

@@AreFarmen I noticed this comment was a year old and wanted to check in on your progress. Were you able to increase your VO2 max with maintaining your strength training & maintaining your muscle mass ? ....or did you ditch the strength training and start running more while trying to lose a lot of muscle mass in oder to increase your VO2 max ?

[@AreFarmen]

@@jsf8145 Hey :). I've mostly been running the last year because of closed Gyms. I've only been doing bodyweight exercices a couple of times a week in an atempt to preserve muscle and strength. At first my VO2 max dropped to 46 (probably the right number), then it started to clim as my fitness became better. Now my VO2 max is 51 and I did PR on 3K: 14:30 and 5K: 24:31 on the same run last week. Sadly I've also lost strengt and muscle. I think my bodyweight is down from 92 kg to 82 kg (and I guess 2-3 kgs are probably muscle).

[@heinifalk809]

Fenix 6X Sapphire. I put in a lot of effort and was cycling nearly daily and my Vo2Max came down from 42 to 38 that is extremely poor for someone that is capable of riding a 100km ride in a single sitting week on week. Vo2Max means nothing. Its just a number

[@NJSportScience]

Heini Falk I agree these wouldn’t be your actual numbers. Unless you directly measure gas exchange you’ll never get accurate numbers. I disagree with the broad statement of VO2max meaning nothing, based on your watch maybe not great, but VO2max itself essentially dictates your aerobic engine.

[@ericmuthersbaugh3364]

Linear line

[@robinbauer1975]

My Garmin shows me 73 😁

[@NJSportScience]

Elite number!

[@Runner8617]

False! There is actually a mathematical formula to calculate your VO2max manually! I'm surprised people don't know it! When I took a fitness class in college, I was blessed with a professor that taught us how to calculate it. That was back when nobody cares or knew about the vo2max, and I remember thinking in my head..."why is she making us do math and plug in all these numbers into this random formula?" Now I know why!! And boy am I grateful!!!😀

[@NJSportScience]

This video is all about how you can go from measuring data during a session to get an estimated VO2max without measuring oxygen consumption directly. The theoretical/mathematical equation is VO2 = Cardiac Output x Arteriovenous oxygen difference, neither of which you can measure using a watch device.

[@davitavagyan1851]

hey, do you own the fenix 6x pro? have you tested the heart rate to see how accurate it is?

[@willchongwei]

I have the 6s pro. I've compared it to my Garmin instinct, my Fenix 5x also. Very accurate and seems to give me the same reading as a heart rate strap give or take 1-2 bpm while moving

[@ChrisHaasMD757]

There's a difference between oxygen delivery and oxygen consumption.

[@NJSportScience]

Chris Haas care to explain your thoughts on this?

[@ChrisHaasMD757]

According to the Fick equation, a more efficient person who is a better oxygen extractor (resulting in a lower arteriovenous oxygen difference), can utilize more oxygen even though his or her cardiac output is lower.

[@NJSportScience]

Chris Haas in theory yes. Consumption doesn’t occur exclusive of delivery though. Theoretically delivery could remain constant and consumption goes up sure but you need delivery in any form to allow consumption so the interrelated nature of these parts is the key factor. Which part of the video does your point stem from?