VO2max Discrepancy (Garmin vs Firstbeat)

Here is a link to the hill repeat workout I just did...

https://connect.garmin.com/modern/activity/13490978215

I have tested many devices (Garmin, Suunto, Polar, Fitbit, and Apple Watch) against a chest strap. Garmin and the Apple Watch are always pretty much spot on with the chest strap, and don't stray more than 1 or 2 BPM once in a while. I hate wearing chest straps, and the main reason I buy devices with optical HRM's is so I don't have to wear a chest strap.

As far as MHR goes, I have mine set to the 220 - age formula (154 for my age (66)), but I know mine is higher than that. Back in my late 50's to early 60's when I was running a lot more, I got my HR up to 170 a couple times. I had an ultra runner on a forum tell me one time, that I should do a 5k as if it was a race, and at the end give it everything I had until I was ready to pass out. Then, take that HR and add 5 to it to get my MHR. He said no one could reach there true MHR.

I think I'm going to turn my auto MHR back on, because it did set itself to 164 after a run/walk interval, before I turned it off. In fact I think I'll set my MHR back to 164, and set the auto detect back on right now.

I started having hip and back pain in my early 60's, and got x-rays done. They said my hips are fine, but I have multi level arthritis in my lower spine that is causing the pain. They said I can still do my workouts, but it would just be painful. I can only take Tylenol, because I'm on blood thinners, and that only takes a little bit of the edge off. I have also started doing strength training, and it seems to be helping as well, and I think losing this 30 lbs. will be a big help in reducing the pain too.

Thank you for your input. It has been helpful and motivating.

Edit: just set my MHR to 165, and my LTHR to 140 (85% of MHR), and turned on auto detect for everything.

I hate wearing chest straps, and the main reason I buy devices with optical HRM's is so I don't have to wear a chest strap.

If you care dearly about your watch metrics, you should wear a chest strap during activities. While wrist HR sensors work well enough for wellness and training purposes, they are simply more prone to spurious data than chest straps in particular for running (cadence lock risks), biking, strength training and any activity where the wrist is moving with uneven patterns (hard to filter the movement inducing frequencies). This in turn will create more challenges for the watch at the data validation level for all the algorithms (including VO2 Max and HR Max detection). Don't get me wrong, the filtering and qualifying algorithms are doing a great job, but they are not perfect.

In fact I think I'll set my MHR back to 164, and set the auto detect back on right now.

Yeah, I turned it off myself for a long time because it was not working. Based on the feedback on this forum from several users, I turned it back off. Clearly it is working much better for me now and I would recommend using it (but with a chest strap!). The 5k race approach is the one I was using before turning it back on and it was very accurate for me also (wearing a chest strap!)+

I predict that your VO2 Max will increase in the next couple of weeks just because your increased your HR Max, but this will just be a technical correction of course. 

Etupes25 said:

If you care dearly about your watch metrics, you should wear a chest strap during activities. While wrist HR sensors work well enough for wellness and training purposes, they are simply more prone to spurious data than chest straps in particular for running (cadence lock risks), biking, strength training and any activity where the wrist is moving with uneven patterns (hard to filter the movement inducing frequencies). This in turn will create more challenges for the watch at the data validation level for all the algorithms (including VO2 Max and HR Max detection). Don't get me wrong, the filtering and qualifying algorithms are doing a great job, but they are not perfect.

All the testing that i have done comparing OHR sensors with chest straps were during walk & run workouts. I have experience cadence lock a couple times with older sensors, and I have done probably 100 tests over the years wearing 1 device with a chest strap on one wrist, and another device on the other wrist using the OHR sensor. With Garmin's and the Apple watch it stays pretty much spot on, with the occasional 1 to 2 BPM drift.

I have a few different chest straps, and they may be slightly more precise for steady state stuff, but not enough for me to wear one. But that's just my personal preference. And, they are not perfect either. I have had weird things happen with them back when I used to wear them (which was for every workout).

I do agree with exercises that have a lot of wrist flexion though. But I'm not really concerned enough with those types of exercises to worry about HR data.

I agree with you. It's largely the same as what I mentioned above.

In a lab test, the amount of oxygen inhaled and exhaled during an all-out exercise test is measured, and the difference is the total oxygen consumption VO2max in L/min for the whole body. This VO2max is normalized to the body mass and thus related to the unit ml/min/kg.

As laboratory tests are expensive and time-consuming, the aim is to avoid them and replace them with a sophisticated mathematical model. In order to develop such a model, many studies were carried out on the relationship between VO2max and HR/speed. The resulting model is described very well in the Firstbeat study:

www.firstbeat.com/.../white_paper_VO2max_30.6.2017.pdf

According to Figure 2 (right diagram), heart rate and speed are extrapolated to estimate VO2max. The advantage is that this also allows submax tests to estimate VO2max.

Dr Phil said:

A little bit of thought, and a little more understanding of simple maths, and it's clear that since the units are volume (ml), time (min), and body mass (kg) these factors must be in the calculation somewhere either directly or indirectly.

According to the paper body mass is not explicitly required as it is included indirectly via the performance increase/decrease.

You can test whether weight is used to estimate VO2max by temporarily increasing/reducing the weight in the settings by, say, 10%-20% and see if this affects the VO2max value. I haven't checked this yet, but according to the Firstbeat paper, it seems unlikely that VO2max would change as a result.

If I lost weight, my body would not have to work as hard to move less weight at the same pace, and my HR would be lower at that pace.

If I weighed 30 lbs. less right now, and did a run, my VO2max would probably measure in the high 30's instead of 30, because I would be able to move my body at a faster pace with less effort.

This is exactly what I said in my post above. The weight isn't included in the estimation of VO2max, but the side effects of the weight loss (reduced HR, increased pace) are important for estimating VO2max and the fitness age.

And in addition it's always a good idea for an athlete to stick in the optimal range of weight, at least to not overload the joints with running activities. This is the reason of the warning "Reduce BMI" in the state report from Garmin.

subra said:

And in addition it's always a good idea for an athlete to stick in the optimal range of weight, at least to not overload the joints with running activities. This is the reason of the warning "Reduce BMI" in the state report from Garmin.

Again, we have Garmin, and others, taking a population measure Body Mass Index(BMI) and applying it to individuals in a way it was never intended.

Some people carry much more muscle mass than others thus have a higher BMI (think here strength and power athletes such as rugby players for example) that cannot be reduced. It's too crude to simply suggest that a person reduce their BMI when in reality there might be little room to do so. Before considering whether or not it is possible to reduce BMI, an individual with a high BMI needs to look at their body composition. Is the weight due to fat or muscle? If fat then that's what needs to be reduced and can have a positive impact on fitness and health in general, and of course allow Garmin to present a lower Fitness Age. If it's lean muscle mass that is high then there can be little to no change that can be made to BMI and thus fitness age is unlikely to be able to be influenced through BMI.

I have always had a BMI that is borderline obese (around 28-29 kg/m) but my body fat percentage is usually around 10 to 12%. Because of that I cannot reduce the fitness age that Garmin gives me any further, especially since I exercise most days and have a relative VO2max of 48 ml/kg/min at age 67 (46 ml/min/kg from the last lab test about three years ago). 

Sorry that I misunderstood some of the posts due to my not understanding all the scientific formulas.

Here is a formula for me that I think everyone will agree with...

VO2 max = 15.3 x (MHR/RHR)

15.3 x (165 / 58) - OldDude's big fat 30 lb. belly = 30 ml/kg/min

Here is a formula for me that I think everyone will agree with.

Not me, way too high for my VO2 Max

Dr Phil said:

But there is no overall impact on that individual's fitness test result and their fitness overall. It’s just a change in the relative VO2max. It’s only a number  

And that's exactly what I mentioned in my post above. Just dividing absolute VO2max by lower body mass doesn't really increase fitness. It's just a numerical effect, and that's why I thought you were joking.