Calculate your VO2 Max
01-31-24, 11:42 AM
#26
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Well, *mostly* all you need to really know is that cardiac stroke volume for the kinds of guys that would read Friel's "Fast after 50" book is ballpark about 70 mL of blood per beat, assuming average ejection fraction. Then, cardiac output is just stroke volume * beats/minute, so if you know your max heart rate you can approximate your max cardiac output. (Resting heart rate helps a tiny bit because lower resting heart rates are associated with slightly higher stroke volume, but this is a relatively small effect). If you don't have some disease that affects the oxygen-carrying capacity of your blood (and once again, guys who're reading "Fast after 50" probably don't) then the amount of O2 being carried by the blood and the amount that it can deliver to muscles for usable work is also ballpark known. So, for each 100 mL of blood at max cardiac output, you can carry around 5 mL of O2. So you can kinda get from max HR to max O2 your heart can deliver to your muscles. So you can sorta kinda get to VO2Max in terms of Liters/minute. I think most of the guys reading "Fast after 50" aren't going to be 50kg or 150kg, so maybe 70 or 75kg puts his readers in the right ballpark.
So there's some (that is, a lot) of hand-waving going on but I can sorta trace back where Friel's rule of thumb comes from, and, importantly, the error bounds on his rule of thumb. (I teach a lot of rules of thumb to my students, but I go through the derivations so they can see what and where I'm making assumptions and which ones are more critical and which are less so. Friel drives me nuts cuz he doesn't do this, and it offends my sense of pedagogical fidelity).
You can do better by measuring power, but many of the readers of Friel's book (at the time of publication) probably didn't have a power meter. [Edited to add:] At average levels of cycling economy, it takes in the ballpark of 1 L of O2 per minute to produce 75 watts for a minute, so it takes around 3 L of O2 to produce 225 watts (or 4 L to produce 300 watts). So the (slightly better) way to calc your VO2Max from power data is to figure out your max sustainable aerobic power, convert that to an approximate volume of O2, and estimate your VO2Max that way. You don't really need to know HR that way at all. That said, VO2Max isn't a particularly actionable piece of information.]
So there's some (that is, a lot) of hand-waving going on but I can sorta trace back where Friel's rule of thumb comes from, and, importantly, the error bounds on his rule of thumb. (I teach a lot of rules of thumb to my students, but I go through the derivations so they can see what and where I'm making assumptions and which ones are more critical and which are less so. Friel drives me nuts cuz he doesn't do this, and it offends my sense of pedagogical fidelity).
You can do better by measuring power, but many of the readers of Friel's book (at the time of publication) probably didn't have a power meter. [Edited to add:] At average levels of cycling economy, it takes in the ballpark of 1 L of O2 per minute to produce 75 watts for a minute, so it takes around 3 L of O2 to produce 225 watts (or 4 L to produce 300 watts). So the (slightly better) way to calc your VO2Max from power data is to figure out your max sustainable aerobic power, convert that to an approximate volume of O2, and estimate your VO2Max that way. You don't really need to know HR that way at all. That said, VO2Max isn't a particularly actionable piece of information.]
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01-31-24, 12:38 PM
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600w for 6.25 seconds? Okay. Probably 10 seconds with some practice. 15 if I was being chased by screaming demons from the underworld.
600w for me is about 10 W/kg. Coggan chart says 10 W/kg for 1 minute is domestic pro level.
600w for 6:25 MINUTES?? That's a hard no -- in this or any other universe.
600w for me is about 10 W/kg. Coggan chart says 10 W/kg for 1 minute is domestic pro level.
600w for 6:25 MINUTES?? That's a hard no -- in this or any other universe.
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01-31-24, 05:22 PM
#28
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600w for 6.25 seconds? Okay. Probably 10 seconds with some practice. 15 if I was being chased by screaming demons from the underworld.
600w for me is about 10 W/kg. Coggan chart says 10 W/kg for 1 minute is domestic pro level.
600w for 6:25 MINUTES?? That's a hard no -- in this or any other universe.
600w for me is about 10 W/kg. Coggan chart says 10 W/kg for 1 minute is domestic pro level.
600w for 6:25 MINUTES?? That's a hard no -- in this or any other universe.
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01-31-24, 07:39 PM
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I sometimes gave my students what are called "ill-conditioned" exam questions. These are questions for which there isn't actually sufficient information to get a closed solution. I'd give them some info, then say the rest of the data was lost in a horrendous dinner accident, and asked them to make their best argument about the missing bits, defend their choices, and come up with a reasonable estimate of some quantity. Basically, it was a chance to turn a regular math or computational problem into an essay question. The undergrads hated that kind of question; the grad students maybe dislike it too, but eventually they think it mimics real life. Anyway, I think with all the hand-wavy stuff that goes into these rules of thumb, an average mass of maybe 70-75 kg gets you close.
01-31-24, 07:45 PM
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The difference is that these guys were (and are) big and they use all their muscles. One of the Boys pulled so hard he broke a rib. The rowers have the advantage of sitting as they almost pass out while someone else steers the boat. I knew a guy who rowed Varsity for Cornell. He was 6'4" and heavily muscled, not much body fat, big chest. That's short. Now I think they average 6'6". They are not like us.
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01-31-24, 08:07 PM
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I sometimes gave my students what are called "ill-conditioned" exam questions. These are questions for which there isn't actually sufficient information to get a closed solution. I'd give them some info, then say the rest of the data was lost in a horrendous dinner accident, and asked them to make their best argument about the missing bits, defend their choices, and come up with a reasonable estimate of some quantity. Basically, it was a chance to turn a regular math or computational problem into an essay question. The undergrads hated that kind of question; the grad students maybe dislike it too, but eventually they think it mimics real life. Anyway, I think with all the hand-wavy stuff that goes into these rules of thumb, an average mass of maybe 70-75 kg gets you close.
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01-31-24, 08:10 PM
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nope, no chance. my resting rate is <40, max rate is limited by common sense due to my heart condition, and the formula yields basically nonsensical results. i'm sure it's intended for those without any rhythm issues or volume issues associated with cardiomyopathies.
02-01-24, 07:51 AM
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Thank goD _ thought I might have to re-live my 20's again.
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02-02-24, 08:20 AM
#34
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Out of curiosity I have a naive question... Does anyone have any idea of how Garmin calculates VO2 Max and what values they use?
I assume they use the latest resting HR or some average of that over some period. I assume they use some value of MHR, but do they use what you actually hit in a recent workout? What you enter as your MHR or barring that what they are using as your MHR in setting zones ( the former doesn't seem like a good way to go and the latter would seem particularly useless)?
They have a lot more info available than just HR numbers, durations, trends, rates of change. Not sure if any of that would be useful for this.
They could maybe use power data, but I know they don't in my case (no power meter).
I assume they use the latest resting HR or some average of that over some period. I assume they use some value of MHR, but do they use what you actually hit in a recent workout? What you enter as your MHR or barring that what they are using as your MHR in setting zones ( the former doesn't seem like a good way to go and the latter would seem particularly useless)?
They have a lot more info available than just HR numbers, durations, trends, rates of change. Not sure if any of that would be useful for this.
They could maybe use power data, but I know they don't in my case (no power meter).
02-02-24, 08:51 AM
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For cycling, I don't know if Garmin Connect uses resting heart rate in their VO2 max calculations, but it does use your heart rate data for a given VO2 max power effort of ~5+ minutes long. You do need to have your proper max heart rate plugged into the profile data, and the if using a Garmin watch, it will collect your resting heart rate over time. I hate wearing a watch overnight, so rarely leave it on, and get my overnight resting rate.
I watch this kind of data not because I'm aiming to win races any more (used to competitively run in my 20s and 30s), but to monitor for signs of progression in my cardiomyopathy. I have LBBB-induced cardiomyopathy, triggered about a dozen years ago when a severe viral infection resulted in myocarditis, followed by LBBB. At that time, in my early 40's, I could eat like a pig, drink more than I should, and still randomly bang out hilly 10km runs in the high 30mins with no training. When LBBB arrived, I would die a 1000 deaths running up even a minor hill due to the impact on stroke volume and cardio efficiency. 5 years after that, I started getting significant left ventricle dilatation, and that scared me straight into a clean diet and no drinking, and regular workouts. Because LBBB causes a dysynchrony between the left and right ventricles, it can cause the heart to fail over time. Miraculously, the dilatation regressed, although the LBBB remains (can never be cured/fixed) and my top end aerobic capacity is decreased by perhaps 15-20% or so vs what it should be. Annual MRIs and VO2 max tests have become semi-annual, so in-between tests, I keep an eye on my power numbers, heart rate, heart rhythm etc to watch for early signs of trouble. Luckily, my cardiologist is a very keen (and strong!) cyclist, and has worked with with a lot of athletes, including doing studies on world tour riders.
I watch this kind of data not because I'm aiming to win races any more (used to competitively run in my 20s and 30s), but to monitor for signs of progression in my cardiomyopathy. I have LBBB-induced cardiomyopathy, triggered about a dozen years ago when a severe viral infection resulted in myocarditis, followed by LBBB. At that time, in my early 40's, I could eat like a pig, drink more than I should, and still randomly bang out hilly 10km runs in the high 30mins with no training. When LBBB arrived, I would die a 1000 deaths running up even a minor hill due to the impact on stroke volume and cardio efficiency. 5 years after that, I started getting significant left ventricle dilatation, and that scared me straight into a clean diet and no drinking, and regular workouts. Because LBBB causes a dysynchrony between the left and right ventricles, it can cause the heart to fail over time. Miraculously, the dilatation regressed, although the LBBB remains (can never be cured/fixed) and my top end aerobic capacity is decreased by perhaps 15-20% or so vs what it should be. Annual MRIs and VO2 max tests have become semi-annual, so in-between tests, I keep an eye on my power numbers, heart rate, heart rhythm etc to watch for early signs of trouble. Luckily, my cardiologist is a very keen (and strong!) cyclist, and has worked with with a lot of athletes, including doing studies on world tour riders.
02-02-24, 10:24 AM
#36
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For cycling, I don't know if Garmin Connect uses resting heart rate in their VO2 max calculations, but it does use your heart rate data for a given VO2 max power effort of ~5+ minutes long. You do need to have your proper max heart rate plugged into the profile data, and the if using a Garmin watch, it will collect your resting heart rate over time. I hate wearing a watch overnight, so rarely leave it on, and get my overnight resting rate.
02-02-24, 10:44 AM
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Garmin connect will definitely calculate something from sub-max efforts, but in my experience, the numbers compare better to a proper lab test when I do a 5-6 min all out sustainable power effort. Better to do that when warmed up too (20-40 min), not straight out of the blocks.
Don't quote me as an expert on the inner working of the Garmin algorithms though, just my opinions/thoughts.
Don't quote me as an expert on the inner working of the Garmin algorithms though, just my opinions/thoughts.
02-02-24, 12:10 PM
#38
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Garmin connect will definitely calculate something from sub-max efforts, but in my experience, the numbers compare better to a proper lab test when I do a 5-6 min all out sustainable power effort. Better to do that when warmed up too (20-40 min), not straight out of the blocks.
Don't quote me as an expert on the inner working of the Garmin algorithms though, just my opinions/thoughts.
Don't quote me as an expert on the inner working of the Garmin algorithms though, just my opinions/thoughts.
I figure a good warm up is always important for hard efforts.
Maybe I try to experiment a little and see.
02-02-24, 12:17 PM
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Put simply, the algorithm compares power to heart rate as a percentage of maximum.
According to the Garmin documentation, in order to record a VO2max estimate, the Garmin software requires the user to maintain a heart rate of at least 70% of maximum for at least 20 minutes.
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02-02-24, 09:47 PM
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[Edited to add:] A couple of days ago, my Garmin wanted me to know that it considered my ride "unproductive." I was outside, the sun was shining, and I ran across a guy who I hadn't seen in maybe a year. I thought the ride was pretty damn productive. I pay about as much attention to Garmin's assessment of my ride as I do its estimation of my VO2Max.
Last edited by RChung; 02-03-24 at 12:13 AM.
02-03-24, 12:19 AM
#41
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Different table from Frei for FIt Cyclists by Age. This puts me in my appropriate age category 60-69 being at 52. So much for being a teenager… His recommendation for stopping the age related slide - injecting high intensity into the workout schedule along with recovery and Zone 2..
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02-03-24, 05:22 AM
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I have never seen that. I went back and looked for something like that. The closest I could find was a day when I went for a really easy spin, all in the "Easy zone". I considered it a rest day. I did see "No Benefit" under the "Anaerobic" and "Aerobic" categories which was probably true.
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02-03-24, 08:39 AM
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Different table from Frei for FIt Cyclists by Age. This puts me in my appropriate age category 60-69 being at 52. So much for being a teenager… His recommendation for stopping the age related slide - injecting high intensity into the workout schedule along with recovery and Zone 2..
02-03-24, 08:53 AM
#45
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I noticed the Concept 2 indoor rowing Vo2 Max calculator. It asks for only:
- Body Weight
- Best 2000m Time
- Gender
- Training level - you have to pick either "highly trained" or "not highly trained" with one being elite and the other not experienced, It would seem the majoity would fall in between. They are supposed to "chose the group that you feel most closely resembles your own level of training."
02-03-24, 10:53 AM
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I have never seen that. I went back and looked for something like that. The closest I could find was a day when I went for a really easy spin, all in the "Easy zone". I considered it a rest day. I did see "No Benefit" under the "Anaerobic" and "Aerobic" categories which was probably true.
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02-03-24, 11:12 AM
#47
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One explanation, which could be true is that the left ventricle gets larger up to a certain age before calcification, mitochondrial diminishment and sarcopenia take over.
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02-03-24, 11:51 AM
#48
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My tale of VO2max.
Track 500 meter time trial from a standing start. 53.3
Road sprints sub maximal effort and track 2k pursuit. 49.6
My Garmin thinks my VO2 max is 46.
Track 500 meter time trial from a standing start. 53.3
Road sprints sub maximal effort and track 2k pursuit. 49.6
My Garmin thinks my VO2 max is 46.
Last edited by Hermes; 02-03-24 at 01:03 PM.
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02-03-24, 01:23 PM
#49
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As I've said, I don't really track VO2Max because I don't think it's particularly actionable information, so I've never looked up how Garmin does it. However, given your information, this afternoon I got on the trainer, raised my HR to 70% of max and did some intervals (which I also hate), keeping my HR above 70% for 20 minutes. Then I looked at Garmin's estimate of my VO2Max: it looks like I raised it a point from yesterday. I'm pretty sure I'm no fitter today than yesterday.
I don't pay much attention to Garmin's VO2max estimate, either. But it is encouraging to watch it gradually rise over time, as I ramp up the training. Sort of a computerized "kudos".
My fitness measure is power to heart rate ratio on segments I do often. If that number's rising over time, it means better fitness.
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02-03-24, 02:54 PM
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1. It says my VO2Max is in the top 5% of my age group, so it already fails the face validity standard. Either that, or my age group is in terrible shape.
2. We generally eschew measurements that can be "gamed" because they're not robust to changes in test conditions.