This is really great. For those who aren't familiar with what these machines can do, the calculation of an athlete's Vo2 max really isn't all that useful. However, a breakdown of the fat and carbohydrate calories burned at various efforts can be incredibly useful for helping an athlete learn how to fuel correctly for performance over distance.
I'm not a physiologist or physician (and I'm sure what I'm about to say may be max cringe to the bonafide experts that are around), but my basic understanding is that when expending effort, you burn calories from fat stores and from glycogen stores. Glycogen stores store around 2000 calories, and expending one's glycogen stores results in hitting "the wall" - your body simply doesn't have any fuel to proceed. Your fat stores, on the other hand, provide access to tens of thousands of calories.
People are generally fat-inefficient - any effort immediately biases towards consumption of glycogen. And when you're out, that's it. Your day is done. So knowing the rate you're burning carbohydrate calories can inform an athlete how often and how much to fuel.
Some people are born "fat-efficient", meaning they can access their fat stores easier. Fat efficiency can also be improved through low-intensity endurance training with improved diet. So athletes will periodically do a VO2 test to stay in-tune with how their body is using the fuel sources available to it.
Many years ago I did an Ironman (Couer d'Alene) and a Vo2 test indicated I needed to aggressively consume calories (at the effort I was planning to ride) on the bike. After all, you have to get off the bike nutritionally prepared and hydrated to run a marathon. So that's what I did, and I had a good day considering I really wasn't all that fit.
Endurance and ultradistance events aren't really tests of toughness. They are science experiments. It's all about figuring out how to take one's fitness and stretch it over the distance of the event.
One additional note - there are machines much less expensive than 60k available, but they are still pretty expensive (in the thousands).
I appreciate the modesty, but talking about completing an Ironman and having the phrase “really wasn't all that fit” anywhere near it is comical.
Getting through any one of the stages of an Ironman (or heck even a half of each stage) represents a level of fitness most adults do not have and will never attain.
Not necessarily true, I think. It’s a mental barrier more, than a physical one. Tell someone you ran 100 m in 12 seconds and they go “meh”. Tell them you did a marathon and they go “i could not do that, awesome, how could you etc.” whereas an average person can do a marathon with a years worth of training and never achieve that sprint time.
It took for me 21 months of training to go from effectively zero to a half ironman and the biggest barrier was swimming, which is very technical in nature. I still can’t swim very well. I was in no shape at all and overweight. If you look at the speeds required to stay within ironman time limits, they are quite low and a person in a slightly better than average condition would be able to sustain them with relative ease. The barriers might be swimming technique (which one might have from training as a kid) and things like biking position and running technique but not necessarily fitness as such. In fact, I see quite a few people visually in much worse shape than I am (i.e. fatter) doing long IMs and beating me at shorter distances.
Sure, but my point was really to suggest I’m just a regular guy who did an Ironman very slowly. There are physiological freaks at Ironman events, but I was certainly not one of them. Regular people with a plan and appropriate training can do it.
The idea that fat efficiency can be improved via diet or training is often said, but the people I have known who both tried it and carefully measured it couldn’t.
Also there are perfectly ordinary ways to figure out you need to eat more, Ive coached some pro cyclists and done a decent amount of my own triathlon and cycling adventures and if someone gave me a free vo2 machine I don’t think I would ever use it.
This is probably not exactly what you mean by diet, but Rob Gray (an Ultraman world champion) says:
in the 10 days before the race I would predominantly eat a high fat diet. Based on all the testing I’ve done, what you eat in this window has a large impact on how your body uses fat vs carb on race day
Carbo loading can be done prior to a race. The day before is usual. But even carbs in the morning before a race is effective.
The fat burning starts when you empty the glycogen chambers, but there is a sweet spot in terms of energy output, because as other people has pointed out, you can't do high intensity work on fat.
So it makes sense as an ultra endurance athlete that you try to pack som fat before a race, because it will be effective as a slow burning resource.
Another interesting thing at the moment are the ketones supplements one can drink.
A friend of mine does keto and after running a marathon reported that they did not experience "the wall". Presumably this is because they were using fat to begin with, not after mile 15 or whatever.
For those interested, Jeff Volek's team published a study in 2016, "Metabolic characteristics of keto-adapted ultra-endurance runners" [1] that compared fax oxidation. One of the "fat adapted" participants Zach Kibbter, an ultra-marathon record holder, posted a personal writeup that included a table of his fat usage at various VO2 Maxes (a ridiculous 98% fat usage at 75% VO2max and 76% even at 84% of VO2max!)[2]
I don't know the numbers for the general population, but Fig2 [1] illustrates the difference between the high-carb and low-carb arms between the elite athletes, and Fig3 [2] shows the difference in absolute fax oxidation rates between the groups. If you're interested in finding out more, I'd also recommend doing a literature search for "maximal fat oxidation" (MFO, FATmax) - eg, here's a recent (2018) review w/ Fig1 that shows MFO peaking at 0.72g/min [3] (the FASTER trial cohorts avgd 0.67g/min for the HC arm, and 1.54g/min for the LC arm)
If you're interested in some of the other physiological impacts of keto adaptation, here's a presentation Volek gave a couple years ago that helps contextualize both the FASTER trial and a related TANK trial his team ran, as well as some other interesting related performance research: https://www.youtube.com/watch?v=BeS_dhM8dsY
It all has to do with intensity. We obviously can't tell from the information provided, but if they ran at a slow pace, that would also skew the fueling towards fat.
Exactly. While the marathon is an endurance event, the intensity when racing is often higher than 65% VO2 max - the "fat max" or point at which fat oxidation peaks. For example, for a 3 hour marathoner (or faster), the intensity would be around 74-84% VO2 max or 80-90% max heart rate. It has also been observed that going on keto reduces your running economy (so you end up running slower for the same effort).
As for "hitting the wall", this often happens around 20 miles as this is where your stored glycogen is depleted. To avoid this happening, you'd be better off to "train the gut" to handle consuming ~60g carbs per hour while running at your target pace/intensity.
Generally competitive endurance athletes try to shift their metabolism to match the length of their target event. For the longest ultra endurance events you have to be pretty well fat adapted because if you relied mostly on glycogen you wouldn't be able to take in enough carbohydrates during the event to avoid hitting the wall. But for shorter, high intensity events you're going to be burning mostly glycogen and barely touching your fat stores. It's a spectrum.
Will this device actually tell you fat versus glycogen metabolism the way a real exercise lab test would? From the description it doesn't seem so. I think all it really tells you is the amount of oxygen used.
Unless you're dealing with mail, in which case you're more likely to succeed with "Coeur D Alene". Our city name apparently isn't sufficiently American in some contexts.
I would say vo2 max is fairly useful but maybe not in a tactical way which you are describing. Its a longer term trend identifier for efficiency of your respiration process.
Well sort of. But you can train VO2 Max in ways that don't result in higher performance. What most athletes really care about isn't VO2 Max per se, but rather ability to sustain a high percentage of VO2 Max for a longer period.
It’s been a while since I’ve read much about this but one explanation I’ve heard is that Vo2 was elevated to importance because it could be accurately measured and therefore studied.
Also unlike aerobic fitness, which can be improved with year after year of consistent training, an athletes peak Vo2 max (for their given fitness) can be maxed out over 4 - 6 weeks of specific training. Doing much more specific Vo2 training can result the athlete (at least in running) becoming ‘flat’.
That said Vo2 measurement can provide a great deal of useful information but for most recreational athletes getting the basics right is more important than having an exact Vo2 measurement.
It’s not useful because it’s not really an indicator of one’s ability to perform and can’t really be affected through training. It’s primarily affected by genetics and weight.
That said, it does provide some correlation to an athletes performance “ceiling”, and you’ll typically find elite endurance athletes are naturally blessed with an impressive Vo2 max. You’re not going to win the Tour de France with a Vo2 max of 50 no matter how hard you train, just like you’ll never play Center in the NBA if you’re 6’1.
Sometimes I wonder if the way to bypass the insane regulations around medical devices is to just publish them online for anyone to build themselves.
Sure I won't have the minutes detail of million dollar medical equipment, but maybe I don't need all that precision, or maybe that's better than having no access at all to the measurements at all
I think this would really be great. The extra regulations of the FDA are showing to be more and more of a burden as years go on (let's not get into their corruption). Something like a chip and a device sold separately but trivially put together. I myself ran into this problem when trying to buy a blood lactate meter as an American, which can be trivially purchased all across Europe and Asia.
One of the common complaints is the lack of accounting for the harm done by delaying a device/therapy/drug.
If $DISEASE kills 10k people/year, and $DEVICE can save 90% of them but 5% suffer $DEVICE related deaths, delaying the release 10 years trying to get to 0% related deaths doesn’t sound like the best strategy.
You are assuming that the existence of regulations means that there’s testing required.
You’d be surprised at how much is just about filling the proper paperwork, paying some fees and knowing the right people. The amount of independent testing is negligible.
I'm sorry, but this is just patently false. The FDA requires extensive V&V testing, especially for medical devices that have a significant chance to kill the people that it's used on. That, and you need to have a very sophisticated quality management system (QMS) in place that tracks all the changes you make during your design and test process, links up source requirements to passing test reports in an auditable way, tracks all of your manufacturing information (including which batches were tested using what procedures, and the results), all of which can be randomly audited at any time, no matter where the facility is located on the world.
You may be referring to the 510k (pre-existing predicate device) pathway, which has been abused by companies to leapfrog and skip _some_ of the more stringent test requirements, but they still need to prove similarities, and that requires real data. However, in the vast majority of cases, these devices are things like masks, IV tubing sets, etc, not complex life saving equipment, which gets an enormous amount of scrutiny. If anything, it's the medical device companies that are at fault for lobbying Congress to allow abuse of 510k pathways, and Congress for allowing these things to happen.
> I'm sorry, but this is just patently false.
[..]
The FDA requires extensive V&V testing
[..]
and you need to have a very sophisticated quality management system (QMS)
Paperwork, they require paperwork.
It’s the same issues that plague FCC and CE, the amount of tricks and handwaving you can get approval for makes a lot of this (self performed/self directed) testing completely useless.
There’s a whole market of “expert consultants” whose job is gaming the tests and finding loopholes, and as long as tests are conducted in this manner, they will exist.
That's a little reductive. Companies get shut down all the time when their quality management is not up to snuff (for a high profile example of this, look at CMS' shutdown of the Theranos labs in 2015). The system generates the paperwork, and the data enclosed is generated by the processes you have to put in place to get approval in the first place.
Like I said, the world of predicate devices is a different ball game, but you're not going to get by with hand waving on a device that can kill people.
> Companies get shut down all the time when their quality management is not up to snuff.
That’s not a good measure for the performance of the regulation. In fact I’d like to see the numbers on the exact reasons for those shut downs, because I’m willing to bet they’re related to bad classification and other technicalities.
If the FDA were to be a test, you’d want it to have good discrimination at a low cost.
Anyone who has been involved in the process knows the cost is enormous, and scandals like Theranos (and good but extremely late good cases) show that discrimination is not that good to begin with.
I have been involved in the process, my company has a de-novo device (with an issued IDE), and I can agree that it is expensive and time consuming, but what their requirements result in is ultimately a better product, better processes, and dramatically reduced risk.
These regulations are written in blood. They're difficult to comply with because if you invite poor engineering you will get poor engineering and dangerous devices.
I don't think I can accept that, especially with regard to items like hearing aids. There's a fundamental difference between things like implants and surgical tools and relatively simple devices like CPAP machines and hearing aids; things where the harm of a failure scenario is extremely limited.
This is a government at the end of the day. It would be imprudent to not consider the effects of regulatory capture, cronyism, and so forth.
do you have experience in the discipline? It doesn’t sound like you do.
I have some experience, and i can think of about a half dozen ways cpap machines and hearing aids could cause serious harm as a result of design flaws or lack of QA that would be de rigeur if not for regulatory pressure.
So can headphones and earbuds, and society seems to do just fine with the normal level of consumer electronics regulation. Is there really value in the medical device regulations for hearing aids beyond that?
> So can headphones and earbuds, and society seems to do just fine with the normal level of consumer electronics regulation.
Do we?
I was under the impression that there has been an uptick in hearing damage in young people due to them increasing the earbud volume above background noise levels (not so much of a problem in earphones that cover the ears as they block out outside noise).
That's a medical problem that will have significant effects downstream over time and the consumer regulation really isn't working.
What are some of those ways that are not addressed by regular old (non-medical-specific) electronics/safety regulation?
Most of the ways I can think of a CPAP failing would be extremely obvious with equally obvious and relatively low-impact effects (I get a crappy night's sleep or wake up in the middle of the night).
Recent case involving very popular Philips Respironics machines: the foam used for internal insulation was degrading and getting into the stream of air, landing those particles in patients lungs. Huge recall, etc. The kind of problem that testing imposed by regulators can detect.
Incorrect use of CPAP can lead to development of central apnea. (Even APAP machines can be programmed to keep the pressure too high which is long term unhealthy).
With that, I am all for liberalization of the laws. My GP did not prescribe me a CPAP machine despite obvious signs of apnea. "Lose some weight instead" (that despite me having apnea even when I had a BMI of 21).
I never felt as much of a positive difference on my life as when I started using the machine and had my first good night of sleep in decades.
I wish my govt would let me buy an insulin measurement device, but nope, those too are regulated and not available for the general public.
What are the devices you have in mind? It doesn't seem like the intersection between "people with biomedical engineering skills" and "people who need treatment limited by the expense of the equipment" would be that large. I suppose I can imagine a sort of shadow economy of cheap medical treatment on home-built equipment, but surely the providers would be uninsurable and sued into oblivion at the first mistake.
I work on a handheld ultrasound device that attached to a phone or a tablet. It is much easier to use than traditional ultrasound machines, because of the attention paid to the UX off the app, and the familiar smartphone UI.
That being said I will haven't learned how to use it in a meaningful way myself. Getting a good image, and then interpreting the 2d video stream requires training!
Making ultrasound easy enough for non specialists to use will require an AI that guides the user and interprets the images. I'm not convinced skipping FDA approval would be a good idea in this case.
If they didn't finish their school their studies are often regulatorily worthless in the US, if they did there's still massive hurdles to jump without existing relationships/wealth to aid the transition.
Once this is done, printing chemicals might be achievable too (thanks to the network effect of lots of people already having 3d printer to produce the required hardware), but maybe not immediately :)
One refinement would be to split the device in to two parts = the mask/tube/sensors and the electronics and battery. Then, the a large portion of the weight could be moved to the back of the headband or a fanny pack reducing the load/torque/etc. on the face.
Neat! I've been thinking about this lately. If you had accurate CO2 and O2 measurements, you could calculate how many milligrams of fat you are burning during exercise.
> I have found that with the calculations for energy expended from the Oxygen utilization algorithm is slightly higher than that calculated by the work/watt output of the Zwift App algorithm.
I beleive this is because Zwift doesn't count a basal metabolic rate. As far as I understand this is a default behavior for all calorie tables and trackers, one must calculate and add that constant manually. This device can actually measure that value!
>My wife is an Ironman as well (Muskoka, Tremblant and Penticton). . She's been using Zwift since last year. Great way to train btw and great idea but. My concern would be a collapsed lung(s) if this wasn't calibrated correctly. To each their own, but stressing your lungs and diaphragm this much isn't a great idea.
In a lab they can at least make sure you don't hurt yourself.
I see where you're coming from I assume that you are talking about the device resistance when breathing in and you're worried that the adhesion between the lung sac and the cavity wall breaks.
You can pull a pretty good vacuum with just your lungs, so I'm not overly worried about that. And pressure is not a problem unless you have a weak spot in your lung.
But still, it's a good point to make and maybe the author could measure the flow resistance in both directions and optimize for that to ensure that it never becomes a problem, even in people that might have a hidden defect.
But the device resistance won't be very big, would it? If I understand correctly, you are just breathing through a tube, and this device measures the flow through the tube. Or is there something in the tube that would cause a lot of resistance?
How would you get a collapsed lung from using this? And how does its calibration influence whether you get a collapsed lung? This device doesn't interfere with inspiration, and a large breath of air inflates your alveoli.
Questions like this are why people should not be building medical devices at home. Your average athlete interested in this may lack the necessary medical knowledge to understand that a collapsed lung is a possibility when using this device, and cause themselves serious bodily harm.
How could it cause one’s lungs to collapse? Isn’t the idea of measuring VO2 max that a tight seal is formed and all input and output is measured for O2 and CO2? It isn’t pressurizing or depressurizing.
It is pressurizing on output due to the flow through the device, the same thing causes some underpressure when breathing in.
But I doubt it is enough to draw a vacuum strong enough to break adhesion. Still, better safe than sorry, it would be good to read the instruction manual of a professional unit to see what kind of failure modes they have listed there.
I read a lot of stuff back in 2020 because I was going to be coding up controls for an emergency ventilator... you would not believe just how little pressure difference it takes to permanently ruin your lungs... less than 1 PSI if I recall correctly.
You really don't want to over-pressure your lungs with 1 PSI, that's huge for tissue. For a regular party balloon that you blow up the pressure is less than 0.5 psi. But a flow meter in a sports measurement device should be a fraction of that, after all, the back pressure is going to take away effort that should go into providing work.
The title should be changed to reflect the title used in the article. "Accurate VO2 Max for Zwift and Strava"
Especially considering the following:
> Physiology labs that are normally used for testing VO2 max cost upwards of $60,000 and are certainly not portable. They have sensors that measure the same things only on a much finer level.
The person who wrote the article must've had a specific audience in mind, so they chose one title.
The person who posted the article here must've had HN's audience in mind, so they chose a different title.
Titles convey ultra-dense summary of the content, so there can be many titles appropriate for any given article. The purpose of the title is to attract _attention_ of the audience who the title-writer thinks would find it most interesting.
The reason someone writes an article, or posts in a forum, is to spread an idea, or a message, and have other like-minded people, or people who may find the info useful, read it. Exception: content written for commercial/monetary gains has no goal other than grabbing eyeballs, to make more money.
So, yes, it's okay to edit titles, but only if they're egregiously misleading, or inappropriate, or if there's a better title to convey the summary and attract the attention of folks in the said forum.
The OP here chose to use a title with an astounding monetary figure in it. I was baited. I would not have read the article if it had the original title. Strict adherence to the guidelines would have saved me here.
Regarding your post, I am curious if "Google" was removed by yourself(and later changed your mind) or the moderators?
After reading through some of the context[1], I'm in favor of being consistent with de-clickbaiting titles. This title should be changed to "Accurate VO2 Max for Zwift and Strava" as it is a much better summary of the article (the article does mention beating $60k machinery, but does not seem to suggest being a portable replacement for that specific machinery like the title)
[1] https://news.ycombinator.com/item?id=25093563
To summarize the contextual thread, the title of a post was de-clickbaited against the OP's intentions. In my opinion, for the better.
It's like HN has a microphone in my home. I've been looking into adding VO2 max measurement capabilities to our VR fitness game and been looking for DIY solutions and then this :)
This is a cool project. The lack of CO2 sensing is a significant limitation. This wouldn’t replace a CPET because of that limitation. I know that’s not what it claims to replace (though the price tag seems to suggest so). But that could be a modification that would have significant value. It would allow you to triangulate your anaerobic threshold, for example.
I'm not a physiologist or physician (and I'm sure what I'm about to say may be max cringe to the bonafide experts that are around), but my basic understanding is that when expending effort, you burn calories from fat stores and from glycogen stores. Glycogen stores store around 2000 calories, and expending one's glycogen stores results in hitting "the wall" - your body simply doesn't have any fuel to proceed. Your fat stores, on the other hand, provide access to tens of thousands of calories.
People are generally fat-inefficient - any effort immediately biases towards consumption of glycogen. And when you're out, that's it. Your day is done. So knowing the rate you're burning carbohydrate calories can inform an athlete how often and how much to fuel.
Some people are born "fat-efficient", meaning they can access their fat stores easier. Fat efficiency can also be improved through low-intensity endurance training with improved diet. So athletes will periodically do a VO2 test to stay in-tune with how their body is using the fuel sources available to it.
Many years ago I did an Ironman (Couer d'Alene) and a Vo2 test indicated I needed to aggressively consume calories (at the effort I was planning to ride) on the bike. After all, you have to get off the bike nutritionally prepared and hydrated to run a marathon. So that's what I did, and I had a good day considering I really wasn't all that fit.
Endurance and ultradistance events aren't really tests of toughness. They are science experiments. It's all about figuring out how to take one's fitness and stretch it over the distance of the event.
One additional note - there are machines much less expensive than 60k available, but they are still pretty expensive (in the thousands).