In the early spring of 2023, I began investigating building my own VO2 mask as an amateur athlete and professional tech enthusiast. I stumbled upon directions to build one, which you can view here.
According to the original designer, “The output includes continuous output of VO2, calories consumed, volumes of expired gas, as well as performing such functions as Basal Metabolic Rate.”
The device looked like it would work, so I ordered the parts, printed them in the GK 3D printer and put it all together. I was dissatisfied with the results.
The ventilation tube threads were weak, and there was no VCO2 option or pressure option (for correcting for altitude.) It was a little bulky for some of the exercises an athlete would do in the normal course of working out (pull ups, almost anything with a bar in the anterior plane), and from my experience was more an exercise in what could be than a great working mask.
However, it was a superb start. It allowed for calibration against local air, and the battery life was good for at least 3 hours with readings every 5 seconds, about 2,160 readings.
The original designer had gotten it to work well enough to output accurate data as measured against a lab unit, so I knew it was possible.
“We tested the device in a physiology lab against a $60,000 machine and found it gave the about the same results.”
Rabbitcreek, Instructables
They had also integrated it with Zwift, a popular biking app, and to an iOS app called Sensirion.
The thing was (is) cool, but I thought there’s plenty of room for creative improvement.
Before we go deeper, I’ll give a little background for readers new to the GK blog. I’m active in the outdoors and tech-savvy enough to follow instructions, add some problem solving, and either deploy or improve geeky projects. Along with a group of like-minded geeks, I’ve worked in the Arduino and Platformio worlds to build projects tracking WiFi and Bluetooth users and developed a soil moisture sensor housing
We’ve also developed a radio bridge that moved data from rtl_433 to a public LoRaWAN.
On the physical side, I’ve run long distances, lifted heavy weights, flown paragliders, and participated in a bunch of sports, mostly endurance related. I’ve paddled the Catalina Classic (32 mile open ocean paddle), was an athlete in the very first CrossFit Games, run Leadville, and a million years ago represented the USA in international competition as a Naval Pentathlon athlete (came in 5th on both of the swims.) I’ve used commercial products like Oura rings, wearable force plates, stride analyzers, and heart rate monitors.
I’ve also been a soldier, with all the usual experiences there; long marches, heavy backpacks, jumping out of planes, diving underwater, lots of guns and explosives. Basically, most of the things in the brochure.
All of that is to say I thought of myself as an excellent user for a VO2 mask; someone who could build it, use it, and improve it. I looked around at the options, and they all face two big problems:
First, they’re super expensive. The VO2 Master is probably the closest thing out there to what I’d want. It’s a very cool piece of kit but at $6k a unit it ain’t going mainstream, and as of this writing it didn’t have the ability to measure VCO2, which is incredibly important if you want to get the maximum value out of the uncomfort of putting a mask on your face while you work out.
We’ll take a very short diversion here into what VO2 and VCO2 are, and why they matter.
First, the obvious thing: VO2. It’s stands for Volume of Oxygen, and a measure of the oxygen in your exhaled breath. If you can do that accurately enough, and you know how much oxygen is in the air around you (from calibrating before you put the mask on) then you know how much oxygen you’re using.
Very simply, the more oxygen you can consume, the more metabolically fit you are.
VO2 measurements for the most part are only used for elite and pretty good athletes to show off at parties, mostly because it’s so damn difficult to get readings frequently enough to inform your training. You go to a lab, strap on a mask attached to a hose attached to a “met cart” (metabolic cart), and then a technician makes you work harder and harder on a bike, treadmill, or if you’re fancy, a rower until you decide you’ve had enough.
The tech goes through your readings with you, explains what they mean, and typically suggests what you might do to improve. It’s very cool, but it’s a cumbersome metric to obtain.
I’m NOT saying it’s not a legitimate marker, I’m just saying that because it’s so difficult to get readings, it’s not really that practical to care about your VO2.
In a perfect world, you’d want to see VO2 (and VCO2, more on that in a minute) as easily as you see your heart rate. That way you can tell if the workouts (“interventions” in lab-speak) are working.
Ok, so what about VCO2? That’s the Volume of Carbon Dioxide you exhale. If you know how much carbon dioxide you produce AND how much oxygen you consume, you can math a little and figure out how many calories you’re burning, and if those calories are coming from burning fat or carbs.
Without going into why someone might want to know that, I’ll just drop this: A device that can show you VO2 and VCO2 accurately, in real time, in the field (meaning you can wear the thing anywhere, not just be hooked up with a plastic octopus on your face in a lab) doesn’t currently exist on the market.
DIY versions like the one I built do exist, but they ain’t ready for prime time. That brings us back to where we are now: Building a VO2/VCO2 mask ready for the market.
That’s what I’m working on now, and it is very likely that’s why you’re reading this; you’re trying to figure out what the heck Gristle King Inc is and why I asked you for help with building a mask. Now you know.
![](https://gristleking.com/wp-content/uploads/2024/02/VO2-Mask-testing-scaled.jpg)
My goal is to build a mask that
- retails for less than $600
- accurately reads VO2 and VCO2 in real time
- transmits short and long distances
- has a display mechanism for that data (app, watch, tablet, etc)
- is comfortable enough to wear that an athlete serious about monitoring it can tolerate it for hours
- easy enough to use that you don’t need much more than the technical ability to put together an Ikea cabinet.
That’s the deal. If you can help, I’d love to hear from you.
Leave a Reply