Treadmill VO₂ & Session Builder – from skier’s spreadsheet to a browser tool
I’m planning future projects on exhaled air temperature and humidity, and a controllable indoor setup is almost mandatory for that. That is why I bought a Technogym MyRun treadmill.
Before you can do “real” research on a device, you have to live with it a bit. So I started by doing what I’ve done as a former cross-country skier: building treadmill workouts and trying to understand what’s happening physiologically and get a fell for a new device.
That is where this treadmill VO₂ calculator and session builder comes from.
The page is essentially a developed and fine-tuned browser version of a scrappy Excel sheet I first built years ago as an athlete. Now it’s cleaner, easier to use, and available for anyone who wants to plan treadmill sessions with a bit more structure than “5.00 min/km until it feels bad”.
The original Excel: locking a session to a VO₂ target
During my skiing years, most of my treadmill sessions were uphill. Flat treadmill running is nice, but if you want to get into race-specific territory for cross-country skiing to activate the muscles differently, you end up at 4–10% inclines pretty quickly.
Because I had done several laboratory VO₂max tests, I knew roughly my VO₂max and lactate thresholds. When I sat down to design a workout, I often thought in VO₂ rather than only speed:
“Let’s say I want to spend 4 × 6 minutes at around 55 mL/kg/min. If I choose 6% incline, what should the speed be?”
The problem: treadmills show speed and incline, not VO₂. So I built a simple spreadsheet to do the conversion:
Input: speed, incline, body mass
Output: estimated VO₂, METs, distance, energy, etc.
Then I’d reverse it: fix VO₂ and incline, solve for speed.
I’d print the sheet or take a screenshot and put it near the treadmill and do the session. It was crude but surprisingly helpful – and it’s exactly the logic that now lives inside this web calculator.
From spreadsheet to treadmill VO₂ calculator
The new Treadmill VO₂ & Session Builder keeps the same core idea but wraps it into something you can actually use.
You set body mass and a running economy adjustment (more on that later)
For each interval you add:
Speed (or pace in min/km)
Incline (%)
Duration or distance
The calculator estimates:
VO₂ (mL/kg/min)
METs
Distance, elevation gain, energy (kcal)
You can then:
Lock VO₂ and solve for speed or incline (e.g. “45 mL/kg/min at 7% – what speed?”).
Build a full session interval by interval.
See total duration, distance, elevation, mean VO₂, mean speed and total calories.
Export the whole thing as TXT, PDF or Excel and take it with you to the treadmill.
I usually keep an iPad next to the MyRun. The exported session sits on the screen while Zwift or another app records the run in the background. It’s a small thing, but being able to see “this rep is meant to be ~50 mL/kg/min” is a very nice mental anchor.
The running economy slider: useful, but wrong in many ways
One new feature compared to my old Excel file is the running economy adjustment slider. This is where we immediately run into trouble from a physiology point of view.
Running economy is, roughly, “how much oxygen you need to run at a given submaximal speed.” Two runners can have the same VO₂max but very different economy, so at 4:30 min/km one might be cruising and the other suffering.
The slider in the calculator lets you scale VO₂ up or down relative to a “typical trained runner”:
90% = very economical (lower VO₂ at a given speed)
100% = typical club-level runner
110% = poor economy (higher VO₂ at a given speed)
Scientifically, a single slider is absolutely an oversimplification:
Economy depends on anthropometry, tendon stiffness, technique, strength, footwear, fatigue, probably even mood and caffeine.
It drifts with session duration, training status, temperature and many other factors.
To really know your profile, you’d need lab measurements at multiple submaximal speeds, not a guess from an internet calculator.
So why include it?
Because it’s a useful teaching and comparison tool.
The underlying equations give you VO₂ for a theoretical “average” runner. The slider simply says: “OK, but what if you’re a bit better or worse than that?” It lets you personalise the numbers enough that the sessions make sense for you, without pretending that we know your physiology exactly.
Where my slider sits and why
A bit of context about my own fitness level, so you see what the numbers mean in practice.
At the time of writing, I’m a moderate runner. My recent 3000 m test is around 10:30, so I’m nowhere near elite, but not a complete beginner either.
In a recent VO₂max test as part of a research study at the University of Jyväskylä, my first lactate / ventilatory threshold (LT1) was:
Pace about 4:48 min/km
VO₂ around 43 mL/kg/min
Incline at 1%
If I plug that into the calculator and try to make the model match those numbers, my slider ends up around 93–94% – slightly more economical than the “typical trained runner” that the equations assume.
For longer steady runs, it’s probably more realistic to use something like 95–96%, because fatigue and biomechanics over 90–120 minutes are not the same as during a short lab stage. When I build my own treadmill sessions, my slider usually lives between 96–98%, depending on how optimistic I’m feeling.
That’s also how I recommend readers treat it:
Use the slider to roughly align the model with what you see in your own testing, races or perceived effort.
Don’t obsess about whether you are a 95% or a 97% person. The difference is smaller than the day-to-day variation in your legs.
How I actually use the treadmill VO₂ session builder
At the moment I’m still in the “getting to know the tool” phase. Over the past winter I’ve been doing roughly 3–4 treadmill sessions per week, partly to get used to the MyRun and partly to see where the calculator behaves nicely and where it doesn’t.
A typical structured session for me might look like this:
15–20 min easy warm-up
4–6 × 5 min uphill, with:
VO₂ locked in around, say, 50–55 mL/kg/min
First interval at lower incline and higher speed
Later intervals at higher incline and slightly lower speed, but same VO₂
Easy running between the intervals
Cool-down
The calculator helps me answer questions like:
“If I want all reps to feel like the same metabolic load, how do I trade speed and incline against each other?”
“How much elevation did I actually climb during this workout?”
“If I know the mean VO₂ and my body mass, how many calories did this session roughly cost?”
On some days I also play with stepwise VO₂ progressions: each interval 2–3 mL/kg/min harder than the previous one, keeping the incline constant and adjusting only speed. It’s a nice way to build a controlled ramp without needing a lab protocol.
Comparing sessions: same VO₂, different story
One reason I wanted this calculator public is to show how different two treadmill sessions can be even if the average VO₂ is the same.
For example, imagine two 5-minute intervals at roughly 50 mL/kg/min:
Session A: moderate incline, moderate speed
Session B: steeper incline, slower speed, same VO₂
Metabolically they’re similar, but mechanically they are not:
Higher incline shifts emphasis towards the posterior chain and feels more like a skiing uphill.
Higher speed with less incline feels more like flat road running, with different coordination and impact patterns.
If you lock the VO₂ at 50 mL/kg/min in the calculator and start moving the incline up and speed down (or vice versa), you see this trade-off numerically. For coaches and self-coached runners, that’s valuable: you can build sessions that are metabolically comparable but specific to the sport or race you care about.
For coaches and hobby runners
I see two main user groups for this treadmill VO₂ calculator.
Coaches and serious athletes
Build a session once, export it to PDF or Excel, and share it with athletes.
“Lock” sessions to VO₂ targets and then adjust for each athlete using a personalised running economy slider
Use the summary row to quickly see how much time an athlete spends near certain VO₂ or MET ranges.
Curious hobby runners
If you’ve just finished a C25K (couch to 5 kilometers) plan or are doing your first structured intervals, the simplest way to use the tool is:
Ignore VO₂ at first and just set your usual speeds and inclines.
Enter your body mass.
Use the calculator to see the estimated VO₂ and calories and how small changes (like +1% incline) move them.
Over time, as you get race results or maybe a lab test, you can start to fine-tune the slider and think in VO₂ terms. But you don’t need to be a physiologist on day one.
How this fits with wearables and apps
Right now my own workflow looks like this:
Plan the workout in the treadmill session builder.
Export as TXT or PDF and open it on an iPad or similar next to the treadmill.
Record the actual run with Zwift (or your preferred app) so the session goes into Garmin / Strava / other platforms.
Export the screenshot with comments to the training log or as Zwift media.
Longer term, one interesting direction would be to generate a .FIT file or similar export directly from the calculator, so you could load the session as a structured workout to your watch or bike computer. That’s not implemented yet, but the structure is there: the calculator already knows every interval, speed and incline.
If you are a developer or heavy user of training software and have opinions on the best export formats, I’d be happy to hear them.
Research side: VO₂, ventilation and heating the air you breathe
The treadmill and this calculator are also part of a bigger research puzzle I’m working on. In simple terms, I’m exploring the relationship between heart rate and ventilation:
If your heart rate is 140 bpm, is ventilation always, say, 80 L/min? (for me it was on VO₂max test)
How much does that relationship change between people and within the same person over time?
The long-term goal is to build a larger model of ventilation and, from that, estimate how much air needs to be heated and humidified by the airways during exercise. This matters for understanding airway stress, especially in cold or dry environments – something that keeps coming up in both asthma and endurance sports.
The treadmill VO₂ calculator is a small building block in this larger project:
It helps me design standardised treadmill sessions for participants, matched to a percentage of their VO₂max (for example, a 120-minute run at ~65% VO₂max).
It gives a structured way to connect treadmill settings with physiological estimates, which then link to ventilation and airway measurements.
So while the calculator is free to use and meant for everyday training, there is a fairly nerdy research agenda hiding behind it.
Safety, limitations and how to “play” with it
A few important points:
This is not a clinical device. It won’t diagnose anything and it won’t replace medical advice.
The VO₂ values are estimates based on standard equations plus the economy slider, not measured gas exchange.
If you have symptoms (chest pain, worrying breathlessness, severe wheeze, etc.), the right place to start is healthcare, not a new treadmill workout.
That said, I built this tool precisely to encourage curiosity:
Change the incline and see how VO₂ and elevation gain react.
Lock VO₂ and experiment with different combinations of speed and gradient.
Try a more economical slider and see what would have to be true for you to “behave” like an elite runner.
Treat it as a way to connect what you feel on the treadmill with some numbers and concepts from exercise physiology, not as a strict prescription engine.
What’s next – and suggestions welcome
This treadmill VO₂ calculator is a second tool after cycling energy consumption calculator in what I hope will become a small collection of sports physiology calculators on this site. Things I’m actively exploring include:
Tools around heart rate–ventilation relationships
Ventilation, inspired volume and airway heating/humidification estimates
If there is a calculator you wish existed – something you repeatedly do in a spreadsheet or on the back of an envelope – I’d be happy to hear about it.
You can find the treadmill VO₂ & session builder under rikhard.fi/calculators. Use it, break it, send feedback, and most importantly: enjoy your time on the treadmill, whether you’re chasing VO₂ numbers or just trying to get through a Finnish winter in one piece.
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Rikhard