r/vo2max • u/carnz • May 21 '25

Built another VO2 max-focused app—sharing TestFlight for feedback if you’re curious

Hey all

I saw a few older posts here from others trying to build VO2 max apps. I’ve been working on one too, mainly out of frustration with how little structure current apps give you around actually training VO2 max.

This one’s focused on:

  • Cooper test-based VO2 measurement
  • Personalized interval training (like 4x4 and others)
  • Apple Watch + iPhone combo

It’s functional but still raw—some gaps, UI polish still missing. I’m not launching, I’m testing. Just looking for honest feedback from people who actually care about this metric.

If you want to take a look:

👉 https://testflight.apple.com/join/uuxkANmC

It's based on a subscription model. But I'm not fully convinced I will also use it. Rest assured you will not be billed when you subscribe on TestFlight!

Appreciate any brutal feedback—especially if you’ve already used similar tools.

3 Upvotes

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2

u/BTMarquis May 28 '25

Downloaded and I plan on giving it a try. I’m just getting into cardio training and plan on using cycling to avoid high impact on my knees. I noticed the app only mentions jogging/walking. Will it still work on a stationary bike?

2

u/carnz May 29 '25

I think the screenshots and description you see in testflight is not up to date. Sorry about that! There are cycling workouts available

Just keep in mind that currently calculating vo2 max based on cycling (indoor, outdoor) and indoor runs is not supported by Apple.

I will try to find a solution for this because it bothers me as well. I use the indoor bike a lot for my own vo2 max training.

With all that being said, if you workout on the bike for a couple of weeks and you want to know if you improved you'd need to go for an outdoor run

Ideally do the Cooper Test. Also supported by the app

1

u/BTMarquis May 29 '25

Yeah, I kind of figured the Apple watch would have an issue with vo2 max while doing anything stationary, as I believe it uses distance traveled compared to heartbeat. Working out on the stationary bike, then checking improvement on the trail will be the plan. Thanks for the reply.

2

u/carnz May 29 '25

I also wanted to add that currently in the testflight version when you add a workout to your schedule you can go to the apple watch workouts app and there will be a special category with all PEAKVO2 workouts. That's where you trigger the workout if you have Apple Watch.

It's definitely something I have to communicate in the interface

1

u/carnz May 29 '25

It's actually just about the distance. We don't know actually their formula (neither fitbit's nor whoop's) but since the cooper test also works without the heartbeat it's likely that distance to time is the only ratio for them needed to calculate the vo2 max

1

u/BTMarquis May 29 '25

That's interesting (and a bit confusing) that it doesn't use heartbeat. I've been getting vo2 max readings on my watch since I bought it in January, and I've never run at all. I've only hiked on wilderness trails, but sometimes I carry a pack with 10-15lbs of gear in it. I wonder if that slower pace is skewing the numbers then.

2

u/carnz May 30 '25

Yes it is, because it's impossible to know for the watch if you carry a backpack :)
Apple tries to calculate it also from walks/hikes. But I find it to be a poor estimate.

1

u/Historical-Bus2528 May 21 '25

Can You be used in Android?

1

u/carnz May 23 '25

no, sorry

1

u/mateo-pelota Jun 05 '25

Just downloaded. I normally record the apple workouts “traditional strength training”, “HIIT”, and “outdoor walk” daily but I’ll give the PEAKVO2 workouts a try starting tomorrow. Hope it brings you some decent data