Name: VO2max Kinetics
Author: Oleksandr_Katsimon

VO2max Kinetics - Real-Time Oxygen Uptake Data Field

This data field models your real-time oxygen uptake (VO2) on the bike. Instead of reacting instantly to every watt, it reproduces how your body actually ramps VO2 up and down with physiological inertia, giving a realistic picture of your true aerobic load second by second.

What it shows

You pick one value in the settings:

- %VO2max: how much of your aerobic ceiling you are using right now

- ml/kg/min: the absolute oxygen uptake

At rest the value never drops to zero. It relaxes to your resting metabolism (about 1 MET, 3.5 ml/kg/min), which is what a living body actually consumes.

How it works

The field uses your power and Critical Power. Power at VO2max is CP divided by the ratio. Live VO2 chases that target with first-order kinetics (a faster rise, a slower recovery) plus a slow upward drift on long efforts above CP. The absolute value comes from your Garmin profile VO2max if present, otherwise it is estimated from CP and weight. It keeps computing through auto-pause, so VO2 recovers when you stop instead of freezing. All timing uses the internal monotonic clock, so it is not affected by GPS or clock changes.

Heart rate (optional, improves accuracy)

A power meter is required. A heart rate strap is optional. When worn, the field learns your personal relationship between heart rate and VO2 and uses it as an independent cross-check, which increases accuracy. This learning is statistical: it needs data collected across several rides with the strap before the personalized correction switches on, and it keeps adapting to your seasonal form over time. The learned data is stored on the device and survives reboots and charging. Important: if you delete and reinstall the app, the learned data is cleared and the collection starts again from zero, so allow several days of riding before it is fully calibrated again.

Heart-rate references (max HR, resting HR, lactate threshold HR) are taken from your Garmin profile, or you can enter them manually in the settings.

How to use

1. Add VO2max Kinetics to a data screen.

2. Pair a power meter (and a heart rate strap if you have one).

3. Start riding. The big number shows your chosen value, with a small stacked ml kg min unit in absolute mode.

Settings

- CP (Watts): your Critical Power, the key input, set it accurately (default 330)

- CP to pVO2max Ratio: CP as a fraction of power at VO2max (default 0.76)

- Display Value: %VO2max or ml/kg/min

- Use Profile Weight and Rider Weight

- VO2max Color

Accuracy and modelling update:

- More realistic VO2 kinetics on hard intervals: the rise now slows in the heavy zone above your threshold instead of jumping up too fast.

- The slow-component drift now starts only after sustained effort above CP (continuous time above CP), not just after some ride time, so easy-then-hard rides read correctly.

- Added a short cardiodynamic delay at the start of an effort, matching how oxygen uptake really behaves in the first seconds.

- Absolute VO2 (ml/kg/min) aligned to the standard ACSM cycling equation.

- New optional heart-rate cross-check: with a strap the field learns your personal heart-rate to VO2 relationship over several rides to refine accuracy.

- New Display Value setting: show %VO2max or ml/kg/min.

- The value now renders like a native data field, matching your other fields in any layout.

- At rest VO2 relaxes to resting metabolism (about 3.5 ml/kg/min) instead of dropping to zero.

Accuracy depends mainly on a correct CP.

Test calculator: https://testcalculator.booleankoa.uk/