How to Track VO2 Max Without an Apple Watch

Your iPhone camera captures the heart rate data you need to log aerobic fitness trends — no $400 smartwatch required. Just your phone.

7 min read
Beginner-friendly
ESC 2021 sourced
LIVE · 14 / 60s
9:41● ● ●
Measurement complete
Your HRV today.
68 ms
Heart-rate variability
Excellent
RMSSD
68 ms
+6% · parasympathetic
SDNN
91 ms
+3% · autonomic
7-day trend
↑ up 4%
What is HRV

The variation between heartbeats — your nervous system's report card.

RMSSD vs SDNN

Two metrics, one number. Why Pulse shows both — and which to watch.

TRIMP load

Training-impulse: your weekly training load, in one chart.

The protocol

4 steps. Sixty seconds. Done before your coffee.

  1. 01
    Morning

    Log Resting Heart Rate Daily

    Open Pulse Rate each morning and take a 60-second resting measurement. A steadily declining resting HR over weeks is a reliable indicator of improving aerobic base fitness.

  2. 02
    60 sec

    Track a Steady-State Effort

    After a moderate-intensity run or bike session, log your effort level and average heart rate. Pulse Rate stores each session for trend analysis.

  3. 03
    Read

    Watch Your HRV Trend

    Heart Rate Variability is closely correlated with aerobic fitness. A rising HRV trend over 4–8 weeks signals improved cardiovascular efficiency.

  4. 04
    Daily

    Sync with Apple Health

    Import workout data from Apple Health to combine your activity history with camera-based HR readings for a fuller picture of your fitness trajectory.

What you'll see in Pulse

Your progress, exactly how the app shows it.

The same chart that lives on your iPhone's Progress screen — rebuilt so you know what you're looking at.

Wellness Index trend
82 / 100 Excellent
Last 30 days
100 75 50 25
Excellent (80+) Borderline (40–60) Very low (0–40)
Excellent 80+

Outstanding score. Your key heart metrics are above normal.

Normal 60 – 80

Most healthy adults fall within this range.

Borderline 40 – 60

Not necessarily alarming — but worth monitoring.

Very Low 0 – 40

If this persists, please consult a healthcare professional.

Bonus · TRIMP

Training Impulse, decoded.

TRIMP = duration × intensity. A 60-minute easy run scores about 70 TRIMP. A 30-minute interval session scores 110. Pulse adds them up daily and tells you when your week is too light, just right, or about to overcook you.

80–140
Optimal weekly load
140–200
Stretch (watch HRV)
200+
Overreaching
More guides

Take your first reading.

You've already got the hardware — your iPhone. Pulse does the rest.

Free to download · Core tracking always free · iOS 15+

Download on the App Store