Garmin vs Polar: VO2max compared
How Garmin and Polar estimate your VO2max, what each needs from you, what else they show and what independent studies say about accuracy.
| Garmin | Polar | |
|---|---|---|
| Called | VO2 Max. | VO2max (Fitness Test, Walking Test) and Running Index |
| Algorithm | Garmin in-house, built on Firstbeat Analytics | Polar in-house |
| App | Garmin Connect | Polar Flow |
| From: Outdoor run | Yes | Yes |
| From: Walk | Yes | Yes |
| From: Treadmill | No | Not confirmed |
| From: Bike (power meter) | Yes | Yes |
| From: Resting test | Not confirmed | Yes |
| From: All-day data | Not confirmed | Not confirmed |
| Fitness age | Yes | Not confirmed |
| Race predictor | Yes | Yes |
| Published accuracy studies | 5 | 4 |
| What you need to do | Run outdoors with GPS for at least 10 minutes at 70%+ of max heart rate, or ride steadily at high intensity for 20+ minutes with a power meter. Set up your user profile and max heart rate. | Running Index: run at least 12 minutes at 6 km/h or faster with heart rate and GPS (or a stride sensor). Fitness Test: lie still for about 5 minutes. Walking Test: 15 minutes of brisk outdoor walking above 65% of max heart rate. |
Key differences
- Fitness age: Garmin shows one (not confirmed for the other).
- Accuracy evidence: we found 5 published studies for Garmin and 4 for Polar.
How each one works
Garmin: Compares your heart rate (wrist or chest strap) with your GPS pace on outdoor runs, or with power from a power meter on rides. It learns over several activities, so early numbers may be off.
Polar: Several routes: a 5-minute resting Fitness Test (resting heart rate, HRV, age, sex, height, weight, training background), Running Index after runs (heart rate vs speed), a 15-minute Walking Test, and running and cycling performance tests.
Which is better for VO2max?
For VO2max specifically, the best device is the one that sees your hardest efforts: if most of your training is outdoor running, both give an estimate (both use outdoor run, walk, bike (power meter)). If you cycle with a power meter, walk more than you run, or want a resting test, check those rows above. Whichever you choose, compare the number with itself over time and with the norms for your age.
Accuracy studies
Garmin
- Howard et al., J Med Eng Technol, 2026: Forerunner 265 overestimated VO2max (43.95 vs 41.10 ml/kg/min at start) but mean absolute percent error stayed under 10%.
- Engel et al., Eur J Appl Physiol, 2026: Forerunner 245 underestimated VO2max by about 4-5 ml/kg/min (MAPE 7.2-7.9%); error was larger in highly trained athletes (MAPE 9.4-10.4%).
- Carrier et al., Sensors, 2025: fēnix 6 VO2max estimates were judged accurate (MAPE 7.05%, concordance 0.73 vs 30 s lab average).
- Düking et al., J Sports Sci Med, 2024: Forerunner 245 in youth soccer players: MAPE 5.58% after one run and 1.06% after a second run.
- Passler et al., Int J Environ Res Public Health, 2019: Forerunner 920XT had a MAPE of 7.3% but significantly underestimated VO2max.
Polar
- Dakule et al., J Funct Morphol Kinesiol, 2025: In 50 masters basketball players aged 51-81, the Polar OwnIndex (Fitness Test) substantially overestimated VO2max with poor agreement.
- Cooper & Shafer, Int J Exerc Sci, 2019: Polar A300 Fitness Test correlated moderately with treadmill VO2max (r = 0.655) and was repeatable (test-retest r = 0.907).
- Köteles et al., Acta Physiol Hung, 2015: OwnIndex on an RS-400 was driven mainly by self-reported activity level (R² = 0.883); authors call it not an appropriate measure of aerobic fitness.
- Niemeyer, Leipziger sportwissenschaftliche Beiträge, 2013: Running Index correlated with lab VO2max in 18 male runners (r = 0.60).
Frequently asked questions
Is Garmin or Polar more accurate for VO2max?
Garmin has more published validation (5 vs 4 studies). Watch estimates are typically within several ml/kg/min of lab tests for groups, with larger individual errors, so use either one to track your trend.
Does Garmin measure VO2max from outdoor run like Polar?
Yes: both estimate from outdoor run, walk, bike (power meter).
Which is better for VO2max: Garmin or Polar?
Pick the one whose data sources match how you train: Garmin uses outdoor run, walk, bike (power meter); Polar uses outdoor run, walk, bike (power meter), resting test.
Built from official documentation (see each brand page for sources). Features vary by model and firmware. Garmin and Polar are trademarks of their owners; VO2max Health is independent and not affiliated with either.