Video summary

Fitbit Air Just Got BETTER!

Main summary

Key takeaways

Product Review

Product reviewed

Google / Fitbit Air wearable tested on two locations: wrist vs biceps (using a DIY biceps band). Performance was checked for night HR/HRV, sleep stages, and exercise heart rate.

Key features & what was tested

  • Heart rate (HR) tracking and heart rate variability (HRV) during sleep
  • Sleep stage tracking: awake, REM, light, deep
  • Exercise HR tracking during:
    • indoor cycling
    • running
    • weightlifting
  • Comparisons against:
    • ECG chest strap (Polar H10) during workouts (reference)
    • ECG/EEG-grade reference (EEG device mentioned for sleep validation)

Main findings (wrist vs biceps)

1) Nighttime heart rate & HRV (sleep)

Conclusion: No clear disadvantage using it on the biceps.

Heart rate vs ECG chest strap reference (ECG)

  • Reported “almost perfect agreement” with minor deviation
  • Example nights showed small HR range differences (roughly ~6 BPM window)
  • The reviewer can’t claim biceps is better—quality appears roughly the same

HRV

  • Patterns matched well overnight, though some HRV values differ slightly
  • On biceps, the reviewer sometimes missed exported HRV data after ~1.5–2 hours
    • Missing data noted; reason unclear (possibly signal quality detection)

Pros

  • ECG agreement for HR/HRV during sleep is very strong
  • Sleep-night HR/HRV patterns are broadly consistent between placements

Cons

  • Potential HRV export dropouts on the biceps (at least in the reviewer’s tests)

2) Sleep stage tracking (deep/light/REM)

Conclusion: Sleep stages are highly stable across wrist and biceps; algorithm appears placement-robust.

  • The reviewer expected biceps might be worse (algorithm possibly tuned to wrist), but observed:
    • Perfect-to-near-perfect agreement in nightly sleep staging patterns
    • Deep sleep: essentially the same (biceps detected tiny additional deep sleep in one night)
    • REM and awake: also closely matched

Agreement percentages (biceps vs wrist)

  • Overall sleep stages agree ~93–96%
  • Deep: ~93%
  • Light: ~94%
  • REM: ~96%
  • Awake: ~95%

The reviewer also notes that other devices can be unstable across sides/positions, but not observed here.

Pros

  • Sleep stage tracking consistency is excellent (no meaningful degradation on biceps)
  • High agreement across major stages

Cons

  • Very limited deep EEG-style validation (two nights)

3) Exercise heart rate tracking (ECG reference)

Conclusion: Biceps placement is noticeably better, especially for weightlifting. Compared against Polar H10 ECG chest strap.

Indoor cycling

  • Wrist: very similar patterns, minor deviations
  • Biceps: described as perfect agreement visually and strongly better by correlation (~1.00 vs wrist 0.99)

Running

  • Wrist: good but with a slight delay and some missing/incorrect moments
  • Biceps: slightly better with fewer deviations in lower HR ranges
  • Correlations:
    • Wrist reference alignment: 0.99
    • Biceps: rounded to ~1.00

Weightlifting (biggest difference)

  • Wrist: struggled—many HR peaks not detected
  • Biceps: detected nearly all peaks (best result described)
  • Correlations:
    • Wrist: 0.89 (not good)
    • Biceps: 0.98 (very strong)

Comparison with other devices (percentiles)

Reviewer ran box plot/correlation comparisons across devices previously tested.

  • Fitbit Air on wrist

    • Indoor cycling: ~71st percentile
    • Running: ~74th percentile
    • Weightlifting: ~55th percentile

  • Fitbit Air on biceps

    • Indoor cycling: ~95th percentile
    • Running: ~92nd percentile
    • Weightlifting: ~87th percentile

Overall takeaway: on the reviewer’s body, biceps placement greatly improves exercise HR accuracy, while wrist is mid-pack for weightlifting.

Sleep validation vs reference (EEG mentioned)

The reviewer also checked biceps vs wrist against an EEG reference.

Deep sleep agreement (two nights)

  • Deep: 80.3% (wrist) vs 80% (biceps) — essentially the same

Other stages

  • Light: ~82% (wrist) vs ~80% (biceps)
  • REM:
    • Wrist: ~75%
    • Biceps: ~76%

The reviewer claims this makes it a “true Whoop competitor” and even outperforms Whoop in both HR and sleep stage tracking (meaningfully, though not by a mile).

App / software experience (pros/cons)

Whoop app vs Fitbit/Google Health app

  • Reviewer says Whoop app is still better (setup/experience), especially for active/athlete users.
  • Google Health app (Fitbit Air pairing) is free for most features (except “AI stuff” per the reviewer).

Recommendation framing

  • If you’re not very athlete-focused, Fitbit Air + Google Health app is a better value
  • If you’re very active and willing to pay, Whoop’s tailored experience is preferable

Reviewer currently uses Whoop due to an existing subscription, but would start with Fitbit Air if beginning again.

Practical notes about biceps band

  • Reviewer built a DIY biceps band hack from a watch strap and modified it (glued/sewed).
  • It works, but is not ideal and needs flexibility/give.
  • Reviewer also mentions:
    • Google allowing third-party manufacturers to create bands
    • Expectation of official/third-party biceps bands soon (within 1–3 months) for a cleaner solution

Pros (overall)

  • Heart rate tracking accuracy improves on biceps, especially for weightlifting
  • Sleep stages remain highly consistent on biceps (no meaningful degradation)
  • Strong agreement vs ECG chest strap during workouts
  • Strong early agreement vs EEG reference for sleep (two-night sample)
  • Likely strong value vs Whoop given app cost structure (per reviewer)

Cons / risks

  • DIY band isn’t the best long-term solution; may affect signal quality/comfort
  • Possible HRV data dropouts on biceps (missing exports after ~1.5–2 hours in one instance)
  • App experience: Whoop still has the better app, and Whoop may be better for hardcore athletes

Verdict / recommendation

Wear it on the biceps if your priority is exercise heart-rate accuracy—especially strength training. Sleep tracking appears just as reliable on biceps as on wrist in this early testing. Overall: Fitbit Air on biceps is a clear win for workout HR performance without sacrificing sleep stage tracking, though the app/software value may still depend on whether you prefer Whoop’s paid experience.

Unique points attributed to the reviewer (all from Rob)

  • Biceps vs wrist comparison methodology (first analysis now, deeper dive later)
  • HR/HRV results: ECG chest strap agreement for sleep; HRV export sometimes missing on biceps
  • Sleep stage agreement %: deep/light/REM/awake around 93–96%
  • Exercise results with correlations:
    • Cycling and running: wrist ~0.99, biceps ~~1.00
    • Weightlifting: wrist 0.89, biceps 0.98
  • Percentile comparisons vs other devices:
    • Wrist: 71/74/55
    • Biceps: 95/92/87
  • Claim: outperforms Whoop in HR and sleep stage tracking (early test basis)
  • App comparison: Whoop app better; Fitbit/Google Health mostly free; value depends on user profile
  • DIY band hack details + expectation of third-party biceps bands soon (1–3 months)

Original video