Video summary

Fitbit Air vs Amazfit Helio Strap (SCIENTIFIC Review)

Main summary

Key takeaways

Product Review

Product(s) compared

  • Fitbit Air (worn on bicep for best results; wrist performance also tested)
  • Amazfit Helio Strap (tested in the basic version on bicep; “Pro” mentioned)

Both are positioned as $99 devices.

Key findings: Heart rate tracking (focus: activity)

Best-case recommendation: Wear on biceps

The reviewer repeatedly finds bicep placement dramatically improves accuracy vs wrist (especially for cycling and weightlifting).

Indoor cycling

  • Fitbit Air (bicep): essentially perfect match vs ECG reference; correlation = 1.00
  • Helio Strap (bicep): also perfect; correlation = 1.00 (ties/possibly slightly closer points than Fitbit)
  • Verdict: both excellent.

Running

  • Fitbit Air (bicep): correlation = 0.99
  • Helio Strap (bicep): correlation = 1.00 after rounding; reviewer notes a small deviation at higher HR
  • Verdict: Helio slightly better by correlation, differences are small.

Outdoor cycling

  • Fitbit Air (bicep): correlation = 0.98
  • Helio Strap (bicep): correlation = 0.99
  • Reviewer also notes:
    • Helio has slight deviations in at least one ride
    • Fitbit shows more minor errors across more examples
  • Verdict: Helio slightly better overall.

Weight lifting (most challenging)

  • Fitbit Air (bicep): correlation = 0.95, misses some HR peaks
  • Helio Strap (bicep): correlation = 0.96, struggles with peak detection but correlation isn’t the whole story
  • Reviewer’s overall read for lifting:
    • Fitbit captures peaks a little better in examples
  • Verdict: close; Fitbit may be slightly better for peak capture despite lower correlation.

Overall heart-rate score (activity)

The reviewer computes overall performance scores from the correlation results:

  • Amazfit Helio Strap (bicep): 99.4 overall (~99)
  • Fitbit Air (bicep): 99.3 overall (~99)
  • Fitbit Air (worse, unspecified context): 96 (notably worse when worn on wrist)

Conclusion: Both bicep-worn devices deliver near-perfect heart-rate tracking for the reviewed cardio workouts, with Helio slightly stronger on average by correlation.

Sleep stage tracking (deep/light/REM)

Reference standard

  • Uses ZMAX EEG headband as a “silver standard” (not perfect gold standard).

Sleep stage consistency (bicep worn)

Fitbit Air (bicep):

  • Deep sleep agreement: 82%
  • Light sleep agreement: 75%
  • REM sleep agreement: 76%

Helio Strap (bicep, basic):

  • Deep sleep agreement: 79%
  • Light sleep agreement: 65%
  • REM sleep agreement: 67%
  • Reviewer says Helio is better than previous firmware, but still behind Fitbit on consistency.

Sleep-stage score / rating

  • Helio Strap overall sleep score: 70 (“good”)
  • Fitbit Air overall sleep score: 78 (“great”)

Conclusion: Fitbit Air is clearly better for sleep stage tracking based on the reviewer’s data.

Application / software experience (Google Health vs Amazfit app)

App comparison

  • Amazfit app:
    • Reviewer likes the home screen more (quick overview of sleep, recovery, workload)
    • Mentions ability to jump into relevant areas quickly
  • Fitbit (Google Health) app:
    • Reviewer says it has improved and is more customizable
    • Can add widgets/metrics (e.g., distance traveled, fitness level, sleep score, readiness, etc.)

Missing/limitations mentioned (Fitbit Air)

  • Hard to find detailed overnight HR + HRV patterns in a way like competitors show.
  • Reviewer wants a visualization similar to the “hammock shape” (pattern throughout the night), but says Fitbit shows mostly averages / limited views.

Missing/limitations mentioned (Amazfit app/device)

  • Reviewer describes some issues:
    • Device can freeze after stopping activity (data still recoverable but “clunky”)
  • Mentions the Amazfit app can provide HRV graphs and tie resting HR/HRV to core metrics (editor note: a feature/setting in the app).

Night heart rate tracking (Fitbit vs Helio)

  • Fitbit Air (bicep): good agreement in the tested HR range (40–60 bpm)
  • Helio Strap (bicep): direct per-beat graph looked worse, but averages correlate better.
  • Reviewer suspects API/data extraction problems or time offset rather than the device itself (mentions a possible 2-hour time offset bug in their method).

Comparisons to other devices (beyond the two)

  • Sleep stage tracking ranking (top five “best” area):
    • Google + Pixel devices (including Fitbit Air) and Pixel Watch
    • Then Apple devices, Whoop Strap, Aura Ring
    • Eight Sleep Pod is mentioned as strong but very expensive (mattress device, not wearable)
  • Reviewer claims:
    • Both apps are “not as polished” as Whoop or Aura ecosystems.

Pros / Cons (as stated)

Fitbit Air — Pros

  • Near-perfect activity heart rate tracking on bicep (correlation up to 1.00 depending on exercise)
  • Best sleep stage tracking:
    • Higher deep/light/REM consistency
    • Sleep score 78 (“great”)
  • More customization in app (via Google Health)
  • Bicep placement notably improves accuracy vs wrist

Fitbit Air — Cons

  • Wrist performance is worse, especially cycling and weightlifting
  • App limitations:
    • Difficulty finding detailed overnight HR/HRV patterns
  • No official bicep strap at first:
    • Reviewer says you may be able to DIY or buy an accessory soon; Google plans accessories for manufacturers

Amazfit Helio Strap — Pros

  • Very strong activity heart rate tracking, often slightly better by correlation on running/outdoor cycling
  • Sleep stage tracking is improving vs earlier firmware
  • App home screen liked for quick overview
  • HRV graph/HRV integration mentioned (editor note)

Amazfit Helio Strap — Cons

  • Sleep stage tracking weaker than Fitbit in this test (score 70 “good”; notably lower light/REM consistency)
  • Basic firmware/app experience described as less polished
  • Some device behavior/clunkiness: freezing after workouts
  • “Pro” version not tested; expected to be ~twice as expensive, making it less directly comparable to $99 Fitbit Air.

Unique points mentioned (consolidated list)

  1. Both devices cost $99
  2. Helio Pro coming soon but likely 2× price; this review focuses on basic
  3. Best accuracy when worn on biceps; wrist is worse (especially cycling, weightlifting)
  4. Indoor cycling HR tracking: Fitbit corr 1.00, Helio corr 1.00
  5. Running HR tracking: Fitbit corr 0.99, Helio corr 1.00 (minor high-HR deviation)
  6. Outdoor cycling HR tracking: Fitbit corr 0.98, Helio corr 0.99; Helio fewer minor errors on average
  7. Weight lifting HR tracking: Fitbit corr 0.95, Helio corr 0.96; Fitbit may catch peaks slightly better in examples
  8. Overall activity HR score: Helio 99.4, Fitbit bicep 99.3, Fitbit wrist 96
  9. Night HR tracking for Helio may be impacted by API extraction/time offset bug in reviewer’s workflow
  10. Sleep stage tracking tested vs ZMAX EEG (“silver standard”)
  11. Sleep stage consistency: - Fitbit: Deep 82% / Light 75% / REM 76% - Helio: Deep 79% / Light 65% / REM 67%
  12. Sleep rating: - Helio 70 (“good”) - Fitbit 78 (“great”)
  13. Fitbit app (Google Health) improvements: more customizable home screen
  14. Reviewer prefers Amazfit app home screen overview, but likes Fitbit customization more overall
  15. Both apps not fully “polished” vs Whoop/Aura
  16. Fitbit app: difficulty finding detailed overnight HR/HRV patterns (wants hammock-like chart)
  17. Amazfit experience: freezes after stopping activity (data recoverable but clunky)
  18. Sleep stage tracking comparison to other ecosystems (Google/Pixel top tier; Apple/Whoop/Aura mid; Eight Sleep Pod referenced as very expensive but strong)

Speakers/views

  • Primary reviewer (Rob):
    • Provides most of the data-driven comparisons and the overall recommendation
    • Emphasizes bicep-worn performance, near-perfect HR tracking, and Fitbit’s superior sleep staging
  • Editor (Alex) contribution (brief):
    • Notes a feature in the Amazfit app to tie resting HR and HRV to core metrics and get HRV graphs at night

Overall verdict / recommendation

  • If your top priority is sleep stage tracking: choose Fitbit Air (significantly better sleep stage agreement and higher sleep score).
  • If your priority is activity heart-rate tracking on biceps: both are excellent (near-perfect overall scores); Helio Strap is slightly stronger on average, but Fitbit ties/very close.
  • Net recommendation from the reviewer: Slightly prefer Fitbit Air overall, mainly due to sleep performance.

Original video