Hi folks,

I am back with a longer term comparison between the most popular no-screen wearables.

TL;DR

• RHR trends align very well across brands.
• HRV trends align well for Helio, Oura, WHOOP, Polar. Garmin HRV trend is the outlier in my data.
• Sleep duration is consistently measured across all devices.
• Recovery and readiness are not interchangeable across brands. Treat them as within-brand trends.

Context

I started wearing Helio on 15 July. The other devices had more history to learn my baseline, at least a month. WHOOP has three years of data on me. That matters when you compare anything that relies on personalized baselines.

How I compared

• Correlation uses Spearman to capture trend agreement.
• Recovery proxies:
• for WHOOP it's plain simple Recovery,
  1. for Oura its Readiness,
  2. for Polar ANS Charge mapped linearly from −10..+10 to 0..100,
  3. for Garmin I used Body Battery,
  4. and for Helio its Biocharge score.
• Polar sleep duration is Deep + Light + REM as it does not give one simple number.
• Oura RHR uses Avg Sleeping HR. Polar RHR uses Avg HR during sleep as a proxy.
• I only compare days where both devices have data. No forward fills.

Key findings

• RHR The trend is consistent across brands. Day to day bumps and drops align, which makes RHR a dependable anchor metric across ecosystems.
• HRV Helio, Oura, WHOOP, and Polar tell broadly the same story about stress and recovery trend. Garmin’s HRV trend looks different in my data. That could be windowing, artifact handling, or how its status is derived. I’ll dig further.
• Sleep duration Everyone agrees on total time asleep. The disagreements live in staging and the scoring layers, not in the hours.