No extra strap.
Wear Apple Watch the way you already do. Screen off and Airplane Mode are fine as long as Health data is recorded.
Alternatives and comparisons
If you already wear an Apple Watch.
Compare recovery rings, straps, body-battery apps, and Apple Watch health tools by the signals they actually read.
Get Body InsightsFree for core features.
Alternatives you can compare.
Start here if you are deciding whether you need another band, a ring, a Garmin-style energy score, or a better read from Apple Health.
WHOOP alternative for Apple Watch.
Use Apple Watch as the sensor strap and Body Insights as the recovery read.
Compare →
WHOOP vs Apple Watch.
Recovery, strain, subscription cost, and what each device actually measures.
Compare →
Oura vs Apple Watch.
What the ring packages, what Apple Watch records, and where recovery data lives.
Compare →
Garmin Body Battery vs Apple Watch.
Garmin packages a live energy score. Apple Health holds many of the same signals.
Compare →
Body Battery on iPhone.
The closest iPhone path if you want a Garmin-style energy read from Apple Watch data.
Read →
Free Body Battery apps for iOS.
Free iPhone apps that turn HRV, sleep, and resting heart rate into an energy read.
Read →
The comparison question is usually simple.
Do you need another wearable, or do you need a better translation of the health data your Apple Watch already records?
Body Insights is built for the second answer: Apple Watch stays the sensor, Apple Health stays the data layer, and the app turns recovery, energy, sleep, stress, and fitness signals into plain language.
No new ecosystem.
The read starts from Apple Health instead of asking you to split your recovery data across another platform.