WHOOP Strap 3.0 uses Bluetooth Low Energy (BLE) to transfer data from the Strap to your mobile phone. An important difference from previous generations of WHOOP is that the WHOOP app will need to stay open in the background to continue transferring data and remain up to date.
When the data on your Strap is not fully synced (meaning the data is not fully current) you may see the following message on the Overview screen, indicating the data is still "Catching Up."
Main Causes of Data "Catching Up"
Force quitting the app
If you are force quitting the app to terminate it, you are indicating to the operating system that you, as the user, no longer wish the app to continue running even in the background. iOS will not allow WHOOP to run in the background once a user has force quit the WHOOP app and data will not transfer until you relaunch the app.
Low power mode is ON
Within your iPhone's settings (i.e. your device's "Settings" app), navigate to "Battery." From here, ensure Low Power Mode is toggled OFF. If it is toggled ON, it will significantly reduce how often the WHOOP Strap syncs data with the phone.
Background app refresh is OFF
Within your iPhone's settings (i.e. your device's "Settings" app), navigate to "General > Background App Refresh." Find the WHOOP app in the list and ensure it is toggled ON.
Activating airplane mode may automatically toggle OFF Bluetooth and Data on your phone. Both are needed in order to sync data from the Strap to the phone. As long as WiFi is enabled and Bluetooth remains on, airplane mode will not have an impact on data syncing.
Being out of Bluetooth range
When out of Bluetooth range, the Strap will become disconnected and data will no longer be able to sync to the phone. However, your Strap will continue to record and store data (up to 3 days worth) until back in range of your mobile device. At this point, you may see "WHOOP is Catching Up" until the Strap has fully synced with your device.
Not having cellular service
Either WiFi or cellular data is required to send the data your Strap collects to our servers for further processing and analysis. If you are out of cellular range, your data will be stored on the Strap (up to 3 days worth). Once the phone has re-established cell service, data will begin to upload again. At this point, you may see "Data Catching Up" until the Strap has fully synced with your device.
WHOOP Strap battery dies
If the WHOOP Strap battery drains completely, the Strap will no longer be able to collect data. Once the Strap has been charged and reconnected, it will begin to collect and sync data again. You can double-tap the WHOOP Strap to check its battery life.
How Long Until Data Catches Up?
The WHOOP Strap is able to hold up to 3 days of data. Depending upon how long it's been since the Strap last synced with your mobile device, it may take some time for the two to catch up. For example, syncing a full day (24 hours) of data may take up to 1 hour.
If you are experiencing anything longer than this, please try rebooting the Strap by opening the menu in the WHOOP app and navigating to "Strap Settings > Advanced Settings > Reboot Strap." No data will be lost when rebooting the Strap.