Reference
Wearable Data for Research: A Practical Reference
Choosing a wearable for a study or trial isn’t really about which watch has the best sensors — it’s about whether the data can reliably reach your data set, and whether every participant’s phone can even run the app. This page lays out the connectivity, operating-system, and data-pipeline facts that decide that. Figures are current as of mid-2026 — app requirements move quickly, so confirm the latest minimums before you commit.
How does a watch’s data actually reach your data set?
Almost every consumer wearable follows the same path: watch → the maker’s phone app → the maker’s cloud. From there, a study collects it one of two ways:
Via the phone’s health store — the app writes to Apple Health (iOS) or Health Connect (Android), and the research app reads from there. Simple, but it depends on each phone’s health-platform plumbing.
Via the vendor’s server API (Garmin Health API, Fitbit / Google Health API) — data flows cloud-to-cloud into your backend, independent of the phone’s health store. More robust for a multi-participant study.
The catch either way: the watch still needs a compatible phone or tablet running the maker’s app to get its data to the cloud at all. A server API changes how you retrieve the data — it does not remove the participant-device requirement.
Which health app does each watch feed — and what OS does it need?
| Watch | Android connector (Google Health) | iPhone connector | iOS min | Android min |
| Garmin | Health Connect (since Jun 2025) | Apple Health | iOS 18.2 | Android 6.0 (9+ for Health Connect) |
| Fitbit Charge 6 (“Google Health” app) | Google Health app / Health Connect | Google Health app — not Apple Health | iOS 16.4 | Android 11 |
| Apple Watch | Not supported on Android | Apple Health (native) | iPhone-only | N/A |
The one that surprises people: Fitbit on iPhone does not use Apple Health — it uses the separate “Google Health (Fitbit)” app, which needs iOS 16.4+. To get Fitbit data on iOS you go through the Fitbit / Google Web API, not Apple Health. And note that legacy Fitbit Web API is being retired in favour of the Google Health API in September 2026 — new integrations should target the Google Health API from the start.
Can data reach the cloud without the participant’s phone?
Sometimes a participant’s phone is too old to run the maker’s app. Whether the watch can still get data to the cloud depends entirely on whether it has its own Wi-Fi.
| Watch | On-watch Wi-Fi | Uploads to cloud with no phone present | Phone role |
| Garmin (Wi-Fi model) e.g. Forerunner / Venu / Fenix | Yes | Yes — auto over Wi-Fi after a one-time phone setup | Setup only |
| Fitbit Charge 6 (and most fitness bands) | No | No — Bluetooth-to-a-phone only | Required for every sync |
A band like the Charge 6 is Bluetooth-only (no Wi-Fi, no cellular, and no desktop sync since 2023), so a participant with an incompatible phone needs a supplied “sync-hub” tablet kept at home. A Wi-Fi-capable Garmin sidesteps that entirely — it uploads on its own over the home network.
Which iPhones are eligible? (the iOS 16.4 line)
iOS support is a hard hardware line on iPhones: iPhone 8 / iPhone X (2017) and newer can run iOS 16.4; iPhone 7 and older cannot.
| iPhone model (release) | Max iOS | Runs iOS 16.4? |
| iPhone 11–16, SE 2nd–3rd gen | iOS 26 (current) | Yes |
| iPhone XS / XS Max / XR (2018) | iOS 18 | Yes |
| iPhone 8 / 8 Plus / X (2017) | iOS 16.7.x | Yes (16 only) |
| iPhone 7 / 7 Plus, SE 1st gen (2016) | iOS 15.8.x | No |
| iPhone 6s / 6s Plus (2015) & older | iOS 15.8.x or lower | No |
How many people is that? The iOS-16.4-incapable devices (iPhone 7 and older) are only ~1–3% of active iPhones and falling. Small — but concentrated in older cohorts, who keep phones longest, so a study recruiting older participants should expect more than the headline figure.
Which Android phones are eligible? (the Charge 6’s Android 11 line)
Android has no clean model → max-version map (fragmented manufacturer updates), so eligibility is by OS version in use, not a fixed hardware ceiling. The Charge 6 app needs Android 11+.
| Android version | Released | Global share (mid-2026) | Runs Charge 6? |
| Android 16 | 2025 | 23.8% | Yes |
| Android 15 | 2024 | 17.3% | Yes |
| Android 13–14 | 2022–23 | 27.0% | Yes |
| Android 12 / 12L | 2021 | 9.9% | Yes |
| Android 11 | 2020 | 7.9% | Yes (minimum) |
| Android 10 & older | ≤2019 | ~13% (combined) | No |
The Android exclusion is bigger than iOS: ~13% of active Android devices globally run a version too old for the Charge 6 — versus ~1–3% on iOS. Developed markets skew newer (lower), but the gap is real. Worth noting: a Garmin’s Android floor is only Android 6.0, so it excludes almost no Android users.
What this means when you choose a device
1. Check the app’s OS floor before the sensors. A watch is only usable if the participant’s phone can run its app. The floors differ a lot — iOS 18.2 for Garmin’s app, iOS 16.4 / Android 11 for the Charge 6, Android 6.0 for Garmin on Android.
2. Budget for the phone/tablet, not just the watch. Every band needs a compatible device to sync. For older cohorts, plan a supplied sync-hub tablet — or pick a Wi-Fi watch that uploads on its own.
3. Pull server-side where you can. For a multi-participant study, a vendor server API (Garmin Health API / Google Health API) is more reliable than depending on each phone’s health store.
4. Mind the roadmap. The legacy Fitbit Web API retires in September 2026 — build new work on the Google Health API.
Planning a study with wearables?
We build the app around your protocol and your devices — ingesting whichever wearable your participants wear, plus the phone itself, with the connectivity, deduplication, and export handled properly. This is our day job.
Figures as of mid-2026 and subject to change. Sources: Apple App Store (Garmin Connect, Google Health/Fitbit); StatCounter iOS & Android version share; Garmin & Fitbit / Google developer documentation.
