Why do standard Bluetooth GATT profiles matter for a fitness app?

Because they turn a per-vendor integration problem into a per-profile one. A heart-rate strap that implements the standard Heart Rate service looks the same to your app whether it costs twenty dollars or two hundred, and a treadmill that implements the Fitness Machine Service exposes the same characteristics as a rower from a different brand. You write the subscription flow once per profile — scan, connect, subscribe to notifications — and inherit every compliant device. The catch is that compliance varies at the edges, which is why this cluster treats capability discovery and per-model testing as first-class topics rather than afterthoughts.

Should my app read live device data over Bluetooth or pull it from HealthKit and Health Connect?

Both, for different jobs. The on-device health stores are records of what already happened — samples and summaries written after the fact — and they are the right source for history, trends, and data from apps you do not control. Live coaching needs a live source: a BLE subscription to a strap or machine, a workout session on watchOS, or Health Services on Wear OS. The practical architecture is a live path for the in-session experience and the store as the durable system of record, with deduplication rules so the same workout counted once.

What changed with ANT+ and does it affect a new fitness app?

Per widely-quoted announcements from the ANT+ organization — which we grade as reported, since we could not fetch the official page directly — the ANT+ membership and certification programs were discontinued at the end of June 2025, with device profiles and documentation reportedly remaining available and existing devices unaffected. For a new app in 2026 the practical reading is straightforward: Bluetooth Low Energy is the default radio for fitness sensors, phone-side BLE APIs are first-class on both platforms, and ANT+ matters mainly where an existing hardware ecosystem carries it. The deadline tracker follows this one as it evolves.

Connected Devices

Connected Fitness Devices

The live-hardware layer of a fitness app: heart-rate straps, treadmills, trainers, rowers, cycling sensors, and the watch itself, speaking the protocols they actually use. Most of it is standard Bluetooth — one Heart Rate profile covers straps from every vendor, and one Fitness Machine Service covers six categories of gym equipment — which means one well-built integration inherits an entire device ecosystem. This cluster documents the standard services and their verified identifiers, the platform layers on iOS, Android, watchOS, Wear OS, and the browser, where control features honestly get murky, and how to test hardware that CI cannot script.

This cluster covers the live path. The stored path — history, trends, and everything after the workout — lives in Integration guides and Architecture; the camera as a sensor lives in AI Motion. Spec identifiers here are verified against the Bluetooth SIG’s published assigned numbers; wire formats belong to the specs themselves, which each page links by name.

Straps and sensors

The standard GATT profiles that make one integration work across vendors.

Machines: FTMS

One Bluetooth service covers treadmills, bikes, rowers, and more — data in, and sometimes control out.

The watch as a sensor

Live workout data from the wrist — a session on watchOS, a platform service on Wear OS.

Protocols, platforms, and proof

Radio choices, browser reach, iOS specifics, and how to test hardware you cannot script.

Byte layouts, from the SIG’s own files

The Bluetooth GATT reference lays out 44 characteristics field by field — type, size, offset, unit and the Flags bit that makes each field present — as the Bluetooth SIG’s GATT Specification Supplement files publish them, and lists 97 in all. The characteristics these guides name by UUID:

Frequently asked questions

Why do standard Bluetooth GATT profiles matter for a fitness app?: Because they turn a per-vendor integration problem into a per-profile one. A heart-rate strap that implements the standard Heart Rate service looks the same to your app whether it costs twenty dollars or two hundred, and a treadmill that implements the Fitness Machine Service exposes the same characteristics as a rower from a different brand. You write the subscription flow once per profile — scan, connect, subscribe to notifications — and inherit every compliant device. The catch is that compliance varies at the edges, which is why this cluster treats capability discovery and per-model testing as first-class topics rather than afterthoughts.
Should my app read live device data over Bluetooth or pull it from HealthKit and Health Connect?: Both, for different jobs. The on-device health stores are records of what already happened — samples and summaries written after the fact — and they are the right source for history, trends, and data from apps you do not control. Live coaching needs a live source: a BLE subscription to a strap or machine, a workout session on watchOS, or Health Services on Wear OS. The practical architecture is a live path for the in-session experience and the store as the durable system of record, with deduplication rules so the same workout counted once.
What changed with ANT+ and does it affect a new fitness app?: Per widely-quoted announcements from the ANT+ organization — which we grade as reported, since we could not fetch the official page directly — the ANT+ membership and certification programs were discontinued at the end of June 2025, with device profiles and documentation reportedly remaining available and existing devices unaffected. For a new app in 2026 the practical reading is straightforward: Bluetooth Low Energy is the default radio for fitness sensors, phone-side BLE APIs are first-class on both platforms, and ANT+ matters mainly where an existing hardware ecosystem carries it. The deadline tracker follows this one as it evolves.

All 37 questions in Connected Devices, answered

Independent comparison, last reviewed August 14, 2026. Pricing, rate limits, and feature availability change often — confirm current details in each provider’s official documentation before you commit. Product and company names are trademarks of their respective owners; AIFitnessAPI is not affiliated with, endorsed by, or sponsored by any product listed here.