Apple is decoupling its connected gym ecosystem from watchOS, introducing native GymKit on iPhone starting in iOS 27. By pairing an iPhone directly with GymKit-compatible treadmills and stationary equipment via NFC, athletes can now track synchronized indoor walking and running sessions even if their watch is absent or charging.
Historically, GymKit established a direct bidirectional bridge exclusively between Apple Watch and studio equipment: the wearable broadcast real-time optical heart rate to the machine, while the treadmill returned speed, exact belt distance, incline angle, and active calorie expenditure. Under iOS 27, iPhone assumes the role of primary telemetry hub. Tapping the top of the handset against the treadmill's NFC reader initiates the session, prompting the user to select an Indoor Walk or Indoor Run directly on the console.
Because an iPhone lacks onboard cardiovascular sensors, the feature relies on biometric earbuds such as AirPods Pro 3 or Powerbeats Pro 2. The earbuds beam continuous pulse data directly to the treadmill display, while the companion iPhone logs precision machine metrics into the Fitness app. This architecture bypasses the need to grasp dirty metallic contact bars or strap on uncomfortable chest transmitters.
Preserved Benefit: High-fidelity machine telemetry—specifically motorized incline elevation and physical belt odometer readings—remains perfectly recorded into Apple Health, matching the exact tracking precision of an Apple Watch workout.
Explicit Trade-Off: Continuous biometric streaming across two independent Bluetooth links noticeably drains earbud battery life during prolonged endurance sessions, and the feature disengages immediately if heart-rate-capable audio hardware is not detected.
This implementation positions iPhone as a resilient fallback when an Apple Watch runs out of battery or is left behind on a magnetic charger. While iOS continues to prioritize watchOS if an active wearable is detected on your wrist, users can manually choose the phone-first route. In testing with early developer betas, workout telemetry and Exercise ring credits sync retroactively into the Fitness app once your watch reconnects.
To utilize this setup, ensure biometric tracking permissions are active under Settings > Bluetooth > Your AirPods] > Health Permissions. For athletes looking to calibrate their indoor training targets, use our [heart rate zones calculator to optimize your intensity tiers, or inspect your device capabilities across our comprehensive sensor matrix.