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# HKMetadataKeyFitnessMachineDuration

The workout duration displayed by a connected GymKit fitness machine.

```
let HKMetadataKeyFitnessMachineDuration: String
```

## Discussion

Set this key on a workout sample representing exercise on a GymKit fitness machine. Set its value to an [`HKQuantity`](/documentation/HealthKit/HKQuantity) object with a time unit.

---

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