lowCardioFitnessEvent: HealthKit category type
HKCategoryTypeIdentifierLowCardioFitnessEvent · read from Apple’s documentation on 2026-10-02
HKCategoryTypeIdentifier.lowCardioFitnessEvent (Objective-C HKCategoryTypeIdentifierLowCardioFitnessEvent) is a HealthKit category type in Apple's "Activity" group. Apple's abstract: “An event that indicates the user’s VO2 max values consistently fall below a particular aerobic fitness threshold.” Apple's page names HKCategoryValueLowCardioFitnessEvent as the enum its sample values come from. Apple states that apps cannot save it: “Low-cardio fitness event samples are read-only.” It is available from iOS 14.3 and watchOS 7.2.
What Apple says lowCardioFitnessEvent is
An event that indicates the user’s VO2 max values consistently fall below a particular aerobic fitness threshold.
Apple’s abstract, quoted from its lowCardioFitnessEvent reference page, read 2026-10-02. Apple’s discussion of the type runs 159 words.
- Swift
HKCategoryTypeIdentifier.lowCardioFitnessEvent- Objective-C
HKCategoryTypeIdentifierLowCardioFitnessEvent- Family
HKCategoryTypeIdentifier- Apple's topic group
- Activity
- Group page
- Activity
- Apple's reference
- lowCardioFitnessEvent on developer.apple.com
Availability
The versions Apple’s documentation data gives for lowCardioFitnessEvent, platform by platform, as read on 2026-10-02.
| Platform | Introduced | Deprecated |
|---|---|---|
| iOS | 14.3 | — |
| iPadOS | 14.3 | — |
| Mac Catalyst | 14.3 | — |
| macOS | 13.0 | — |
| visionOS | 1.0 | — |
| watchOS | 7.2 | — |
The rest of that release: HealthKit Types Introduced in iOS 14.
What a sample holds
Value enum
HKCategoryValueLowCardioFitnessEvent — the enum Apple’s page for lowCardioFitnessEvent names. Every category type’s enum is on the HKCategoryValue reference.
Aggregation style and unit family apply only to quantity types. For a category type the dataset records neither, because the concept does not apply — not because Apple declined to say.
Can apps write lowCardioFitnessEvent?
No. Apple’s documentation states that these samples are read-only:
Low-cardio fitness event samples are read-only.
On Android Health Connect
No verified Health Connect counterpart. The cross-platform matrix pairs only metrics checked against both Apple’s and Google’s documentation, and lowCardioFitnessEvent is not among them. A similarly named Health Connect record may exist, but a name match is not a verified mapping.
Metadata keys Apple ties to it
The HKMetadataKey constants whose own Apple text names lowCardioFitnessEvent, with the sentence that does, from Apple’s metadata-key pages read 2026-10-04.
- HKMetadataKeyVO2MaxValuevalue: HKQuantity
The system sets this key on lowCardioFitnessEvent samples.
- HKMetadataKeyLowCardioFitnessEventThresholdvalue: HKQuantity
The system sets this key on lowCardioFitnessEvent samples.
Questions
- Which enum decodes lowCardioFitnessEvent sample values?
- HKCategoryValueLowCardioFitnessEvent. Apple's page for lowCardioFitnessEvent names that enum as the one its sample values come from.
- Can my app write lowCardioFitnessEvent samples to HealthKit?
- No. Apple's documentation for lowCardioFitnessEvent states: "Low-cardio fitness event samples are read-only." (read 2026-10-02).
- Which HealthKit metadata keys mention lowCardioFitnessEvent?
- HKMetadataKeyVO2MaxValue and HKMetadataKeyLowCardioFitnessEventThreshold. Apple's text for HKMetadataKeyVO2MaxValue: "The system sets this key on lowCardioFitnessEvent samples." Apple's text for HKMetadataKeyLowCardioFitnessEventThreshold: "The system sets this key on lowCardioFitnessEvent samples."
- Which iOS version added lowCardioFitnessEvent?
- iOS 14.3. Apple's availability data for lowCardioFitnessEvent lists iOS 14.3, iPadOS 14.3, Mac Catalyst 14.3, macOS 13.0, visionOS 1.0 and watchOS 7.2.
Sources checked
- Apple — HKCategoryTypeIdentifier.lowCardioFitnessEvent · read 2026-10-02
- Apple — HKCategoryTypeIdentifier · read 2026-10-02
- Apple — HKMetadataKeyVO2MaxValue · read 2026-10-04
- Apple — HKMetadataKeyLowCardioFitnessEventThreshold · read 2026-10-04
Apple’s abstract and sentences are quoted for identification; the page layout, the capsule and the cross-platform pairing are AIFitnessAPI’s. Generated from Apple’s documentation by scripts/fetch-healthkit-identifiers.mjs, not typed by hand — the same data as the full identifier table.