Activity and energy metrics
Vita reads steps, exercise minutes, stand time, active energy, basal energy, flights climbed and physical effort — the last three of which make up the activity load score.
Step count步
Field: step_count
- What it measures
- Steps detected by the iPhone or the Apple Watch. When both record, Apple Health de-duplicates rather than summing.
- What Vita does with it
- Body Age (±2 years, age-referenced) and the Health-tab trend.
- Easily misread
- Pushing a wheelchair or a pram, and cycling, do not register as steps — nor does leaving the phone on a desk. Low steps does not always mean inactive.
Exercise minutesmin
Field: apple_exercise_time
- What it measures
- Minutes Apple judges to be at brisk-walk intensity or above, based on heart rate and motion rather than steps alone.
- What Vita does with it
- Activity load (20%).
Physical effort (MET)MET
Field: physical_effort
- What it measures
- Apple's estimate of activity intensity in metabolic equivalents. One MET is roughly the energy cost of sitting quietly.
- What Vita does with it
- Activity load (50% — its largest term).
- Easily misread
- Strength training is understated: its metabolic cost is far below the stress it actually imposes.
Active energykcal
Field: active_energy
- What it measures
- Energy burned by activity on top of your basal rate. **Note** this is not the same quantity as the whole-day total WHOOP reports.
- What Vita does with it
- Activity load (30%).
- Easily misread
- 🚨 WHOOP's `kilojoule` is a whole-day total, measured at roughly 6.7× Apple's active energy. The two cannot be interchanged, and Vita keeps them explicitly distinct when merging sources.
Basal energykcal
Field: basal_energy_burned
- What it measures
- The energy needed at rest, estimated from height, weight, age and sex — not measured.
- What Vita does with it
- Daily energy context for nutrition analysis.
Stand timemin
Field: apple_stand_time
- What it measures
- Minutes the watch judges you to be standing and moving. It is also the cleanest signal that someone owns an Apple Watch — only a watch produces it.
- What Vita does with it
- Displayed in the Health tab.
Flights climbed层
Field: flights_climbed
- What it measures
- Flights ascended, estimated from the barometer in the iPhone or Apple Watch at roughly 3 metres of climb per flight. It captures vertical activity specifically — no amount of level walking adds to it.
- What Vita does with it
- Displayed in the Health tab.
- Easily misread
- Lifts, sudden pressure changes and weather all disturb the barometer.
Limitations
- Activity load uses where these sit as a PERCENTILE within your own past 30 days, not their absolute values — the same 500 kcal means very different things to different people.
- Time without the watch cannot be counted, and activities with little wrist motion (cycling) tend to read low.
References
Apple. HealthKit — HKQuantityTypeIdentifier reference. Apple Developer Documentation, accessed 2026.
What it supports：The official definition, unit and aggregation style of each metric — the source for how every field on this page is described.
What it supports：Dose-response between daily steps and mortality, with the plateau varying by age.
Ainsworth BE, Haskell WL, Herrmann SD, et al. 2011 Compendium of Physical Activities: a second update of codes and MET values. Medicine & Science in Sports & Exercise. 2011;43(8):1575-81.
What it supports：MET values for physical activities — the standard table behind intensity conversion.
Related metrics
Every metric on this page is a reference index for observing your own trends. It is not medical advice and cannot replace a professional diagnosis. If you have health concerns, consult a qualified clinician.
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