Gait and mobility metrics
Walking speed, step length, walking asymmetry, double support time, walking steadiness, stair speed and six-minute walk distance — Apple's mobility family, which relates to long-term functional health and fall risk, and is the group closest to “healthspan” that most people never look at.
Walking speedm/s
Field: walking_speed
- What it measures
- Average everyday walking speed, estimated from iPhone or Apple Watch motion sensors.
- What Vita does with it
- Displayed as a trend in the Health tab.
- Easily misread
- Walking speed is treated in geriatrics as a summary indicator of functional health, so a long-term decline is worth noticing — but terrain, footwear and carrying things all affect it.
Step lengthcm
Field: walking_step_length
- What it measures
- How far a single step carries you, estimated from iPhone or Apple Watch motion sensors. Step length shortens with age, fatigue, pain and reduced walking confidence, making it the most legible of the gait metrics.
- What Vita does with it
- Displayed as a trend in the Health tab.
Walking asymmetry%
Field: walking_asymmetry_percentage
- What it measures
- The share of walking time in which your steps are unevenly timed between legs — lower is more symmetric. Apple treats it as part of its mobility assessment, and healthy adults are usually near 0%.
- What Vita does with it
- Displayed as a trend in the Health tab.
- Easily misread
- Injury, pain or a compensating gait raise it — so does carrying weight on one side.
Double support time%
Field: walking_double_support_percentage
- What it measures
- The share of the walking cycle with both feet on the ground. Faster, more confident walking lowers it; a more cautious gait raises it. It is an indirect read on balance.
- What Vita does with it
- Displayed as a trend in the Health tab.
- Easily misread
- A higher share generally goes with a more cautious gait and reduced balance confidence.
Walking steadiness%
Field: apple_walking_steadiness
- What it measures
- Apple's combined assessment of balance and coordination from several gait features, intended to flag fall risk, banded as OK / low / very low.
- What Vita does with it
- Displayed in the Health tab.
- Easily misread
- 🚨 This is Apple's own assessment; Vita displays it as-is and neither reinterprets nor re-bands it. It requires the iPhone to be carried near the waist to be captured.
Stair ascent / descent speedm/s
Field: stair_speed_up
- What it measures
- Vertical speed on stairs, which reflects lower-body strength better than level walking.
- What Vita does with it
- Displayed as a trend in the Health tab.
Six-minute walk distancem
Field: six_minute_walking_test_distance
- What it measures
- Apple's estimate, from everyday walking, of how far you could walk in six minutes — mirroring the clinical six-minute walk test.
- What Vita does with it
- Displayed as a trend in the Health tab.
- Easily misread
- This is an ESTIMATE, not an actual six-minute walk test, and does not substitute for the clinical measurement.
Limitations
- None of this group feeds a Vita score — their value is in the multi-YEAR trend, not any single day.
- Capture requires the iPhone carried on your person or the Apple Watch worn while walking; left in a bag or on a desk, most of these produce nothing.
- This group sits closest to the idea of healthspan: they measure function rather than risk factors.
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：Definitions and capture conditions for the mobility metrics (they need an iPhone carried or an Apple Watch worn while walking).
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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