---
title: stairDescentSpeed
framework: healthkit
role: symbol
role_heading: Type Property
path: healthkit/hkquantitytypeidentifier/stairdescentspeed
---

# stairDescentSpeed

A quantity sample type measuring the user’s speed while descending a flight of stairs.

## Declaration

```swift
static let stairDescentSpeed: HKQuantityTypeIdentifier
```

## Discussion

Discussion This is a measurement of how fast the user walks down stairs. The system automatically records stair descent samples on Apple Watch Series 5 or later. The user must walk down a 10-foot (3-meter) flight of steps while wearing the watch. The system records 20 samples on a typical day; however, some days may go over 100 samples, for example if the user goes on a long hike. The watch doesn’t record stair descent speed samples if the user’s wheelchair status is on. These samples use distance/time units (described in HKUnit) and measure discrete values (described in HKQuantityAggregationStyle). For example, the following code shows two ways to create a meters/second unit. The first uses explicit constructors, while the second initializes the unit from a string. let mps = HKUnit.meter().unitDivided(by: HKUnit.second()) let mpsFromString = HKUnit(from: "m/s") The sample’s quantity property represents the average descent speed between the sample’s startDate and endDate properties.

## See Also

### Related Documentation

- [HKDevicePlacementSide](healthkit/hkdeviceplacementside.md)

### Mobility

- [appleWalkingSteadiness](healthkit/hkquantitytypeidentifier/applewalkingsteadiness.md)
- [appleWalkingSteadinessEvent](healthkit/hkcategorytypeidentifier/applewalkingsteadinessevent.md)
- [sixMinuteWalkTestDistance](healthkit/hkquantitytypeidentifier/sixminutewalktestdistance.md)
- [walkingSpeed](healthkit/hkquantitytypeidentifier/walkingspeed.md)
- [walkingStepLength](healthkit/hkquantitytypeidentifier/walkingsteplength.md)
- [walkingAsymmetryPercentage](healthkit/hkquantitytypeidentifier/walkingasymmetrypercentage.md)
- [walkingDoubleSupportPercentage](healthkit/hkquantitytypeidentifier/walkingdoublesupportpercentage.md)
- [stairAscentSpeed](healthkit/hkquantitytypeidentifier/stairascentspeed.md)