Running Metrics API: Speed, Power, Stride Length and Running Form Data

Running dynamics arrived on the platforms at different times and in different units, and only some of them made it into a shared store. A form feature that works on an Apple Watch can find nothing to read on Android, and a feature built on a Bluetooth foot pod reads values the phone stores never hold. The shape of the problem is in the table.

What each platform has#

Read from Apple's documentation on 2026-10-02, Google's Health Services reference on 2026-10-04, its Health Connect reference on 2026-10-03 and the Bluetooth SIG's files on 2026-10-17. Wear OS's stride length, vertical oscillation and ground contact time are rows on the data-type table without pages of their own, because this site's thin-page rule holds them back.

The Google Health API has no running speed, power or form data type. Its exercise type carries a per-exercise summary with an average speed, an average pace and a mobilityMetrics field that Google says is "Only present in the advanced running exercises"; the discovery documents this site reads do not define that object's fields, and exercise data is outside this page's scope.

Apple's five types#

All five are discrete quantities available from iOS 16.0 and watchOS 9.0. Apple's descriptions:

• runningSpeed measures "the runner’s speed."
• runningPower measures "the rate of work required for the runner to maintain their speed."
• runningStrideLength measures "the distance covered by a single step while running."
• runningVerticalOscillation measures "pelvis vertical range of motion during a single running stride."
• runningGroundContactTime measures "the amount of time the runner’s foot is in contact with the ground while running."

Being discrete, each is averaged, or its minimum or maximum taken, in a statistics query; summing them gives a meaningless number.

Units: the same quantity in four scales#

• Speed: distance-per-time units you choose on iOS, meters per second on Wear OS, Velocity in Health Connect's aggregates, 1/256 meter per second on Bluetooth.
• Pace: only Wear OS has it, in milliseconds per kilometer, and Google notes it "Will be 0 if the user stops moving." A zero pace is a stop, not infinite speed.
• Stride length: meters on Wear OS, centimeters on Bluetooth, length units you choose on iOS. Google's Wear OS description, "Distance covered by a single step," matches Apple's single-step definition.
• Vertical oscillation: centimeters on Wear OS, which describes it as the distance "the center of mass moves up-and-down with each step"; Apple's is pelvis range of motion during a stride, in length units. The words differ as well as the units.
• Ground contact time: milliseconds as a Long on Wear OS, time units on iOS.

Wear OS's VERTICAL_RATIO is "Vertical oscillation / stride length." Google's example in the same reference reads: "a vertical oscillation of 5.0cm and stride length .8m (80 cm) would have a vertical ratio of 0.625." Five divided by eighty is 0.0625, so the example's figure is ten times the ratio its own definition gives. Check the scale of real values on a device before you display them.

Speed is one type on Android and many on Apple#

Health Connect's SpeedRecord "Captures the user's speed, e.g. during running or cycling," and Wear OS has one SPEED. HealthKit makes the activity part of the type: runningSpeed, cyclingSpeed, walkingSpeed, rowingSpeed, crossCountrySkiingSpeed, paddleSportsSpeed, stairAscentSpeed and stairDescentSpeed. One of them needs care: Apple's abstract for paddleSportsSpeed is the same sentence as for distancePaddleSports, and its stored sentence says the samples measure cumulative values, where every other speed type says discrete. The cycling power API guide covers the cycling side.

Bluetooth RSC#

The RSC Measurement 0x2A53 characteristic always carries Instantaneous Speed, a uint16 in 1/256 m/s, and Instantaneous Cadence, a uint8 per minute. Flags bit 0 adds Instantaneous Stride Length, a uint16 in centimeters, and bit 1 adds Total Distance, a uint32 in tenths of a meter. Bit 2 is a walking-or-running status: 0 for walking, 1 for running. Our guide to reading cycling power, cadence and speed sensors lists it under the Running Speed and Cadence service 0x1814 and covers the subscription, the same pattern as the two cycling services.

Traps#

• An Apple-only feature by default. Stride, oscillation and ground contact have no Health Connect record, so an Android build reads them from Wear OS Health Services, or stride length alone from an RSC sensor, not from the store.
• Oscillation is defined two ways. Pelvis range of motion during a stride on Apple, center of mass with each step on Wear OS; do not compare across platforms.
• Zero pace. Filter it before averaging pace.
• Units at the boundary. Convert 1/256 m/s, milliseconds per kilometer and centimeters once, at ingestion.
• Permissions. Wear OS SPEED and PACE sit under ACTIVITY_RECOGNITION in Google's permissions table; the stride, oscillation, ground-contact and vertical-ratio types do not appear in that table at all.

Before you ship#

Re-read each type page before release; they regenerate from Apple's, Google's and the SIG's sources. Label every form metric with its platform's definition, test VERTICAL_RATIO's scale on a device, and plan the Android path through Wear OS or Bluetooth rather than Health Connect.