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A new Apple Watch patent describes Biomechanical Triggers for improved responsiveness in grade estimation for Runners & Touch ID

1 cover - Apple Watch Patent for athletes

Apple Watch and more specifically Apple Watch Ultra is an advanced wearable device that provides athletes with important feedback during their various workouts. This week the US Patent & Trademark Office published a patent application from Apple that describes possible new functionality coming to Apple Watch/Watch Ultra regarding biomechanical triggers for improved responsiveness in grade estimation for runners. The patent also describes the possibility of adding Touch ID to one button surface, much like it's used on the iPad Air

Biomechanical Triggers for Improved Responsiveness in Grade Estimation

In Apple's patent background they noted that fitness applications often utilize an estimate of grade (also referred to as “incline”) to compute fitness metrics. For example, grade is used to compute running power. Running power is a measure of how much work a runner puts into their run in units of watts. In many wearable devices (e.g., smartwatches, fitness bands), grade is determined as a ratio of elevation change to horizontal speed change.

Filters used to remove confounds in elevation data can cause delays in grade estimates, which in turn can cause errors in the fitness metrics that rely on grade estimates, such as running power. This is what Apple's latest patent aims to rectify.


Apple's patent covers a system and method for detecting a potential onset of changes in incline during continuous running. The method uses a pattern of recent running speed and running cadence to form grade onset indicators (hereinafter also called “triggers”) that are uncorrelated to altitude measurements (based on elevation data), and can be used to corroborate incline measurements even before sufficient evidence of incline is collected to pass a confidence filter used to remove confounds.

The triggers indicate recent consistency in running cadence and changes in fractional horizontal speed, in combination with elevation based metrics of excessive vertical speed and raw grade.

The biomechanical triggers are context-cues that make it possible to respond to and identify transitions to inclined running from a flat state and more quickly minimize impact on additional variability during flat running.

These improvements to grade responsiveness are important for certain fitness metrics in mobile fitness applications, such as grade-adjusted pace and running power, where the timeliness of feedback based on grade is important to assist in pacing before negative effects occur such as over-exertion.

The triggers also improve downstream processing of fitness metrics that can be corrupted by the occurrence of invalid inclined data, such as maximal oxygen uptake (VO2 Max) estimation during running.

Apple's patent FIG. 1 below illustrates calculation of grade (incline); The graph shown in FIG. 4A is divided by vertical dashed lines into flat, transition to uphill and steep uphill regions; FIG. 5 is a flow diagram of a process (#500) for using biomechanical triggers to improve responsiveness of grade estimation.

2 Apple patent figs. 1  4a  5

Apple's patent FIG. 7 below is an example system architecture implementing the features and operations described throughout the patent relating to Apple Watch, Apple Watch Ultra. For those wanting to dive deeper into the details of every major aspect of FIG. 7,  review patent points 0036 through to 0046 in the patent linked to below.


One feature to point out is Touch ID added to a future Apple Watch. Apple notes that "Touch surface #746 or other controllers #744 (e.g., a button) can include, or be coupled to, fingerprint identification circuitry for use with a fingerprint authentication application to authenticate a user based on their fingerprint(s).

For athletes wanting to dive into finer details and additional supporting graphics, review patent application 20230390605.

10.51FX - Patent Application Bar


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