Apple Won 5 Apple Watch Patents today covering Estimating Caloric Expenditure using Hear Rate Model specific to Motion Class and more

Today was a big day for Apple Watch as the U.S. Patent and Trademark Office officially granted Apple five patents covering various mechanical and health related features related to motion, a heart rate model, optical sensors and more.

Estimating Caloric Expenditure Using Heart Rate Model Specific To Motion Class

In Apple's patent background they note that the metabolic equivalent of task (MET) is defined as a ratio of the rate of energy expended by an individual during physical activity to the rate of energy expended by the user at rest (referred to as the resting metabolic rate (RMR)). Many studies have shown that the conventional 1-MET baseline overestimates actual resting oxygen consumption and energy expenditures by about 20% to 30% on average. Therefore, an accurate calculation of MET for a specific individual requires data specific to the user and the activity.

Modern wearable devices (e.g., smart watches, fitness bands) are often used by individuals during fitness activities to determine their caloric expenditure during the fitness activity. Some wearable devices include inertial sensors (e.g., accelerometers, angular rate sensors) that are used to estimate a work rate (WR) based MET for the user wearing the device. Some wearable devices include a heart rate (HR) sensor that provides HR data that can be used with user estimated maximal oxygen consumption (VO.sub.2Max) and other data (e.g., users weight, age) to estimate HR based MET.

Because studies have shown that upper limb exercise leads to higher heart rate than lower limb motion there is a need for different HR models for upper limb exercise and lower limb exercise and thus a need to detect upper and lower limb motion.

Apple's granted patent covers a method of obtaining and using one or more processors, acceleration and rotation rate from motion sensors of a wearable device worn on a limb of a user while the user is engaged in a physical activity; determining, using the one or more processors, a vertical component of inertial acceleration and a vertical component of rotational acceleration from the acceleration and rotation rate, respectively; determining, using the one or more processors, a magnitude of the rotation rate; determining, using the one or more processors, a correlation between the vertical component of inertial acceleration and the vertical component of rotational acceleration rate; determining, using the one or more processors, a percentage of motion outside a dominant plane of motion; predicting, using the one or more processors, a motion class based on a motion classification model that takes as input the vertical components of inertial acceleration and rotational acceleration, the magnitude of rotation rate, the correlation between the vertical component of the inertial acceleration and the vertical component of rotational acceleration and the percentage of motion outside the dominant motion plane; determining, using the one or more processors, a likelihood the user is walking; in accordance with determining that the user is likely not walking, configuring, using the one or more processors, a heart rate model based on the predicted motion class; and estimating, using the configured heart rate model, a caloric expenditure of the user.

Apple's patent FIG. 1A below illustrates a compound exercise where the participant is lifting dumbbells while performing side squats; FIG. 1B illustrates three-dimensional (3D) motion in a wearable device body frame for side squat plus arm raise and front arm raise.