Detecting unmeasurable loads using heart rate and work rate

• US 10,687,752 B2
• Filed: 08/29/2017
• Issued: 06/23/2020
• Est. Priority Date: 08/29/2016
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Pham, Hung A., Raghuram, Karthik Jayaraman, Zhang, Hengliang, Arnold, Edith Merle
• Primary Examiner(s): Hindenburg, Max F
• Application Number:
  US15/689,113
• Publication Number:
  US 20180055439A1
• Time in Patent Office: 1,029 Days
• CPC Class Codes: A61B 2505/09 Rehabilitation or training
• CPC Class Codes: A61B 2560/0209 adapted for power saving
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/1107 Measuring contraction of parts of the body, e.g. organ, muscle apparatus for measuring work or force in general G01L
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/1123 Discriminating type of movement, e.g. walking or running A61B5/1116, A61B5/112 take precedence
• CPC Class Codes: A61B 5/222 combined with detection or measurement of physiological parameters, e.g. heart rate
• CPC Class Codes: A61B 5/681 Wristwatch-type devices

Abstract

A method and a system for determining an energy expenditure of a user by detecting unmeasurable loads using heart rate and work rate are described. Time-stamped heart rate data and work rate data can be collected by one or more sensing modules. A processor circuit can calculate a heart rate-based energy expenditure and a work rate-based energy expenditure. The processor circuit can output a hybrid energy expenditure based on a heart rate confidence parameter, an exercise type, a fraction of heart rate reserve, and a hear rate-based metabolic equivalents of task.

Claims

1. A method for determining an energy expenditure of a user with a wearable device, the method comprising:

determining, by a processor circuit of the wearable device, a start of an exercise session for the user;

detecting, by the processor circuit, an exercise type associated with the exercise session wherein the exercise type is walking or running;

measuring, by a heart rate sensing module of the wearable device, heart rate data of the user, wherein the heart rate sensing module comprises a photoplethysmogram (PPG) sensor and the PPG sensor is configured to be worn adjacent to the user'"'"'s skin;

applying, by the processor circuit, a first time stamp to the measured heart rate data;

collecting, by one or more work rate sensing modules of the wearable device, work rate data of the user;

applying, by the processor circuit, a second time stamp to the collected work rate data;

calculating, by the processor circuit, a heart rate-based energy expenditure based on the heart rate data measured at the first time stamp;

calculating, by the processor circuit, a work rate-based energy expenditure based on the work rate data collected at the second time stamp;

determining, by the processor circuit, an energy expenditure of the user based on the calculated heart rate-based energy expenditure and the calculated work rate-based energy expenditure; and

outputting the energy expenditure of the user.

2. The method of claim 1, wherein calculating the heart rate-based energy expenditure comprises:

measuring, by the heart rate sensing module, a maximum heart rate and a resting heart rate;

determining, by the processor circuit, a heart rate confidence parameter based on the measured heart rate data;

calculating, by the processor circuit, a fraction of heart rate reserve (FHR) based on the measured heart rate data, the maximum heart rate, and the resting heart rate; and

calculating, by the processor circuit, the heart rate-based energy expenditure based on the FHR.

3. The method of claim 2, wherein determining the energy expenditure of the user comprises:

determining the energy expenditure of the user as the calculated work rate-based energy expenditure when;

the determined heart rate confidence parameter is less than a pre-defined heart rate confidence threshold,

the detected exercise type is running and the calculated fraction of heart rate reserve is greater than a pre-defined fraction of heart rate reserve threshold, or

the detected exercise type is walking and a heart rate-based metabolic equivalents of task is greater than a pre-defined metabolic equivalents of task threshold; and

determining the energy expenditure of the user as the greater of the calculated heart rate-based energy expenditure and the calculated work rate-based energy expenditure when;

the determined heart rate confidence parameter is greater than or equal to a pre-defined heart rate confidence threshold,

the detected exercise type is running and the calculated fraction of heart rate reserve is less than or equal to a pre-defined fraction of heart rate reserve threshold, or

the detected exercise type is walking and a heart rate-based metabolic equivalents of task is less than or equal to a pre-defined metabolic equivalents of task threshold.

4. The method of claim 3, wherein the pre-defined metabolic equivalents of task threshold is between 0 and 50.

5. The method of claim 1, wherein determining the start of the exercise session comprises determining the start of the exercise session in response to receiving an input from the user.

6. The method of claim 1, wherein the one or more work rate sensing modules comprises a motion sensing module.

7. The method of claim 6, wherein the motion sensing module comprises at least one of an accelerometer, a gyroscope, a magnetometer, an altimeter, a barometer, or a GPS sensor.

8. A system for determining an energy expenditure of a user with a wearable device, the system comprising:

a heart rate sensing module configured to measure heart rate data of the user, wherein the heart rate sensing module comprises a photoplethysmogram (PPG) sensor and the PPG sensor is configured to be worn adjacent to the user'"'"'s skin;

one or more work rate sensing modules configured to collect work rate data of the user; and

a processor circuit in communication with the heart rate sensing module and the one or more work rate sensing modules and configured to execute instructions causing the processor circuit to;

determine a start of an exercise session for the user;

detect an exercise type associated with the exercise session, wherein the exercise type is walking or running;

apply a first time stamp to the measured heart rate data;

apple a second time stamp to the collected work rate data;

calculate a heart rate-based energy expenditure based on the heart rate data measured at the first time stamp;

calculate a work rate-based energy expenditure based on the work rate data collected at the second time stamp;

determine an energy expenditure of the user based on the calculated heart rate-based energy expenditure and the calculated work rate-based energy expenditure; and

output the energy expenditure of the user.

9. The system of claim 8, wherein the heart rate sensing module is configured to measure a maximum heart rate and a resting heart rate, and the instructions further cause the processor circuit to:

determine a heart rate confidence parameter based on the collected heart rate data;

calculate a fraction of heart rate reserve (FHR) based on the collected heart rate data, the maximum heart rate, and the resting heart rate; and

calculate a heart rate-based energy expenditure based on the FHR.

10. The system of claim 8, wherein the instructions further cause the processor circuit to:

determine the energy expenditure of the user as the calculated work rate-based energy expenditure when;

the determined heart rate confidence parameter is less than a pre-defined heart rate confidence threshold,

the detected exercise type is running and the calculated fraction of heart rate reserve is greater than a pre-defined fraction of heart rate reserve, or

the detected exercise type is walking and a heart rate-based metabolic equivalents of task is greater than a pre-defined metabolic equivalents of task threshold; and

determine the energy expenditure of the user as the greater of the calculated heart rate-based energy expenditure and the calculated work rate-based energy expenditure when;

the determined heart rate confidence parameter is greater than or equal to a pre-defined heart rate confidence threshold,

the detected exercise type is running and the calculated fraction of heart rate reserve is less than or equal to a pre-defined fraction of heart rate reserve, or

the detected exercise type is walking and a heart rate-based metabolic equivalents of task is less than or equal to a pre-defined metabolic equivalents of task threshold.

11. The system of claim 10, wherein the pre-defined metabolic equivalents of task threshold is between 0 and 50.

12. The system of claim 8, wherein the one or more work rate sensing modules comprises a motion sensing module.

13. The system of claim 12, wherein the motion sensing module comprises at least one of an accelerometer, a gyroscope, a magnetometer, an altimeter, a barometer, or a GPS sensor.

14. A mobile device comprising:

a wearable case;

a heart rate sensing module disposed in the wearable case and configured to measure heart rate data of the user, wherein the heart rate sensing module comprises a photoplethysmogram (PPG) sensor and the PPG sensor is configured to be worn adjacent to the user'"'"'s skin;

one or more work rate sensing modules configured to collect work rate data of the user; and

a processor circuit in communication with the heart rate sensing module and the one or more work rate sensing modules and configured to execute instructions causing the processor circuit to;

determine a start of an exercise session for the user;

detect an exercise type associated with the exercise session, wherein the exercise type is walking or running;

apply a first time stamp to the measured heart rate data;

apple a second time stamp to the collected work rate data;

calculate a heart rate-based energy expenditure based on the heart rate data measured at the first time stamp;

calculate a work rate-based energy expenditure based on the work rate data collected at the second time stamp;

determine an energy expenditure of the user based on the calculated heart rate-based energy expenditure and the calculated work rate-based energy expenditure; and

output the energy expenditure of the user.