Energy Expenditure Computation Based On Accelerometer And Heart Rate Monitor

• US 20140213920A1
• Filed: 01/31/2013
• Published: 07/31/2014
• Est. Priority Date: 01/31/2013
• Status: Active Grant

• Current Assignee: Salutron, Inc.
• Original Assignee: Salutron, Inc.
• Inventors: Lee, Yong Jin, Hui, Eddy, Chen, Kaiping
• Granted Patent: US 9,089,285 B2
• Time in Patent Office: Days
• US Class Current: 600/509
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/222 combined with detection or measurement of physiological parameters, e.g. heart rate
• CPC Class Codes: A61B 5/4866 Evaluating metabolism A61B5/083 takes precedence
• CPC Class Codes: A61B 5/681 Wristwatch-type devices

Abstract

An activity monitor such as a wrist-worn device has an accelerometer which continuously detects motion of the user. The activity monitor also has an on-demand heart rate monitor which is activated by the user touching it from time to time. A calorie expenditure based on the motion of the user can be modified based on a heart rate measurement. Further, a determination can be made as to whether the user has made repetitive motions for a period of time. If the repetitive motions are detected, a calorie expenditure based on the heart rate is determined and compared to the calorie expenditure based on the user motion, and the higher value prevails. A situation is avoided in which the activity monitor underestimates the calories expended, such as when the user is exercising strenuously but the accelerometer indicates relatively little motion, e.g., during strength training.

Claims

1. An activity monitor, comprising:

an accelerometer, the accelerometer is adapted to measure activity of a user during a monitoring period;

an on-demand heart rate monitor, the on-demand heart rate monitor is adapted to measure a heart rate of the user in response to the user touching the heart rate monitor at an end of the monitoring period; and

a processor, the processor is in communication with the accelerometer and the on-demand heart rate monitor, the processor determines an activity-based energy expenditure during the monitoring period based on the activity and a heart rate-based energy expenditure based on the heart rate and provides an output energy expenditure for the monitoring period based on a comparison of the activity-based energy expenditure with the heart rate-based energy expenditure.

2. The activity monitor of claim 1, wherein:

the heart rate-based energy expenditure comprises a calorie burn rate based on the heart rate; and

the activity-based energy expenditure comprises a calorie burn rate during the monitoring period.

3. The activity monitor of claim 1, wherein:

the processor makes a determination that the measured activity indicates the user has performed a repetitive activity in a time period during the monitoring period; and

the processor provides the output energy expenditure using the heart rate-based energy expenditure during the time period in response to the determination.

4. The activity monitor of claim 3, wherein:

the processor provides the output energy expenditure using the activity-based energy expenditure but not the heart rate-based energy expenditure during a remainder of the monitoring period.

5. The activity monitor of claim 3, wherein:

the repetitive activity indicates that the user has been exercising by strength training during the time period.

6. The activity monitor of claim 3, wherein:

the activity of the user which is measured by the accelerometer comprises accelerations of the user; and

the processor evaluates at least one of a frequency, a magnitude and a number of zero crossings of the accelerations to determine that the user has performed the repetitive activity in the time period.

7. The activity monitor of claim 1, wherein:

the processor makes a determination that the measured activity indicates the user has not performed a repetitive activity during the monitoring period; and

the processor provides the output energy expenditure using the heart rate-based energy expenditure for a predetermined period during the monitoring period.

8. The activity monitor of claim 7, wherein:

the processor provides the output energy expenditure using the activity-based energy expenditure during a remainder of the monitoring period.

9. The activity monitor of claim 1, wherein:

the activity of the user which is measured by the accelerometer comprises accelerations of the user; and

the processor determines the activity-based energy expenditure based on at least one of a frequency, a magnitude and a number of zero crossings of the accelerations.

10. The activity monitor of claim 1, further comprising:

a display device, the processor is in communication with the display device, and the display device is adapted to display the output energy expenditure in response to the user touching the heart rate monitor.

11. The activity monitor of claim 1, wherein:

the on-demand heart rate monitor comprises an ECG heart rate monitor comprising a plurality of electrodes and measures the heart rate in response to the user touching at least one of the electrodes.

12. A method for determining an energy expenditure by a user, comprising:

obtaining acceleration readings of a user over a time period;

determining an activity-based energy expenditure of the user in the time period based on the acceleration readings;

obtaining a heart rate of the user after the time period;

determining a heart rate-based energy expenditure of the user in the time period based on the heart rate of the user;

comparing the activity-based energy expenditure to the heart rate-based energy expenditure; and

providing an energy expenditure output to the user based on the comparing.

13. The method of claim 12, wherein:

the energy expenditure output is between the activity-based energy expenditure and the heart rate-based energy expenditure if the heart rate-based energy expenditure is different than the activity-based energy expenditure.

14. The method of claim 12, wherein:

the energy expenditure output is equal to the heart rate-based energy expenditure if the heart rate-based energy expenditure is greater than the activity-based energy expenditure.

15. The method of claim 12, wherein:

the energy expenditure output is equal to the activity-based energy expenditure if the activity-based energy expenditure is greater than the heart rate-based energy expenditure.

16. The method of claim 12, further comprising:

determining based on the acceleration readings that the user has performed a repetitive activity over the time period, the comparing is responsive to the determining that the user has performed the repetitive activity over the time period.

17. The method of claim 16, wherein:

the repetitive activity indicates that the user has been exercising by strength training

18. The method of claim 12, wherein:

the heart rate is obtained from an on-demand heart rate monitor in response to the user touching an electrode of the heart rate monitor.

19. A computer-readable storage apparatus having computer-readable software embodied thereon for programming a processor to perform a method, the method comprising:

obtaining acceleration readings of a user;

determining based on the acceleration readings that the user has performed a repetitive activity;

determining a time period of the repetitive activity;

determining an activity-based energy expenditure of the user in the time period based on the acceleration readings;

obtaining a heart rate of the user after the time period from an on-demand heart rate monitor;

determining a heart rate-based energy expenditure of the user in the time period based on the heart rate of the user;

comparing the activity-based energy expenditure to the heart rate-based energy expenditure; and

providing an energy expenditure output to the user based on the comparing.

20. The computer-readable storage apparatus of claim 19, wherein the method further comprises:

providing the energy expenditure output equal to the heart rate-based energy expenditure.