WO2010095934A1

WO2010095934A1 - Heartbeat analysis system and method for analyzing a sequence of heartbeats

Info

Publication number: WO2010095934A1
Application number: PCT/NL2010/000029
Authority: WO
Inventors: Constance Desiré VAN DER POEL
Original assignee: SUPERVISIE SPORTS BV
Current assignee: SUPERVISIE SPORTS BV
Priority date: 2009-02-20
Filing date: 2010-02-19
Publication date: 2010-08-26
Anticipated expiration: 2011-08-20

Abstract

The invention relates to a heartbeat analysis system with a detector for detecting a heartbeat, a timer for measuring time and, a calculator constructed and arranged to calculate in communication with the detection system and the timer a heart rate and a heart rate variability from a sequence of heartbeats. The system has a signaling system in communication with the calculator for providing a single signal to a person which is a function of the heart rate variability and the heart rate. Heart rate variability is calculated as the time difference between subsequent longest and shortest time intervals. The heart rate variability may be compared to a predetermined minimal heart rate variability.

Description

Title: Heartbeat analysis system and method for analyzing a sequence of heartbeats

BACKGROUND

Field of the Invention

The present invention relates to a heartbeat analysis system comprising: a detector for detecting a heartbeat; a timer for measuring time; and a calculator constructed and arranged to calculate in communication with the detection system and the timer a heart rate and a heart rate variability from a heart beat. The invention further relates to a method for analyzing a sequence of heartbeats comprising: detecting a heartbeat with a detector; using a timer; and calculating a heart rate variability and a heart rate with a calculator in communication with the detector and the timer.

Description of the Related Art The use of a heartbeat analysis system for physical training of a person may help a person to optimize its training or to warn for training which exceeds a person's capacity. In general heartbeat analysis systems focus on the heart rate (i.e. the number of heart beats per minute) of a person. The heart rate in normal circumstance however doesn't reflect much information of the physical state of a person and therefore the training cannot be optimized to the physical state of a person. The heart rate variability (HRV) is a measure of the beat-to-beat variations in the heart rate. HRV is regarded as an indicator of the activity of autonomic regulation of circulatory function and is believed to reflect information of the physical state of a person.

An electrocardiograph can be used as a heartbeat analysis system to determine the heart rate and the heart rate variability. The electrocardiograph may produce an electrocardiogram (ECG) which is a recording of the electrical activity of the heart over time produced by a usually noninvasive recording via skin electrodes. ECG's are complicated to interpret for a person, especially when he is concentrating on his training.

EP 1133950 discloses a system in which the user's heart rate and the standard deviation of the heart rate is measured. It is desirable to provide an improved heartbeat analysis system or an alternative for the above mentioned system.

According to an embodiment of the invention there is provided a heartbeat analysis system comprising: a detector for detecting a heartbeat; a timer for measuring time; and, a calculator constructed and arranged to calculate in communication with the detection system and the timer a heart rate and a heart rate variability from a sequence of heart beats, wherein the system is further provided with: an interval memory to store a series of time intervals between a series of subsequent heartbeats; a comparing unit for comparing the time intervals so as to determine the shortest and/or the longest time interval in a portion of the series of time intervals stored in the interval memory; the calculator is constructed and arranged to calculate a heart rate variability as the time difference between subsequent longest and shortest time intervals and the system comprises a signaling system in communication with the calculator for providing a single signal to a person which is a function of the heart rate variability and the heart rate. By providing a single signal which is a combination of the heart rate variability and the heart rate the signal is easier to interpret for a person. Since the signal is a combination of the heart rate variability and the heart rate the signal reflect also the physical state of a person better. By determining the heart rate variability a reliable signal can be provided which reflect the physical state of a person real time during an exercise. According to a further embodiment of the invention a method for analyzing a sequence of heartbeats is provided comprising: detecting a heartbeat with a detector; determining a series of time interval between a sequence of heartbeats using a timer; memorizing the series of time intervals into an interval memory; comparing the time intervals in the series of time intervals so as to determine the shortest and/or the longest time interval over a portion of the time intervals stored in the interval memory; calculating a heart rate variability as the difference between subsequent longest and shortest time intervals with a calculator; and, signaling a single signal to a person which is a function of the heart rate variability and the heart rate with a signal system which is in communication with the calculator. According to yet a further embodiment of the invention the invention relates to a use of a heartbeat analysis system according the invention for analyzing the heartbeat sequence during an exercise and signaling the signal during the exercise to the person.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which: - Figure 1 depicts a heartbeat analysis system apparatus according to an embodiment of the invention;

Figure 2 depicts a schematic view on the functions within the watch 5 of figure 1 ; Figure 3a depicts a depicts a series of heartbeat intervals; and, Figure 3b depicts a diagram of the heart rate variability HRV and the heart rate HF.

DETAILED DESCRIPTION

Figure 1 depicts a heartbeat analysis system according to an embodiment of the invention which is worn by a person or user 1. The heartbeat analysis system comprises a detector 3 for detecting a heartbeat of the user 1. The heartbeat analysis system is provided with a timer, a calculator and a signaling system which is provided to a watch 5. The watch 5 is in radiographic communication with the antenna 4 of the detector 3 to provide freedom to the user 1 in his or her sports activity. The calculator is constructed and arranged to calculate in communication with the detection system 3 and the timer a heart rate and a heart rate variability from a sequence of heartbeats, wherein the system comprises a signaling system in communication with the calculator for providing a single signal to the user which is a function of the heart rate variability and the heart rate on a display of the watch 5. The calculator, timer and signaling system may also be provided in a separate unit which will not be worn by the user. Figure 2 depicts a schematic view on the functions within the watch 5 of figure 1. The watch 5 is provided with an antenna 7 for wireless communication with the detector 3 via the antenna 4 of figure 1.The antenna 7 is connected with the calculator 13. The calculator is also connected to the timer 11 and the signaling system 9. The calculator 13 may calculate a heart rate from the heartbeats received from the detector 3. This may be done by counting - A -

the heartbeats per minute received from the timer in the calculator 13 which produces the heart rate.

The heartbeat analysis system is provided with an interval memory 10 to store a series of time intervals between a series of subsequent heartbeats. The time intervals are calculated by the calculator 13 in response to a heartbeat signal received via the antenna 7 and a timing signal from the timer 11. The calculator 13 may subtract the time signal (t(n)) of a first heartbeat of the time of a subsequent time signal (t(n+1)) of a subsequent heartbeat to calculate an heartbeat interval and store it in the interval memory 10. Alternatively, the timer 11 may be designed so that each heartbeat received via the calculator 13 may reset the timer 11 to zero and just before the reset the time is saved in the interval memory 10.

The interval memory 10 may be connected to a comparing unit 12 for comparing the time intervals in the interval memory. The comparing unit may determine the shortest and/or the longest time interval in a portion of the series of time intervals stored in the interval memory 10. The comparing unit 10 is connected to the calculator 13 and the calculator 13 is calculating a time difference between subsequent longest and shortest time intervals which is the heart rate variability.

A memory 15 may function as a minimal heart rate variability memory for storing a predetermined minimal heart rate variability. This minimal heart rate variability may be 50 milliseconds, preferably 25 milliseconds, more preferably 10 millisecond and most preferably 5 milliseconds. The minimal heart rate variability may be programmed upfront or it may be programmed by the user.

A controller 17 may compare the minimal heart rate variability in the memory 15 with the heart rate variability calculated by the calculator 13. If the heart rate variability calculated by the calculator 13 is longer than the minimal heart rate variability in the memory 15 the controller 17 will use the heart rate variability for producing a signal to the signaling system 9. If the heart rate variability calculated by the calculator is shorter than the heart rate variability in the memory 15 the controller 17 will use the heart rate for producing a signal to the signaling system 9. The controller 17 may store the heart rate at the moment the heart rate variability is equal to the minimal heart rate variability as a reference value in the memory 15.

The heartbeat analysis system may be provided with a wireless connection for connecting the heartbeat analysis system to a computer. Also multiple heartbeat analysis systems may be connected wireless to a computer so that multiple people doing an exercise can be monitored simultaneously during a work out. Figure 3a depicts a series of heartbeat intervals 21 in milliseconds (ms) as a function of time (t). The series of heartbeat intervals were the result of heartbeats detected during an exercise with increasing intensity in time. The first three heartbeats detected 22 indicate an increase in the heartbeat intervals. The fourth heartbeat 23 has a shorter time interval than the third and therefore the third heartbeat indicates a longest time interval 24. The comparing unit 12 may compare all four intervals and conclude from first the increase in time intervals and suddenly the decrease of the interval with the fourth interval the one before the fourth interval is the longest. Equally the comparing unit 12 may compare the time intervals before the shortest time interval 25 with the time interval after shortest time interval 25 to conclude that time interval 25 is the shortest time interval. The calculator 13 can calculate a heart rate variability 26 by subtracting the minimal time interval 25 from the longest time interval 24. The series of heartbeat intervals 21 makes it clear that during an exercise with progressing intensity the heart rate variability decreases. For example, the heart rate variability 27 is much smaller than the heart rate variability 26. Timeline t is not to scale and the exercise may take many more measurement points than as depicted here to get a decrease in the heart rate variability as depicted between 26 and 27. The minimal time interval and the longest time interval may be taken form a portion of the series of time intervals. The portion may be preferably at least 20, more preferably 10, even more preferably 5 heart beats. The portion of the time intervals compared by the comparing unit may be a function of the number of heartbeats between the shortest time interval and the longest time interval. The comparing unit may use the derivative of the series of heartbeat interval to determine what the shortest and the longest time intervals are. A chance of the derivative from increase to decrease indicates the longest time interval 24 as well as a chance from decrease to increase indicates a shortest time interval 25. The portion of the series of the time intervals that should be compared in the comparing unit should preferably comprise one decrease and one increase in the time intervals to provide enough time intervals to make a good comparison possible. The system may optionally be constructed and arranged to calculate inspiration and expiration times for the series of time intervals. A decrease in time intervals (between 24 and 25) represents a period of inspiration (inhalation) of air into the lungs and an increase in time interval represents a period of expiration (exhalation) from the lungs. A respiration quotient may be calculated by dividing the inspiration time by the expiration time in the calculation unit 13.

The heartbeat analysis system according to the invention may be used during an exercise. The system may provide direct feedback to the person during the exercise. For example all the persons participating in a spinning class may be provided with the heartbeat analysis system so that each of them may be provided with direct feedback on his or her exercise. The teacher may be provided with a wireless e.g. wifi system which gives the teacher information of different persons doing the exercise and, optionally, a feedback of the complete class. Figure 3b depicts a diagram of the heart rate variability 31 with respect to axis HRV and the heart rate 33 with respect to axis HF as function of the time a person wearing a heart beat detector is doing a training with increasing intensity. The controller 17 may compare the heart rate variability with the minimal heart rate variability and if the heart rate variability is longer than the minimal heart rate variability send a first signal to the signaling system which makes the signaling system to emit a light with a first color, for example yellow. If the heart rate variability after, for example 8 minutes of exercise becomes equal to the memorized minimal heart rate variability (e.g. 5 milliseconds) at point 35 the heart rate (e.g. 130 beats per minute) at point 37 wil memorized in the memory 15 and the calculator will send a second signal to the signaling system which in response may emit a light with a second color, for example green. The second signal will be send to the signaling system until the heart rate becomes higher than a first factor (e.g. 1.1) multiplied with the memorized heart rate (130) is 143 at point 39. If the heart rate becomes higher than 143 a third signal will be send to the signaling system which in response will emit light with a third color, for example blue. If the heart rate becomes higher than a second factor (e.g. 1.2) multiplied with the memorized heart rate (130) is 156 at point 41 a fourth signal will be send to the signaling system which in response will emit light with a fourth color, for example orange. If the heart rate becomes higher than a third factor (e.g. 1.3) multiplied with the memorized heart rate (130) is 169 at point 43 a fifth signal will be send to the signaling system which in response will emit light with a fifth color, for example red. The red signal may indicate that the person should decrease his or her training activity. The red signal may be accompanied with a sound signal to alert the person. The system also works the other way, so that when the heart rate becomes lower than 169 the orange color will appear again. This makes it very easy for a user to train with a chosen intensity which via the heart rate variety is related to the user his physical state.

In addition to the above mentioned system it is also possible to provide two colors if the heart rate variability is longer than the memorized minimal heart rate variability, for example the color white can be depicted for a heart rate variability which is longer than 10 millisecond and between 10 and 5 milliseconds the color yellow can be used. The signaling system may be provided with a tactile signaling system for providing a tactile signal to a person. For example, the tactile signaling system may be a vibrating or temperature controlled part which is in contact with a skin of a user to provide a signal to the user.

The signaling system may be a visual indicator for providing a visual indication to the user, or a trainer who is supervising the training. The visual indicator may comprise lights or a visual display unit. The signaling system may comprise an acoustic indicator for providing an acoustic indication to the user, or a trainer who is supervising the training.

In the example the predetermined minimal heart rate variability is 5 milliseconds but also 10, 25, or 40 milliseconds may be chosen and stored in the memory 15. The heart rate variability may be used to calculate an inspiration and an expiration time of a person with the calculator 13 and a respiration quotient by dividing the inspiration time by the expiration time.

While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. For example, the invention may take the form of a computer program containing one or more sequences of machine-readable instructions describing a method as disclosed above. If the computer program is run on a computer receiving data from a heartbeat detector, the computer program may instruct the computer to determine a series of time interval between a sequence of heartbeats; memorize the series of time intervals into a computer memory; compare the time intervals in the series of time intervals so as to determine the shortest and/or the longest time interval over a portion of the time intervals stored in the computer memory; calculate a time difference between subsequent longest and shortest time intervals with a calculator; and, provide a graph of the person which is a function of the heart rate variability and the heart rate. The invention relates to a data storage medium (e.g. semiconductor memory, magnetic or optical disk) having such a computer program stored therein.

The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.

Claims

1. A heartbeat analysis system comprising: a detector for detecting a heartbeat; a timer for measuring time; and, a calculator constructed and arranged to calculate in communication with the detection system and the timer a heart rate and a heart rate variability from a sequence of heartbeats, wherein the system is further provided with: an interval memory to store a series of time intervals between a series of subsequent heartbeats; a comparing unit for comparing the time intervals so as to determine the shortest and/or the longest time interval in a portion of the series of time intervals stored in the interval memory; and, the calculator is constructed and arranged to calculate a heart rate variability as the time difference between subsequent longest and shortest time intervals and the system comprises a signaling system in communication with the calculator for providing a single signal to a person which is a function of the heart rate variability and the heart rate.

2. The heartbeat analysis system according to claim 1 , wherein the calculator is constructed and arranged to calculate the series of time intervals from a signal from the timer and the detector.

3. The system according to claim 1 , wherein the portion of time intervals compared by the comparing unit is preferably at least 20, more preferably 10, even more preferably 5 heart beats.

4. The system according to the claim 1 , wherein the portion of the time intervals compared by the comparing unit is a function of the number of heartbeats between the shortest time interval and the longest time interval.

5. The system according to any of claims 1 to 4, wherein the system is provided with a variability memory for storing a predetermined minimal heart rate variability.

6. The system according to claim 5, wherein the signal which the system provides to a person is a function of the heart rate variability if the heart rate variability is higher than the predetermined minimal heart rate variability stored in the variability memory and the signal is a function of the heart rate if the heart rate variability is lower than the predetermined minimal heart rate variability stored in the variability memory.

7. The system according to claim 5, wherein the system comprises a heart rate memory 5 which stores the heart rate at the predetermined minimal heart rate variability stored in the variability memory to provide a reference value.

8. The system according to claim 7, wherein the system is constructed and arranged to compare the heart rate with the reference value and for providing a signal to the person

10 being a result from that comparison.

9. The system according to claim 1, wherein the signaling system comprises a tactile signaling system for providing a tactile signal to a person.

15 10. The system according to claim 1 , wherein the signaling system comprises a visual indicator such as lights or a visual display unit for providing a visual indication to the person.

11. The system according to claim 1 , wherein the signaling system comprises an acoustic indicator for providing an acoustic indication to the person.

20

12. The system according to any of the preceding claims, wherein the predetermined heart rate variability is lower than 25 millisecond, preferably lower than 5 millisecond.

13. Method for analyzing a sequence of heartbeats comprising: 25 detecting a heartbeat with a detector; determining a series of time interval between a sequence of heartbeats using a timer; memorizing the series of time intervals into an interval memory; comparing the time intervals in the series of time intervals so as to determine the shortest and/or the longest time interval over a portion of the time intervals stored in the 30 interval memory; calculating a heartbeat variability as the difference between subsequent longest and shortest time intervals with a calculator; and, signaling a single signal to a person which is a function of the heart rate variability and the heart rate with a signal system which is in communication with the calculator. 35

14. Method according to claim 13, wherein the method comprises memorizing a predetermined minimal hart rate variability and memorizing the heart rate if the heart rate variability is equal to the predetermined minimal heart rate variability and the method comprises if the heart rate variability is higher than the predetermined minimal heart rate variability signaling a first signal, if the heart rate variability is lower than the predetermined minimal heart rate variability: 5 signaling a second signal if the heart rate is higher than the memorized heart rate and lower than a first factor multiplied with the memorized heart rate; signaling a third signal if the heartbeat frequency is higher than the first factor multiplied with the memorized heart rate and lower than a second factor multiplied with the memorized heart rate; 10 signaling a fourth signal if the heart rate is higher than the second factor multiplied with the memorized heart rate and lower than a third factor multiplied with the memorized heart rate; and, signaling a fifth signal if the heart rate is higher than the third factor multiplied with the memorized heart rate. 15

15. Method according to claim 13, wherein the method comprises analyzing the sequence of heartbeats during an exercise and signaling the signal during the exercise to the person.

20 16. Use of a heartbeat analysis system according to claim 1 for analyzing the sequence of heartbeats during an exercise and signaling the signal during the exercise to the person.