Method and system to determine anaerobic threshold of a person non-invasively from freely performed exercise and to provide feedback on training intensity
A method and system for determining anaerobic threshold intensity (AnT) of a user in a freely performed physical exercise. A physiological response of a user is measured by heart rate and measured heart rate values are recorded as heart rate data. An external workload values are recorded and are each associated with one measured heart rate values to form a plurality of data points. The data points are filtered to form accepted data points, which are classified within a plurality of heart rate segments representing a heart rate within an anaerobic threshold (AnT) of the user. A data point with highest probability is stored for each segment. A first probability factor for each accepted data point is calculated. The calculated first probability factor is compared to a stored probability factor in each segment, and the higher probability factor is retained. AnT is calculated using the stored probabilities in each segment.
1. A method for determining anaerobic threshold intensity (AnT) of a user in a freely performed physical exercise, comprising:
continuously measuring, by a heart rate sensor, a physiological response of a user by heart rate, wherein a plurality of measured heart rate values are recorded with time stamps as heart rate data;
continuously measuring an external workload including at least one of speed and velocity, wherein a plurality of measured workload values are recorded and each measured workload value is associated with one of the plurality of measured heart rate values to form a plurality of data points;
filtering, by a processor, one or more data points based on a predetermined criteria to form a plurality of accepted data points;
classifying, by the processor, accepted data points within a plurality of heart rate segments representing a heart rate within an anaerobic threshold (AnT) of the user, wherein at least one segment is below a probable heart rate value of AnT, and at least one segment is above the probable heart rate value of AnT;
calculating, by the processor, a first probability factor for each of the plurality of accepted data points based on the measured external workload value and a measured heart rate variability of each data point;
comparing, by the processor, the calculated first probability factor with at least one probability factor in a respective segment, and if the first probability factor is higher than the at least one stored probability factor, the first probability factor replaces the at least one stored probability factor in the respective segment so that the data point with the highest first probability factor is stored in a memory for each segment;
calculating, by the processor, an estimate of the user's AnT as a weighted value of heart rate values recorded for each segment, wherein each recorded heart rate value in each segment is multiplied by the first probability factor stored for that segment when all weighted values are added together;
outputting, by the processor to a display, the estimate of the user's AnT.
2. The method of claim 1 , wherein the first probability factor is calculated based on the relationship between current measured external workload and highest measured external workload, and the relationship between current measured heart rate variability level and lowest measured heart rate variability level.
3. The method of claim 2 , wherein the first probability factor (P1) is calculated according to the equation:
P 1=(1500−100*( v max− v )−600*(MAD−MADmin))/15,
wherein v=current measured external workload as at least one of current speed or velocity, vmax=highest measured external workload as at least one of highest speed or velocity, MAD=current measured heart rate variability level, and MADmin=lowest measured heart rate variability level.
4. The method of claim 1 , wherein the estimate of the user's AnT as a weighted value of the recorded heart rates (HR) of each segment (i) is calculated according to the equation:
An
T
(
t
)
=
∑
(
HR
[
i
]
*
(
P
[
i
]
y
)
∑
(
P
[
i
]
y
)
wherein P[i] is the first probability factor stored for each segment (i), and y is a chosen power value.
5. The method of claim 1 , wherein the estimate of the user's AnT can be displayed to the user during the exercise or after the exercise.
6. The method of claim 1 , wherein the estimate of the user's AnT can be displayed to the user as a value describing external workload.
7. The method of claim 1 , wherein the plurality of heart rate segments include 5-30 segments.
8. The method of claim 7 , wherein the size of each segment is 0.5-3% of the user's maximum heart rate.
9. A system for determining anaerobic threshold intensity (AnT) of a user in a freely performed physical exercise, comprising:
means for continuously measuring a physiological response of a user by heart rate, wherein a plurality of measured heart rate values are recorded with time stamps as heart rate data;
means for continuously measuring an external workload including at least one of speed and velocity, wherein a plurality of measured workload values are recorded and each measured workload value is associated with one of the plurality of measured heart rate values to form a plurality of data points;
means for filtering one or more data points based on a predetermined criteria to form a plurality of accepted data points;
means for classifying accepted data points within a plurality of heart rate segments representing a heart rate within an anaerobic threshold (AnT) of the user, wherein at least one segment is below a probable heart rate value of AnT, and at least one segment is above the probable heart rate value of AnT;
means for calculating a first probability factor for each of the plurality of accepted data points based on the measured external workload value and a measured heart rate variability of each data point;
means for comparing the calculated first probability factor with at least one stored probability factor in a respective segment, and if the first probability factor is higher than the at least one stored probability factor, the first probability factor replaces the at least one stored probability factor in the respective segment so that the data point with the highest first probability factor is stored for each segment;
means for calculating an estimate of the user's AnT as a weighted value of heart rate values recorded for each segment, wherein each recorded heart rate value in each segment is multiplied by the first probability factor stored for that segment when all weighted values are added together; and
means for outputting and displaying the estimate of the user's AnT.
10. The system of claim 9 , wherein the first probability factor is calculated based on the relationship between current measured external workload and highest measured external workload, and the relationship between current measured heart rate variability and lowest measured heart rate variability level.
11. The system of claim 9 , wherein the estimate of the user's AnT can be displayed to the user during the exercise or after the exercise.
12. The system of claim 9 , wherein the plurality of heart rate segments include between 5-30 consecutive 0.5-3% segments of the maximum heart rate of the user.
13. A method for determining anaerobic threshold intensity (AnT) of a user in a freely performed physical exercise, comprising:
continuously measuring, by a heart rate sensor, a physiological response of a user by heart rate, wherein a plurality of measured heart rate values are recorded with time stamps as heart rate data;
continuously measuring an external workload including at least one of speed and velocity, wherein a plurality of measured workload values are recorded and each measured workload value is associated with one of the plurality of measured heart rate values to form a plurality of data points;
filtering, by a processor, one or more data points based on a predetermined criteria to form a plurality of accepted data points;
classifying, by the processor, accepted data points within a plurality of heart rate segments representing a heart rate within an anaerobic threshold (AnT) of the user, wherein at least one segment is below a probable heart rate value of AnT, and at least one segment is above the probable heart rate value of AnT;
calculating, by the processor, a first probability factor for each of the plurality of accepted data points based on at least the measured external workload value and a measured heart rate variability of each data point;
comparing, by the processor, the calculated first probability factor with at least one stored probability factor in a respective segment, and if the first probability factor is higher than the at least one stored probability factor, the first probability factor replaces the at least one stored probability factor in the respective segment so that the data point with the highest first probability factor is stored in a memory for each segment;
calculating, by the processor, AnT using the stored probabilities in each segment; and
outputting, by the processor to a display, the estimate of the user's AnT.
14. The method of claim 13 , wherein the first probability factor is calculated based on the relationship between current external workload and highest measured external workload, and the relationship between current and lowest measured heart rate variability level.
15. The method of claim 13 , wherein the first probability factor (P1) is calculated according to the equation:
P 1=(1500−100*( v max− v )−600*(MAD−MADmin))/15,
wherein v=current external workload as at least one of current speed or velocity, vmax=highest measured external workload as at least one of highest speed or velocity, MAD=current heart rate variability level, and MADmin=lowest measured heart rate variability level.
16. The method of claim 15 , wherein the estimate of the user's AnT as a weighted value of the highest recorded heart rates (HR) of each segment (i) is calculated according to the equation:
An
T
(
t
)
=
∑
(
HR
[
i
]
*
(
P
[
i
]
y
)
∑
(
P
[
i
]
y
)
wherein P[i] is the first probability factor stored for each segment (i) and y is a chosen power value.
17. The method of claim 13 , wherein the plurality of heart rate segments includes 5-30 segments.
18. The method of claim 13 , wherein the plurality of heart rate segments includes 6-15 segments.
19. The method of claim 18 , wherein a size of each segment is 0.5-3% of the user's maximum heart rate.
20. The method of claim 13 , wherein a final AnT estimate is calculated from at least two AnT estimates weighted by a chosen criteria.
21. The method of claim 13 , wherein an AnT estimate is given to a user only if exercise heart rate reaches a chosen limit.