Method and system to determine anaerobic threshold of a person non-invasively from freely performed exercise and to provide feedback on training intensity

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, said means disposed on the body of the user, wherein a plurality of measured heart rate values are recorded with time stamps as heart rate data forming a recorded heart rate of the user;
• means for continuously measuring an external workload in terms of speed and inclination or measured power, 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 calculating heart rate variability (HRV) values from intervals between successive heartbeats and storing each calculated HRV value associating to a data point;
• 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 (i) 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 (P1) for each of the plurality of accepted data points based on the measured external workload value and a calculated heart rate variability value 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 stored probability factor is updated by the probability factor;
• means for determining whether a second probability factor (P2) needs to be created or updated, and for calculating the second probability factor of each stored data point for each respective segment based on a deviation between change in recorded external workload and expected change in external workload;
• means for determining whether a third probability factor (P3) needs to be created or updated, and for calculating the third probability factor of each stored data point for each respective segment based on the recorded heart rate of the user in proportion to the maximum heart rate of the user;
• means for calculating a total probability (P) of each recorded heart rate in each segment using the first probability factor, the second probability factor, and the third probability factor wherein the total probability is derived from a sum of the first probability factor, the second probability factor, and the third probability factor, the sum being raised by the power of a constant;
• 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 total probability stored for that segment when all weighted values are added together;
• means for outputting the estimate of the user's AnT to an output device.

A method for determining anaerobic threshold intensity (AnT) of a user in a freely performed physical exercise, comprising:

• continuously measuring, by a body-mounted 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 forming a recorded heart rate of the user;
• continuously measuring an external workload in terms of speed and inclination or measured power, 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;
• calculating, by a processor, heart rate variability (HRV) values from intervals between successive heartbeats and storing each calculated heart rate variability value associating to a data point;
• filtering, by a processor, one or more data points based on a predetermined criteria to form a plurality of accepted data points;
• classifying, by a processor, accepted data points within a plurality of heart rate segments (i) 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, wherein a data point with highest probability is stored for each segment;
• calculating, by a processor, a first probability factor (P1) for each of the plurality of accepted data points based on at least the measured external workload value and a calculated heart rate variability value of each data point;
• retrieving, by the processor, from a set of stored probability data, at least one stored probability factor for a respective segment, the set of stored probability data further comprising a second probability factor (P2) and a third probability factor (P3);
• comparing, by a processor, the calculated first probability factor with the at least one stored probability factor in the respective segment, and if the first probability factor is higher than the at least one stored probability factor, the stored probability factor is updated by the first probability factor, and at least one further calculation is triggered to update stored probability data other than with the first probability factor;
• and
• calculating, by a processor, AnT using the stored probabilities in each segment;
• and
• outputting, to an output device, the estimate of the user's AnT to an output device.