CN-121971069-A - Oxygen-free threshold value calculation method and system based on dynamic change of concentration of carbon dioxide at end of expiration

CN121971069ACN 121971069 ACN121971069 ACN 121971069ACN-121971069-A

Abstract

The invention provides a portable oxygen-free threshold value calculation method and system based on dynamic change of end-tidal carbon dioxide concentration, belongs to the technical field of oxygen-free threshold value calculation, and solves the problems that an existing AT measurement mode is invasive, complex to operate, poor in portability and the like. The method comprises the steps of enabling a subject to conduct load increasing movement on a power vehicle, collecting end-tidal carbon dioxide concentration, respiratory frequency and movement power of the power vehicle of the subject in real time, preprocessing the collected end-tidal carbon dioxide concentration and respiratory frequency sequences of the subject to obtain interpolation sequences of the end-tidal carbon dioxide concentration and the respiratory frequency taking the movement power of the power vehicle as an X axis, identifying characteristic inflection points of the movement power according to the interpolation sequences of the end-tidal carbon dioxide concentration and the respiratory frequency, and taking the characteristic inflection points as calculation results of an anaerobic threshold of the subject.

Inventors

GU YANLI
FENG XUE
GAO JUDONG
SONG YOUCHENG

Assignees

中国医学科学院阜外医院
北京金嘉信商贸有限公司

Dates

Publication Date: 20260505
Application Date: 20260317

Claims (10)

1. An oxygen-free threshold calculation method based on dynamic change of concentration of carbon dioxide at end of expiration, which is characterized by comprising the following steps: The method comprises the steps that a subject performs load increasing movement on a power vehicle, and the concentration of end-tidal carbon dioxide, the respiratory rate and the movement power of the power vehicle of the subject are collected in real time; respectively preprocessing the collected sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency of the subject to obtain an interpolation sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency taking the motion power of the power vehicle as the X axis; And identifying characteristic inflection points of the motion power according to interpolation sequences of the end-tidal carbon dioxide concentration and the respiratory frequency, and taking the characteristic inflection points as a calculation result of the anaerobic threshold of the subject.
2. The portable end-tidal carbon dioxide concentration dynamic change based anaerobic threshold calculation method according to claim 1, wherein the preprocessing comprises: Respectively carrying out signal cleaning on the sequence of the concentration of carbon dioxide at the end of expiration and the respiratory frequency; respectively smoothing signals with the motion power of the power vehicle as an X axis on the cleaned sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency; And respectively mapping the motion power of the cleaned sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency to form a sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency taking the motion power of the power vehicle as the X axis.
3. The method for calculating the oxygen-free threshold based on the dynamic change of the concentration of the carbon dioxide at the end of expiration according to claim 2, wherein the performing of the signal smoothing with the motion power of the power vehicle as the X axis is performed by: Respectively mapping the motion power of the cleaned sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency to form a sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency taking the motion power of the power vehicle as the X axis; And respectively smoothing the sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency by using the motion power of the power vehicle as the X axis by using an S-G filter.
4. The method for calculating an anaerobic threshold based on dynamic change of end-tidal carbon dioxide concentration according to claim 3, wherein the step of smoothing the sequence of end-tidal carbon dioxide concentration and respiratory rate with the motion power of the power cart as the X axis by using an S-G filter, respectively, is performed by: In each local window of the power shaft, respectively adopting a k-order polynomial to perform parameter fitting on the relation between the end-tidal carbon dioxide concentration sequence, the respiratory frequency sequence and the motion power; And performing signal smoothing on the sequence of the end-tidal carbon dioxide concentration in the local window by using a fitting k-order polynomial corresponding to the end-tidal carbon dioxide concentration, and performing signal smoothing on the sequence of the respiratory frequency in the local window by using a fitting k-order polynomial corresponding to the respiratory frequency.
5. The portable end-tidal carbon dioxide concentration dynamic change based anaerobic threshold calculation method according to any one of claims 1-4, wherein the identifying a characteristic inflection point of motion power is performed by: Calculating the second derivative of the motion power of the relative power vehicle in each local window of the interpolation sequence of the end-tidal carbon dioxide concentration and the respiratory frequency respectively; Carrying out data normalization on the opposite number of the second derivative of the motion power of the relative power vehicle in each local window on the interpolation sequence of the end-tidal carbon dioxide concentration, and carrying out data normalization on the second derivative of the motion power of the relative power vehicle in each local window on the interpolation sequence of the respiratory frequency; Respectively carrying out weighted fusion on the data normalization result of the opposite number of the interpolation sequence of the end-tidal carbon dioxide concentration relative to the second derivative of the motion power of the power vehicle and the data normalization result of the interpolation sequence of the respiratory frequency relative to the second derivative of the motion power of the power vehicle in each local window, and sequentially splicing the weighted fusion results of all the local windows according to the sequence of increasing the motion power to construct and obtain a fusion objective function; And taking the motion power when the fusion objective function takes the maximum value as a characteristic inflection point.
6. The portable end-tidal carbon dioxide concentration dynamic change based anaerobic threshold calculation method of claim 5, further comprising: Collecting the rotating speed of a power vehicle of a subject in the load increasing movement process; drawing a power curve of the motion power of the power vehicle relative to time and a rotating speed curve of the rotating speed of the power vehicle relative to time; And if the power curve keeps increasing at a constant speed within the preset power deviation range and the rotating speed curve keeps increasing at a constant speed within the preset rotating speed deviation range, executing the pretreatment.
7. The portable end-tidal carbon dioxide concentration dynamic change based anaerobic threshold calculation method of claim 6, further comprising: If the power curve does not keep constant speed increasing within the preset power deviation range or the rotating speed curve does not keep constant speed within the preset rotating speed deviation range, the acquired data are invalid, and the test subject restarts to develop load increasing motion on the power vehicle.
8. An oxygen-free threshold computing system based on a dynamic change in end-tidal carbon dioxide concentration, the system comprising: the data acquisition module is used for enabling the subject to develop load incremental movement on the power vehicle and acquiring the concentration of end-tidal carbon dioxide, the respiratory rate and the movement power of the power vehicle of the subject in real time; the pretreatment module is used for respectively carrying out pretreatment on the collected sequence of the concentration of the end carbon dioxide of the expiration and the respiratory frequency of the subject to obtain an interpolation sequence of the concentration of the end carbon dioxide of the expiration and the respiratory frequency by taking the motion power of the power vehicle as the X axis; And the anaerobic threshold calculation module is used for identifying characteristic inflection points of the motion power according to interpolation sequences of the end-tidal carbon dioxide concentration and the respiratory frequency, and taking the characteristic inflection points as calculation results of the anaerobic threshold of the subject.
9. The portable end-tidal carbon dioxide concentration dynamic change based anaerobic threshold computing system of claim 8, wherein the data acquisition module comprises: the end-tidal carbon dioxide monitor is used for collecting the end-tidal carbon dioxide concentration and the respiratory rate of a subject in real time; And the feedback sensor of the power vehicle is used for collecting the motion power of the power vehicle in real time.
10. The portable end-tidal carbon dioxide concentration dynamic change based anaerobic threshold computing system of claim 8 or 9, further comprising a motion detection module, wherein the preprocessing module further collects rotational speed of the power cart during the incremental load motion of the subject; the motion detection module performs: drawing a power curve of the motion power of the power vehicle relative to time and a rotating speed curve of the rotating speed of the power vehicle relative to time; and if the power curve keeps constant speed increasing within the preset power deviation range and the rotating speed curve keeps constant speed within the preset rotating speed deviation range, executing the preprocessing, otherwise, invalidating the acquired data, and enabling the subject to restart the load increasing motion on the power vehicle.

Description

Oxygen-free threshold value calculation method and system based on dynamic change of concentration of carbon dioxide at end of expiration Technical Field The invention relates to the technical field of anaerobic threshold calculation, in particular to an anaerobic threshold calculation method and system based on dynamic change of concentration of carbon dioxide at end of expiration. Background The gold standard of Anaerobic Threshold (AT), blood lactate assay, determines this motor physiology core index by measuring blood biochemical index, which marks the key turning point for the movement intensity from aerobic metabolism as the main to anaerobic metabolism participation in significant increase. Currently, gold standard measurement methods for Anaerobic Threshold (AT) are to collect arterial blood by invasive means, measure blood lactate concentration or perform blood gas analysis (e.g. venous blood lactate/lactate threshold detection, or ventilation equivalent method). However, this approach has the following inherent drawbacks: (1) The method is invasive, the arterial puncture needs to be carried out for a plurality of times, pain is brought to a subject, the infection risk is increased, and frequent operation is difficult in the exercise process; (2) Hysteresis, namely, compared with metabolic change, the change of blood lactic acid concentration has delay of tens of minutes, and real-time feedback cannot be realized; (3) The discontinuity that only data AT discrete time points can be provided, and the dynamic change of the AT can not be continuously monitored; (4) The equipment is complicated, an expensive blood lactic acid analyzer or a blood gas analyzer is required to be used, and the requirement on the professional performance of the operation is high. In addition, some existing non-invasive methods are based primarily on ventilation parameters, such as V-Slope, ventilation equivalent methods. However, these methods rely on accurate gas metabolism analysis (i.e., cardiopulmonary exercise test, CPET), which not only has large and expensive equipment and complex algorithm, but also has extremely high requirements on environmental conditions and operator skills, and is difficult to popularize and apply in bedside, competition fields or common gymnasiums. Disclosure of Invention In view of the above analysis, the embodiment of the invention aims to provide an anaerobic threshold calculation method and system based on the dynamic change of the concentration of carbon dioxide AT the end of expiration, which are used for solving the problems of originality, complex operation, poor portability and the like of the existing AT measurement mode. In one aspect, the invention provides a portable end-tidal carbon dioxide concentration dynamic change-based anaerobic threshold calculation method, which comprises the following steps: The method comprises the steps that a subject performs load increasing movement on a power vehicle, and the concentration of end-tidal carbon dioxide, the respiratory rate and the movement power of the power vehicle of the subject are collected in real time; respectively preprocessing the collected sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency of the subject to obtain an interpolation sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency taking the motion power of the power vehicle as the X axis; And identifying characteristic inflection points of the motion power according to interpolation sequences of the end-tidal carbon dioxide concentration and the respiratory frequency, and taking the characteristic inflection points as a calculation result of the anaerobic threshold of the subject. Based on the scheme, the invention also makes the following improvements: further, the preprocessing includes: Respectively carrying out signal cleaning on the sequence of the concentration of carbon dioxide at the end of expiration and the respiratory frequency; respectively smoothing signals with the motion power of the power vehicle as an X axis on the cleaned sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency; And respectively mapping the motion power of the cleaned sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency to form a sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency taking the motion power of the power vehicle as the X axis. Further, the performing signal smoothing with the motion power of the power car as the X axis performs: Respectively mapping the motion power of the cleaned sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency to form a sequence of the concentration of the end-tidal carbon dioxide and the respiratory frequency taking the motion power of the power vehicle as the X axis; And respectively smoothing the sequence of the concentra