Arrangement and method for measuring a vital parameter signal

Abstract

The invention relates to an arrangement and a method for measuring a vital parameter signal, in particular a respiration signal, during physical exertion of a test subject, comprising: a holding element for arranging sensors on the body of a test subject (1), in particular on the chest in the form of a chest strap, – a sensor arrangement (100) which can be arranged on the body of a test subject (1) by means of the holding element, said sensor arrangement comprising – a respiration sensor, designed as a force sensor (2), which is designed to measure the pressing force, preferably the pressing pressure, of the sensor arrangement (100) on the body of the test subject (1), and – an acceleration sensor (4), and – a processing unit (5), which is connected to and / or is in data communication with the sensor arrangement (100) and is designed to determine, based on the pressing force determined by the force sensor (2), a respiration signal for calculating respiration parameters of the test subject, preferably the respiration frequency and / or respiration volume, and to remove, based on the acceleration determined by the acceleration sensor (4), movement artefacts from the respiration signal.

Description

[0001] Arrangement and method for measuring a vital parameter signal

[0002] The invention relates to an arrangement for measuring a vital parameter signal, in particular a respiratory signal, during physical exertion of a test subject according to patent claim 1, a sensor arrangement for such an arrangement, and a method for removing movement artifacts from a vital parameter signal determined during physical activity of a test subject according to patent claim 21.

[0003] State-of-the-art systems for performance diagnostics are known, which are often complex and can therefore usually only be used with the supervision of specialist personnel and under controlled conditions, for example on an ergometer. For example, in spiroergometry, the tidal volume or the respiratory rate of the subject is determined via respiratory gas analysis. This requires a mask and a complex, often stationary evaluation unit. Determining the respiratory parameters with a chest strap is much easier to use. However, existing systems often cannot be used during strenuous physical activity and are therefore not suitable for performance diagnostics during this type of activity. This is due, among other things, to the fact that during strenuous physical activity such as running, the steps and movements of the subject induce disturbances that, for example,distort the subject's breathing signal because the disturbances are in the frequency range of the breathing signal.

[0004] In this context, WO 2014083079 A1 discloses a method with which the ventilatory threshold of a test subject can be determined in real time during training or physical activity, automatically and without supervision by specialist personnel, e.g. a doctor. For this purpose, physiological parameters such as the respiration or heart rate of the test subject are determined using a chest strap and, if necessary, an abdominal belt and stored as a function of time. Based on this data, the ventilatory threshold is determined using at least two different methods and a confidence interval is specified. WO 2021072493 A1 discloses a device for long-term monitoring of a patient's physiological parameters, in which a force sensor and a displacement sensor, which are mechanically coupled to the patient's skin, are used to determine the physiological parameters.The displacement force and velocity of the skin are measured, and the displacement velocity measured by the displacement sensor is corrected using the data measured by the force sensor in order to calibrate the displacement sensor. WO 2018049531 A1 discloses a device in the form of a piece of clothing with a sensor for recording respiratory parameters and a sensor for recording the heart rate of a test subject. Performance diagnostic parameters such as the test subject's ventilatory threshold can be determined in real time during training based on this data. Using an additional acceleration sensor, phases are determined during which the test subject is at rest, and the measured data from the sensors can therefore be discarded. US 2010274100 A1 discloses wearable devices for the real-time monitoring of physiological parameters such as the respiratory volume of a test subject in stressful or dangerous situations.The devices include sensors and a computing unit and provide real-time information about the condition of the wearer, for example a firefighter, soldier, etc. For example, the subject's posture is determined using an acceleration sensor.

[0005] A disadvantage of the known methods, however, is that artifacts caused by the subject's movements during training due to strong body movements, e.g. during running, are not taken into account in the physiological parameters or vital parameters measured by the sensors and thus the measured physiological parameters and the performance diagnostic parameters determined on this basis can be falsified.

[0006] The object of the invention is therefore to remedy this situation and to provide an arrangement or a sensor arrangement for such an arrangement, as well as a method, which enable the determination of unadulterated physiological parameters or vital parameters of a test subject during physical activity in order to provide optimal raw data for the determination of performance diagnostic parameters and thus enable a test subject to carry out a reliable, meaningful performance test independently and without supervision by specialist personnel.

[0007] The invention solves this problem with an arrangement for measuring a vital parameter signal, in particular a respiratory signal, during physical exertion of a subject according to claim 1. According to the invention, the arrangement comprises

[0008] - a holding element for arranging sensors on the body of a test subject, in particular on the chest in the form of a chest strap

[0009] - a sensor arrangement that can be arranged on the body of a test person by means of the chest strap, comprising

[0010] - a vital parameter sensor which is designed to measure a physical quantity which is dependent on a vital parameter of the subject when arranged on the body of the subject, in particular a force sensor which is designed to measure the contact force, preferably the contact pressure, of the sensor arrangement on the body of the subject, or a respiratory sensor designed as a force sensor which is designed to measure the contact force, preferably the contact pressure, of the sensor arrangement on the body of the subject, and

[0011] - an acceleration sensor, and

[0012] - a processing unit which is connected to the sensor arrangement and / or is in data communication and is designed to

[0013] - to determine a vital parameter signal based on the physical quantity determined by the vital parameter sensor, in particular for calculating at least one vital parameter of the subject, in particular to determine a breathing signal based on the contact force determined by the force sensor for calculating breathing parameters of the subject, preferably the breathing frequency and / or the breathing volume, and

[0014] - to remove motion artifacts from the vital sign signal of the vital sign sensor, in particular from the respiratory signal, based on the acceleration determined by the acceleration sensor.

[0015] With an arrangement according to the invention, it is advantageously possible to measure vital parameters or physiological parameters of a test subject, such as a pulse signal or a respiratory signal, from which respiratory parameters can be calculated, for example in the form of respiratory rate and / or respiratory volume, during physical activity and at the same time to remove movement artifacts in the measured values ​​caused by the physical activity, ie the movements performed by the test subject, or to clean up the measured values.

[0016] In the context of the invention, a "vital parameter sensor" is understood to mean a sensor that can be placed on the body of a test subject, worn during physical exertion, and measures a physical quantity that depends on or is influenced by one or more of the test subject's vital parameters. Based on the measured values ​​of the vital parameter sensor, a vital parameter signal can be generated that either directly reflects or represents these vital parameters or from which these vital parameters of the test subject can be derived or calculated. The crucial point here is that the vital parameter sensor can be worn during physical activity, and that the measured values ​​of the physical quantity are potentially influenced, overlaid, or falsified by the body movements, steps, etc. that the test subject performs during the physical activity.

[0017] In the context of the invention, a “vital parameter signal” is understood to mean the measured values ​​of a vital parameter sensor described above, for example a respiratory sensor, plotted over time.

[0018] In the context of the invention, “vital parameters” of a test subject are understood to mean, on the one hand, metrics that reflect basic functions of the human body, such as heart rate, blood pressure, respiratory rate, oxygen saturation, and that can be calculated or derived from a physical quantity measured by the vital parameter sensor plotted over time, i.e. the corresponding vital parameter signal. An example of this would be optical physical quantities such as light absorption or light remission when x-raying the skin as part of pulse oximetry, which are influenced by arterial oxygen saturation and can therefore be used to derive arterial oxygen saturation. The same applies to the recording of the reflection of emitted infrared light rays as part of photoplethysmography to derive blood volume changes, or the acoustic recording of heart sounds to derive the pulse.

[0019] In the context of the invention, "vital parameters" also include, for example, biosignals that can be recorded or measured as physical quantities in the form of, for example, electrical voltages that are the result of biological activities, such as ECG, EEG, EMG, or ERG. In this case, the physical quantity measured by the vital parameter sensor plotted over time, i.e., the corresponding vital parameter signal, directly represents the corresponding vital parameters at a given point in time.

[0020] In the context of the invention, "motion artifacts" are understood to mean disturbances induced by movements of subject 1, such as steps or pedaling movements while cycling, that lie in the frequency range of the vital parameter signal, in particular the respiratory signal. In the context of the invention, a "signal" is understood to mean measured values ​​plotted over time.

[0021] In the context of the invention, a "breathing signal" is understood to mean the measured values ​​of a breathing sensor, for example a force sensor, plotted over time. In the context of the invention, a "breathing sensor" is understood to mean a sensor that determines measured values ​​from which the lung volumes of a subject during physical activity can be derived and that can be pressed against the body of a subject so that the breathing sensor can be worn on the subject's body during physical activity and thereby contacts the subject's body, whereby the breathing sensor or the measured values ​​determined by the sensor are influenced by the subject's body movements.

[0022] By removing motion artifacts from the vital parameter signal, in particular the respiratory signal, by the processing unit, it is advantageously possible to provide optimal raw data for the determination of performance diagnostic parameters without the test subject having to resort to locally bound, complex or invasive systems or support from specialist personnel.

[0023] In an advantageous embodiment of the invention, a breathing signal is determined as a vital parameter signal, and breathing parameters such as breathing volume and / or breathing rate are derived from this. In such an inventive arrangement, breathing volume is determined via the expansion of the chest. The associated change in length of the holding element, for example a chest strap, results in greater tension in the holding element and leads to an increase in the contact force or contact pressure of the sensor arrangement against the body, which is measured by the force sensor. The force sensor therefore functions as a breathing sensor, or the breathing sensor is designed as a force sensor, and the measured values ​​of the contact force or contact pressure determined by the force sensor represent a breathing signal from which the subject's breathing parameters, in particular the breathing rate and / or breathing volume, can be derived or calculated.

[0024] The object of the invention is further to provide a sensor arrangement for an arrangement according to the invention. The invention achieves this object with a sensor arrangement according to claim 12, comprising

[0025] - a vital parameter sensor which, when arranged on the body of the subject, is designed to measure a physical quantity which is dependent on a vital parameter of the subject, in particular a force sensor or a respiratory sensor designed as a force sensor which is designed to measure the contact force, in particular the contact pressure, of the sensor arrangement on the body of a subject, and

[0026] - an acceleration sensor, wherein the vital parameter sensor, in particular the force sensor, and the acceleration sensor are accommodated in a housing that can be arranged on a holding element, in particular on a chest strap.

[0027] A sensor arrangement according to the invention configured in this way is advantageously characterized by a particularly compact and robust construction, so that the sensor arrangement can be easily mounted on a commercially available holding element such as a chest strap, a cuff, or the like. Furthermore, this configuration of a sensor arrangement according to the invention enables reliable measurement of the relevant physical quantity, in particular the contact force, preferably the contact pressure, which can be used to derive a vital parameter signal, in particular a respiratory signal or respiratory parameters, as well as the acceleration occurring during the subject's movements, which can be used to correct the measured values ​​of the vital parameter sensor, in particular the force sensor.

[0028] For a further measurement of vital parameters or physiological parameters of the test subject, such as the heart rate, it can be provided in an arrangement according to the invention that the holding element, in particular the chest strap, comprises an electrode arrangement for measuring the heart rate of the test subject, in particular in the form of an ECG, wherein the processing unit is connected to the electrode arrangement and / or is in data communication and wherein for a particularly exact determination of the heart rate it is provided in particular that the electrode arrangement is designed in the form of at least two electrodes arranged on the chest strap.

[0029] According to an advantageous variant of an arrangement or a sensor arrangement according to the invention, the force sensor can be designed as a force-sensitive resistor. In the context of the invention, a force-sensitive resistor is understood to be a sensor element that changes its electrical resistance under the influence of force or pressure. This design of the force sensor advantageously makes it possible to make it flat and easily mount it on a holding element, such as a chest strap.

[0030] In order to optimally transmit the contact pressure or the contact force with which the force sensor is pressed against the body of the test subject to the force sensor, it can be provided according to an advantageous variant of an arrangement according to the invention or a sensor arrangement according to the invention that a force transmission element is coupled to the force sensor, in particular glued to it, wherein the force transmission element is designed to transmit the contact force to the force sensor over a large area, wherein it is provided in particular that the force transmission element is plate-shaped and / or that surface of the force transmission element with which the body of the test subject can be contacted is larger than the cross-sectional surface of the force sensor and is preferably curved.

[0031] A sensor arrangement according to the invention can be designed to be particularly compact and at the same time particularly reliable in transmitting the contact pressure or the contact force on the body of the subject to the force sensor if the force transmission element forms a wall of the housing and / or is integrated into it.

[0032] According to an advantageous variant of an arrangement according to the invention or a sensor arrangement according to the invention, it can be provided that the force sensor is designed as an air cushion coupled to a pressure sensor.

[0033] In order to be able to record movement during physical activity of the subject and to use it for the removal of movement artifacts, it can be provided in an arrangement according to the invention or a sensor arrangement according to the invention that the acceleration sensor is a 6-axis acceleration sensor comprising a 3-axis gyroscope and a 3-axis acceleration sensor or a 9-axis acceleration sensor comprising a 3-axis gyroscope, a 3-axis acceleration sensor and a 3-axis magnetic field sensor.

[0034] In order to be able to easily derive the speed and power with which the test subject moves during training or during physical exertion, it can be provided that an arrangement according to the invention and / or a sensor arrangement according to the invention comprises a GPS sensor, wherein it can be provided in particular that the GPS sensor is accommodated in the housing of the sensor arrangement.

[0035] An arrangement according to the invention can be designed for particularly versatile use if the holding element is designed as a chest strap, cuff, or piece of clothing, in particular as a T-shirt. According to a particularly advantageous variant of an arrangement according to the invention, it can be provided that the arrangement is designed in such a way, in particular that the sensor arrangement and / or the processing unit are arranged on the arrangement in such a way that the center of gravity of the arrangement lies between the torso of the subject and the holding element. Such a design advantageously optimizes the position of the center of gravity with regard to the body movements of the subject during physical exertion, so that fewer movement artifacts occur.

[0036] In order to enable a test subject to carry out professional performance diagnostics, for example by determining the lactate threshold and / or the respiratory thresholds, in a simple manner and with little effort and without the support of specialist personnel, it can be provided that the processing unit of an arrangement according to the invention for the non-invasive determination of performance diagnostic parameters of a test subject, in particular the lactate threshold and / or respiratory threshold, is designed to calculate performance diagnostic parameters of the test subject based on the determined measured values ​​of the heart rate and the vital parameter signal, in particular the respiratory signal.

[0037] A particularly effective and simple removal of motion artifacts from a vital parameter signal, in particular a breathing signal of a breathing sensor, can be achieved if the processing unit of an arrangement according to the invention is designed to carry out a method according to the invention for removing motion artifacts from a vital parameter signal determined during physical activity of a subject from a vital parameter sensor that can be arranged on the body of the subject, in particular a method according to the invention for removing motion artifacts from the breathing signal of a breathing sensor.

[0038] For reliable contacting of electrodes that may be located on a chest strap, the sensor arrangement may comprise a textile element, particularly attached to the housing, with electrode contacts for contacting the electrodes of an electrode arrangement of a chest strap. Furthermore, such a textile element is flexible, and a holding element such as a chest strap, a cuff, or a piece of clothing therefore fits snugly against the pressure body and presses the sensor arrangement evenly against the body.

[0039] In order to enable simple and thorough cleaning of both the sensor arrangement and a chest strap on which the sensor arrangement is arranged, it can be provided that the housing of the sensor arrangement is designed so that it can be plugged onto a chest strap.

[0040] It is a further object of the invention to provide a computer-implemented method for measuring a vital parameter signal, in particular a respiratory signal, during physical exertion of a subject, which method makes it possible to record unadulterated physiological parameters of a subject during physical activity and thus to provide optimal raw data for determining performance diagnostic parameters.

[0041] The invention solves this problem with a computer-implemented method according to claim 21. According to the invention, it is provided that a vital parameter sensor that can be arranged on the body of the subject and an acceleration sensor that can be arranged on the body of the subject are used, wherein the vital parameter sensor is designed to measure a physical quantity that is dependent on a vital parameter of the subject when arranged on the body of the subject. In particular, it is provided that within the scope of the method according to the invention, a sensor arrangement according to the invention that can be arranged on a holding element, in particular a chest strap, and comprising

[0042] - a force sensor designed to measure the contact force, preferably the contact pressure, of the sensor arrangement against the body of the subject, or a breath sensor designed as a force sensor designed to measure the contact force, in particular the contact pressure, of the sensor arrangement against the body of a subject, and

[0043] - an acceleration sensor is used.

[0044] A method according to the invention comprises the following steps:

[0045] - during physical exertion of the subject

[0046] Measuring the physical size of the subject by means of the vital parameter sensor, in particular measuring the contact force, preferably the contact pressure, of the sensor arrangement on the subject's body by means of the force sensor, and

[0047] - Measuring the acceleration occurring during the physical exertion of the subject by means of the acceleration sensor, - Determining a vital parameter signal, in particular for calculating at least one vital parameter of the subject, based on the physical quantity determined by the vital parameter sensor, in particular determining a respiratory signal for calculating respiratory parameters of the subject, preferably the respiratory rate and / or the respiratory volume, based on the contact force determined by the force sensor, and

[0048] Removal of motion artifacts from the vital sign sensor signal, in particular the respiratory sensor signal, based on the acceleration detected by the accelerometer.

[0049] With such a method, the advantages mentioned above - particularly in connection with an arrangement according to the invention - are also advantageously achieved.

[0050] With such a method according to the invention, it is advantageously possible to remove these motion artifacts from any sensor data which are generated by vital parameter sensors which are worn on the body of a test subject during physical activity and whose measured values ​​are therefore distorted or superimposed by motion artifacts caused by the movements, e.g. the steps of the test subject, and thus to provide unadulterated vital parameters for further diagnostics or evaluation.

[0051] A particularly simple and reliable removal of motion artifacts from the vital parameter signal, especially the respiratory signal, can be achieved if motion artifacts are reduced by

[0052] - based on the acceleration determined by the acceleration sensor, the step frequency of the subject is determined and

[0053] - based on the step frequency, an adaptive filter is created which is applied to the vital parameter signal of the vital parameter sensor, in particular the respiratory signal of the respiratory sensor.

[0054] According to a particularly advantageous variant of a method according to the invention, the adaptive filter can be designed as a notch filter, wherein the stop frequency is determined by the step frequency, in particular being an integer multiple thereof. In this context, it can further be provided that the notch filter comprises a plurality of bandstop filters, in particular notches, wherein the bandstop filters are each provided at integer multiples of the step frequency.

[0055] A particularly advantageous consideration of the step frequency when removing motion artifacts can be ensured if the step frequency is determined by using the acceleration in the Z direction measured by the acceleration sensor, in particular the Z-axis signal of the acceleration sensor, as the raw step rate signal and low-pass filtering the raw step rate signal and applying a peak detection algorithm to the thus filtered signal.

[0056] According to a particularly advantageous variant of a method according to the invention, the low-pass filter applied to the raw step rate signal can be a moving average filter or a FIR low-pass filter. In the context of the invention, an FIR filter is understood to be a finite impulse response filter (FIR), which is usually implemented as a discrete, usually digitally implemented filter in digital signal processing.

[0057] A particularly reliable removal of motion artifacts from the vital parameter signal, in particular the respiratory signal, can be achieved if motion artifacts are removed from the vital parameter signal of the vital parameter sensor, in particular the respiratory signal of the respiratory sensor, by applying the following processing steps to the raw vital parameter signal, in particular the raw respiratory signal in the form of the raw signal of the force sensor: a) high-pass filtering of the raw vital parameter signal, in particular the raw respiratory signal, b) subsequent low-pass filtering of the vital parameter signal, in particular the respiratory signal, high-pass filtered according to step a), c) creating an adaptive filter based on the acceleration determined by the acceleration sensor and applying it to the vital parameter signal, in particular the respiratory signal, filtered according to step b), d) subsequent low-pass filtering of the vital parameter signal, in particular the respiratory signal, filtered according to step c).

[0058] According to a particularly advantageous variant of a method according to the invention, the raw vital parameter signal, in particular the raw respiratory signal, is high-pass filtered in step a) by calculating a moving average of the raw 72

[0059] Vital parameter signal, in particular the raw respiratory signal, is determined over a predetermined period of time, in particular over a period of several respiratory cycles, and is subtracted from the raw vital parameter signal, in particular from the raw respiratory signal in the form of the raw signal of the force sensor.

[0060] According to a particularly advantageous variant of a method according to the invention, it can be provided that an FIR filter is used as the low-pass filter in steps b) and d).

[0061] In order to enable a test person to carry out a professional performance diagnosis with 0, for example, determination of the lactate threshold and / or the respiratory thresholds in a simple manner and with little effort and without support from specialist personnel, it can be provided that

[0062] - that for the non-invasive determination of performance diagnostic parameters of a subject, the subject's heart rate is determined during increasing physical exertion

[0063] = 5 and

[0064] - that based on the measured values ​​of the heart rate and the vital parameter signal, in particular the respiratory signal, performance diagnostic parameters of the subject, in particular the lactate threshold and / or respiratory threshold, are calculated.

[0065] For particularly precise determination of performance diagnostic parameters such as ventilatory thresholds, it can be provided that the test subject’s performance diagnostic parameters are determined by

[0066] - the heart rate and relative respiratory volume are plotted against the power and / or the running speed,

[0067] - the relative respiratory volume is calculated from the respiratory rate and the depth of breathing, and

[0068] - the break points of a respiratory curve in the form of respiratory volume plotted against performance are determined, whereby the break points correspond to the ventilatory thresholds, whereby the second ventilatory threshold correlates with the lactate threshold.

[0069] A particularly reliable performance test or a particularly reliable determination of performance diagnostic parameters can be ensured if a gradually or continuously increasing physical load is applied to the test subject, in particular a step test. In order to monitor the training progress of a test subject, a method according to the invention can be performed repeatedly at intervals of several weeks or months. Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

[0070] The invention is schematically illustrated below in the drawings using particularly advantageous, but not restrictive, embodiments and is described by way of example with reference to the drawings.

[0071] The following shows schematically:

[0072] Fig. 1 is a first perspective view of an embodiment of a sensor arrangement according to the invention,

[0073] Fig. 2 is a second view of the sensor arrangement from Fig. 1,

[0074] Fig. 3 is a sectional view through the sensor arrangement of Fig. 1,

[0075] Fig. 4 is a schematic representation of an embodiment of data transmission within the framework of a method according to the invention,

[0076] Fig. 5 is a perspective view of an embodiment of a chest strap of an arrangement according to the invention comprising the sensor arrangement of Fig. 1,

[0077] Fig. 6 shows an example of the arrangement of the chest strap including the sensor arrangement from Fig. 5 on a test subject,

[0078] Fig. 7 is a representation of the electronic components of an arrangement according to the invention comprising the sensor arrangement from Fig. 1,

[0079] Fig. 8 is a representation of the operation of an embodiment of a method according to the invention for removing motion artifacts,

[0080] Fig. 9 shows an embodiment for the determination of training areas from a cleaned breathing signal,

[0081] Fig. 10a shows an embodiment of the detection of the step rate from the raw step rate signal,

[0082] Fig. 10b shows an embodiment of the step frequency in [Hz] derived from the step rate in Fig. 10a,

[0083] Fig. 11 a shows an embodiment of the Fourier transform of the raw respiratory signal of a respiratory sensor and the Fourier transform of the cleaned respiratory signal after application of the method steps according to the invention,

[0084] Fig. 11 b shows an embodiment of an adaptive filter generated from the step frequency,

[0085] Fig. 12 shows an exemplary embodiment of a raw respiratory signal from the respiratory sensor and the adjusted respiratory signal after application of the method steps according to the invention. The following describes exemplary embodiments of an arrangement or sensor arrangement according to the invention and of a method according to the invention in connection with a respiratory sensor as a vital parameter sensor or the respiratory signal of a respiratory sensor as a vital parameter signal of the vital parameter sensor.

[0086] Sensor arrangement 100 for arrangement on a chest strap or arrangement for removing motion artifacts from a breathing signal of a breathing sensor

[0087] 1, 2, 3 show views of an embodiment of a sensor arrangement 100 according to the invention, which can be arranged on a commercially available chest strap 3 as a holding element, which serves, for example, to determine the heart rate of a test subject 1, and can thus be arranged on the body of the test subject 1 by means of a chest strap 3, which will be discussed in more detail below. As an alternative to a chest strap 3 as a holding element, a piece of clothing such as a T-shirt or a cuff can of course also be used to fix the sensors of the sensor arrangement 100 and, if applicable, other components of the arrangement to the body of the test subject 1.

[0088] In the illustrated embodiment, the sensor assembly 100 comprises a housing 7 in which a force sensor 2, which functions as a breathing sensor, and an acceleration sensor 4 are housed. However, the force sensor 2 and the acceleration sensor 4 do not necessarily need to be housed in a housing 7. If the holding element is a T-shirt, for example, the sensors can simply be arranged on the T-shirt at suitable positions.

[0089] Together with a processing unit 5, which is connected to the force sensor 2 and the acceleration sensor 4 or is in data communication, and a chest strap 3, a sensor arrangement 100 according to the invention forms an arrangement according to the invention for removing motion artifacts from a breathing signal of a breathing sensor.

[0090] In the exemplary embodiment in Fig. 1, 2, 3, the housing 7 is closed with a lid to make the sensor arrangement 100 resistant to weather influences and perspiration. In the exemplary embodiment, a charging port designed as a USB port is located on the underside of the sensor arrangement. The acceleration sensor 4 in the exemplary embodiment is designed as a 6-axis acceleration sensor, which records the acceleration during the movements of the test subject 1. The accelerations in the X, Y, Z directions (accelerometer) and the angular accelerations around the X, Y, Z axes (gyroscope) are measured.

[0091] Optionally, the acceleration sensor 4 can of course also be designed as a 9-axis acceleration sensor and additionally carry out a 3-axis magnetic field measurement.

[0092] The force sensor 2 measures the contact force or pressure of the sensor arrangement 100 against the body of the test subject 1. In the exemplary embodiment, the force sensor 2 is designed as a force-sensitive resistor (FSR). A force-sensitive resistor is characterized by the fact that it changes its resistance depending on the applied force. A voltage divider converts the measured resistance into a voltage value, which can be used for further processing or evaluation.

[0093] In an advantageous embodiment, the voltage divider is designed as a low-pass filter with an additional capacitor. This low-pass filter acts as an anti-aliasing filter and prevents high-frequency interference from entering the frequency range of the vital parameter signal during sampling. The desired cutoff frequency w c This filter results from the resistance of the force-sensitive resistor R FSRas well as the reference resistor R and the capacitor C with

[0094] In the exemplary embodiment, the measured values ​​determined by force sensor 2 are used as a breathing signal for deriving breathing parameters of subject 1. This is possible because the breathing volume correlates with the expansion of the chest. The change in length of the chest strap 3 associated with the expansion of the chest results in increased tension in the chest strap 3, which in turn leads to an increase in the contact pressure against the body. This pressure is measured by force sensor 2.

[0095] The contact surface between the test subject 1 and the force sensor 2 is formed in the exemplary embodiment by a force transmitter 21, which transmits or forwards the contact pressure of the chest strap on the body of the test subject 1 to the force sensor 2. The force transmitter 21 is designed in the exemplary embodiment as a small plate that is slightly curved on the side facing the body of the test subject 1 in order to improve contact with the body surface (see Fig. 3). The surface of the force transmitter 21 that faces the body of the test subject 1 is, as shown in Fig. 3, larger than the cross-sectional area of ​​the force sensor 2 in order to ensure optimal force transmission from the body of the test subject 1 to the force transmitter 21. The force transmitter 21 is adhesively bonded to the force sensor 2 in the exemplary embodiment.The area of ​​the force transmitter 21 which is glued to the force sensor 2 is, in the exemplary embodiment, smaller than the cross-sectional area of ​​the force sensor 2, which has proven to be optimal for the force transmission to the force sensor 2 in test experiments.

[0096] Furthermore, the sensor arrangement 100 has a textile element 8, which is arranged on the side of the sensor arrangement 100 facing away from the force sensor 2 and thus, when arranged on a chest strap 3, comes into contact with the front of the chest strap 3. The textile element 8 has electrode contacts 81, which, when arranged on the chest strap 3, contact the electrodes of an electrode arrangement 6 of the chest strap 3. In the exemplary embodiment, the electrode contacts 81 are designed as push buttons (see Fig. 1 and Fig. 2). In this way, measured values ​​measured by the electrodes can be transmitted to the sensor arrangement and thus easily stored and / or evaluated together with measured values ​​from the force sensor 2 and / or the acceleration sensor 4.

[0097] In the exemplary embodiment, a battery 9 and a circuit board 10 are located inside the housing 7. When the sensor arrangement 100 is arranged on a chest strap 3, the chest strap 3 is placed in a passage 11 of the sensor arrangement 100 and secured thereto with a clip 12 (see Fig. 5). The sensor arrangement can thus be attached in a simple and robust manner between a commercially available chest strap 3 and the upper body of the test subject 1 (see Fig. 6). For washing the chest strap 3, the sensor arrangement 100 can advantageously be easily removed or detached again.

[0098] In the illustrated embodiment, the electronic components, force sensor 2, acceleration sensor 4, and battery 9, which form the center of gravity of sensor array 100, are located between chest strap 3 and the skin. Such a location of the center of gravity behind chest strap 3 has proven advantageous in tests, as the sensor array 100 then vibrates less during training or physical exertion than if positioned closer to chest strap 3, thus advantageously minimizing the occurrence of motion artifacts in the breathing signal.

[0099] Fig. 7 shows an exemplary embodiment of the electronic structure of an arrangement according to the invention comprising the previously described sensor arrangement 100. In the exemplary embodiment, the processing unit 5 of the arrangement is designed as a microprocessor and is accommodated on the circuit board 10 of the sensor arrangement 100. In the exemplary embodiment, the processing unit 5 is connected to the various sensors, i.e., the force sensor 2 and the acceleration sensor 3, and reads the determined measured values, as well as, in the exemplary embodiment, the measured values ​​of the electrode arrangement 6. In the exemplary embodiment, the processing unit 5 transmits these measured values ​​via Bluetooth Low Energy to, for example, a smartphone application and / or a server 15.

[0100] Alternatively or additionally, the processing unit 5 can also directly store and further process the read-in data and transmit only the evaluated or further processed data to, for example, an application and / or a server 15. Furthermore, alternatively or additionally, the processing unit 5 can also be external, i.e. separate from the circuit board 10, wherein the measured values ​​determined by the force sensor 2 and the acceleration sensor 3, and optionally also the measured values ​​of the electrode arrangement 6, are transmitted to the external processing unit 5 for further processing. Such an external processing unit 5 can, for example, be included in a smartphone 14 or mobile phone worn on the body by the test subject 1, wherein the processing unit 5 can receive the measured values ​​determined by the force sensor 2 and the acceleration sensor 3 and optionally by the electrode arrangement 6, for example by means of Bluetooth, WLAN or the like.

[0101] Based on the contact pressure determined by the force sensor 2, the processing unit 5 determines a breathing signal for calculating the subject's breathing parameters, e.g., breathing rate and / or breathing volume, and removes motion artifacts from the breathing signal based on the acceleration determined by the acceleration sensor 4. These process steps will be discussed in more detail below.

[0102] In addition, a circuit 91 for charging the battery 9 with a charge level indicator in the form of an LED is mounted on the circuit board 10 in the exemplary embodiment, although this is optional in each case. Furthermore, a sensor arrangement 100 according to the invention can optionally also include a GPS sensor, which can be accommodated, for example, in the housing 7. Alternatively or additionally, an external GPS sensor can also be included in an arrangement according to the invention, which can be incorporated, for example, in a smartphone 14 or mobile phone worn on the body by the test subject 1.

[0103] Optionally, an arrangement according to the invention, more precisely the chest strap 3, as is the case in the exemplary embodiment, can comprise an electrode arrangement 6 for measuring the subject's heart rate in the form of an ECG. In this context, the second derivative according to Einthoven is determined and subjected to further signal processing steps such as common-mode feedback, instrumentation amplifiers, a high-pass filter in two switchable configurations, and a low-pass filter. This can be implemented, for example, with an AD8232 component, which can be integrated into the processing unit 5 or independent of it. This signal is then digitized and evaluated using an AD converter of the processing unit 5.

[0104] As previously mentioned, in the exemplary embodiment, the breathing signal is generated using force sensor 2 in the form of a force-sensitive resistor. The determined voltage value is low-pass filtered in the exemplary embodiment and digitized and read by the AD converter of processing unit 5, as are the accelerations in the X, Y, and Z directions measured by acceleration sensor 4, as well as the angular accelerations around the X, Y, and Z axes. Alternatively, acceleration sensor 4 can also be integrated via a bus.

[0105] Method for measuring a respiratory signal of a respiratory sensor during physical exertion of a subject 1

[0106] A further aspect of the invention relates to a measurement method using an advantageous signal processing algorithm for removing motion artifacts from the vital parameter signal of a vital parameter sensor, for example, from the respiratory signal of a respiratory sensor, which can be performed, for example, by the processing unit 5. Only with such a measurement method is it even possible to obtain a reliable respiratory signal for deriving respiratory parameters from a respiratory sensor worn on the body during physical exertion.

[0107] In general, a breathing signal for calculating breathing parameters of the subject 1, e.g. the breathing frequency and / or the breathing volume, is determined based on the contact force or contact pressure determined by the force sensor 2, and motion artifacts are removed from the breathing signal of the breathing sensor based on the acceleration determined by the acceleration sensor 4.

[0108] Fig. 8 provides an overview of the functionality of an embodiment of a method according to the invention for removing motion artifacts from the respiratory signal. In the embodiment, the respiratory sensor, as already explained above, is a force sensor 2 in the form of a force-sensitive resistor.

[0109] Generally speaking, motion artifacts are removed from the breathing signal of the breathing sensor, i.e., the force sensor 2, by first determining the step frequency of subject 1 based on the acceleration determined by the acceleration sensor 4. Subsequently, an adaptive filter (AF) is created based on the determined step frequency and applied to the breathing signal of the breathing sensor. Further process steps, such as extensive filtering of the (raw) breathing signal before or after applying the adaptive filter (AF), are optional.

[0110] To determine the step frequency, the acceleration measured by acceleration sensor 4 in the Z direction or along the Z axis is first used as the raw signal SR raw of the step rate. The acceleration signal of the Z axis has proven particularly advantageous for deriving the step rate, since the vibrations induced by the steps of subject 1 are the strongest in this acceleration signal, making the step rate easiest to detect. Alternatively or additionally, more complex approaches using combinations of the accelerations measured by acceleration sensor 4 along multiple axes can of course also be used.

[0111] This raw step rate signal (SR raw) is first low-pass filtered (step "LP" in Fig. 8), e.g., using a moving average filter or an FIR-LP filter. The step rate is then read or detected from the filtered signal (step "SRD" in Fig. 8). This is achieved by applying a peak detection algorithm to the filtered signal, for example, a well-known software component such as Matlab FindPeaks. If the peak lies above a specified threshold, a step is considered detected.

[0112] These processing steps for detecting the step rate SR are schematically illustrated in Fig. 10a. The raw step rate signal SR raw, in this example the raw signal of the Z-axis of acceleration sensor 4, is shown in gray, the low-pass filtered signal SR Ip is shown in black, and the detected peaks or steps after applying a threshold are indicated by circles in the low-pass filtered signal. Fig. 10b shows the derived step frequency in [Hz].

[0113] To create an adaptive filter AF based on the step rate SR, which is applied to the raw signal from the breath sensor, three IIR notch filters are created in the exemplary embodiment. Their stopband frequencies are the step rate and its first and second harmonics (see Fig. 11 b). Thus, in the exemplary embodiment, the filter comprises three band-stop filters, each at the step rate and the first and second harmonics of the step rate. However, more or fewer than three such IIR notch filters can optionally be created.

[0114] Since the step rate can change over time, the notch filter is adaptively adjusted to the prevailing step rate at a given time. The filter coefficients are recalculated at each discrete time n and applied to the raw signal.

[0115] Equation (1 ) shows an embodiment of a pseudo-code for calculating a filtered signal (y) from a raw signal (x).

[0116] The filter coefficients b n , a n The values ​​in equation (2) can be calculated at any discrete time n based on the prevailing step rate at that time, for example, using the well-known MATLAB iirnotch software component. In the illustrated embodiment, this is a third-order IIR filter. The filtered signal y at time n is then calculated from the filter coefficients, the raw signal, and the past values ​​of the raw signal and the filtered signal.

[0117] In the exemplary embodiment, the following processing steps a) to d) are applied to the raw respiratory signal RR raw, i.e. the raw signal of the force sensor 2 in the form of the force-sensitive resistor: a) High-pass filtering of the raw respiratory signal RR raw over a time period of several respiratory cycles (step "HP" in Fig. 8). In the exemplary embodiment, "demeaning" is carried out for this purpose, i.e. the moving average of the raw respiratory signal RR raw is determined over a time period of several respiratory cycles and subtracted from the raw respiratory signal RR raw. In this context, Fig. 11a shows the Fourier transform of the raw respiratory signal.

[0118] In step b), the respiratory signal, which has been high-pass filtered in step a), is then low-pass filtered (step "LP1" in Fig. 8). In the exemplary embodiment, an FIR filter is used for this purpose. Furthermore, a high-pass filter is applied to remove high-frequency interference (mains frequency, BLE artifacts, etc.).

[0119] Subsequently, in step c), as previously described, an adaptive filter AF is created based on the acceleration determined by the acceleration sensor 4 and applied to the respiratory signal filtered in step b) (step "AF" in Fig. 8). This adaptive filter makes it possible to reliably remove disturbances induced by the steps or movements of subject 1 that lie in the frequency range of the respiratory signal, i.e., motion artifacts.

[0120] Finally, in step d), the respiratory signal filtered in step c) is low-pass filtered (step "LP2" in Fig. 8) to obtain the cleaned respiratory signal RR after removing motion artifacts. The repeated low-pass filtering smooths the respiratory signal filtered in step c) to simplify peak detection for determining respiratory rate and volume.

[0121] Fig. 1 1 a shows the Fourier transform of the raw respiratory signal of a respiratory sensor as well as the Fourier transform of the cleaned respiratory signal after application of the method steps according to the invention.

[0122] In this context, Fig. 12 shows the raw breathing signal RR raw (grey), i.e. the raw signal of the force sensor 2, as well as the cleaned breathing signal RR filtered (black) after applying the process steps a)-d) in comparison.

[0123] The artifacts caused by physical activity, in the form of high-frequency, high-amplitude oscillations, were removed. The signal caused by respiratory movement of the chest remains intact. This makes it possible to further extract respiratory parameters such as respiratory rate or respiratory volume from the respiratory signal. Peak detection, for example, is used for this purpose. The respiratory rate can then be determined from the times of the peaks. The amplitude, i.e., the minimum and maximum between two detected peaks, is used to determine the relative respiratory volume.

[0124] Performance diagnostics

[0125] As already described above, an arrangement or sensor arrangement 100 according to the invention and a method according to the invention enable the removal of motion artifacts from a respiratory signal of a respiratory sensor and thus enable a test subject 1 to conduct a performance test independently, i.e., using a "do-it-yourself" method, from home. Thus, a test subject 1 can independently estimate parameters of a professional performance diagnostic, such as the lactate threshold or the ventilatory thresholds, easily and with little effort.

[0126] Fig. 9 shows an embodiment of such a non-invasive determination of performance diagnostic parameters, e.g. the lactate threshold and / or ventilatory threshold, of a subject 1 with an arrangement according to the invention, as already described in detail above.

[0127] The heart rate is measured in the form of an ECG using the chest strap 3 of the assembly. The heart rate is derived from the ECG via the electrodes of the electrode assembly 8. The respiratory volume is determined based on the expansion of the chest and the contact pressure of the force sensor 2 of the sensor assembly 100 against the body of the subject 1. Based on the acceleration measured by the acceleration sensor 4, motion artifacts in the respiratory signal of the respiratory sensor are removed using the previously described method according to the invention.

[0128] In addition, in the exemplary embodiment, processing unit 5 is configured to calculate performance diagnostic parameters of the subject based on the measured heart rate and respiratory signal. In the exemplary embodiment in Fig. 9, these are the lactate threshold and the second ventilatory threshold VT2.

[0129] In this context, an arrangement according to the invention can optionally comprise a smartphone 14 and a server 15, as shown in Fig. 4. Using an application installed on the smartphone 14, the test subject 1 can be guided through a step-by-step test commonly used in performance diagnostics, during which the vital parameters of the test subject 1 are measured by the arrangement in order to determine the desired performance diagnostic parameters. Alternatively or additionally, the arrangement can also comprise, for example, a smartwatch, a tablet, or the like, on which such an application can be accessed.

[0130] The measured values ​​of the vital parameters of the test subject 1, as well as the measured values ​​of the force sensor 2 and the acceleration sensor 4, are transmitted by the processing unit 5 to the application and / or the server 15 and synchronized with GPS coordinates in order to be able to determine, for example, the running speed of the test subject 1. Therefore, no additional training equipment such as an ergometer or a treadmill is required to conduct a performance test; due to the removal of motion artifacts from the breathing signal, the performance test can also be conducted, for example, while running outdoors.

[0131] Optionally, the application can guide Subject 1 step by step through the performance test. As is common with performance diagnostics, a performance test can be conducted as a step-by-step test with gradually increasing workload for Subject 1. In this context, Subject 1's running speed can be determined using GPS coordinates and communicated to Subject 1 via acoustic signals on the smartphone. This allows performance to be increased accordingly during the step-by-step test.

[0132] When running, performance correlates with pace, i.e. running speed, especially when running on flat terrain. In the exemplary embodiment, the running speed is calculated using the GPS data from the arrangement's GPS sensor, for example the GPS sensor on the smartphone, and communicated to test subject 1 via an acoustic signal. To ensure the simplest possible handling, test subject 1 can also only be told "faster" or "slower". This acoustic and / or visual feedback, for example, can be given to test subject 1 via the application, so that test subject 1 actually increases their running speed in stages during the performance test and keeps it constant throughout each performance stage.

[0133] In the exemplary embodiment, the processing unit 5 then calculates the desired performance diagnostic parameters such as lactate threshold, ventilatory thresholds VT1, VT2, maximum oxygen uptake VO2Max, etc. from the data measured during physical exertion, as described, for example, in Gouw, AH, Van Guilder, GP, Larusson, A., Laredo, G., Weatherwax, RM, Byrd, BR, Dalleck, LC, 2021: Ventilation can exclusively be used to predict ventilatory thresholds: a retrospective analysis, International Journal of Research in Exercise Physiology, Vol. 16, No. 2, pp. 1-18 or Zechner, N., 2011, Determination of changeover points in heart rate and heart rate variability with stepwise increasing ergometer load in comparison to metabolic and respiratory changeover points, Univ. Graz, Dipl.-Arb.Optionally, however, this can also be done on the server 15, which is part of an external processing unit 5, for example, separate from the sensor arrangement 100.

[0134] The performance parameters are then determined from the progression of the respiratory parameters and the applied power. For this purpose, measured values ​​of the relative respiratory volume Vent. [1 / max] are plotted against the power P [W], as shown in Fig. 9. The relative respiratory volume is calculated from the respiratory rate times the respiratory depth and then normalized to the maximum. The breakpoints of the respiratory curve or respiratory signal are then determined.

[0135] In the example shown in Fig. 9, the performance test comprises three performance levels P1, P2, and P3. Therefore, to determine the breakpoints, three straight lines are fitted to best represent the data within their range. The intersection points of the straight lines are the two ventilatory thresholds VT1 and VT2, where VT2 correlates with the lactate threshold.

[0136] Based on the ventilatory thresholds VT1, VT2, the subject's training zones are determined. The training zones are indicated by the running speed and heart rate.

[0137] Using the determined performance diagnostic parameters, the personal training zones of subject 1 can optionally be calculated and a training plan tailored to them can be created. By repeating the performance test, training progress can be verified and the training plan adjusted accordingly. With an arrangement according to the invention, possibly with an associated smartphone application, performance diagnostics can thus be performed independently, non-invasively, and without the need for specialist personnel.

[0138] The method steps described above for removing motion artifacts from the respiratory signal of the respiratory sensor based on the acceleration determined by the acceleration sensor 4 can advantageously also be applied to any other vital parameter signals determined by vital parameter sensors worn on the body of a subject 1 during physical exertion, so that their measured values ​​are influenced by the body movements of the subject 1.

[0139] For example, the described arrangement, sensor arrangement, or method can also be applied to measuring blood pressure and / or pulse. In this case, for example, it is not the expansion of the chest due to respiratory movements that is measured, but rather the expansion of an artery or vein as a result of blood flow, such as the expansion of the carotid artery. The resulting vital parameter signal can be used to measure the pulse and, if used correctly, also systolic / diastolic blood pressure. During physical activity, interference in the frequency range of the measurement signal also occurs in this case, which can be eliminated using the described method.

Claims

Patent claims 1. An arrangement for measuring a vital parameter signal, in particular a respiratory signal, during physical exertion of a subject, comprising: a holding element for arranging sensors on the body of a subject (1), in particular on the chest in the form of a chest strap, a sensor arrangement (100) that can be arranged on the body of a subject (1) by means of the holding element, comprising a vital parameter sensor that is designed to measure a physical quantity that is dependent on a vital parameter of the subject (1) when arranged on the body of the subject (1), in particular a force sensor (2) that is designed to measure the contact force, preferably the contact pressure, of the sensor arrangement (100) on the body of the subject (1), or a respiratory sensor designed as a force sensor (2) that is designed to measure the contact force, preferably the contact pressure, of the sensor arrangement (100) on the body of the subject (1), and an acceleration sensor (4),and a processing unit (5) which is connected to the sensor arrangement (100) and / or is in data communication and is designed to determine a vital parameter signal, in particular for calculating at least one vital parameter of the subject (1), based on the physical quantity determined by the vital parameter sensor, in particular to determine a breathing signal for calculating breathing parameters of the subject, preferably the breathing frequency and / or the breathing volume, based on the contact force determined by the force sensor (2), and to remove movement artifacts from the vital parameter signal of the vital parameter sensor, in particular from the breathing signal, based on the acceleration determined by the acceleration sensor (4).

2. Arrangement according to claim 1, characterized in that the holding element, in particular the chest strap (3), comprises an electrode arrangement (6) for measuring the heart rate of the subject (1), in particular in the form of an ECG, wherein the processing unit (5) is connected to the electrode arrangement (6) and / or is in data communication and wherein it is provided in particular that the Electrode arrangement (6) is designed in the form of at least two electrodes arranged on the chest strap (3).

3. Arrangement according to claim 1 or 2, characterized in that the force sensor (2) is designed as a force-sensitive resistor.

4. Arrangement according to claim 3, characterized in that a force transmission element (21) is coupled to the force sensor (2), in particular glued to it, wherein the force transmission element (21) is designed to transmit the contact force to the force sensor (2) over a large area, wherein it is provided in particular that the force transmission element (21) is plate-shaped and / or the area of the force transmission element (21) for contacting the body of the test subject (1) is larger than the cross-sectional area of the force sensor (2) and is preferably curved.

5. Arrangement according to one of the preceding claims, characterized in that the force sensor (2) is designed as an air cushion coupled to a pressure sensor.

6. Arrangement according to one of the preceding claims, characterized in that the acceleration sensor (4) is a 6-axis acceleration sensor comprising a 3-axis gyroscope and a 3-axis acceleration sensor or a 9-axis acceleration sensor comprising a 3-axis gyroscope, a 3-axis acceleration sensor and a 3-axis magnetic field sensor.

7. Arrangement according to one of the preceding claims, characterized in that the arrangement, in particular the sensor arrangement (100), comprises a GPS sensor.

8. Arrangement according to one of the preceding claims, characterized in that the holding element is designed as a chest strap (3), cuff or piece of clothing, in particular as a T-shirt.

9. Arrangement according to one of the preceding claims, characterized in that the arrangement is designed in such a way, in particular that the sensor arrangement (100) and / or the processing unit (5) are arranged on the arrangement in such a way that the center of gravity of the arrangement lies between the torso of the subject (1) and the holding element.

10. Arrangement according to one of the preceding claims, characterized in that the processing unit (5) for the non-invasive determination of performance diagnostic parameters of the test subject (1), in particular the lactate threshold and / or ventilatory threshold, is designed to calculate performance diagnostic parameters of the test subject (1) based on the determined measured values of the heart rate and the vital parameter signal, in particular the respiratory signal.

11. Arrangement according to one of the preceding claims, characterized in that the processing unit (5) is designed to carry out a method for removing movement artifacts from a vital parameter signal determined during physical activity of a test subject (1) from a vital parameter sensor that can be arranged on the body of the test subject (1), in particular from the breathing signal of a breathing sensor, according to one of claims 21 to 32.

12. Sensor arrangement (100) for an arrangement according to one of claims 1 to 11, comprising a vital parameter sensor which, when arranged on the body of the test subject (1), is designed to measure a physical quantity which is dependent on a vital parameter of the test subject (1), in particular a force sensor (2) which is designed to measure the contact force, preferably the contact pressure, of the sensor arrangement (100) on the body of the test subject (1), or a breathing sensor designed as a force sensor (2) which is designed to measure the contact force, in particular the contact pressure, of the sensor arrangement on the body of a test subject (1), and an acceleration sensor (4), wherein the vital parameter sensor, in particular the force sensor (2), and the acceleration sensor (4) are accommodated in a housing (7) which can be arranged on a holding element, in particular on a chest strap (3).

13. Sensor arrangement (100) according to claim 12, characterized in that the sensor arrangement (100) comprises a textile element (8), in particular fastened to the housing (7), with electrode contacts (81) for contacting the electrodes of an electrode arrangement (6) of a chest strap (3).

14. Sensor arrangement (100) according to one of claims 12 or 13, characterized in that the force sensor (2) is designed as a force-sensitive resistor.

15. Sensor arrangement (100) according to one of claims 12 to 14, characterized in that a force transmission element (21) is coupled to the force sensor (2), in particular glued to the force sensor (2), wherein the Force transmission element (21) is designed to transmit the contact force to the force sensor (2) over a large area, wherein it is provided in particular that the force transmission element (21) is plate-shaped and / or the area of the force transmission element (21) for contacting the body of the test subject (1) is larger than the cross-sectional area of the force sensor (2) and is preferably curved.

16. Sensor arrangement (100) according to claim 15, characterized in that the force transmission element (21) forms a wall of the housing (7) and / or is integrated into it.

17. Sensor arrangement (100) according to one of claims 12 to 16, characterized in that the force sensor (2) is designed as an air cushion coupled to a pressure sensor.

18. Sensor arrangement (100) according to one of claims 12 to 17, characterized in that the acceleration sensor (4) is a 6-axis acceleration sensor comprising a 3-axis gyroscope and a 3-axis acceleration sensor or a 9-axis acceleration sensor comprising a 3-axis gyroscope, a 3-axis acceleration sensor and a 3-axis magnetic field sensor.

19. Sensor arrangement (100) according to one of claims 12 to 18, characterized in that the sensor arrangement (100) comprises a GPS sensor accommodated in the housing (7).

20. Sensor arrangement (100) according to one of claims 12 to 19, characterized in that the housing (7) is designed to be pluggable onto a chest strap (3).

21. Method for removing movement artifacts from a vital parameter signal determined during physical activity of a subject (1) by a vital parameter sensor that can be arranged on the body of the subject (1) with aAn acceleration sensor (4) that can be arranged on a test subject (1), wherein the vital parameter sensor is designed to measure a physical quantity that is dependent on a vital parameter of the test subject (1) when arranged on the body of the test subject (1), in particular a method for measuring a breathing signal during physical exertion of a test subject (1) with a sensor arrangement (100) that can be arranged on a holding element, in particular a chest strap (3), according to one of claims 12 to 20, comprising a force sensor (2) that is designed to measure the contact force, preferably the contact pressure, of the sensor arrangement (100) on the body of the test subject (1), or a breathing sensor designed as a force sensor (2) that is designed to measure the contact force, in particular the contact pressure, of the sensor arrangement (100) on the body of a test subject (1), and an acceleration sensor (4), comprising the following steps: during physical exertion of the test subject (1) Measuring the physical quantity on the test subject (1) by means of the vital parameter sensor, in particular measuring the contact force, preferably the contact pressure, of the sensor arrangement (100) on the body of the test subject (1) by means of the force sensor (2), and Measuring the acceleration occurring during the physical exertion of the subject (1) by means of the acceleration sensor (4), Determining a vital parameter signal, in particular for calculating at least one vital parameter of the subject (1), based on the physical quantity determined by the vital parameter sensor, in particular determining a respiratory signal for calculating respiratory parameters of the subject (1), preferably the respiratory frequency and / or the respiratory volume, based on the contact force determined by the force sensor (2), and Removing motion artifacts from the vital parameter signal of the vital parameter sensor, in particular the respiratory signal of the respiratory sensor, based on the acceleration determined by the acceleration sensor (4).

22. Method according to claim 21, characterized in that motion artifacts are removed by based on the acceleration determined by the acceleration sensor (4), the step frequency of the test subject (1) is determined and based on the step frequency, an adaptive filter (AF) is created which is applied to the vital parameter signal of the vital parameter sensor, in particular the respiratory signal of the respiratory sensor.

23. Method according to claim 22, characterized in that the adaptive filter (AF) is designed as a notch filter, wherein the blocking frequency is determined by the step frequency, in particular is an integer multiple thereof.

24. Method according to claim 23, characterized in that the notch filter comprises a plurality of band-stop filters, in particular notches, wherein the band-stop filters are each provided at integer multiples and / or divisors of the step frequency.

25. Method according to one of claims 21 to 24, characterized in that the step frequency is determined by using the acceleration in the Z direction measured by the acceleration sensor (4) as the raw signal (SR raw) of the step rate and low-pass filtering the raw signal (SR raw) of the step rate and applying a peak detection algorithm to the signal thus filtered.

26. The method according to claim 25, characterized in that the low-pass filter applied to the raw signal (SR raw) of the step rate is a moving average filter or an FIR low-pass filter.

27. Method according to one of claims 21 to 26, characterized in that movement artifacts are removed from the vital parameter signal of the vital parameter sensor, in particular the respiratory signal of the respiratory sensor, by applying the following processing steps to the raw vital parameter signal, in particular the raw respiratory signal (RR raw) in the form of the raw signal of the force sensor (2): a) high-pass filtering of the raw vital parameter signal, in particular the raw respiratory signal (RR raw), b) subsequently low-pass filtering the vital parameter signal, in particular the respiratory signal, high-pass filtered according to step a), c) creating an adaptive filter (AF), in particular according to one of claims 22 to 26, based on the acceleration determined by the acceleration sensor and applying it to the vital parameter signal, in particular the respiratory signal, filtered according to step b), d) subsequent low-pass filtering of the vital parameter signal filtered according to step c), in particular the respiratory signal.

28. The method according to claim 27, characterized in that the raw vital parameter signal, in particular the raw respiratory signal (RR raw), is high-pass filtered in step a) by determining a moving average of the raw vital parameter signal, in particular the raw respiratory signal (RR raw), over a predetermined time period, in particular over a period of several respiratory cycles, and subtracting it from the raw vital parameter signal, in particular from the raw respiratory signal (RR raw).

29. Method according to claim 27 or 28, characterized in that an FIR filter is used as the low-pass filter in step b).

30. Method according to one of claims 21 to 29, characterized in that for the non-invasive determination of performance diagnostic parameters of a test subject (1), the heart rate of the test subject (1) is determined during increasing physical exertion and that based on the determined measured values of the heart rate and the vital parameter signal, in particular the respiratory signal, performance diagnostic parameters of the test subject (1), in particular the lactate threshold and / or ventilatory thresholds, are calculated.

31. Method according to claim 30, characterized in that the performance diagnostic parameters of the test subject (1) are determined by plotting the heart rate and the relative respiratory volume against the performance and / or the running speed, the relative respiratory volume is calculated from the respiratory rate and the depth of breathing, and the break points of a respiratory curve in the form of the respiratory volume plotted against the performance are determined, the break points each corresponding to a ventilatory threshold (VT1, VT2), the second ventilatory threshold (VT2) correlating with the lactate threshold.

32. Method according to one of claims 21 to 31, characterized in that the method is carried out repeatedly at intervals of several weeks or months and / or that a step-like or continuously increasing physical load, in particular a step test, is carried out on the test subject (1).

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