FI112845B - Method and apparatus for measuring electrical activity in muscles - Google Patents

Description

112845

Method and apparatus for measuring muscle electrical activity

Area

The invention relates to a method for measuring muscle electrical activity.

The invention also relates to an apparatus for measuring muscle electrical activity which comprises means for detecting an EMG signal produced by a muscle from the surface of the body, and which means are operatively connected to data processing means comprising the apparatus.

BACKGROUND 10 Prior art methods and apparatus for measuring muscle electrical activity are either needle EMG or wire EMG or surface EMG. Measurements with needle EMG or wire EMG are such that muscle electroactivity is measured through the skin using a probe needle or probe wire injected intramuscularly, whereas the easier version for the subject is a so-called. surface EMG, where 15 electrodes from the skin surface measure muscle electrical activity. However, the known surface EMG measurement is inconclusive because it does not take into account the distortions of the measurement result due to the human body.

BRIEF DESCRIPTION OF THE INVENTION It is an object of the invention to provide a method and apparatus for performing the method so as to achieve a problem with respect to the previous embodiments; a less sophisticated and more appropriate method and device for research and care. tracking equipment.

; This object is achieved by a method characterized by: detecting an EMG signal produced by a muscle from a surface of the body: by measuring equipment and compensating for tissue effect by correcting the measured based on the tissue information provided on the subcutaneous tissue by altering the 30 EMG signal values observed on the surface of the body based on the known dependency information between the tissue information and the EMG signal.

The apparatus of the invention is characterized in that the data processing means are configured to perform tissue effect compensation, which corrects the EMG signal value detected on the body surface to determine the corrected EMG-2 signal value based on known dependency information between the tissue information and the EMG signal that is available to the hardware.

Preferred embodiments of the invention are claimed in the dependent claims.

The invention is based on measuring the subcutaneous tissue information of the human body, such as tissue thickness, and transferring this measurement data either directly or indirectly to the data processing equipment of the measuring apparatus, on the basis of said measurement data and on the basis of sensory information perform tissue effect compensation, which eliminates the distortion factor caused by 15 surface EMG measurements of human subcutaneous adipose tissue, thus allowing comparison of measurement results between individuals. This is not a diagnostic method, but a means of providing assistance to professionals, such as sports coaches, physiotherapists and physicians, which is independent of the characteristics of the subcutaneous tissue and comparable between individuals. Tissue information for subcutaneous tissue is measured within the muscle signal measurement range.

The method and system of the invention achieve: several advantages. The most important benefit is a significant improvement in the accuracy, reliability and comparability of surface EMG measurement, while using • comfortable and easy-to-use equipment for the subject and the equipment * 25 personnel.

List of figures

The invention will now be described in greater detail in connection with the preferred embodiments, with reference to the accompanying drawings, in which: Figure 1 illustrates apparatus for carrying out the method of the invention, Figure 2 shows a measurement of skin fold thickness,; Figure 3 shows the relationship between tissue thickness and EMG measurement.

'I

Figure 4 shows EMG signals, thus illustrating the difference in intensity caused by subcutaneous tissue thickness between needle EMG measurement and surface EMG measurement.

3, 112845

Description of Embodiments

Referring to the accompanying drawings, the subject matter of the invention is the measurement of muscle electrical activity of muscles, in particular joints. In a preferred embodiment, the target area is dorsal, but other target areas are also possible. The object of measurement is indicated by reference numeral 1 and the measuring apparatus is represented by reference numeral 2. The muscle of the subject of measurement 1, such as, for example, in the back, is represented by reference numeral 1a. The measuring apparatus is divided into two main parts, the measuring means 20 and the data processing means 40 processing the data of the measuring means, which in the example of Figure 1 is a computer 10, such as a conventional microcomputer. The measuring means 20 comprises a sensor structure 21-22 for measuring an EMG signal from the skin surface and a signal processing section 23 connected to the sensor structure, comprising, for example, an amplifier 23a and an A / D converter 23b. The signal processing block 23, in practice the output of the signal processing block, i.e. the output of the A / D converter 23b, is connected to the data processing unit 15, for example via cable 25. The sensor structure or electrodes 21-22 are connected by cable 200, 200a, 200b to the signal processing block 23. In addition, the measuring means 20 comprise a measuring device 50 for measuring the skin fold or subcutaneous tissue thickness. The skin measurement device 50 is also connected, either in a wired connection 27 or wirelessly, to a data processing unit 40. It is also possible to use the separate measuring device 60 shown in Fig. 2, from which the value of the tissue thickness provided by the measuring device 60 is input to the data processing unit by means of a user interface 70, such as a keyboard.

: The hardware also includes a display 300.

! In a preferred embodiment, the measuring means comprises: a motion sensor 80 for measuring the movement of the object, which is also in communication with the information; ; the processing unit 40, i.e. the data processing means. The motion sensor 80 communicates with the data processing means, for example, via cable 28. The function of the motion sensor is to • measure the movement of the support arm or joints and thereby to detect the mobility caused by the muscle activity.

, 'As a method, it is a method of measuring muscle electrical activity. The method involves detecting a muscle-generated EMG signal from the body surface by measuring equipment. Surface EMG measurement is performed during muscle function. In addition, a tissue effect compensation is performed to correct the EMG signal value observed on the body surface to determine the corrected EMG signal value and to eliminate 4,118,445 individual basic 5 tea.

The corrected value corresponds as closely as possible to that obtained by needle EMG or wire EMG or other muscle measuring (IM, IntraMuscular) method, whereby the values measured from different individuals become comparable.

In a preferred embodiment of the invention, the method is such that in tissue compensation the tissue information supplied to the measuring apparatus is the thickness of the subcutaneous tissue, for example in millimeters, i.e. the distance of the measuring electrode from the muscle to be examined. Subcutaneous tissue thickness is measured within the muscle signal measurement range.

Tissue information may be information expressed in units of thickness (e.g., mm) or other information describing subcutaneous tissue, the value of which is directly or indirectly related to the properties of the skin fold.

Referring to Figure 2, in a preferred embodiment of the invention, the method is such that tissue information is measured by a separate meter 60, and the measurement result displayed by the meter 20 is fed to the measuring apparatus via the user interface 70. This implementation is simpler in technical terms.

Referring to Fig. 1, in a preferred embodiment of the invention, the method is such that tissue information is measured with: a measuring transducer 50 to directly obtain a measurement result using the measuring apparatus. 25 to work. This implementation is more automated and thus easier to use.

Referring to Figure 3, in a preferred embodiment of the invention, the method is such that the known dependency information between tissue information and EMG measurement utilized in the method is dependency information generated from a large human population of dependency measurements stored in a measuring apparatus.

The dependency information shown in Figure 3 is obtained by performing EMG measurement and simultaneous surface EMG measurement of approximately 50 healthy human spinal muscles and also measurement of subcutaneous tissue information such as thickness. Based on the measurement results, the shape of the dependence curve, i.e. its mathematical function, has been determined by statistical mathematical methods. : One way to determine the dependency, or dependency graph, is to fit the dependency graph to the measurement results, that is, using the curve fitting method. In Figure 3, the Y-axis unit is in percent, meaning the ratio of the surface EMG measurement amplitude to the needle EMG measurement amplitude, i.e. the ratio EMG-S (Surface) / EMG-IM (Intramuscular). The X-axis unit 5 is the subcutaneous tissue thickness sc (subeutius) in millimeters. It is found that, for example, at a tissue thickness of 20 mm, the dependence graph R gives a value of 30% or 0.30. It can be seen from Figure 3 that the dependency graph is an exponential regression curve. According to the applicant's observations, the Y-axis reading is between 12% -75%, i.e. 0.12-0.75, when the skin fold varies between 5-35 mm.

10 It is further noted from Figure 3 that the graph drawn through the coordinate points of the EMG-S (Surface) / EMG-IM ratios and their associated subcutaneous tissue thickness values is represented by the OB (Observed) graph, while the exponential graph fitted to the observation points is represented by R.

The dependency of the type shown in Fig. 3 or the like is stored in use by the measuring apparatus, most preferably stored in the measuring apparatus, for example, memory 150 in the apparatus according to the block diagram of Fig. 1. In practice, the information shown in Figure 3, i.e. the information provided by the Y-axis, functions as a divider operator for the surface EMG measurement result in the data processing unit 40, i.e. the 20 calculating unit 40. That is, if the tissue thickness is measured, for example, by 20 mm, then the data processing unit 40, i.e. the calculation unit 40, divides the measured surface EMG amplitude by 0.30 (or 30%), which results in an EMG value that is as high as possible. exactly corresponds to the value that would have been obtained by needle EMG measurement or other IM (Intramuscular) type measurement. The data processing unit 40 is; implemented with a processor, for example.

Figure 4 illustrates the EMG signals thus illustrating the difference in tissue thickness caused by the needle EMG measurement and the surface EMG measurement amplitude value. The upper pattern pair of Figure 4 shows EMG signals from two persons P1 and 30 P2 of different thickness subcutaneous tissue thicknesses, as measured by needle EMG measurement (IM). The lower pattern pair in Figure 4, in turn, shows: EMG signals from the surface EMG measurement of the two persons P1 and P2, thus having different thicknesses of subcutaneous tissue thickness. Comparing the upper patterns with the lower ones, a tissue thickness attenuating effect is observed. And comparing the lower patterns with one another, it is found that the person P2 having a stronger tissue thickness has a much more radical effect on the value of the surface EMG signal than the person P1 having a thinner tissue thickness.

When the subject of measurement is invited to make a target area yl-hasaktivaatio, such as, for example, the back bending or straightening of the arrow in Figure 2 of BE to 5, results in the back muscles generated by the EMG signal, which is thus measured surface EMG measurement, and the measurement result is lower in Figure 4 ku vionparin type of signal. When the tissue thickness compensation is performed in the manner of the invention, a corrected EMG signal of the same type as the signals of the upper 10-pair pattern of FIG. 4 is obtained starting from the surface EMG measurement. The measuring apparatus display 300 can display the result of tissue thickness compensated surface EMG measurement, which is substantially equivalent in level, i.e. amplitude, to that which would have been obtained by a needle EMG measurement or other IM (lntramuscular) measurement. If desired, the surface EMG measurements themselves can also be displayed on screen 300.

The invention can be applied, for example, in the context of the Applicant's US 5,755,675, that is, in a preferred embodiment, the EMG measurement provides simultaneous motion measurements in the target area by means of skin-mounted motion sensors such as 80 and comparing the measurement results with the pre-collected reference values. In addition, the application in question performs an evaluation of that application. impaired mobility and muscle function, particularly as a result of pain. Additionally: said application includes a method step for determining working muscle fatigue based on changes in frequency content of a muscle electrical signal. Other applications are also possible.

Although the invention has been described above with reference to the example of the accompanying drawings, it is clear that the invention is not limited thereto, but that it can be modified in many ways within the scope of the inventive idea set forth in the appended claims.

Claims (10)

1. A method for measuring muscle-related electrical activity, characterized by the method: - an EMG signal generated by the muscle is observed from the surface of the body with a measuring device, and - compensation of the tissue effect is performed, where the EMG signal value observed from the body surface is corrected. clarifying the corrected EMG signal value and to eliminate individual variation due to the subcutaneous tissue based on the measurement apparatus fed tissue information pertaining to the subcutaneous tissue by changing the observed EMG signal value from the body surface on the basis of known dependency information between the tissue information signal. 2. A method according to claim 1, characterized in that the tissue information which, when compensating the tissue effect, is measured in the measuring apparatus, information is given in a measuring unit (mm) for thickness or other information describing the subcutaneous tissue. Method according to claim 1, characterized in that the tissue information is measured with a separate meter, and the measurement result which the meter shows is measured to the measuring apparatus via a user interface. 20 4. A method according to claim 1, characterized in that the weaving information is measured with a measurement sensor belonging to the measuring apparatus to make the measurement result directly available to the measuring apparatus. Method according to claim 1, characterized in that the known dependency information between tissue information and the EMG signal, which dependency information is to be used in the method, is dependency information * formed by dependency measurements carried out on a sufficient number of healthy persons, which dependency information is stored. available for the measuring device. Apparatus for measuring muscle-related electrical activity which comprises apparatus (20) for observing an EMG signal generated by the muscle from the body surface, and which observational means interfere with functional communication with data processing means (40) which is included in the apparatus, known as the data processing means (40) are configured to compensate for the tissue effect, where it is observed from the surface of the body. The EMG signal value is corrected to clarify the corrected EMG signal value and to eliminate an individual variation due to subcutaneous tissue based on tissue information fed to the subcutaneous tissue by changing the observed EMG signal value from the body surface. on the basis of known dependency information used by the apparatus, between the tissue information and the EMG signal. Apparatus according to claim 6, characterized in that the apparatus comprises a user interface (70) for feeding tissue information measured to a measuring apparatus with a separate meter (60). 8. Apparatus according to claim 7, characterized in that the user interface (70) is a keyboard. Apparatus according to claim 7, characterized in that the apparatus comprises a measurement sensor (50) which measures the tissue information of the subcutaneous tissue, in order to make the measurement information of the tissue information directly available to the apparatus. Apparatus according to claim 6, characterized in that the apparatus comprises a memory (150) in which known dependency information between the tissue information relating to the subcutaneous tissue and the EMG signal is stored.