RU2773610C2 - Method for measurement of skeletal muscle hypertrophy and complex for its implementation - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: group of inventions relates to medicine, namely to a method and a complex for the measurement of skeletal muscle hypertrophy. When implementing the method, a sensor system is precisely positioned on the skin surface above the area of study at rest or when performing muscle contractions with a load, using a stand. At the same time, the stand includes a system of stepper motors along X, Y and Z coordinates. Signals are controlled from a control unit of stepper motors, using operator commands entered via a personal computer. Electrical impedance signals from measuring electrodes, ultrasonic signals from an ultrasonic sensor and mechano-myographic signals from force sensors are registered to control the force of pressing measuring sensors to the area of interest. As a result of the joint analysis of electrical impedance signals, electromyogram, mechanomyogram and ultrasound, an assessment of the level of muscle hypertrophy is formed by analyzing their functional state, strength, stiffness, muscle volume parameters and muscle structure resistance. The complex consists of a stand, an ultrasound device and a personal computer, a video capture card. The stand consists of a bio-signal registration unit, a mechanical signal registration unit, a control unit of stepper motors, an optical encoder of movement along the Z axis, a force to control the force of pressing measuring sensors to the area of interest along the Z axis, and a sensor system. The sensor system includes an electrode system for registering the electromyogram and electro-impedance, and a linear ultrasonic sensor. At the same time, outputs of the bio-signal registration unit and the mechanical signal registration unit are connected to PC. Outputs of the optical encoder of movement along the Z axis, force sensors along the Z axis are connected to an input of the mechanical signal registration unit. An output of the electrode system is connected to an input of the bio-signal registration unit. An output of the linear ultrasonic sensor is connected to the ultrasound device, an output of which is connected to an input of the video capture card. An output of the video capture card is in turn connected to PC. The control unit of stepper motors is a system of stepper motors along X, Y and Z coordinates.

EFFECT: due to the introduction of a system of stepper motors in along X, Y and Z coordinates into a complex, a precise positioning of sensors of a stand over the area of interest in space is ensured, due to the control of the pressure force of sensors and a set of information channels, the quality of measurement of indicators is improved, due to the joint analysis of signals of electrical impedance, electromyogram, mechanomyogram and ultrasound, the assessment of the level of muscle hypertrophy is provided by analyzing their functional state, strength, stiffness, muscle volume parameters and muscle structure resistance, the accuracy of diagnostics of hypertrophy and atrophy of skeletal muscles is increased, and the possibility of early diagnostics of hypertrophy is achieved by combining methods for the assessment of muscle volume based on data from an ultrasound sensor, an electromyogram and an electrical impedance signal.

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Description

The invention relates to the field of medicine and medical technology, more precisely to diagnostics and can be used to assess hypertrophy and atrophy of skeletal muscles, to measure muscle volume.

It is known that diseases of the musculoskeletal system, leading to inflammation, hypertrophy and atrophy of muscles, are accompanied by a change in the volume of the aerial fiber and the entire muscle. Measuring skeletal muscle thickness also allows assessment of the degree of adaptation in response to exercise in sports or rehabilitation [Han, P., Chen, Y., Ao, L. et al. Automatic thickness estimation for skeletal muscle in ultrasonography: evaluation of two enhancement methods. BioMed Eng OnLine 12.6(2013)].

Skeletal muscle hypertrophy is a process of increasing the volume and mass of skeletal muscle, an increase in the total cross-sectional area of muscle fibers, accompanied by an increase in muscle strength. A decrease in the volume or mass of a muscle is called atrophy.

Distinguish between short-term and long-term hypertrophy. Short-term hypertrophy is due to the filling of capillaries surrounding muscle fibers with blood, and an increase in their number. Long-term hypertrophy is divided into myofibrillar (associated with an increase in the volume of myofibrils) and sarcoplasmic (associated with an increase in the volume of the sarcoplasm) [Samsonova, Alla Vladimirovna. Human skeletal muscle hypertrophy [Text]: textbook].

A known method for assessing the cross-sectional area of the muscle using computed tomography (RU No. 2108768, 2007; RU No. 2309678, 2007), which consists in measuring the thickness and diameter of the muscle by multiplanar reconstructions of muscle sections. However, the known method is expensive and the procedure takes a long time, which makes them unsuitable for use in research and rehabilitation purposes involving a large number of patients.

Known "Method of measuring the muscle diameter and thickness of the skin-fat layer in athletes" (R.N. Volkhovskikh et al., "Method of ultrasonic echolocation of the muscle diameter and thickness of the skin-fat layer in athletes", J. "Theory and practice of physical culture, 1972, No. 12, pp. 66-68), based on the use of B-mode ultrasound (ultrasound) to measure muscle volume.

This method is chosen as a prototype of the invention.

In this method, a technical ultrasonic apparatus is used to measure the muscle diameter and the thickness of the skin-fat layer. A transducer producing ultrasonic vibrations was placed on the surface of the skin above the region of interest. The limb (hand) of the subject was located in a special setup, which made it possible to fix the coordinates of the sensor position and carry out repeated measurements in the same place of the limb. For this, a vertical stand was used, on which divisions were applied, which indicated the location along the height of a moving horizontal rail (which made it possible to find the position of the sensor horizontally) with the sensor fixed to it. Also, for the constancy of the direction of the ultrasound beam during repeated measurements, a protractor was mounted in the sensor head.

The advantage of the known method is its relative simplicity and low cost. The method allows obtaining information about changes in the cross-sectional area of the muscle, but excludes the possibility of studying the density structural characteristics of the muscles, and this method is also characterized by the subjectivity of visual assessment and the absence of quantitative criteria for such an analysis (Urgent ultrasound diagnostics in the practice of a military doctor. // Edited by M. Cheremisin /VMedA/ SPb, 1996, 133 p.).

To overcome the disadvantage associated with the impossibility of obtaining information about microscopic changes in the composition and structure of the muscles, it is preferable to add an electrical impedance signal to the ultrasound signal, which will increase the information content of the diagnostic method by assessing the electrical properties of the tissues of the measurement area [Miyatani, M., Kanehisa, N ., & Fukimaga, T. (2000). Validity of bioelectrical impedance and ultrasonographic methods for estimating the muscle volume of the upper arm. European Journal of Applied Physiology, 82(5-6), 391-396; Rutkove, S. B., Gregas, M. C, & Darras, B. T. (2012). Electrical impedance myography in spinal muscular atrophy: A longitudinal study. Muscle & Nerve, 45(5), 642-647].

Electrical impedance myography is a non-invasive method for determining neuromuscular activity, which consists in passing a high-frequency probing current between current electrodes and recording the resulting potential difference on the measuring electrodes. Most applications use a tetrapolar measurement technique to minimize electrode polarization, thus maintaining signal quality [Sanchez B., Rutkove S.B. Electrical Impedance Myography and Its Applications in Neuromuscular Disorders//Neurotherapeutics. neurotherapeutics. 2017. V. 14, No. 1. pp. 107-118. doi: 10.1007/sl3311-016-0491-x].

Another disadvantage of this method is the impossibility of detecting hypertrophy in the early stages, since in hypertrophy, in addition to changes in the architecture and thickness of skeletal muscles, changes also occur in the nervous apparatus (adaptive reactions occur not only in the muscular, but also in the nervous systems): improvement in muscle innervation, increased excitability of the neuromuscular apparatus, increased speed of muscle contraction and relaxation [Moritani T., deVries N.A. Neural factors versus hypertrophy in the time course of muscle strength gain. // American journal of physical medicine. 1979. No. 3 (58). C. 115-130; HAKKINEN K., KOMI P. Electromyographic changes during strength training and detraining // Medicine & Science in Sports & Exercise. 1983. No. 6 (15). C 455-460].

To overcome this limitation, it is preferable to increase the number of informative channels by adding a surface electromyogram signal to the ultrasound signal and the electrical impedance signal, which can be used to record the electrical activity of the muscles and evaluate changes in their nervous activation, which will make it possible to diagnose hypertrophy at early stages. [Moritani T, deVries NA. Neural factors versus hypertrophy in the time course of muscle strength gam. Am J Phys Med 58: 115-130, 1979] [Sale DG. Neural adaptation to resistance training. Med Sci Sports Exerc 20: S135-S145, 1988].

For measurements of the electrical impedance signal and the surface electromyography signal, it is possible to use one electrode system with further channel separation.

The next disadvantage of this method is the high probability of distorting the results due to uncontrolled excessive pressing of the ultrasonic sensor to the surface of the structure under study, which can affect the internal anatomy and geometry of the muscle section. [Mauris N, Beenakher E., van Schraik G. et al. Muscle ultrasound in children: normal values and application to neuromuscular disorders // Ultrasound Med Biol, 2004; 30 (8): 107-1027; Delyagin BM. Muscle ultrasound in normal and neuromuscular pathology // SonoAce-Ultrasound. 2015. No. 27].

To overcome this limitation, it is necessary to use force sensors to register the pressing of the ultrasonic transducer to the measurement area in order to control the pressing force and the effect of pressing on changes in the internal anatomy, which will also increase the information content of the diagnostic method by assessing the rheological properties of tissues.

To register mechanical signals, it is preferable to use force sensors that are located in the projection of the muscle belly, since as a result of contraction, a change (thickening and thinning) of the muscle body in the transverse direction occurs, simultaneously with a longitudinal displacement of the muscle belly, which in turn will affect the sensors force, according to the principle that the resistance of piezoresistors will change under the influence of an applied force - the amount of resistance changes in proportion to the amount of force applied, in turn, a change in the resistance of the circuit leads to a corresponding output voltage level.

To minimize transducer pressure on the skin, it is preferable to use a sufficient amount of high-density gel, position the transducer directly over the region of interest, and then move the transducer closer to the skin surface until the transducer is in full contact with the gel transition layer and a clear optical image is obtained.

Precise positioning of the transducer is preferred to ensure parallel or transverse movement of the transducer during the examination.

Preferably, the insonation angle (the angle between the longitudinal part of the muscle and the direction of the Doppler beam) is 90° to ensure optimal measurement of echogenicity [Mayans, David et al. "Neuromuscular ultrasonography: quantifying muscle and nerve measurements." Physical medicine and rehabilitation clinics of North America vol. 23.1 (2012): 133-48, xii. doi:10.i0i6/j.pmr.2011.11.009].

Patent and literature searches have shown that methods have been proposed for measuring hypertrophy based on the use of one or two different signals. To overcome the existing shortcomings and limitations inherent in various methods for assessing hypertrophy and muscle volume, it is necessary to increase the number of channels and combine information from different signals.

The technical objective of the present invention is to obtain accurate information about the structure and volume of skeletal muscles by controlling the pressing force of the sensors, as well as by increasing the number of information channels.

The expected technical result of the application of this invention is to increase the accuracy of diagnosing hypertrophy and atrophy of skeletal muscles and to enable early diagnosis of hypertrophy by combining methods for assessing muscle volume based on data from an ultrasound sensor, electromyogram (EMG) and electrical impedance signal (EI).

In this case, it became possible to accurately position the ultrasound transducer and electrode system relative to the area under study, providing control of the pressing force to obtain high-quality contact and signals, minimizing pressure on the skin and the impact on changes in the internal anatomy, cross section of the muscle and muscle fibers. Early diagnosis of skeletal muscle hypertrophy/atrophy has become possible by obtaining information not only about the cross section of the muscle, but also about its structure and composition, and by assessing the nervous activation of the muscles.

To achieve this technical result, a method for measuring skeletal muscle hypertrophy lies in the fact that the sensor system is accurately positioned on the skin surface above the study area at rest or when performing muscle contractions with a load using a stand that includes a system of stepper motors along the X, Y and Z coordinates , which are controlled by signals from the stepper motor control unit using operator commands entered through a personal computer, register signals from measuring electrodes, an ultrasonic (US) sensor and force sensors, as a result of a joint analysis of the signals of electrical impedance, electromyogram, mechanomiogram and ultrasound form an estimate of the level muscle hypertrophy by analyzing their functional state, strength, stiffness, parameters of muscle volume and resistance of muscle structures, also register electrical impedance signals from measuring electrodes, ultrasound and mechanomyographic signals from force sensors to control force pressing the measuring sensors to the area of interest.

The task is also achieved by the fact that the complex for measuring skeletal muscle hypertrophy consists of a stand, an ultrasound machine and a personal computer (PC), a video capture card, the stand consists of a biosignal registration unit, a mechanical signal registration unit, a stepper motor control unit, an optical encoder for moving along Z axis, which has force sensors to control the pressing force of the measuring sensors to the area of interest along the Z axis and a sensor system that includes an electrode system for recording electromyogram and electrical impedance and a linear ultrasound sensor, the outputs of the biosignal recording unit and the mechanical signal recording unit are connected to PC, the outputs of the optical encoder for movement along the Z axis, the outputs of the force sensors along the Z axis are connected to the input of the mechanical signal recording unit, the output of the electrode system is connected to the input of the biosignal recording unit, the output of the linear ultrasound sensor is connected to the ultrasound machine, the output of which is connected to the input of the video capture card , the output of which, in turn, is connected to a PC, in addition, the stepper motor control unit is a system of stepper motors along the X, Y and Z coordinates.

Thus, in the implemented complex, an ultrasonic sensor is used to assess the local thickness of the muscle, detect macroscopic architectural changes, measure the pennation angle of muscle fibers, parameters used to measure hypertrophy and assess the functional state of the muscles.

To overcome the limitations of the ultrasound method associated with the localization and one-dimensionality of the measurement, the implemented method registers the EI signal, which is used to assess muscle thickness and volume, as well as to analyze microscopic changes in the composition and structure of the muscle, which will determine the type and nature of hypertrophy. Another recorded biological signal is the surface electromyogram signal, which can be used to record the electrical activity of muscles and assess changes in their nervous activation, thereby providing an opportunity to diagnose hypertrophy in the early stages.

In the implemented method, to overcome the disadvantage associated with the dependence of the results of ultrasound measurements on the force of pressing the sensor to the study area, a mechanomyographic signal recorded by the force sensor is used, which makes it possible to control the degree of pressing the system and exclude the influence on the internal anatomy. The use of the MMG signal together with the proposed stand, which allows the step-by-step movement of the sensors, can serve to assess the strength characteristics of the muscles, measure the stiffness of the muscle at rest and in tension, defined as the ratio of the pressing force to the deepening of the sensor into the biological tissue.

The essence of the invention is illustrated by the following graphics:

In FIG. 1 shows a generalized scheme of the complex.

In FIG. 2 shows a block diagram of a complex for measuring skeletal muscle hypertrophy.

In FIG. Figure 3 shows a block diagram of a biosignal registration unit and a mechanical signal registration unit.

Fig. 4. Stand complex for measuring skeletal muscle hypertrophy.

Fig.5. Dependence of biosignals during grasping/opening of the hand with an iterative increase in the pressing force of the electrode system.

Fig. 6. Dependence of EI on the pressing force of the electrode system.

Fig. 7. Dependence of the pressing force of the sensor system on the displacement of the sensor system.

Fig. Fig. 8. Dependence of the EMG signal on the grip strength of the hand.

Fig. 9. Ultrasound image of muscle thickness measurement.

Fig. 10. An example of an ultrasound image for measuring the pennation angle. A and B - pennation angles of muscle fibers, ARC - aponeurosis (Kawakami, Y. Muscle-fiber pennation angles are greater in hypertrophied than in normal muscles / Y. Kawakami, T. Abe, T. Fukunaga // J. Appl. Physiol. 1993.-V.74.-N 6.-P 2740-2744).

The presented complex for measuring skeletal muscle hypertrophy consists of three fundamental blocks (Fig. 1): Stand 3, ultrasound machine 5 and Personal computer (PC) 4.

The considered complex for measuring skeletal muscle hypertrophy (Fig. 2) contains a stand that includes a sensor system (19), including an electrode system (17) connected to a biosignal recording unit (6), and a linear ultrasound sensor (18), the output of which is connected to an ultrasound machine (5) connected in series with a video capture card (13) connected to a personal computer (4). The complex under consideration includes stepper motors along the X (10), Y (11) and Z (12) coordinates, respectively, the input of each stepper motor along the X (10), Y (11) and Z (12) coordinates is the output of the stepper control unit motors (9), to which a personal computer (4) is connected. The displacement encoder (14) and force sensors along the Z axis (15) are the inputs of the mechanical signal recording unit (7). The outputs of the mechanical signal recording unit (7) and the biosignal recording unit (6) are connected to a personal computer (4).

The biosignal recording unit (Fig. 3) includes a current source (20) connected to two current electrodes (TE1, TE2). The differential signal from two measuring electrodes (IE1, IE2) is fed to the input amplifier (25). The output of the input amplifier (25) is connected to the input of the EMG signal processing unit, represented by the band pass filter of the EMG channel (26) and the scaling amplifier of the EMG channel (28) and to the input of the EI processing unit, represented by the band pass filter of the EI channel (27 ), synchronous detectors (29) and EI channel scaling amplifier (30). The signals from the processing units are digitized and transferred to a PC (4).

The mechanical signals of the stand to control the pressing force of the ultrasound probe and the electrode system to the skin, as well as their movements along the Z axis, are recorded in the mechanical signal recording unit (Fig. 3), represented by two force sensors (23) located at the edges of the ultrasound mount. sensor and electrode system, optical digital displacement encoder (24), connected to the axis of the stepper motor along the Z coordinate (12), which are powered by a reference voltage source (21). Signals from force sensors and displacement encoder are fed to the block of analog processing of mechanical signals (31), the output signals from which are digitized and transmitted to the PC (4).

The complex for measuring skeletal muscle hypertrophy described above works as follows.

The limb of the patient to be examined is fixed in the stand. To position the sensor system (19), the operator enters a command through a personal computer (4) connected to the stepper motor control unit (9), in which a control signal is generated for the linear movement of the sensor system, which is implemented by stepper motors along the X (10), Y coordinate (11) and Z (12), which allows you to accurately position the sensor system (19), as well as move the sensor system (19) during the entire series of measurements.

To implement feedback on linear displacement and pressing force of the sensor system, the stand contains a displacement encoder (14) and force sensors along the Z axis (15), the outputs of which are fed to the input of the mechanical signal recording unit (7).

The sensor system (19) includes an electrode system (17) of two current electrodes and two measuring electrodes and a linear ultrasonic sensor (18). The differential signal from the current and measuring electrodes is fed to the input of the biosignal recording unit (6), the output of the linear ultrasound sensor is connected to the ultrasound machine (5), the signal from which is recognized by the video capture card (13) and fed to the input of the personal computer (4). The outputs of the biosignal recording unit (b) and the mechanical signal recording unit (7) are connected to a personal computer (4).

Implementation example.

To implement the method under consideration for the proposed complex for measuring skeletal muscle hypertrophy, a stand was developed (Fig. 4), which allows mounting, positioning and movement of the stepper motor system along the X (10), Y (11) and Z (12) coordinates of the sensor system (19) , which may include, but is not limited to, an ultrasound sensor (18) and an electrode system (17) for recording electrophysiological signals, EMG and EI.

The electrode system (17) and the ultrasonic sensor (18) are fixed in the fixture of the sensor system of the stand, the operator, using the stepper motor control unit (9), positions the sensor system (19) so that it is located above the limb of the volunteer, in the projection area of the muscles of interest. From the measuring electrodes, ultrasound probe (18) and force sensors (15), signals are recorded, which, after processing and analysis, carry information about the degree of hypertrophy, muscle stiffness and their functional state. From the force sensors (15) a signal is recorded that characterizes the force of pressing the sensor system (19) to the area of interest.

An example of biosignals in the framework of one study with the location of the sensor system (19) in the projection of the muscles involved in the grip, when the volunteer performs the grip/opening of the hand with different grip strength, recorded with an iterative increase in the pressing force of the electrode system, is shown in Fig. 5. To analyze the signals (Fig. 5) that carry information about the functional state of the muscles, their strength, stiffness, as well as the parameters of muscle volume and resistance of muscle structures required to assess the degree of muscle hypertrophy, the data of Figs. 5 are presented as separate dependencies of FIG. 6 - fig. eight.

The dependence of EI on the pressing force of the sensor system in the framework of this study is shown in Fig.6. It characterizes the effect of pressing the electrode system on the EI signal and changes in the electrical parameters of the medium due to changes in the internal anatomy and tissue response to pressure.

The dependence of the pressing force on the displacement of the sensor system is shown in Fig. 7 makes it possible to measure muscle stiffness, which is expressed in the tissue reaction force, defined as the ratio of the pressing force to the movement of the sensor system (deepening of the sensor into the biological tissue). The muscle stiffness parameter measured in this way is one of the indicators of the functional state of the muscles.

An example of an EMG signal within one study when a volunteer performs a grip/opening of the hand, depending on the strength of the grip, is shown in Fig. 8. Analysis of the EMG signal (Fig. 8) makes it possible to assess the strength of muscle contraction and the level of nervous activation - parameters that indirectly characterize the degree of hypertrophy (atrophy).

The value of the EI signal carries information about the muscle volume and specific resistance of muscle structures, the change in the EI signal during the performance of an action carries information about the strength of the perfect movement. The EMG signal allows you to assess the degree of muscle contraction and the level of neuromuscular activation.

Analysis of ultrasound images (Fig. 9 and Fig. 10) allows determining the local thickness of the muscle, revealing macroscopic architectural changes, and measuring the pennation angle of the muscle fibers. Using the obtained parameters, it is possible to assess the degree of muscle hypertrophy (atrophy).

Adding an EI signal to an ultrasound signal will increase the information content of the diagnostic method, determine the volume and thickness of the muscle, study the structure of the area under study, determine the nature of hypertrophy, and distinguish between short-term, myofibrillar and sarcoplasmic hypertrophy.

The force sensor used to register the MMG signal, together with a system of stepper motors, makes it possible to obtain the dependence of the pressing force on the displacement (Fig. 7), which carries information about the stiffness of the muscle.

As a result of a joint analysis of biological signals, mechanical signals and ultrasound, an assessment of the level of muscle hypertrophy and their functional state is formed.

Claims (2)

1. A method for measuring skeletal muscle hypertrophy, which consists in the fact that the sensor system is accurately positioned on the skin surface above the study area at rest or when performing muscle contractions with a load using a stand that includes a system of stepper motors along the X, Y and Z coordinates, which are controlled signals from the stepper motor control unit using operator commands entered through a personal computer, signals from measuring electrodes, an ultrasonic (US) sensor and force sensors are recorded; analysis of their functional state, strength, stiffness, parameters of muscle volume and resistance of muscle structures, characterized in that they register electrical impedance signals from measuring electrodes, ultrasound and mechanomyographic signals from force sensors to control the pressing force of measuring yes points to the area of interest. 2. A complex for measuring skeletal muscle hypertrophy, consisting of a stand, an ultrasound machine and a personal computer (PC), a video capture card, the stand consists of a biosignal recording unit, a mechanical signal recording unit, a stepper motor control unit, an optical encoder for movement along the Z axis, characterized in that that there are force sensors to control the pressing force of the measuring sensors to the area of interest along the Z axis and a sensor system that includes an electrode system for recording electromyogram and electrical impedance and a linear ultrasound sensor, the outputs of the biosignal recording unit and the mechanical signal recording unit are connected to a PC, the outputs optical encoder for movement along the Z axis, force sensors along the Z axis are connected to the input of the mechanical signal recording unit, the output of the electrode system is connected to the input of the biosignal recording unit, the output of the linear ultrasound sensor is connected to the ultrasound machine, the output of which is connected to the input of the video capture card, the output of which in its turn connected to a PC, in addition, the stepper motor control unit is a system of stepper motors in X, Y and Z coordinates.

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