Analysis system, analysis method, and analysis device

Abstract

[Problem] To provide an analysis system which can accurately and conveniently analyze a function of a muscle. [Solution] This analysis system 1 comprises: an electric stimulus device 2 which applies an electric stimulus formed of short pulses on a muscle; an ultrasonic wave pulse echo device 3 which transmits an ultrasonic wave to the muscle and receives a reflected ultrasonic wave; and an analysis unit 33 which analyzes, on the basis of the reflected ultrasonic wave, contraction characteristics of the muscle at the time of a simple contraction response of the muscle with respect to the electric stimulus.

Description

[Technical Field]

[0001] The present invention relates to an analysis system, an analysis method, an analysis device, and an analysis program for analyzing changes in muscles caused by electrical stimulation using ultrasound. [Background technology]

[0002] BACKGROUND ART Conventionally, techniques have been proposed in which electrical stimulation is applied to a muscle and changes in the muscle due to the electrical stimulation are analyzed by ultrasound (for example, Patent Documents 1 and 2).

[0003] Patent Document 1 discloses a training tool that incorporates an ultrasound probe into an EMS (electrostimulation) device, which allows users to easily check the thickness of their muscles and subcutaneous fat before and after training, as well as the state of muscle movement during training, using ultrasound images.

[0004] Patent Document 2 discloses an ultrasound diagnostic device that includes an ultrasound probe and EMS electrodes arranged around the ultrasound probe, applies electrical stimulation to muscles using the EMS electrodes, and measures the muscle strain (stretching speed, stretching acceleration, and amount of stretch) caused by the electrical stimulation using the ultrasound probe. By applying electrical stimulation to muscles and measuring muscle strain that is not affected by the environment or physical condition, it is said that it is possible to predict muscle development. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 147384 [Patent Document 2] Patent No. 5159326 Summary of the Invention [Problem to be solved by the invention]

[0006] Although Patent Document 1 detects changes in muscle thickness etc. from a long-term perspective (comparison before and after training, confirmation of training effects), it does not mention instantaneous changes in muscle thickness in response to electrical stimulation (muscle contraction response). In other words, since only static muscle morphological information (thickness) is quantified, no indicators of muscle function can be obtained.

[0007] In Patent Document 2, since muscle contraction characteristics change depending on input conditions such as the transmission cycle of electrical stimulation, skin condition (humidity, sebum content, impedance, etc.), and muscle position (depth), it is necessary to specify the input conditions of electrical stimulation in order to analyze muscle function more accurately. However, Patent Document 2 does not specifically mention the input conditions of electrical stimulation, and it is unclear what kind of distortion during electrical stimulation is being focused on.

[0008] The present invention has been made to solve the above problems, and an object of the present invention is to provide an analysis system etc. that can accurately and easily analyze muscle function. [Means for solving the problem]

[0009] The analysis system of the present invention is characterized by comprising an electrical stimulation device that applies electrical stimulation consisting of short pulses to a muscle, an ultrasonic pulse echo device that transmits ultrasonic waves to the muscle and receives the reflected ultrasonic waves, and an analysis unit that analyzes the contraction characteristics of the muscle during the muscle's contraction response to the electrical stimulation based on the reflected ultrasonic waves.

[0010] The analysis method according to the present invention includes applying an electrical stimulus consisting of a short pulse to a muscle, transmitting ultrasound to the muscle, receiving reflected ultrasound, and, based on the reflected ultrasound, The method is characterized in that the contraction characteristics of the muscle are analyzed during the muscle contraction response to the electrical stimulation.

[0011] The analysis device of the present invention is characterized in that it analyzes the contraction characteristics of a muscle during its contraction response to an electrical stimulus consisting of a short pulse applied to the muscle, based on ultrasound transmitted to the muscle and reflected back from the muscle.

[0012] The analysis program of the present invention is characterized by operating a computer as an analysis device that analyzes the contraction characteristics of a muscle during its contraction response to an electrical stimulus consisting of a short pulse applied to the muscle, based on ultrasound transmitted to the muscle and reflected back from the muscle. [Effects of the Invention]

[0013] According to the present invention, muscle function can be analyzed accurately and simply. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a block diagram of an analysis system according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram of an analysis system according to an embodiment of the present invention. [Figure 3] 1 is a flowchart showing a processing flow in an analysis method according to an embodiment of the present invention. [Figure 4] 1 is a flowchart showing a processing flow in an analysis method according to an embodiment of the present invention. [Figure 5] (A) is an example of an M-mode image, (B) is a waveform showing the displacement of the muscle boundary in the ROI (region of interest) of the M-mode image shown in (A), and (C) is a waveform obtained by normalizing a portion of the waveform showing the displacement in (B). [Figure 6] FIG. 1 is a diagram for explaining a method for observing a contraction response using B-mode ultrasound. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0016] (System Configuration) Fig. 1 is a block diagram of an analysis system 1 according to one embodiment of the present invention, and Fig. 2 is a schematic diagram of the analysis system 1. The analysis system 1 includes an electrical muscle stimulation (EMS) device 2, an ultrasonic pulse echo device 3, and a control device 4. Note that the control device 4 is not shown in Fig. 2.

[0017] The electrical stimulation device 2 is a device that applies electrical stimulation to human tissue such as muscles, and includes an electrical pulse generating unit 21 and electrodes 22. The shape of the electrical stimulation device 2 is not particularly limited, but in this embodiment, as shown in FIG. 2 , the electrical stimulation device 2 is belt-shaped and the electrodes 22 are attached so as to contact the skin surface of the leg (the thigh in this embodiment). The electrical pulses generated by the electrical pulse generating unit 21 are propagated into the human body via the electrodes 22. When the electrical pulses reach the muscles, the muscles contract in response to the electrical stimulation.

[0018] The ultrasonic pulse echo device 3 has the function of transmitting ultrasonic waves to muscles and receiving reflected ultrasonic waves. As shown in Fig. 1, the ultrasonic pulse echo device 3 includes an ultrasonic transmitting / receiving unit 31, an ultrasonic probe 32, and an analyzing unit 33. In this embodiment, as shown in Fig. 2, the ultrasonic pulse echo device 3 is attached to the skin surface of the thigh. The ultrasonic transmitting / receiving unit 31 transmits ultrasonic waves toward the inside of the human body via the ultrasonic probe 32 in contact with the skin surface. The ultrasound waves are transmitted and reflected from within the human body and received. In this embodiment, two modes are used: ultrasound waves for imaging (B mode) to confirm the evaluation site and ultrasound waves for motion detection (M mode) to quantitatively evaluate muscles; however, only ultrasound waves for motion detection may be transmitted. Alternatively, only ultrasound waves for imaging (B mode) with a high frame rate capable of motion detection may be used.

[0019] The analysis unit 33 is an analysis device having a function of analyzing muscle function based on ultrasonic waves transmitted and received by the ultrasonic pulse echo device 3. To achieve this function, in this embodiment, the analysis unit 33 includes an ROI (hereinafter also referred to as region of interest) designation unit 331, a movement detection unit 332, and a feature calculation unit 333. These functional blocks may be realized in hardware terms by logic circuits formed on an integrated circuit, or may be realized in software terms by the processor of the ultrasonic pulse echo device 3 loading and executing a predetermined program in memory.

[0020] The control device 4 is a device that controls the electrical stimulation device 2 and the ultrasonic pulse echo device 3, and can be configured, for example, by a general-purpose computer. As shown in Figure 1, the control device 4 includes an electrical pulse setting unit 41, a pulse echo setting unit 42, and a feedback control unit 43.

[0021] The electrical pulse setting unit 41 has the function of setting the pulse width, repetition frequency, voltage, etc. of the electrical pulses generated by the electrical pulse generating unit 21 of the electrical stimulation device 2. The pulse width is set (for example, 1 ms) to be sufficiently small compared to the muscle contraction time (on the order of about 100 ms). The repetition frequency of the electrical pulses is set (for example, 2 Hz) so that the pulse interval is such that the muscle contraction response (a single muscle contraction response when a short-pulse electrical stimulus is applied to a muscle) can be sufficiently observed.

[0022] Here, a short pulse is defined as an electrical pulse wave of 10 ms or less, which is sufficiently short compared to the muscle contraction response time (on the order of about 100 ms). A pulse width of 1 ms or less (for example, one rectangular wave with a fundamental frequency of 2 kHz (pulse width of 0.5 ms)) is desirable, but even a rectangular burst wave with 20 waves (pulse width of 10 ms) at a fundamental frequency of 2 kHz is defined as a short pulse here. The voltage of the electrical pulse is initially set by the user, and is reset under the control of feedback control unit 43 while electrical stimulation device 2 is applying electrical stimulation to the muscle.

[0023] The pulse-echo setting unit 42 has a function of setting the waveform, transmission center frequency, transmission repetition period (frame rate), transmission pulse repetition frequency, sampling frequency, etc. of the ultrasound waves transmitted by the ultrasound transmission / reception unit 31 of the ultrasound pulse-echo device 3. For example, the transmission center frequency and frame rate of ultrasound waves for imaging (B mode) are set to 5 MHz and 30 Hz, respectively. For example, the transmission center frequency and transmission pulse repetition frequency of ultrasound waves for motion detection (M mode) are set to 10 MHz and 2 kHz, respectively.

[0024] Even in M-mode, if the system does not have a sufficient repetition frequency to observe muscle contraction responses, it is effective to reduce the frame rate of B-mode ultrasound and prioritize the repetition frequency of M-mode ultrasound, setting it to a higher value. In this case, by separating the transmission frequency band for imaging and the transmission frequency band for motion detection and separating each signal by filtering processing during reception, it becomes possible to achieve both functions without interference.

[0025] Furthermore, even with normal B-mode ultrasound at a low frame rate, it is possible to observe the contraction response by slightly shifting the repetition period of the electrical pulses from an integer multiple of the ultrasound frame rate and undersampling. For example, as shown in Figure 6(A), If the ultrasound frame rate is T1 and the repetition period of the electrical pulse (short pulse) is T2, then T2=m×T1-△t △t=T1 / n where m and n are predetermined integers. If T1 = 1 / 30 s, m = 15, and n = 60 (△t = 1 / 1800 s), one single contraction response can be observed by ultrasound imaging the response to 60 electrical pulses. That is, by sampling the muscle boundary displacement detected by ultrasound in the time frame of each electrical pulse period and superimposing the muscle boundary displacements in 60 time frames within one time frame, the muscle boundary displacement in the single contraction response can be estimated as shown in Figure 6(B).

[0026] The above sampling method is an example, and it is also possible to set T2 = m × T1 + Δt so that the timing of transmitting the electrical pulse is slightly later than the sampling point of the ultrasound imaging. Furthermore, although we have described a setting where the waveform obtained by superposition is sampled at equal intervals, it is still possible to estimate the muscle boundary displacement during the target contraction response even if Δt is not an integer division of T1.

[0027] The feedback control unit 43 has a function of controlling the magnitude of the electrical stimulation in accordance with the muscle contraction. In this embodiment, the feedback control unit 43 controls the electrical pulse setting unit 41 to reset the voltage of the electrical pulses generated by the electrical pulse generation unit 21 in accordance with the magnitude of the muscle contraction detected by the movement detection unit 332 of the analysis unit 33 when the electrical stimulation is applied.

[0028] The electrical stimulation device 2, the ultrasonic pulse echo device 3, and the control device 4 may be integrated to form the analysis system 1 as a single device. The analysis unit 33 may also be configured as an analysis device separate from the ultrasonic pulse echo device 3, or the function of the analysis unit 33 may be provided in the control device 4.

[0029] (Processing Procedure) 3 and 4 are flowcharts showing the flow of processing in the analysis method according to this embodiment. The analysis method according to this embodiment can be implemented by the analysis system 1 shown in FIG.

[0030] In step S1, the electrical stimulation device 2 and the ultrasonic pulse echo device 3 are attached to the human body. In this embodiment, as shown in Fig. 2, the electrical stimulation device 2 and the ultrasonic pulse echo device 3 are attached to the thighs.

[0031] In step S2, the electric pulse setting unit 41 sets an initial voltage value for the electric pulses generated by the electric pulse generating unit 21. The initial voltage value can be changed as appropriate depending on the type, size, and position (depth) of the muscle. If necessary, the electric pulse setting unit 41 may further set the pulse width and repetition frequency of the electric pulses. Furthermore, if the initial voltage value is set in advance, step S2 may be omitted.

[0032] In step S3, the electrical pulse generator 21 generates electrical pulses to start applying electrical stimulation to the muscle via the electrodes 22. In this embodiment, the repetition frequency of the electrical pulses is 2 Hz. When the electrical stimulation is applied to the muscle, the muscle contracts, and the boundary surface of the muscle is displaced in a direction perpendicular to the longitudinal direction of the muscle (the direction of the muscle fibers).

[0033] In step S4, the ultrasonic wave transmitting / receiving unit 31 starts transmitting and receiving ultrasonic waves via the ultrasonic probe 32. The transmitted ultrasonic waves are transmitted to the muscle boundary surface (the boundary surface between a muscle and another muscle, the boundary surface between a muscle and a soft tissue, etc.). The ultrasound waves are reflected from the tissue boundary, the muscle-bone boundary, and the like, and the reflected ultrasound waves are received by the ultrasound transmitter / receiver 31 via the ultrasound probe 32. An M-mode image showing muscle movement is obtained based on the time difference between the transmission and reception of the ultrasound waves. An example of an M-mode image is shown in Figure 5(A). This M-mode image contains peaks with a 0.5-second cycle corresponding to the contraction of each muscle.

[0034] The order of steps S3 and S4 is not particularly limited.

[0035] In step S5, the analysis unit 33 analyzes the contraction characteristics of the muscle. Figure 4 shows the detailed procedure of step S5.

[0036] In step S51, the ROI designation unit 331 sets an ROI in the M-mode image shown in Fig. 5(A). Waveform B1 in Fig. 5(A) corresponds to the boundary between the vastus intermedius muscle and the rectus femoris muscle, and waveform B2 corresponds to the boundary between the vastus intermedius muscle and the femur. In this embodiment, the ROI designation unit 331 sets the region between lines L1 and L2 corresponding to the vastus intermedius muscle to be analyzed as the ROI. The ROI may be set manually by the user while referring to an echo tomographic image or the like, or may be set automatically.

[0037] In step S52, the motion detection unit 332 extracts a waveform indicating the displacement of the muscle boundary in the ROI by a tracking process or the like, and detects the magnitude of contraction of the muscles (vastus intermedius and rectus femoris) based on the waveform. Figure 5(B) shows the extracted waveform indicating the displacement of the muscle boundary. In this embodiment, the magnitude of contraction refers to the amount of displacement of the muscle boundary surface in a predetermined direction perpendicular to the longitudinal direction of the muscle. The motion detection unit 332 calculates the difference between the maximum and minimum values of the waveform corresponding to one contraction (e.g., the waveform between lines L3 and L4) as the magnitude of contraction. The calculated magnitude of contraction is sent to the feedback control unit 43 of the control device 4.

[0038] In this embodiment, an example of analyzing the muscle contraction response of both the rectus femoris and vastus intermedius muscles has been shown. However, if it is desired to extract the contraction characteristics of the vastus intermedius muscle individually, the time response of the displacement of each of the waveforms B1 and B2 shown in Figure 5(A) can be extracted by tracking processing or the like, and the differential displacement can be analyzed.

[0039] In step S53, the feedback control unit 43 controls the magnitude of the electrical stimulation depending on the magnitude of muscle contraction. In this embodiment, the feedback control unit 43 controls the electrical pulse setting unit 41 so that the electrical stimulation increases until the maximum contraction during muscle contraction reaches saturation (a state in which the muscle contracts at an intensity of electrical stimulation composed of short pulses that maximizes muscle contraction). When step S7 is performed for the first time, the feedback control unit 43 causes the electrical pulse setting unit 41 to reset the voltage so that the voltage of the electrical pulses is higher than the initial value by a predetermined value.

[0040] In step S54, movement detection unit 332 recalculates the magnitude of muscle contraction in the same manner as in step S52. If the magnitude of muscle contraction is greater than before the increase in electrical stimulation (YES in step S55), the process returns to step S53, and feedback control unit 43 causes electrical pulse setting unit 41 to reset the voltage so that the voltage of the electrical pulse is further increased by a predetermined value.

[0041] On the other hand, if the magnitude of muscle contraction remains unchanged from before the increase in electrical stimulation (NO in step S55), the feedback control unit 43 does not instruct the electrical pulse setting unit 41 to reset the voltage, and the voltage of the electrical pulse is maintained as is.

[0042] In this embodiment, a state in which the magnitude of the maximum contraction of the muscle does not change substantially before and after the increase in electrical stimulation is defined as a state in which the contraction of the muscle is saturated. The criteria for determining whether or not the contraction has saturated are not particularly limited, but it may be determined that the contraction of the muscle has saturated if the increase rate of the contraction after the increase in electrical stimulation relative to the contraction before the increase in electrical stimulation is equal to or less than a predetermined value (for example, 2%).

[0043] Next, the process proceeds to step S56, where the feature amount calculation unit 333 calculates a feature amount that indicates the contraction characteristics of the muscle when the muscle contraction in response to the electrical stimulation is saturated (hereinafter referred to as saturated contraction). In this embodiment, the feature amount calculation unit 333 calculates the half-width of the peak corresponding to the muscle contraction in the waveform that indicates the displacement as the feature amount.

[0044] Specifically, the feature calculation unit 333 extracts a waveform indicating the displacement in one contraction (for example, the waveform between lines L3 and L4 shown in FIG. 5(B)), and performs normalization processing so that the maximum value of the displacement is 1 and the minimum value is 0. The waveform after normalization processing is shown in FIG. 5(C). The feature calculation unit 333 calculates the time during which the displacement in the waveform is 0.5 or more as the half-width.

[0045] The calculated half-width can be an index of muscle function, as described below. For example, when comparing the vastus intermedius and soleus muscles of the same person, the soleus muscle tends to have a larger half-width than the vastus intermedius because slow-twitch muscles are more prevalent in the soleus than in the vastus intermedius. Furthermore, even for the same type of muscle, subjects with diseases such as sarcopenia will have a different half-width from healthy subjects due to the loss of fast-twitch muscle fibers and the infiltration of fat between muscle fibers, as described below.

[0046] The feature amount is not limited to the half-width as long as it indicates the muscle contraction characteristics, and may be, for example, a 10% width of the peak, or the rise time or fall time of the peak. Furthermore, the manner of analyzing the muscle contraction characteristics is not limited to calculating the feature amount, and may also be a determination of the quality of muscle function, etc.

[0047] (Summary) As described above, in this embodiment, the contraction characteristics of a muscle are analyzed during saturated muscle contraction, i.e., when the magnitude of muscle contraction does not substantially change even with further increase in electrical stimulation. The contraction characteristics during saturated contraction are not influenced by the subject's will, and are independent of the input conditions of the electrical stimulation, so they reflect objective muscle function. Therefore, muscle function can be analyzed accurately and simply without using a CT or MRI device. In contrast, for example, the prior art described in Patent Document 2 does not disclose the input conditions of the electrical stimulation, and it is unclear whether muscle function can be accurately detected.

[0048] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. [Industrial Applicability]

[0049] The present invention can be applied, for example, to the prevention of sarcopenia and to training support for athletes.

[0050] Regarding the prevention of sarcopenia, the early symptoms are known to be the loss of fast-twitch muscle fibers and fat infiltration between muscle fibers, and as sarcopenia progresses, muscle cross-sectional area decreases, leading to a significant decline in quality of life, such as difficulty walking. Therefore, the present invention measures muscle contractile properties at predetermined intervals (e.g., every six months) and, based on the changes over time, detects early sarcopenic changes before a decrease in muscle cross-sectional area is observed, i.e., the loss of fast-twitch muscle fibers and fat infiltration into muscle fibers, thereby preventing the progression of sarcopenia.

[0051] In addition, when training athletes, it is important to understand the muscle composition (ratio of fast-twitch / slow-twitch muscles) appropriate for the sport and to know whether these muscles are changing in the desired direction as a result of training. This is important for improving performance. Therefore, by measuring the fast-twitch / slow-twitch muscle ratio and the like according to the present invention, the effects of training can be known more objectively and simply. [Explanation of symbols]

[0052] 1. Analysis system 2. Electrical stimulation device 3. Ultrasonic pulse echo device 4. Control device 21 Electrical pulse generator 22 electrodes 31 Ultrasonic transmitter / receiver 32 Ultrasound probe 33 Analysis Department 331 ROI specification section 332 Motion detection unit 333 Feature Calculation Unit 41 Electric pulse setting unit 42 Pulse echo setting section 43 Feedback control section

Claims

1. an electrical stimulation device that applies electrical stimulation consisting of short pulses to muscles; an ultrasonic pulse-echo device that transmits ultrasonic waves into the muscle and receives reflected ultrasonic waves; an analysis unit that analyzes the contraction characteristics of the muscle during the contraction response of the muscle to the electrical stimulation based on the reflected ultrasound; Equipped with The analysis unit calculates the half-width of the peak corresponding to the contraction in a waveform indicating the contraction response of the muscle as a feature indicating the contraction characteristics.

2. An electrical stimulation device that applies electrical stimulation consisting of short pulses to muscles; an ultrasonic pulse-echo device that transmits ultrasonic waves into the muscle and receives reflected ultrasonic waves; an analysis unit that analyzes the contraction characteristics of the muscle during the contraction response of the muscle to the electrical stimulation based on the reflected ultrasound; a feedback control unit that controls the magnitude of the electrical stimulation in accordance with the magnitude of the muscle contraction; An analysis system equipped with

3. An electrical stimulation device that applies electrical stimulation consisting of short pulses to muscles; an ultrasonic pulse-echo device that transmits ultrasonic waves into the muscle and receives reflected ultrasonic waves; an analysis unit that analyzes the contraction characteristics of the muscle during the contraction response of the muscle to the electrical stimulation based on the reflected ultrasound; Equipped with the repetition period of the short pulse is shifted by a predetermined time from an integral multiple of the transmission repetition period of the ultrasonic waves transmitted by the ultrasonic pulse echo device, and the predetermined time is shorter than the transmission repetition period of the ultrasonic waves; The analysis system includes an analysis unit that samples the muscle boundary displacement detected by the ultrasound in the time frame of each period of the short pulse, and estimates the muscle boundary displacement of the contraction response by superimposing the muscle boundary displacements in multiple time frames into one time frame.

4. The analysis system according to claim 1 , wherein the electrical stimulus is constituted by the short pulses at a predetermined repetition frequency.

5. The analysis system according to claim 2 , wherein the analysis unit calculates a feature quantity indicating the contraction characteristic.

6. The analysis system according to claim 5 , wherein the analysis unit calculates, as the feature, a half-width of a peak corresponding to the contraction in a waveform indicating the contraction response of the muscle.

7. The analysis system according to claim 1 or 3, further comprising a feedback control unit that controls the magnitude of the electrical stimulation depending on the magnitude of the muscle contraction.

8. The analysis system according to claim 2 or 7, wherein the feedback control unit increases the electrical stimulation until a contraction response of the muscle is saturated.

9. the repetition period of the short pulse is shifted by a predetermined time from an integral multiple of the transmission repetition period of the ultrasonic waves transmitted by the ultrasonic pulse echo device, and the predetermined time is shorter than the transmission repetition period of the ultrasonic waves; 3. The analysis system according to claim 1, wherein the analysis unit samples the muscle boundary displacement detected by the ultrasound in the time frame of each period of the short pulse, and estimates the muscle boundary displacement of the contraction response by superimposing the muscle boundary displacements in multiple time frames into one time frame.

10. It applies electrical stimulation consisting of short pulses to the muscles, Transmitting ultrasound waves to the muscle and receiving reflected ultrasound waves; analyzing the contraction characteristics of the muscle during the muscle contraction response to the electrical stimulation based on the reflected ultrasound; The analysis is an analysis method in which the half-width of the peak corresponding to the contraction in a waveform showing the contraction response of the muscle is calculated as a feature indicating the contraction characteristics.

11. analyzing contractile characteristics of a muscle during a twitch response of the muscle to an electrical stimulus consisting of a short pulse applied to the muscle based on ultrasound transmitted to and reflected from the muscle; The analysis device calculates the half-width of the peak corresponding to the contraction in a waveform showing the contraction response of the muscle as a feature indicating the contraction characteristics.

12. Applying electrical stimulation consisting of short pulses to muscles, Transmitting ultrasound waves to the muscle and receiving reflected ultrasound waves; analyzing the contraction characteristics of the muscle during the muscle contraction response to the electrical stimulation based on the reflected ultrasound; An analysis method in which the magnitude of the electrical stimulation is controlled according to the magnitude of the contraction of the muscle.

13. Analyzing the contraction characteristics of a muscle during its contraction response to an electrical stimulus consisting of a short pulse applied to the muscle based on ultrasound transmitted to and reflected from the muscle; An analysis device that controls the magnitude of the electrical stimulation depending on the magnitude of the muscle contraction.

14. Applying electrical stimulation consisting of short pulses to muscles, Transmitting ultrasound waves to the muscle and receiving reflected ultrasound waves; analyzing the contraction characteristics of the muscle during the muscle contraction response to the electrical stimulation based on the reflected ultrasound; the repetition period of the short pulse is shifted by a predetermined time from an integer multiple of the transmission repetition period of the ultrasonic wave to be transmitted, and the predetermined time is shorter than the transmission repetition period of the ultrasonic wave; The analysis involves sampling the muscle boundary displacement detected by the ultrasound in the time frame of each period of the short pulse, and estimating the muscle boundary displacement of the contraction response by superimposing the muscle boundary displacements in multiple time frames into one time frame.

15. Analyzing the contraction characteristics of a muscle during its contraction response to an electrical stimulus consisting of a short pulse applied to the muscle based on ultrasound transmitted to and reflected from the muscle; the repetition period of the short pulse is shifted by a predetermined time from an integer multiple of the transmission repetition period of the ultrasonic wave to be transmitted, and the predetermined time is shorter than the transmission repetition period of the ultrasonic wave; The analysis involves sampling the muscle boundary displacement detected by the ultrasound in the time frame of each period of the short pulse, and superimposing the muscle boundary displacements in multiple time frames into one time frame, thereby estimating the muscle boundary displacement of the contraction response.

Images