JP5574333B2 - Viscoelastic property measurement method and viscoelastic property measurement device - Google Patents

Description

  The present invention relates to a novel viscoelastic property measurement method. The present invention also relates to a novel viscoelastic property measuring apparatus that realizes the viscoelastic property measuring method.

  Quantitative examination of the mechanical properties of muscle deformation is very important for scientific evaluation in the fields of medicine, welfare, sports engineering, etc., because it is an organ directly responsible for human motor function It is. As a method for evaluating the mechanical properties of deformation, a tensile test is standard in a material testing method in the engineering field, but minimal invasiveness is required when considering application to humans. In this regard, the inventor has established a method for identifying elasticity and viscoelasticity such as Young's modulus (Young's modulus) and viscosity coefficient based on a minimally invasive material test method called a ball indenter indentation test (for example, Patent Document 1).

Mitsuhiro Tani, Satoshi Sakuma, Makoto Ogasawara, Measurement of in situ viscoelasticity of human soft tissue by ball indenter indentation test simulating palpation, Proceedings of the 22th Bioengineering Lecture Meeting of the Japan Society of Mechanical Engineers, No.09-55, (2010-1) , P.127.

As described above, the inventor has established a method for identifying elasticity and viscoelasticity such as Young's modulus and viscosity coefficient based on a minimally invasive material test method called a ball indenter indentation test. Furthermore, when evaluating the functional role of muscles in human movement, in addition to passive deformation characteristics for acting force such as response to external force, we investigate active deformation characteristics during self-contraction process. This is very important.
However, in addition to passive deformation characteristics for acting force such as response to external force, no attempt has been made to investigate active deformation characteristics in the process of contracting itself.

  Therefore, the development of a novel viscoelastic property measurement method and viscoelastic property measurement device that solves such problems is desired.

The present invention has been made in view of such problems, and an object thereof is to provide a novel viscoelastic property measurement method.
Another object of the present invention is to provide a novel viscoelastic property measuring apparatus that realizes the viscoelastic property measuring method.

  In order to solve the above-described problems and achieve the object of the present invention, a viscoelastic property measurement method of the present invention is a method for measuring viscoelastic properties of muscles, and uses the muscle force and driving input stimulus to measure the viscoelastic properties. Is a method of calculating

  Here, the muscles are preferably animal muscles such as humans, monkeys, horses, and tuna, although not limited thereto. Moreover, although not necessarily limited, it is preferable that a viscoelastic property is a Young's modulus and viscous compliance in a Kelvin model. Although not limited, it is preferable that the viscoelastic property is the Young's modulus of the elastic part, the viscosity compliance of the viscoelastic part, and the Young's modulus of the elastic part in the viscoelastic part in the three-element solid model. . Moreover, although not necessarily limited, it is preferable that a muscular strength is a muscular strength in isometric contraction. Although not limited, it is preferable that the signal of the driving input stimulus is surface myoelectric, needle myoelectric, or neuromuscular stimulation.

  The viscoelastic property measuring apparatus of the present invention is a device that measures the viscoelastic property of a muscle, and includes a calculation unit that calculates the viscoelastic property using muscle force and driving input stimulus.

  Here, the muscles are preferably animal muscles such as humans, monkeys, horses, and tuna, although not limited thereto. Moreover, although not necessarily limited, it is preferable that a viscoelastic property is a Young's modulus and viscous compliance in a Kelvin model. Although not limited, it is preferable that the viscoelastic property is the Young's modulus of the elastic part, the viscosity compliance of the viscoelastic part, and the Young's modulus of the elastic part in the viscoelastic part in the three-element solid model. . Moreover, although not necessarily limited, it is preferable that a muscular strength is a muscular strength in isometric contraction. Although not limited, it is preferable that the signal of the driving input stimulus is surface myoelectric, needle myoelectric, or neuromuscular stimulation.

  The present invention has the following effects.

  The viscoelastic property measurement method of the present invention is a method for measuring the viscoelastic property of a muscle, and calculates the viscoelastic property using muscle force and driving input stimulus, and thus provides a novel viscoelastic property measurement method. be able to.

  The viscoelastic property measuring apparatus of the present invention is a device that measures the viscoelastic property of a muscle, and has a calculation unit that calculates the viscoelastic property using muscle force and driving input stimulus, and thus has a novel viscoelastic property. A measuring device can be provided.

It is the figure which represented the passive deformation | transformation which changes a shape according to the force which acted about the muscle, and the active deformation which changes a shape itself in order to move with a dynamic serial model. It is a figure which shows the Kelvin model as a structural model showing the deformation | transformation characteristic of a passive part. It is a figure which shows the 3 element solid model as a structural model showing the deformation | transformation characteristic of a passive part. It is a figure which shows the test apparatus which consists of a handle which bends around an elbow joint in order to make isometric contraction of the muscle of a human upper arm, and a measuring device for measuring the load value and surface myoelectric potential at that time. It is a figure which shows the outline of the indentation test machine for measuring the representative Young's rate of the muscle of a forearm. It is a figure which shows the muscular strength-time graph and surface myoelectric potential ratio-time graph which were measured in each speed. It is a figure which shows the relationship between the generated muscular strength and surface myoelectric potential ratio measured in each speed. It is a figure which shows each physical-property value in a Kelvin model and a 3 element solid model.

  Hereinafter, the form for implementing invention concerning a viscoelastic property measuring method and a viscoelastic property measuring device is explained.

The viscoelastic characteristic measurement method is a method for measuring the viscoelastic characteristic of a muscle, and is a method for calculating the viscoelastic characteristic by using a muscle force and a driving input stimulus.
The viscoelastic property measuring apparatus is a device that measures the viscoelastic property of a muscle, and has a calculation unit that calculates the viscoelastic property using muscle force and driving input stimulus.

  As the viscoelastic property, Young's modulus and viscous compliance in the Kelvin model (Kelvin model) can be adopted. Alternatively, as the viscoelastic characteristics, the Young's modulus of the elastic part, the viscosity compliance of the viscoelastic part, and the Young's modulus of the elastic part in the viscoelastic part in the three-element solid model can be adopted.

  In addition, in the text of this specification, an English character symbol with an over dot is described as “(English character symbol) over dot”, and an English character symbol with an over wavy line is represented by “(English character symbol) an over wavy line. "And an English character symbol with an overbar as" (English character symbol) overbar ".

  In the present invention, in order to clarify the mechanical characteristics of muscles that are indispensable for analyzing the mechanics of various motor functions of humans, the muscle strength is measured in situ by measuring the viscoelastic characteristics of the muscles during the contracting movement process. And a method to identify from surface electromyography (sEMG) is presented. Regarding this viscoelastic property, we show here how to identify the elastic element and the viscous element in parallel by the Kelvin model and the three-element solid model.

A muscle deformation model will be described.
First, exercise and muscle deformation will be described. Muscles have two dynamic functions: passive deformation that changes according to the force on which the shape acts, and active deformation that changes the shape itself to move. In the present invention, as a model representing these deformations, a series model of two functions of a passive part that deforms according to an acting force and an active part that deforms itself is considered. For example, in the upper arm model of FIG. 1 (a), the length l _H of the muscle of the upper arm changes according to the rotation angle theta _E elbow. When considering the strain that accompanies this change in length l _H by replacing it with a series model of passive part 9 and active part 8 as shown in FIG. 1 (b), the total strain rate ε overdot in this model is As shown in FIG. 1 (c), the sum of the strain rate ε ^P overdot of the passive portion 9 and the strain rate ε ^a overdot of the active portion 8 can be expressed by the following equation.

Next, the configuration model will be described. Regarding the total strain rate ε overdot shown in this equation (1), the general relationship between the strain rate ε ^P overdot of the passive portion and the stress rate σ overdot acting on the passive portion, the deformation resistivity D was used in the present invention. It is expressed by the following formula.

Further, the strain rate ε ^a overdot of the active portion is expressed by the following equation using the signal μ indicating the magnitude of the active deformation and the proportionality constant Λ.

This proportionality constant Λ is referred to as a muscle contraction coefficient in the present invention.
Next, identification of viscoelastic properties will be described. In the present invention, first, after identifying the deformation characteristics of the active part, a method for identifying the deformation characteristics of the passive part from this information is examined.

  Here, first, regarding the deformation characteristics of the active part to be identified, isometric contraction that exerts muscle strength without changing the total length of the muscle is considered. In this case, since the length of the streak does not change, the following equation holds for the total strain rate ε overdot.

Therefore, from the relationship between the equations (5) and (4), the strain rate ε ^a overdot of the active part can be expressed by the following equation.

  Under this condition, it is assumed that the deformation characteristics of the passive part are represented only by a typical Young's modulus E.

Given this relationship, the following equation can be derived when the muscular strength speed here is F overdot and the cross-sectional area of the muscle is A.

  Therefore, the muscle contraction coefficient Λ can be identified by the following equation from the muscular strength velocity F overdot and the signal velocity μ overdot when the typical Young rate E and the cross-sectional area A of the muscle are known.

  Here, when the Kelvin model shown in FIG. 2 is considered as a constitutive model representing the deformation characteristics of the passive part, a method of identifying the physical property value of this model from the muscular strength speed F overdot and the signal speed μ overdot is shown.

  First, a method for identifying the muscle contraction coefficient Λ when the Kelvin model is considered for the passive part will be described. Here, the ideal very low strain rate ε overdot condition that can ignore the influence of viscosity

In this case, the following relationship is established in the passive part of the viscoelastic body represented by the Kelvin model in FIG.

Further, the muscle contraction coefficient Λ can be identified by the following equation from the muscular strength velocity ^Fγ overdot and the signal velocity μγ ^{overdot at} this time.

Next, identification of the deformation characteristics of the passive part. First, the strain rate affected by the viscosity is expressed using the ε ^{Pα overdot} and the subscript α, then the following equation is established from the characteristics of the Kelvin model shown in Fig. 2. To do.

  From the condition of isometric shrinkage,

think of. At this time, when the comparison is made with the same signal μ ^α = μ ^γ under the condition that the active portion distortion ε ^a depends only on the signal μ, ε a ^α = ε a ^γ, that is, ε ^Pα Since = ε ^Pγ holds, the following relationship can be considered.

  From these formulas (13) and (14), the viscous compliance C can be expressed by the following formula.

In addition, the stress σ ^α from the muscle strength F ^α and the cross-sectional area A of the muscle is

From the equation (16), the stress σ ^veα is

Therefore, the viscosity compliance C in the equation (17) becomes the following equation.

  Here, as a constitutive model for evaluating the deformation of the passive part in FIG.

First, regarding the constitutive equation, the model shown in Fig. 3 is divided into an elastic part and a viscoelastic part that are in series, and from this relation, the strain rate ε ^P overdot of the passive part is the strain rate of the elastic part and the viscoelastic part as the sum of epsilon ^e over dots and epsilon ^v over dots represented by the following equation.

  Here, each part has the following relationship with respect to stress and strain.

Regarding the constitutive expressions represented by these equations (22), (23), and (24), an identification method when the physical property values E ^e , E ^ve , and C are constant will be considered. At this time, the muscular strength F when the cross-sectional area of the muscle is A can be expressed by the following equation from the relationship of these equations (22), (23), and (24).

Here, the ideal very low-speed active part strain rate ignoring the viscosity near zero represented by the subscript γ ε ^aγ over-dot, the two high-speed active unit strain ^rates represented by the subscripts α and β ε ^{aα overdot} and ε ^{aβ overdot} are considered as follows.

Considering the isometric contraction of the muscle (ε overdot = 0) at this time, the following relationship holds for the strain rate ε ^P overdot of the passive portion.

Thus when the difference in the speed occurs, exerts strength F ^alpha corresponding to the speed, F ^beta, difference occurs in the F ^gamma. Given the demonstrated strength F ^gamma at speeds negligible viscosity criteria, this difference can be expressed by the following relation from Eq. (25).

If the comparison is made with the same signal μ ^α = μ ^β = μ ^γ under the condition that the active part distortion ε ^a depends only on the signal μ, then ε a ^α = ε a ^β = ε ^{Since aγ} holds, equations (28) and (29) can be rearranged as follows using the relationship between equations (6) and (21).

  Furthermore, from Equations (8) and (22), Equations (30) and (31) are as follows:

Here, in the extremely low strain rate ε ^{aγ overdot} where the viscosity can be ignored, the following relationship is established between the representative Young's modulus E, the elastic Young's modulus E ^e , and the viscoelastic Young's modulus E ^ve .

This relationship holds regardless of the strain rate when these Young's moduli are constant.
When this equation (34) is used to rearrange equations (32), (33) and C, the following relationship is obtained.

Further, when this equation (35) is arranged with respect to the elastic portion Young's modulus E ^e , the following relationship is obtained.

  Here, the variable B represents the following relationship.

By substituting the elastic part Young's modulus E ^e obtained here into the equation (35), the viscosity compliance C is obtained by the following equation.

Further, the viscoelastic portion Young's modulus E ^ve can be obtained from the following equation from the equation (34).

The viscoelasticity measurement of the human upper arm muscle will be described.
First, the test apparatus will be described. For the purpose of investigating the characteristics of the muscles inside the upper arm during flexion of the upper arm, a surface myoelectric potential is used as the drive input stimulus μ, and an isometric contraction test regarding the rotational motion of the elbow joint is performed. FIG. 4 shows a test apparatus including a handle 16 that bends around the elbow joint in order to cause isometric contraction of the human upper arm muscle, and a measuring device for measuring the load value and surface myoelectric potential at that time. The handle 16 is directly connected to the reel 15, and the wire end is connected to the strain gauge 17 via a pulley. The surface electromyograph 12 uses a self-made one with a differential amplification circuit that can change the amplification magnification to an arbitrary value with a pass band of 4.7 Hz to 3.3 × 10 ³ Hz, and has a diameter of 10 mm and a center distance of 20 mm. 11 is affixed to the elbow side of the biceps, and the surface myoelectric potential is measured. Each voltage output was measured at a sampling frequency of 500 Hz using a sensor interface PCD320A manufactured by Kyowa Denki Co., Ltd. The PC 20 has a calculation unit, and the calculation unit calculates the viscoelastic characteristics of the muscle using the load value and the surface myoelectric potential.

  Next, test conditions will be described. Table 1 shows the conditions of the isometric shrinkage test. The elbow angle is defined as the angle at which the forearm bone is bent from this reference state with the forearm bone and the humerus being collinear. In the test, at an elbow angle of 0 degrees, the speed α is the maximum speed at which the muscle is maximally voluntarily contracted at the highest speed, the speed β is the maximum voluntary contraction of the muscle at 0.75 seconds, and the speed γ is the maximum voluntary contraction of the muscle at 10 seconds. Isometric contraction was performed 5 times each. At this time, the maximum voluntary contraction was maintained for 3 seconds and a 60-second rest was taken after each test. In this test, the load value and surface myoelectric potential are measured, and the generated muscle strength of the upper arm muscle at each speed is obtained from the load value. In addition, since it is thought that fatigue caused by repeating the maximum voluntary contraction affects the load, the order of speed in the test is β → α → γ → α → γ → β → γ → β → α → β → γ → α → γ → α → β.

Next, the derivation of the generated muscle force and the surface myoelectric potential ratio will be described. The load value measured at each speed is f ^I , the handle load is F ^I _Hi over wavy line, the diameter of the wire winding part is φ ₁ , and the distance from the elbow joint to the forearm rough surface is φ _E / 2, the distance from the elbow joint to the loading point and l _O. The subscript I represents α, β or γ. In this case, the elbow joint torque T _E, the following equation from the distance l _RU from the applied load F ^I _Hi over wavy and elbow joint diameters phi ₁ and the handle load value f ^I and the wire take-up unit of measurement to the loading point become that way.

Therefore, from equation (40) and equation (41), the handle load F ^I _Hi over wavy line can be expressed as follows.

  Here, the following equation is established from FIG.

Therefore, from formula (43), the generated muscle force F ^I _Hi is calculated from the handle load load F ^I _Hi over wavy line, the distance l _RU from the elbow joint to the load point, and the distance φ _E / 2 from the elbow joint to the muscle connection position. It can be obtained from
This time, the muscular strength F ^I _Hi is calculated as [2], assuming that the diameter φ ₁ of the wire winding part is 102 mm, the distance l _O from the elbow joint to the load point is 300 mm, and the ratio of l _RU to φ _E / 2 is 5. It was. The surface myoelectric potential ratio is defined as a ratio μ ^I / μ overbar obtained from the average value μ overbar of the surface myoelectric potential from the maximum voluntary contraction at the start of contraction at the speed α to 2 seconds.

Next, the derivation of the slope by the sigmoit function will be described. In the muscle contraction process, it is considered that the muscle is maximally driven when it exerts half the maximum muscular strength. Here, when the muscle is driven to the maximum, the load load speed F ^I _Hi overdot and the input stimulus specific speed μ ^I overdot / μoverbar are maximum. Therefore, if the largest inclination can be obtained in each speed graph, the inclination in a state where the muscle is driven to the maximum can be obtained. From this, the sigmoid function represented by Equation (44) is approximated to the generated muscle force F ^I _{Hi -time} t graph and surface myoelectric potential ratio μ ^I / μ overbar-time t graph obtained from the test results. Then, we studied to find the slope of each graph.

This is because the maximum slope of the sigmoid function expressed by the equation (44) can be obtained when it is half the maximum value f (x) _max . Therefore, the load load speed F ^I _Hi overdot and the input stimulus specific speed μ ^I overdot / μoverbar are obtained from the maximum slope of the sigmoid function f (x) approximating the test result.

Next, measurement of the representative young rate will be described. Using the indentation test [1] of the valley, the representative Young's rate of the forearm muscle is measured using the test apparatus shown in FIG. The test equipment has a mechanism to control the load shaft 25 attached to the Mechatronic Actuator XY-HRS400-RH202 made by NSK Ltd. with a maximum of 1.2m / s by PC. The load is obtained from the load cell LUR-A100NSA1 manufactured by Kyowa Denki Co., Ltd. attached to the load shaft 25, and the displacement is the amount of movement of the stage 24 of the actuator to which the ball indenter 26 is attached. Measured with volume RSA0N11S9002. The indentation test was performed once on the muscles of the forearm of one adult male. The ball indenter 26 used at this time is made of acrylic and has a diameter of 2.0 × 10 ⁻² m. The friction is reduced by applying oil to the contact surface between the ball indenter 26 and the forearm. The speed condition is 0.1 mm / s to reduce the effect of muscle viscosity as much as possible. By measuring the amount of displacement and load under these conditions, the representative Young's rate could be obtained as 12.7 kPa. This time, the representative Young rate obtained with the forearm is used as the representative Young rate E _Hi of the upper arm muscle.

Next, identification of physical property values in each model will be described. FIG. 6 shows a five-time average value-time graph of the generated muscle force measured at each speed and a five-time average value-time graph of the surface myoelectric potential ratio. The test results at each speed at this time are approximated by a sigmoid function, and the load load speed F ^I _Hi overdot and the input stimulus specific speed μ ^I overdot / μoverbar are obtained from the maximum slope. Further, assuming that the cross-sectional area A _{Hi of the} muscle is constant, a circular shape having a diameter of 40 mm is assumed, and [3] approximately 13 cm ² is used.

Fig. 8 shows the physical properties of the Kelvin model and the three-element solid model. Here, the viscosity compliance C is expressed as μ ^α over dot / (F ^α _Hi over dot−F ^γ _Hi over dot) in the equation (20) between μ ^I over dot / μ over bar and F ^I _Hi over dot in FIG. As a ratio. Here, the viscosity compliance C _Hi and the Young's modulus E ^ve _{Hi of the} viscoelastic part in the Kelvin model and the three-element individual model are close to each other. In the three-element solid model, the Young's modulus E ^e _Hi of the elastic part is larger than the Young's modulus E ^ve _{Hi of the} viscoelastic part.

As described above, an isometric contraction test was performed on human upper arm muscles in order to identify viscoelastic characteristics of muscles. In addition, the obtained muscle strength F ^I _{Hi -time} t graph and the surface myoelectric potential ratio μ ^I / μ overbar -time t graph are approximated by a sigmoid function, and the muscle viscosity in the Kelvin model and three-element solid model is calculated. The values required for elastic property identification were obtained. At this time, it was also shown that the viscoelastic characteristics of the muscle can be identified from the obtained inclination.

  In addition, as muscle, animal muscles such as humans, monkeys, horses, and tuna can be employed.

  As the type of muscle, striated muscle, smooth muscle, and myocardium can be employed. This is because the correlation between myoelectric potential and muscle activity is the same.

  The isometric contraction test is preferably performed at a speed α at which the muscle is maximally voluntarily contracted at the highest speed, a speed β at which the muscle is maximally voluntarily contracted at a medium speed, and a speed γ at which the muscle is maximally voluntarily contracted at a low speed. Here, the speed β is smaller than the speed α, and the speed γ is much smaller than the speed β.

  At speed α, the time for maximum voluntary contraction of the muscle is preferably in the range of 0.05 to 5 seconds. When the maximum voluntary contraction time is 0.05 seconds or more, there is an advantage that signal measurement is easy. When the maximum voluntary contraction time is 5 seconds or less, there is an advantage that evaluation of viscoelasticity is easy.

  At speed β, the time for maximum voluntary contraction of the muscle is preferably in the range of 0.1 to 10 seconds. When the maximum voluntary contraction time is 0.1 seconds or more, there is an advantage that the muscle at the speed α can cause a significant difference from the maximum voluntary contraction. When the maximum voluntary contraction time is 10 seconds or less, there is an advantage that the muscle at the speed γ can make a significant difference from the maximum voluntary contraction.

  At speed γ, the time for maximum voluntary contraction of the muscle is preferably in the range of 5-50 seconds. When the maximum voluntary contraction time is 5 seconds or more, there is an advantage that the influence of viscosity can be reduced. When the maximum voluntary contraction time is 50 seconds or less, there is an advantage that the influence of muscle fatigue due to the passage of time can be reduced.

  When an isometric contraction test is performed for the purpose of examining the characteristics of muscles inside the upper arm, the elbow angle is preferably in the range of 0 to 150 degrees. If the elbow angle is 0 degree or more, there is an advantage that the maximum angle of the joint can be used as a reference. When the elbow angle is 150 degrees or less, there is an advantage that the upper limit can be set in a state where the muscles are most contracted.

  Muscle strength is not limited to muscle strength in isometric contraction. In addition, isotonic contraction can be employed as the muscle strength. Employing isotonic contraction has the advantage of being able to evaluate the characteristics of the muscles in the movement process where the elbow angle changes.

  When the viscoelastic properties of muscle are expressed by the Kelvin model, the Young's modulus is preferably in the range of 10 kPa to 100 MPa. If the Young's modulus of the muscle is 10 kPa or more, there is an advantage that the representative Young's modulus can be measured by pressing. When the Young's modulus of the muscle is 100 MPa or less, there is an advantage that it is possible to evaluate characteristics that have been difficult to measure in the past.

When the viscoelastic property of muscle is expressed by the Kelvin model, the viscosity compliance is preferably in the range of 10 ⁻¹⁴ to 10 ³ (PaS) ⁻¹ . If the viscosity compliance of the muscle is 10 ⁻¹⁴ (PaS) ⁻¹ or more, there is an advantage that the viscous behavior can be identified. When the muscle viscosity compliance is 10 ³ (PaS) ⁻¹ or less, there is an advantage that measurement can be performed with minimal invasiveness.

  When the viscoelastic characteristics of muscles are represented by a three-element solid model, the Young's modulus of the elastic part is preferably in the range of 100 Pa to 100 MPa. When the Young's modulus of the elastic part is 100 Pa or more, there is an advantage that measurement can be performed with minimal invasiveness. If the Young's modulus of the elastic part is 100 MPa or less, there is an advantage that an indentation test can be performed with a soft indenter.

When the viscoelastic properties of muscles are represented by a three-element solid model, it is preferable that the viscosity compliance of the viscoelastic part is in the range of 10 ⁻¹⁴ to 10 ³ (PaS) ⁻¹ . If the viscosity compliance of the viscoelastic part is 10 ⁻¹⁴ (PaS) ⁻¹ or more, there is an advantage that the viscous behavior can be identified. When the viscosity compliance of the viscoelastic part is 10 ³ (PaS) ⁻¹ or less, there is an advantage that measurement can be performed with minimal invasiveness.

  When the viscoelastic properties of muscles are represented by a three-element solid model, the Young's modulus of the elastic part in the viscoelastic part is preferably in the range of 100 Pa to 100 MPa. When the Young's modulus of the elastic part in the viscoelastic part is 100 Pa or more, there is an advantage that measurement can be performed with minimal invasiveness. If the Young's modulus of the elastic part in the viscoelastic part is 100 MPa or less, there is an advantage that an indentation test with a soft indenter can be performed.

  As the driving input stimulus signal, surface myoelectric, needle myoelectric, neuromuscular stimulation or the like can be employed.

  In this embodiment, both the Kelvin model and the three-element solid model are adopted as the constituent models, and the versatility of this identification method is shown.

  As a constitutive model, the Kelvin model has an advantage that the number of elements is small and physical property values can be easily identified. The three-element solid model has the advantage of expressing more complex viscoelastic properties.

  According to the present embodiment, if the deformation characteristics of muscles during exercise can be identified, guidelines for muscle strengthening in sports training will be provided, muscle rehabilitation methods in medicine will be evaluated, and myocardial status examined in situ And so on.

  Applications of the present invention include medical / welfare, sports science, and racehorse training that are greatly affected by differences in muscle activity.

  It is to be noted that the present invention is not limited to the embodiment for carrying out the above-described invention, and various other configurations can be adopted without departing from the gist of the present invention.

[References]
[1] Mitsuhiro Tani, Atsushi Sakuma, Makoto Ogasawara, Masamitsu Shinomiya, Evaluation of indentation characteristics for minimally invasive measurements on soft tissues, 21st Bioengineering Lecture, No.08-53, (2009), pp.183- 184.
[2] Kazuo Funato, http://www.jiss.naash.go.jp/column/saizensen 10.html, viewed on January 22, 2010
[3] Akagi, Toka, Ota, Takada, Kawakami, Fukunaga, Effectiveness of muscle shape index by combination of muscle thickness and morphometrics, IEICE Tech., MBE2005-18, (2005).

8 ... Active part, 9 ... Passive part, 11 ... Double electrode, 12 ... Surface electromyograph, 15 ... Reel, 16 ... Handle, 17 ... Strain gauge, 20 ... PC, 24 ... Stage, 25 ... Load axis, 26 ... Ball indenter

Claims (12)

A method for measuring viscoelastic properties of muscles,
Obtaining a representative Young ratio of the muscle by an indentation test;
When the total strain rate of the muscle is expressed as the sum of the strain rate of the active part and the strain rate of the passive part, assuming that the strain rate of the active part is proportional to the speed of the drive input stimulus of the muscle Identifying a value of the proportionality constant Λ using a representative Young's ratio of the muscle and a cross-sectional area of the muscle;
Identifying a value of viscosity compliance by using the value of the proportionality constant Λ for the constitutive model of the passive part; and
A viscoelastic characteristic measurement method comprising: Obtaining the muscle strength of the muscle with respect to the drive input stimulus by an isometric contraction test,
The viscoelastic characteristic measurement method according to claim 1, wherein the drive input stimulus and the muscle force obtained by the isometric contraction test are used in the step of identifying the proportionality constant Λ and the step of identifying the viscous compliance. The viscoelastic property measuring method according to claim 1 or 2, wherein the muscle is an animal muscle including human, monkey, horse and tuna. The configuration model is a Kelvin model,
In the step of identifying the viscous compliance, in Kelvin model, viscoelastic properties measuring method according to any one of claims 1 3 for identifying the values of Young's modulus and the viscous compliance. The constituent model is a three-element individual model,
In the step of identifying the viscous compliance, the three elements solid model, the Young's modulus of the elastic portion, the viscous compliance of the viscoelastic unit, and from the claims 1 to identify the values of Young's modulus of the elastic portion in the viscoelastic unit 3 The viscoelastic property measuring method according to any one of the above. The viscoelastic characteristic measurement method according to claim 1, wherein the drive input stimulus signal is surface myoelectric, needle myoelectric, or neuromuscular stimulation. A device for measuring viscoelastic properties of muscles,
Obtain a representative Young ratio of the muscle by an indentation test,
When the total strain rate of the muscle is expressed as the sum of the strain rate of the active part and the strain rate of the passive part, assuming that the strain rate of the active part is proportional to the speed of the drive input stimulus of the muscle Is determined using the representative Young's ratio of the muscle and the cross-sectional area of the muscle,
Identifying the value of the viscous compliance by using the value of the proportionality constant Λ for the constitutive model of the passive part;
A viscoelastic characteristic measuring apparatus having a calculation unit. The computing unit is
The muscle strength of the muscle with respect to the drive input stimulus is acquired by an isometric contraction test,
The viscoelastic characteristic measurement device according to claim 7, wherein the drive input stimulus and the muscle force obtained by the isometric contraction test are used when identifying the proportionality constant Λ and identifying the viscous compliance. The viscoelastic property measuring apparatus according to claim 7 or 8, wherein the muscle is a muscle of an animal including humans, monkeys, horses and tuna. The configuration model is a Kelvin model,
The arithmetic unit is configured in the case of identifying a viscous compliance, in Kelvin model, viscoelastic properties measuring device according to claim 7 to identify the values of Young's modulus and the viscous compliance in any one of 9. The constituent model is a three-element individual model,
The arithmetic unit, in the case of identifying the viscous compliance, the three elements solid model, identifying the Young's modulus of the elastic portion, the viscous compliance of the viscoelastic unit, and the value of the Young's modulus of the elastic portion in the viscoelastic unit The viscoelastic property measuring apparatus according to any one of claims 7 to 9 . The viscoelastic characteristic measurement device according to any one of claims 7 to 11, wherein the drive input stimulus signal is surface myoelectric, needle myoelectric, or neuromuscular stimulation.

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