WO2016125312A1

WO2016125312A1 - Electric stimulation apparatus

Info

Publication number: WO2016125312A1
Application number: PCT/JP2015/053434
Authority: WO
Inventors: 純生山田; 正宏成澤
Original assignee: 国立大学法人名古屋大学; ミナト医科学株式会社
Priority date: 2015-02-06
Filing date: 2015-02-06
Publication date: 2016-08-11
Also published as: JP6547215B2; JPWO2016125312A1

Abstract

The feature disclosed herein provides an electric stimulation apparatus capable of more effectively causing muscle contractions. The electric stimulation apparatus is provided with a signal generation unit for generating an electric stimulation signal, and an electrode unit for applying the electric stimulation signal generated by the signal generation unit to the body. The electric stimulation signal contains a pulse group signal containing a plurality of pulsed signals. All the pulsed signals of the pulse group signal are characterized by being unipolar pulse waves that rise either positively or negatively.

Description

Electrical stimulator

The present invention relates to an electrical stimulation device that applies electrical stimulation to a living body.

In patients after cardiac surgery, in addition to the decrease in pre- and post-operative physical activity associated with pathologic management, increased muscle protein catabolism associated with surgical invasion inevitably results in decreased muscle strength throughout the body. In particular, elderly people can remarkably decrease muscular strength due to atrophy and attenuation of skeletal muscles with aging, so that recovery of postoperative function can be delayed and can be a discharge inhibiting factor. In addition, patients after cardiovascular surgery are forced to rest due to the necessity of circulatory management and respiratory management, and therefore, postoperative rehabilitation programs tend to be delayed.

Therefore, electrical stimulation therapy is being studied as an intervention method for promoting bed leaving that can be applied early after surgery. Electrical stimulation therapy is an involuntary movement of muscles caused by contraction and relaxation of muscles by applying electrical stimulation to muscles in the body (typically patients) or nerves that give commands to muscles. To be expressed. This involuntary muscle movement is expected to suppress a decrease in muscle strength after surgery. With regard to such electrical stimulation, the mode and effect of contraction caused to the muscle vary depending on conditions such as the intensity (output) of the electrical stimulation signal for applying the stimulus, the pulse width, and the frequency. Therefore, for the purpose of obtaining desired effects such as patient treatment and function improvement, an electrical stimulation device that applies electrical stimulation under various conditions has been proposed.

Japanese Patent Application Publication No. 2005-185660 Japanese Patent Application Publication No. 2011-143061

For example, Patent Literature 1 discloses an electrical stimulation device in which a voltage signal having a predetermined waveform alternately set on the plus side and the minus side is divided into a plurality of divided waveforms and applied to the patient. . In this electrical stimulation apparatus, one voltage signal is divided into a plurality of parts so that a plurality of initial peak currents having a large current value are generated in the body of the patient according to the number of divisions, thereby increasing the amount of electrical stimulation. Thus, it is disclosed that a greater stimulation amount can be obtained without causing pain to the patient.

However, the technique disclosed in Patent Document 1 imparts electrical stimulation to such an extent that a massage effect can be obtained without causing pain to the patient. That is, no electrical stimulation was given that would affect the patient's muscle strength.
The present invention has been created in view of the above circumstances, and an object of the present invention is to provide an electrical stimulation device capable of obtaining a predetermined muscle output more effectively with less current than in the past. .

The present inventors have earnestly studied the relationship between the form of the electrical stimulation signal and the muscle output (other dynamic muscle contraction) induced in the living body by the signal. As one result of such research, there has already been proposed an electrical stimulation device that can impart muscle stimulation to an organism with electrical stimulation that can prevent muscle weakness (see, for example, Patent Document 2). . As a result of further research, we have found a form of electrical stimulation signal that can efficiently promote muscle contraction with less current. The technology disclosed herein has been completed based on such knowledge.

That is, the invention disclosed herein provides an electrical stimulation device including a signal generation unit that generates an electrical stimulation signal and an electrode unit that applies the electrical stimulation signal generated from the signal generation unit to a living body. . The electrical stimulation signal includes a pulse group signal including a plurality of pulse-like signals, and each of the plurality of pulse-like signals in the pulse group signal is a unipolar pulse wave that rises at one of the positive and negative poles. It is characterized by being.
This electrical stimulation device oscillates an electrical stimulation signal that promotes muscle contraction (muscle output) as a unipolar pulse signal (unipolar pulse wave). According to such a configuration, it is possible to induce significantly higher muscle contraction, for example, at the same voltage and / or the same current as compared with an electrical stimulation signal by a bipolar pulsed signal having the same shape (bipolar pulse wave). Muscle output (muscle strength) as well as muscle movement can be obtained. Therefore, according to this electrical stimulation device, electrical stimulation that acts more effectively on biological functions can be applied.

In a preferred aspect of the electrical stimulation device disclosed herein, the electrical stimulation signal generated from the signal generator is N, and the electrical stimulation signal including a pulse group signal composed of a bipolar pulse wave with a frequency of 20 Hz is M. Then, the parameters X _N and X _M indicating the muscle output per unit peak current applied to the living body based on the electrical stimulation signal N and the electrical stimulation signal M are expressed by the following formula: X _N ≧ 1.3 × X _M It is characterized by satisfying; Here, the parameter X _N and X _M are each thigh of the living body, 30% of the transitive muscles of the electrical stimulation signals N and isometric maximum strength of the electrical stimulation signal M (MVC) Regarding the muscle output during knee joint extension measured by applying a voltage at which an output is obtained, (1) an integrated value obtained by integrating the muscle output per one pulse group signal is defined as a total muscle output value (2 ) When the average peak current value obtained by averaging the maximum current values flowing through the living body from one pulse group signal is calculated as follows: (3) The following formula: X = (total muscle output value) / (average peak current value) Is done.

The parameter X (X _N and X _M ) is defined as the total muscle output value per unit peak current. According to the electrical stimulation device disclosed herein, than the parameter X _M obtained for conventional general electrical stimulation signal M, it is possible to generate electrical stimulation signals N to achieve more than 30% higher parameter X _N. According to such a configuration, more muscle output can be induced per unit peak current. In other words, for example, the amount of current required to obtain a predetermined muscle output can be suppressed to a small amount. Thereby, for example, an electrical stimulation device that can reduce a burden such as pain caused to a living body and suppress a decrease in muscle strength is provided. Alternatively, an electrical stimulation device that can enhance muscle strength is provided.
The isometric maximum muscle force (also called maximum voluntary contraction force (MVC)) is the force exerted by contraction of the muscle while maintaining a constant joint angle or muscle length. The maximum value, for example, muscle strength measured by grip force measurement or back muscle strength measurement that is generally performed corresponds to this. Such MVC can be measured by, for example, an MVC measuring method described later.

In a preferred aspect of the electrical stimulation apparatus disclosed herein, the pulse group signal includes a high frequency pulse component and a low frequency pulse component oscillated after the high frequency pulse component. In muscle contraction caused by electrical stimulation, muscle fatigue called low frequency fatigue (LFF) is likely to occur. According to this configuration, muscle contraction is promptly promoted by the high frequency pulse component, and muscle contraction is sustained by the low frequency pulse component. Therefore, the electrical stimulation signal can be efficiently applied to the living body.

In a preferred aspect of the electrical stimulation apparatus disclosed herein, the high-frequency pulse component includes a high-frequency pulse signal of 1 cycle or more and 4 cycles or less. The low-frequency pulse component includes a low-frequency pulse signal of 2 cycles or more and 20 cycles or less. By configuring the pulse group signal with such a waveform, higher muscle contraction force can be obtained while suppressing fatigue.

In a preferred aspect of the electrical stimulation apparatus disclosed herein, the waveform of the pulse signal is a rectangular pulse that rises from a reference potential and then falls, and continues to the fall and rises further than the reference potential. It is characterized by having an undershoot that returns to the reference potential after being lowered. According to such a configuration, muscle contraction can be brought about without causing the living body to further feel pain based on the electrical stimulation signal.
In the present specification, a unipolar pulse wave having such an undershoot is particularly referred to as a “unidirectional pulse composite wave” and may be distinguished from a unipolar pulse wave having no undershoot.

In a preferred aspect of the electrical stimulation device disclosed herein, the intensity of the pulse signal is set to a stimulation intensity that induces exercise of 1 to 30%, more preferably 10 to 20% of the isometric maximum muscle strength. It is characterized by being. By adopting such a configuration, muscle contraction can be promoted without adding a burden such as excessive pain or fatigue to the muscle.

In a preferred aspect of the electrical stimulation device disclosed herein, the electrical stimulation signal includes a first stimulation signal having a plurality of the pulse group signals with a first rest period interposed therebetween. By setting it as this structure, the 1st stimulation signal which acts on a muscle effectively can be provided to a biological body with a moderate frequency, and the amount of stimulation can be reduced on average. Thereby, generation | occurrence | production of fatigue can be suppressed reliably and muscle contraction can be induced.

In a preferred aspect of the electrical stimulation device disclosed herein, the electrical stimulation signal includes a second stimulation signal having a plurality of the first stimulation signals with a second rest period interposed therebetween. With such a configuration, even when fatigue occurs due to the first stimulus signal, the fatigue can be recovered in the second rest period. Thereby, muscle contraction can be induced while suppressing the occurrence of fatigue more reliably. In addition, for example, electrical stimulation can be applied to a living body over a long period and a long period as a whole. Alternatively, a greater amount of muscle movement can be induced in a shorter time without causing fatigue.

In a preferred embodiment of the electrical stimulation device disclosed herein, the time for applying the electrical stimulation signal to the living body is configured to be 1 minute or more and 180 minutes or less. According to the electrical stimulation device disclosed herein, the electrical stimulation signal works more effectively on the muscle than in the past. Therefore, such an apparatus can provide sufficient muscle movement for the purpose of treatment, health maintenance and muscle training without causing fatigue to the living body, for example, by using the apparatus for the above-mentioned time for each time. .

In a preferred aspect of the electrical stimulation device disclosed herein, the electrical stimulation signal is configured to give a signal so that the electrical stimulation signal travels to the peripheral side of the living body. According to such a configuration, the electrical stimulation signal can be output so as to act more effectively on the biological function, and high muscle output and muscle movement can be induced.

According to the electrical stimulation device disclosed here, for example, muscle contraction can be induced more effectively with a smaller amount of current. Therefore, it is possible to reliably suppress pain and fatigue generated in the living body. Thereby, for example, it becomes possible to reduce the electrical stimulation application time for obtaining a certain effect. Therefore, such an electrical stimulation device suppresses the muscular weakness of the patient who is difficult to actively exercise due to illness or injury, and also the living body that is difficult to exercise itself such as after cardiac surgery or acute exacerbation of heart failure. Can be used effectively. In addition, since such an electrical stimulation device can promote muscle output and muscle movement even for a healthy living body, it can be used comfortably for the purpose of maintaining the muscle strength of the living body and, consequently, enhancing the muscle strength. it can.

FIG. 1 is a schematic view illustrating the configuration of an electrical stimulation apparatus according to an embodiment. FIG. 2A is a diagram schematically illustrating one form of a waveform of a pulse group signal in the electrical stimulation signal of the technique disclosed herein. FIG. 2B is a diagram schematically illustrating another form of the waveform of the pulse group signal in the electrical stimulation signal of the technology disclosed herein. FIG. 2C is a diagram schematically illustrating one form of the waveform of the electrical stimulation signal of the technology disclosed herein. FIG. 3 is a diagram showing one form of a waveform of a pulse group signal in a conventional electrical stimulation signal. FIG. 4 is a graph showing the parameter X for the electrical stimulations A and B applied from the electrical stimulation apparatus of each example. FIG. 5 is a graph showing [1] maximum contractile force, [2] momentum, and [3] pain caused to the living body by the electrical stimulation device in Test 1. FIG. 6 is a graph showing [1] maximum contractile force, [2] momentum, and [3] pain caused to the living body by the electrical stimulation device in Test 2. FIG. 7 is a graph showing [1] maximum contractile force, [2] momentum, and [3] pain caused to the living body by the electrical stimulation device in Test 5.

Hereinafter, preferred embodiments of the present invention will be described with appropriate reference to the drawings. It should be noted that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field. In addition, in the following drawings, the same code | symbol is attached | subjected and demonstrated to the member and site | part which show | plays the same effect | action, and the overlapping description may be abbreviate | omitted or simplified. In addition, the embodiments described in the drawings are modeled as necessary to clearly explain the present invention, and do not necessarily accurately reflect actual dimensional relationships (length, width, thickness, etc.). is not.

FIG. 1 is a schematic diagram for explaining the configuration of the electrical stimulation apparatus 1 disclosed herein. The electrical stimulation apparatus 1 includes a signal generation unit 10 that generates an electrical stimulation signal and an electrode unit 20 that applies the electrical stimulation signal generated from the signal generation unit 10 to a living body. The electrical stimulation apparatus 1 may include a control unit (not shown) that comprehensively controls the form of the electrical stimulation signal generated by the signal generation unit 10. Alternatively, the control unit as an external device may be configured to be connectable by wire or wireless so that various types of information such as the form of the electrical stimulation signal can be transmitted and received.

Typically, the signal generation unit 10 can be configured mainly by an oscillation unit that can generate a predetermined electrical stimulation signal. The signal generation unit 10 is typically configured to be electrically connectable to the electrode unit 20.
The configuration of the oscillating unit is not particularly limited, and for example, an oscillating unit used in this type of conventional electrical stimulation device can be used. Specifically, any device that can induce contraction of muscles included in the stimulation applying region by applying an electrical stimulation signal to a part of the living body can be used without particular limitation. The form of the electrical stimulation signal formed in the signal generation unit 10 will be described later, but any oscillation unit that can form a pulse group signal including a plurality of pulse signals may be used. The frequency of the signal that can be oscillated by the oscillating unit is not particularly limited, and as an approximate guide, for example, an oscillating unit that can oscillate at a frequency of about 1 Hz to about 4000 Hz can be used. More preferably, a frequency region having a frequency of 1 Hz to 1000 Hz (1 Hz to less than 1000 Hz) may be generated. Particularly preferably, a low-frequency oscillator or the like that can oscillate a low frequency of about 1 to 500 Hz with an arbitrary pulse waveform may be more suitable. Such an oscillating unit can form and output a predetermined form of electrical stimulation signal. The signal generation unit 10 may be configured to have, for example, an arithmetic function so that a predetermined form of electrical stimulation signal can be oscillated with a predetermined output value.

The electrode unit 20 is configured to be electrically connectable to the signal generation unit 10, and typically includes at least one set of electrode pads (for example, an electrode composed of a positive electrode (+) and a negative electrode (−)). Pad). This electrode pad may be provided detachably with respect to the signal generator 10, or may be fixedly connected at all times. Further, the signal generation unit 10 itself may be integrated with the electrode unit 20. One set of electrode pads may be provided, or two or more sets may be provided. Further, the shape of the electrode pad is not particularly limited. The electrical stimulation signal generated by the signal generator 10 can be applied to a part of the living body through this electrode pad. Although there is no restriction | limiting in particular in the site | part of the biological body to which an electrical stimulation signal is given, Typically, it can be made into the muscle or the nerve which issues a command to the said muscle. The form in which this electrode pad is attached to the living body is not particularly limited. For example, the electrode pad may be formed as an adhesive pad having adhesiveness, and may be attached to the skin of a living body with an adhesive force. Or it is formed in the suction cup shape which has adsorptivity, and may be made to adhere to the skin of a biological body by adsorption power. The pair of electrode pads are brought into contact with the skin of the living body, and an electric current is applied between the electrode pads, thereby applying electrical stimulation to the living body muscles and nerves included in the region where the current flows, and contracting the muscles. Can be triggered.

When the electrode unit 20 outputs the electrical stimulation signal of a predetermined form, the positive output signal is typically directed from the positive electrode pad to the negative electrode pad of the set of electrode pads. Washed away. The negative output signal is typically flowed from the negative electrode pad to the positive electrode pad in the set of electrode pads. Therefore, typically, it is preferable to attach the positive electrode pad to the more central side of the living body and the negative electrode pad to the more peripheral side of the living body. Alternatively, the signal is output so that the positive output in the electrical stimulation signal is output from the more central side of the living body toward the peripheral side, and the negative output is output from the more peripheral side of the living body toward the central side. The generator 10 may be configured to automatically adjust the direction of signal output. The central side here means the upstream side of the arterial blood flow in the living body, and the peripheral side means the downstream side of the arterial blood flow. For example, for the extremities, the central side can be proximal closer to the trunk and the peripheral side can be distal farther from the trunk.

The control unit is not an essential component, but can be provided as means for suitably controlling the form of the electrical stimulation signal output from the signal generation unit 10. For example, the control unit can store various data such as data input from the outside, and can perform predetermined calculation and processing on the data based on various programs such as a system program. Specifically, for example, when the waveform of the electrical stimulation signal output from the signal generation unit 10 is input from the outside, such waveform data can be stored or the waveform can be sent to the signal generation unit 10. Alternatively, for example, various data input from the outside can be calculated and processed, and an instruction can be issued to the signal generation unit 10 based on the data after the calculation and processing. Such a control unit is not particularly limited. For example, various microprocessors such as a central processing unit (CPU) and a digital signal processing unit (DSP), an ASIC (Application Specific) Integrated (Circuit), electric and electronic elements such as IC memory, etc. can be mainly configured. When the control unit is an external device of the electrical stimulation apparatus 1, the control unit can be configured by a computer such as a personal computer, for example.

Hereinafter, an electrical stimulation signal generated by the signal generation unit 10 and its form, which are characteristic of the electrical stimulation apparatus 1 disclosed herein, will be described.
In the technology disclosed herein, the electrical stimulation signal output from the electrical stimulation device 1 includes a pulse group signal including a plurality of pulse signals. The pulse-like signal in the pulse group signal is a unipolar pulse wave in which the main pulse-like signal rises to either the positive or negative pole. Typically, as shown in FIG. 2A, a unipolar pulse wave in which all pulse signals are oscillated on the plus side. With this configuration, the electrical stimulation signal acts more effectively on the living body, and the muscle can be contracted more greatly with a constant effective current. In other words, a predetermined muscle output can be obtained with a small current. In addition, a high muscle output can be obtained while suppressing the occurrence of pain due to the electrical stimulation signal.

On the other hand, FIG. 3 is a diagram showing a typical example of the waveform of a bipolar pulse wave that has been generally used conventionally. In this bipolar pulse wave, one pulse signal is oscillated toward both the plus side and the minus side. Here, typically, the pulse waveforms oscillated on the plus side and the minus side may have substantially the same shape although the oscillation directions are opposite. In addition, the conventional signal waveform is typically oscillated alternately on the plus side and the minus side, as represented by this bipolar pulse wave (see, for example, Patent Documents). (See paragraph 1, 0005, etc.). Thus, as is clear from the comparison between FIG. 2A and FIG. 3, for example, the waveform of the pulse group signal in the technique disclosed herein is the same as the prior art because the output poles of the pulse-like signal are aligned. And can be clearly distinguished.

Note that the electrical stimulation device 1 disclosed herein has less pain than, for example, a conventional electrical stimulation signal, when attention is paid to the relationship between the effects of pain and muscle output that can be brought to the living body by the electrical stimulation signal. It can be understood that it can induce higher muscle output. That is, for example, when the electrical stimulation signal generated from the signal generation unit 10 of the electrical stimulation device 1 disclosed herein is N, the total per unit peak current applied to the living body based on the electrical stimulation signal N parameters X _N, which is defined as the muscle output value than the parameter X _M based on the electrical stimulation signal M by the conventional electrical stimulation device can be recognized as a device obtained as sufficiently high value.

Note that the parameter X is specifically a value calculated as follows. That is, the electrical stimulation signal N and the electrical stimulation signal M are applied to a living body at a voltage at which 30% other dynamic muscle output of isometric maximum muscle strength (MVC) is obtained. Then, based on such an electrical stimulation signal, a living body muscle or a nerve that issues a command to the muscle is stimulated to induce muscle contraction. For example, when an electrical stimulation signal is applied to the thigh of a living body, an extension movement of the knee joint is involuntarily induced. When the degree of muscle contraction force at this time is measured as a muscle output, an integrated value obtained by integrating the muscle output per one pulse group signal can be set as a total muscle output value. In addition, a value obtained by averaging the maximum current values flowing through the living body from one pulse group signal can be set as the average peak current value. The parameter X is defined as follows: X = (total muscle output value) / (average peak current value);

At this time, for example, an electrical stimulation signal M including a pulse group signal composed of a bipolar pulse wave with a frequency of 20 Hz can be assumed as a typical electrical signal generated by a conventional electrical stimulation device. Then, the parameter X _N calculated for the electrical stimulation signal N generated from the electrical stimulation device 1 disclosed herein is expressed by the following formula: X _{N in} relation to the parameter X _M based on the conventional electrical stimulation signal M. ≧ 1.3 × X _M ; That is, the parameter _{X N,} to the parameters _{X M,} is increased more than 130%. X _N is preferably satisfies _{X N} ≧ 1.35 × _{X M,} more preferably satisfy _{_X N} ≧ 1.50 × _X _M.

The isometric maximum muscle strength (MVC) can be measured using, for example, an isometric muscle strength measuring device. For example, taking as an example knee extension muscle strength that can be recognized as a representative value of lower limb muscle strength, it can typically be measured as follows. Specifically, first, the subject is seated on the measuring device (half-sitting posture), and the chest and abdomen are fixed to the chair by the seat belt. Then, the living body part having the muscle to be measured is fixed to the measuring lever of the isometric strength measuring device. For example, when measuring the isometric maximum muscle strength of the lower extremity extensor muscle of a subject as a living body, the right neck joint of the subject's right leg is set to 90 degrees with the arm lever of the isometric strength measuring device. Fix in the hold state. Next, in this state, the knee is extended when the subject is subjected to a knee joint flexion and extension exercise of 0 degrees / second with several attempts (for example, about 2 to 5 times) with maximum effort. Measure the muscle output when doing. At this time, each bending and extending movement is continuously performed while securing a sufficient time interval. The maximum value of the peak torque thus obtained can be set as the isometric maximum muscular strength. Such isometric maximum muscle strength can be expected to be increased by the use of the electrical stimulation device disclosed herein, so when using the device over a long period of time (eg, over a month) It is preferable to remeasure the isometric maximum muscle strength every time a certain period (for example, about one week to one month) elapses.

Also, isometric maximum muscle strength can be roughly grasped using a clinically convenient method. In this method, for example, the following index is adopted as the stimulation intensity for the isometric maximum muscular strength of the leg extensor muscle. In other words, 10% MVC is understood as “muscle strength for lifting the heel from the bed”, 20% MVC is identified as “muscle strength for which the calf is lifted from the bed”, and 30% MVC is identified as “muscle strength at which the knee joint is almost fully extended”. For other muscle MVCs, clinically convenient methods may be used as appropriate according to conventional methods.

The other dynamic muscle output is a muscle output obtained by muscle contraction by an electrical stimulation signal, and is clearly distinguished from a muscle output when a living body performs muscle contraction (voluntary muscle contraction) by its own intention. obtain. In the present specification, this other dynamic muscle output may be simply expressed as “muscle output”. This other dynamic muscle output is, for example, the joint motion induced by the muscle when a 30% MVC electrical stimulation signal is applied to a living body muscle (for example, quadriceps muscle), an isometric strength measuring device, etc. The muscle output value can be grasped by using and measuring.

The total muscle output value is an integrated value obtained by integrating the measured muscle output per one pulse group signal (that is, one group of the pulse signals) included in the electrical stimulation signal. This total muscle output value can be calculated from a muscle output waveform (that is, time transition data of muscle output) actually induced in the living body when a 30% MVC electrical stimulation signal is applied to the living body. Since the pulse group signal is repeatedly given to the living body, the total muscle output value may be an average value of the total muscle output value calculated for each pulse group signal.

The peak current can be grasped by measuring the maximum value of the current (effective current) that actually flows through the living body using one pulse group signal included in the electrical stimulation signal. The average peak current can be an average value of peak currents calculated for each pulse group signal. Such an effective current may vary depending on individual differences such as differences in essential resistance among individual living bodies, skin conditions, muscle strength (physical ability), and muscle mass.
The total muscle output value per unit peak current (that is, parameter X) is the total muscle output value (for example, the unit is kgf) obtained per 1 mAp of the peak current, and the total muscle output value is the average peak current. It can be calculated by dividing by.

This parameter X may vary from individual to individual even when the same electrical stimulation is applied. For example, in a conventional general electric stimulation apparatus for the purpose of enhancing muscle strength or the like, it has been common knowledge of those skilled in the art that the waveform of an electric stimulation signal or the like is a bipolar pulse wave. The parameter X was about 100 to 300 kgf / mAp (typically about 150 to 250 kgf / mAp) for healthy adult males. For example, conventionally, when an electrical stimulation signal is applied to a living body for the purpose of maintaining or enhancing muscle strength such as strength training, the amount of effective current that actually flows through the living body is increased in order to increase the amount of electrical stimulation to the muscle. It was hoped that. However, simply increasing the effective current output may result in an increase in peak current. As a result, it may lead to an increase in pain due to the electrical signal felt by the patient.
On the other hand, in the technique disclosed here, although there is an individual difference as described above, the parameter X can be set to a value improved by about 30% or more (for example, 1.3 times or more). For example, for an adult male, this parameter X can typically be improved to approximately 200-400 kgf / mAp. That is, it is possible to obtain a high other dynamic muscle output per unit peak current. As a result, a high passive muscle output can be obtained by an electrical stimulation signal having a small peak current and no pain.

No particular limitation is imposed on the waveform of the electrical stimulation signals for realizing such high parameters X _N. However, the electrical stimulation apparatus disclosed herein has a configuration in which the following electrical stimulation signal that efficiently acts on muscles is applied to a living body.

That is, the pulse group signal as described above is composed of a plurality of (that is, two or more) pulse signals. Such a pulse signal can typically be grasped as an electric signal having a pulse width of 1000 μs or less. Although there is no strict limitation on the pulse width, the pulse width is preferably 100 μs or more and more preferably 200 μs or more in order to give a suitable stimulation to the muscle by such an electrical stimulation signal. More preferably, it is 500 μs or more. However, an electrical stimulus that is too strong is not preferable because it causes muscle fatigue in the living body or causes burns in some cases. From this viewpoint, the pulse width is preferably 900 μs or less, more preferably 800 μs or less, for example, 700 μs or less.

Note that the intensity of the pulse signal is not strictly limited, and can be set as appropriate within a range in which a desired muscle contraction effect can be obtained, for example. Here, not only a healthy living body, but also stimulation with excessive pain is not preferable for a living body patient who is difficult to actively exercise due to illness or injury. From this viewpoint, the intensity of the pulse signal is, for example, 1 to 30% MVC (more preferably 10 to 20% MVC) based on the isometric maximum muscle strength (MVC) of the subject (biological body) to which the electrical stimulation signal is applied. It is preferable to set the stimulation intensity to induce a movement corresponding to the degree. In addition, 20% MVC can be used as one standard as a stimulus intensity that hardly causes fatigue or pain. However, when it is desired to induce muscle contraction even with some pain (for example, during strength training), the intensity of the pulse signal exceeds 20% MVC and is 30% MVC or more, for example, 40 to 60 It is also possible to set in the range of about% MVC. For example, specifically, an electrical stimulation signal is configured by appropriately combining a pulse group signal exceeding 20% MVC (for example, 30% MVC) and a pulse group signal not exceeding 20% MVC (for example, 10% MVC). Therefore, it is preferable because greater muscle contraction can be induced in a state that is difficult to be accompanied by fatigue and pain. The electrical stimulation signal having the minimum strength necessary for maintaining muscle strength (for example, about 10 to 20% MVC) is less burdensome (comfortable) for the living body and is less likely to cause pain and muscle fatigue. It may be suitable for extending the use time of one time or using it for a long time.

It is preferable that the pulse group signal is applied to the living body in a state that is difficult to be accompanied by pain, for example, in a state where stimulation is further suppressed. From this point of view, the pulse group signal can typically be composed mainly of low-frequency pulse components. In the present specification, “low frequency” related to a low frequency pulse component means that the frequency is less than 80 Hz. Such a low-frequency pulse component preferably has a frequency of 50 Hz or less, more preferably 40 Hz or less, for example, 30 Hz or less. The lower limit of the frequency of the low-frequency pulse component is not particularly limited, but if the frequency is too low, it is not preferable because effective stimulation cannot be applied to the muscle. Moreover, it is not preferable also in that it is difficult to maintain muscle contraction. From such a viewpoint, the frequency of the low frequency pulse component is preferably 5 Hz or more, and more preferably 10 Hz or more. Although depending on the desired effect, the low frequency component is preferably about 15 Hz to 25 Hz, for example.

Also, the pulse group signal preferably includes a high frequency pulse component preceding the group of low frequency pulse components. By applying high-frequency pulse components to muscles prior to low-frequency pulse components, the effect of instantly stimulating and activating the muscles can be enhanced, and the muscle contraction due to subsequent low-frequency pulse components can be effectively promoted. it can. Here, “high frequency” means that the frequency is relatively high in comparison with the frequency in the low frequency pulse component, and means that the frequency is 80 Hz or more. In order to stimulate (activate) the muscles more effectively, the high-frequency pulse component preferably has a frequency of 90 Hz or higher, preferably 95 Hz or higher, such as 100 Hz or higher, more preferably 200 Hz or higher. can do. In addition, when the frequencies of the low frequency pulse component and the high frequency pulse component are close to each other, it is not preferable because it is difficult for the living body to distinguish between the two.

It is preferable that the low-frequency pulse component and the high-frequency pulse component included in one pulse group signal have a frequency difference of 50 Hz or more, for example. The upper limit of the frequency of the high-frequency pulse component is not particularly limited. However, if the frequency is too high, the effect of stimulating muscles is reduced and it is difficult to induce muscle contraction, which is not preferable. From this viewpoint, the frequency of the high-frequency pulse component is preferably 500 Hz or less (less than 500 Hz), more preferably 450 Hz or less, and for example, 400 Hz or less. Depending on the desired effect, the high frequency component is preferably about 50 Hz to 400 Hz (150 Hz to 250 Hz), for example. Although specific data is not shown, the present applicants effectively reduced the pain sufficiently when the frequency of the high-frequency pulse component is, for example, 50 Hz to 400 Hz (150 Hz to 250 Hz). It has been confirmed that muscle contraction can be induced.

The high-frequency pulse component includes one (that is, one cycle high-frequency pulse signal) preceding the low-frequency pulse component, so that the effect of stimulating muscles can be enhanced, and the number is not particularly limited. For example, the pulse group signal shown in FIG. 2A has nine low-frequency pulse components (which is a nine-cycle high-frequency pulse signal; hereinafter sometimes referred to as “9 pulses”). An example including one (one cycle) high-frequency pulse component is shown. However, an increase in the number of high-frequency pulse components is not preferable because the amount of stimulation increases and muscle fatigue may occur. In addition, the stimulation by the high frequency pulse component is perceived as pain, and the pain may be increased. It was confirmed that the number of high-frequency pulse components is not proportional to the effect of promoting muscle contraction for the purpose of muscle activation before stimulation by the low-frequency pulse component. From this viewpoint, the number of high-frequency pulse components is preferably 5 (5 cycles) or less, typically 4 (4 cycles) or less, preferably 3 (3 cycles) or less, for example, 1 to Two (one to two cycles) are preferable.

In addition, if such a pulse group signal is continuously given to a living body without interruption, the living body may be fatigued. Therefore, it is preferable to apply the pulse group signal intermittently. In other words, the electrical stimulation signal is preferably configured to include a plurality of the above-described pulse group signals with a pause period during which no electrical signal is output.
The rest period is not particularly limited, but can be designed from various viewpoints. For example, (1) it is possible to appropriately adjust the amount of stimulation by the pulse group signal and to maintain a state in which muscle fatigue (LFF) due to the electrical stimulation signal is unlikely to occur. (2) Even if muscle fatigue occurs, it can be considered that the metabolites generated in the body due to muscle contraction are washed away in the bloodstream so that the fatigue is recovered.

Therefore, in the art disclosed herein, in view of the above (1), for example, as shown in Figure 2C, the electrical stimulus signal, a has a plurality of pulse groups signal P across the first pause period T ₁ It is the preferred embodiment comprises a 1 stimulus signal S _1. That is, after applying a high pulse group signal P of muscle contraction action on muscles, by the first rest period T _1, by relaxing the muscle stimulation amount by pulse group signal P, so as to reliably reduce the occurrence of fatigue I have to. In other words, it is preferable to appropriately control the length of the pulse group signal P and to configure the first stimulation signal S ₁ with the first pause period T ₁ sandwiched between the pulse group signals P.

The number of pulse signals constituting one pulse group signal P is not particularly limited, and is determined in consideration of, for example, the form (pulse width, wave number, intensity, etc.) of the above-described high frequency pulse component and low frequency pulse component. be able to. As an example, a combination of a high-frequency pulse component and a low-frequency pulse component may be determined based on the fact that muscle contraction can be suitably maintained. Specifically, from the viewpoint that fatigue can be further suppressed, the number of pulse signals can be determined, for example, with about 50 pulses or less as a guide. The number of such pulse signals is more preferably 40 pulses or less, even more preferably 30 pulses or less, and for example, 20 pulses or less. On the other hand, it is preferable to apply a certain amount of stimulation to the living body in order to make the electrical stimulation signal act on the muscle more effectively. From this viewpoint, the number of pulse signals included in the pulse group signal is preferably 4 pulses or more, more preferably 6 pulses or more, and even more preferably 8 pulses or more. As a suitable example, for example, the number of high-frequency pulse components is 1 to 4 pulses (for example, 1 to 2 pulses), and the number of subsequent low-frequency pulse components is about 2 to 20 pulses (for example, 5 to 15 pulses). Is exemplified. Although specific data is not shown, the applicants are induced when the number of high-frequency pulse components is, for example, 1 to 3 pulses (especially 1 to 2 pulses), rather than 0 pulses. It has been confirmed that the momentum increases.

Further, the first rest period T ₁ may be set to a relatively short time. Such first rest period _{T 1} include, but are not strictly limited, for example, can be less 1000 ms, preferably 800ms or less, for example, 700ms or less. Further, from the viewpoint of reducing the occurrence of fatigue, it is preferably 200 ms or more, and more preferably 300 ms or more, for example, 400 ms or more.

In the technique disclosed herein, from the viewpoint of (2) above, the second stimulation signal S ₂ having a plurality of the first stimulation signals S ₁ with the second rest period T ₂ sandwiched between the electrical stimulation signals. It is a preferable aspect to contain. In other words, in consideration of the possibility of fatigue accumulated by the first stimulus signal S _1, it is at a suitable frequency by providing the second rest period T ₂ of the order of fatigue during the first stimulus signal S _1, it is preferable to configure the second stimulus signal S _2.

Since the second rest period T ₂ may differ depending on the total application time of the electrical stimulation signal, it cannot be generally described. For example, when the total application time of the electrical stimulation signal is about 30 to 60 minutes, to promote recovery of muscle fatigue can be as a guide of the first 2 to 4 times approximately stimulation signals S ₁ providing the second rest period T _2. For example, specifically, sets the electrical stimulation period by the first stimulus signals S ₁ to several seconds to several tens of seconds is exemplified that subsequently providing the second rest period T ₂ of the order of 20 seconds to 60 seconds.
Thus, even when fatigue occurs due to the pulse group signal P that effectively acts on the muscle, the muscle fatigue substance generated in the living body is washed away by the blood flow, and the fatigue recovery is performed while performing electrical stimulation. Can do. That is, muscle atrophy can be prevented while sufficiently obtaining other dynamic muscle outputs.

In the electrical stimulation signal as described above, the output waveform of the pulse signal is not necessarily limited, and may be any of a rectangular wave pulse shape, a sine wave pulse shape, a triangular wave pulse shape, a sawtooth pulse shape, and the like. Among these, a rectangular wave pulse shape is preferable. Although specific data is not shown, the applicants have confirmed that muscle contraction can be effectively induced with a relatively small current when the output waveform of the pulse signal is a rectangular wave. ing. Specifically, for example, a rectangular pulse signal widely used in a digital switching circuit or the like can be used as such a rectangular wave. Use of this rectangular pulse signal is preferable in that a large amount of electrical stimulation can be secured and waveform control can be performed more easily. Needless to say, this waveform is the shape of the output wave of the electrical stimulation signal from the electrical stimulation device. Therefore, a slight change can be seen in the actual current waveform when the electrical stimulation signal is applied to the living body.

Here, the rectangular pulse means a signal form that changes sharply in a short time, rises from a reference potential (for example, lower limit value) to a set potential (upper limit value), maintains the set potential for a certain period of time, and then re-references It has a shape that falls to a potential (for example, a lower limit value, which can be 0 V on a biological basis). In general, it is a concept that can include various signals other than the above-described sinusoidal pulse signal (ie, sinusoidal pulse signal; the same applies hereinafter), a triangular wave pulse signal, and a sawtooth pulse signal. The shape (output shape) of such a rectangular pulse is not necessarily limited to a geometric rectangle, and there is a slight slope at the rise and fall, or the boundary between the rise and fall and the upper and lower limits. The corners at the corners may be smoothly curved.

However, in such a rectangular pulse, it is difficult to completely inhibit the living body from pain based on the electrical stimulation signal. Therefore, in the technique disclosed herein, a unidirectional pulse composite wave having an undershoot that vibrates (protrudes) in a direction further falling below the reference potential (base line) following the falling of the pulse signal. This is a preferred embodiment.
Here, in general, undershoot means that when a unipolar rectangular wave (square wave) is output as a pulse signal, the waveform protrudes to the opposite polarity side from the reference potential at which the waveform becomes a steady value at the falling portion. The part of the waveform. However, in the technique disclosed herein, it may be a more preferable form to output a rectangular pulse waveform intentionally (steadily) provided with such a protruding portion.

The shape of the undershoot (protruding portion) is not particularly limited as long as the waveform exceeds the reference potential and protrudes to the opposite potential. Typically, it may have the same form as a reaction peak or the like seen due to an inductance component or the like in a general rectangular wave pulse signal. Preferably, the waveform may be a substantially U-shaped or le-shaped (no corner) waveform protruding to the opposite side of the pulsed signal following the pulsed signal as illustrated in FIG. 2B. That is, the shape of the undershoot does not include a potential fluctuation that is steeper than that of the pulse-like signal, and the pulse-like signal falls while continuously reducing the potential fluctuation width beyond the reference potential, to a certain depth. After reaching (potential fluctuation range zero), the shape may gradually converge to the reference potential.
In order to clarify the difference from the bipolar pulse wave, the undershoot may be such that the waveform does not include a straight line portion.

The strength of the undershoot (projection depth in the falling direction) is not strictly limited. For example, it can be determined in accordance with a desired secondary effect in addition to the action on the muscle by electrical stimulation. The intensity of the undershoot can be appropriately set within a range of less than 0% and about −100%, for example, when the intensity of the pulse signal is 100% (reference).
For example, when it is desired to prevent a decrease in muscle strength due to electrical stimulation or increase the strength enhancement effect, it is preferable to induce a higher muscle output. In this respect, the strength of the undershoot is preferably −20% or less (that is, a depth of 20% or more in the falling direction; the same applies hereinafter), more preferably −40% or less, for example − It can be 45% or less. However, even when a high streak output is obtained, an undershoot whose depth in the falling direction is too large can be regarded as a pulse signal having a polarity different from that of the pulse signal. This is not preferable because the effects of the technology disclosed herein may be impaired. Therefore, the strength of the undershoot is preferably −100% or more (that is, a depth of 100% or less in the falling direction; the same applies hereinafter), more preferably −90% or more, for example, −85%. This can be done.

In addition, from the viewpoint of reducing pain due to electrical stimulation, it is more preferable that the strength of the undershoot is small. In this case, the strength of the undershoot is preferably −20% or less (that is, a depth of 20% or more in the falling direction; the same applies hereinafter), more preferably −30% or less. It can be 40% or less. However, an undershoot that is too deep in the falling direction reduces the effect of alleviating pain due to an electrical stimulation signal. Therefore, the strength of the undershoot is preferably −65% or more (that is, a depth of 65% or less in the falling direction; the same applies hereinafter), more preferably −63% or more, and −60% or more. It is particularly preferable that it can be -58% or more, for example.

The application time of the above electrical stimulation signal is not particularly limited, and an appropriate time that can induce desired muscle contraction can be set according to each living body. For example, it can be applied to a living body over a period of 1 minute to 180 minutes, more preferably 5 minutes to 120 minutes, for example, 10 minutes to 90 minutes.
That is, according to the electrical stimulation apparatus 1 disclosed herein, for example, muscles can be contracted efficiently with a small current. As a result, for example, muscle contraction can be induced without causing muscle fatigue in the living body. Moreover, according to a desired effect, muscle contraction can be induced in a state where pain is further suppressed. Therefore, for example, an electrical stimulation program of 5 minutes or more (for example, 30 to 90 minutes) as a whole can be safely received over a long period of time. Or the use time of the electrical stimulation apparatus for obtaining the equivalent muscle output effect can be shortened. These things can surely reduce the burden on the living body caused by the electrical stimulation device, and thus can realize comfortable use of the electrical stimulation device.

From these facts, the technology disclosed herein can be grasped as a method of applying an electrical stimulation signal that can more effectively induce the contraction of the muscles of a living body. That is, the electrical stimulation signal applied to the living body in this electrical stimulation method includes a pulse group signal including a plurality of pulse signals, and each of the plurality of pulse signals in the pulse group signal is either plus or minus. It may be characterized by a unipolar pulse wave rising to one pole.

Examples of the present invention will be described below with reference to the drawings. However, the present invention is not intended to be limited to those shown in the following examples.
<Embodiment 1>
In the present embodiment, an electrical stimulation signal is introduced into a living body using the electrical stimulation device 1 shown in FIG. 1, and the relationship between the waveform of the electrical stimulation signal and the muscle exercise effect induced by the electrical stimulation signal is evaluated. .
As a living body, four healthy male university students without regular training experience were selected as subjects (subjects).

[MVC measurement]
First, the isometric maximum muscle strength during the knee extension of the subject was measured. For this measurement, a self-training exercise apparatus with a measurement function (manufactured by Minato Medical Science Co., Ltd., WT-C20) was used. In the measurement, first, the subject was seated on the measuring device (half-sitting posture), and then the abdomen was fixed to the chair with a seat belt. Then, the thigh of the right foot as the measurement target was fixed to the arm lever with the knee joint being 90 degrees, and then the measurement attachment pad was attached to the distal part of the lower leg. After that, the subjects were allowed to exercise their knee joint extension with maximum effort while securing a sufficient time interval. And the muscle output accompanying the extension exercise | movement of this right leg was measured, and the maximum value was made into isometric maximum muscle strength (MVC).

[Electric stimulation]
Next, an electrode pad of an electrical stimulation device was attached to the thigh of the subject, and the following electrical stimulation signals A and B were applied for 3 minutes, respectively. The electrode pads were attached to the proximal side (central side) and the distal side (peripheral side) so as to sandwich the right quadriceps muscle, which is the test muscle. Unless otherwise specified, a positive electrode pad was attached to the proximal side, and a negative electrode pad was attached to the distal side, unless otherwise specified.

The electrical stimulation signal A is a signal obtained by repeatedly applying the pulse group signal (a) for 3 minutes through a rest period of 600 ms. The pulse group signal (a) outputs 10 pulses of a unidirectional pulse composite wave at a predetermined frequency as described below. Here, each pulse component in the unipolar composite pulse wave is constituted by outputting a rectangular wave of 600 μs on the plus side and then including −75% undershoot on the minus side.
(A) Unidirectional pulse composite wave Plus side: rectangular wave High frequency pulse component: frequency 200 Hz, single pole (plus side only) total 1 pulse Low frequency pulse component: frequency 20 Hz, single pole (plus side only) total 9 pulses Minus Side: Undershoot (depth -75%)

The electrical stimulation signal B is a signal obtained by repeatedly applying the pulse group signal (b) for 3 minutes through a rest period of 600 ms. The pulse group signal (b) outputs 10 pulses of a bipolar pulse wave at a predetermined frequency as described below. Here, each pulse component in the bipolar pulse wave is configured by continuously outputting a rectangular wave of 300 μs on the plus side and 300 μs on the minus side.
(B) Bipolar pulse wave Plus side and minus side: Rectangular wave Pulse component: Frequency 20Hz, bipolar meter 10 pulses

[Confirmation of 30% MVC output]
The self-exercising exercise device with a measuring function (manufactured by Minato Medical Science Co., Ltd., WT-), similar to the MVC measurement, the magnitude of the extension movement (muscle contraction amount) induced in the knee joint by the electrical stimulation signals A and B C20) was used to measure the muscle output during knee joint extension. For each electrical stimulation signal, the voltage at which the maximum contractile force induced was 30% MVC was examined.

[Measurement of muscle output and current value]
The magnitude of the extension exercise (muscle contraction amount) induced in the knee joint when the electrical stimulation signals A and B are applied to the living body at the voltage of 30% MVC obtained above with a sufficient rest period in between. Was measured by the above-mentioned self-exercise exercise apparatus with a measurement function.
The muscle output at the time of knee joint extension measured for one group of pulse signals (one pulse group signal) is defined as the muscle contraction force in the pulse signals, and the value is integrated per one pulse group signal. The integrated value was calculated as the total muscle output value.
Further, the voltage and current amount actually applied to the living body were measured by the electrical stimulation output from the electrical stimulation device, and the peak current value was examined.

[Evaluation]
The output from the electrical stimulator varies slightly with the output voltage depending on the impedance of the load (living body). In this embodiment, the current applied to the living body by each electrical stimulation signal has some differences due to the difference in impedance for each subject, but the tendency to change with respect to the electrical stimulation signal is uniform and can be stably energized. It was confirmed that
According to the unidirectional pulse composite wave in the electrical stimulation signal A, it can be seen that a large peak current based on a high frequency component flows to the living body at the rising edge of the plus-side pulse of the current waveform, and then a low current flows stably. It was. It can be said that the generation of the peak current at the rising edge of the rectangular wave pulse signal of the high frequency pulse component is due to the characteristics of the pulse composite wave. It was also confirmed that a relatively large peak current flows in the negative undershoot portion because of the high frequency component, and slowly converges to a current value of zero.

On the other hand, in the bipolar pulse wave in the electrical stimulation signal B, the current flows in a substantially rectangular wave shape as it is in the plus-side rectangular wave portion of the current waveform, and the voltage is reduced to 0 in the subsequent minus-side rectangular wave portion. On the other hand, it was confirmed that a large overshoot current was generated at the switching portion, and then slowly converged to a current value of 0. That is, it has been found that a sharp change in voltage occurs as the overshoot at the end of one cycle of the bipolar pulse wave. In addition, in the electrical stimulation signal B in which the overshoot current flows, it has been found that the effective current flowing through the living body increases in order to obtain a 30% MVC muscle output.

It should be noted that the peak current value that is the peak of the current that actually flows in the living body due to the electrical stimulation signal can reflect the magnitude of pain due to the electrical stimulation. Therefore, the total muscle output value X per unit peak current (1 mAp) was calculated for each subject by dividing the total muscle output value calculated above by the peak current value. The parameter X defined in this way represents the muscle output induced by the unit peak current, and as the parameter X increases, it means that more muscle output can be obtained with less pain. The values of the parameter X for the electrical stimulation signals A and B are shown in FIG. Each marker in FIG. 4 indicates a parameter X calculated for the electrical stimulation signals A and B for four subjects. And the dotted line in a figure is a line which connected the average of the parameter X of four test subjects in each electric signal.

As shown in FIG. 4, for all subjects, the parameter X (ie, X _N ) based on the electrical stimulation signal A applied by the electrical stimulation device disclosed herein is the electrical stimulation signal applied by the conventional device. It was found that the value was higher than the parameter X (ie, X _M ) due to B. For the four subjects, the parameter X related to the electrical stimulation signal A is about 44% to 70% higher than the parameter X related to the electrical stimulation signal B (that is, about 1.44 to 1.70 times the value). ) Was confirmed. That is, according to the electrical stimulation device disclosed herein, it has been confirmed that, for example, higher muscle output can be obtained without pain or with less pain compared to the conventional electrical stimulation device. .

<Embodiment 2>
[Test 1]
Below, the effect of the electrical stimulation waveform output from the electrical stimulation device on the muscle output and the like was examined in detail. In the various tests described below, nine healthy male university students without regular training experience were selected as subjects (subjects). And about each test subject, the MVC measurement was performed in the procedure similar to Embodiment 1. FIG.
[Determining 30% MVC]
Next, the stimulation intensity (30% MVC output) that induces a muscle output (30% MVC output) corresponding to 30% of the MVC of each subject based on the reference waveform is given to each subject by electrical stimulation according to the following “output setting reference waveform”. Voltage).

(Reference waveform for output setting)
High-frequency pulse component: frequency 200 Hz, 1 bipolar (plus-minus) total Low frequency pulse component: frequency 20 Hz, 9 bipolar (plus-minus) total This output setting reference waveform is a bipolar that can be said to be a conventional waveform It consists of a pulse signal.

[Measurement of maximum contraction force]
After a sufficient time had elapsed from the 30% MVC measurement, the electrical stimulation device disclosed herein was used to apply electrical stimulation to the subject and to measure the muscle strength induced by the electrical stimulation. In this embodiment, the induced muscular strength was evaluated by muscle output (kgf) measured according to a conventional method.
Specifically, first, an electrode pad of an electrical stimulation device is attached to the thighs of nine subjects, and a pulse group consisting of pulse components (pulse-like signals) shown by the following (r1) (a1) (a2) An electrical stimulation signal (R1) (A1) (A2) formed by combining a plurality of signals was applied. In addition, each pulse component was provided with the voltage used as the 30% MVC output based on the reference | standard waveform of each test subject calculated | required above.

(R1)
High frequency pulse component: frequency 200 Hz, unipolar (plus side) total 1 pulse Low frequency pulse component: frequency 20 Hz, bipolar (minus side-positive side) total 9 pulses (a1)
High frequency pulse component: None Low frequency pulse component: Frequency 20Hz, single pole (plus side only) total 10 pulses (a2)
High frequency pulse component: frequency 200 Hz, single pole (plus side only) total 1 pulse Low frequency pulse component: frequency 20 Hz, single pole (plus side only) total 9 pulses

The signal (r1) is the same as the signal (r1) in the above reference test 1, and is a known pulse group waveform having signals on the plus side and the minus side as shown in FIG. The signal (a1) is a pulse group waveform of the present proposal having a signal only on the plus side, and is composed of only a low-frequency pulse component. The signal (a2) is a pulse group waveform of the present proposal having a signal only on the plus side as shown in FIG. 2A, and has a high-frequency pulse component and a low-frequency pulse component.
As a result, each of the pulse signals constituting the pulse group signal is a bipolar pulse wave (r1) or a unipolar pulse wave (a1) (a2). We evaluated whether there was a difference. Further, in the case of a unipolar pulse wave, the difference was evaluated between the absence (a1) and the existence (a2) of the high-frequency pulse component.

Each of the electrical stimulation signals (R1) to (A2) “applies the above pulse group signal for 10 seconds (ie, 10 groups with the first pause period) once per second”. One cool (corresponding to the first stimulus signal), and this one cool is repeated five times (that is, five cools) with a 30 second rest period (second rest period) (corresponding to the second stimulus signal) did.

In addition, the test muscle is the right quadriceps as in the first embodiment, and the two electrode pads provided in the electrical stimulation device are placed on the proximal side (central side) of the front of the thigh so as to sandwich the right quadriceps. ) And the distal side (peripheral side).
Nine subjects were randomized according to the Latin square method after setting the output with the reference waveform for output setting to increase the reliability of the test, after the three types of electrical stimulation signals (R1) to (A2). In the correct order. Each electrical stimulation signal was applied with sufficient muscle rest time.

Using the above-mentioned self-exercise training device (manufactured by Minato Medical Science Co., Ltd., WT-C20) with the same function as the MVC measurement, the magnitude of the extension movement (muscle contraction) induced in the knee joint by the electrical stimulation signal And measured as muscle output. The average value during the treatment of the maximum muscle output measured for one group of pulse signals was taken as the muscle contraction force. The measurement result showed the average value of the muscle contraction force of nine subjects as a relationship with the electrical stimulation application time. The integrated value of the muscle contraction force was calculated as the amount of exercise of the muscle by electrical stimulation.

[Measurement of pain]
In addition, when applying the electrical stimulation signals (R1) to (A2), the pain caused by the electrical stimulation that the subject felt in the 2nd, 4th, and 5th cools was evaluated using a visual evaluation scale (Visual Analog Scale: VAS). ) Method. Specifically, where “0” is a painless state and “10” is the strongest pain state experienced so far, at which point on the 10 cm straight line the pain caused by electrical stimulation in each evaluation course is located Was shown in 10 stages. The result was shown as an average value of VAS values indicating pain by nine subjects.

[Evaluation]
FIG. 5 [1] is a diagram showing a time transition of muscle output (kgf) accompanying application of an electrical stimulation signal. Note that the data group in each figure after FIG. 5 shows data of the first cool, the second cool,... From the left. Since there is no muscle output (zero) during the rest period, the rest period is shortened (omitted) in FIG. In each figure, the scale indicating the value of the muscle output or the like is appropriately adjusted so that the tendency of the data over time is clear. As shown in [1] of FIG. 5, when the unipolar electrical stimulation signals (A1) and (A2) are applied, the muscles are compared with the case where the bipolar electrical stimulation signals (R1) are applied. It was confirmed that the output value was significantly large and a high maximum contractile force was obtained. In contrast, there was no significant difference in evoked muscle output values between unipolar electrical stimulation signals (A1) and (A2).
FIG. 5 [2] is a graph showing the transition of the amount of exercise (kgf · sec) of the muscle by electrical stimulation. As shown in FIG. 5 [2], when the unipolar electrical stimulation signals (A1) and (A2) are applied to the momentum, the bipolar electrical stimulation signal (R1) is applied. In comparison, there was a clear tendency to increase. In addition, regarding the momentum by the unipolar electrical stimulation signals (A1) and (A2), there is a difference between the two compared to the case of muscle output, but this is the time of applying electrical stimulation (energization time). It is thought to be due to the difference, and is not considered to be a special difference.

On the other hand, FIG. 5 [3] is a diagram showing a time transition of pain (cm) perceived by electrical stimulation. The pain due to the electrical stimulation signal is the smallest when the bipolar electrical stimulation signal (R1) is applied, and becomes relatively strong when the unipolar electrical stimulation signals (A1) and (A2) are applied. It was. Such a difference in pain is considered to be based on a difference in effective current amount flowing in the living body by an electrical stimulation signal and a difference in induced muscle strength. That is, in the second embodiment, the output of each pulse signal component of the electrical stimulation signal applied to the living body is set to a voltage corresponding to 30% MVC when the electrical stimulation signal based on the “output setting reference waveform” is applied to the subject. It was set. Therefore, when there is a difference in the maximum contraction force of the muscle induced by the electrical stimulation signal of this magnitude, the magnitude of the pain is different as a result. More specifically, even with the same output (voltage), more electric currents are introduced into the living body by applying the electrical stimulation signals (A1) and (A2) by the unipolar pulse composite wave, and are induced by the unipolar pulse composite wave. It was predicted that the maximum contractile force to be applied was larger than 30% MVC (approximately 50% MVC or more). As for the pain caused by the electrical stimulation signals (A1) and (A2), the electrical stimulation signal (A2) having a high frequency pulse component is smaller. It was found that the electrical stimulation signal (A2) having a high-frequency component can induce muscle contraction with a good balance between the muscle movement effect and pain.

[Test 2]
The pulse group signal was (r1) (a2) (a3) shown below, and the other conditions were the same as in Reference Test 1 above, and the electrical stimulation signals (R1) (A2) (A3) were applied to the living body. Then, [1] maximum contractile force, [2] momentum and [3] pain induced by the electrical stimulation signals (R1) to (A3) were measured in the same manner as in Reference Test 1, and the results are shown in FIG. Indicated.
In addition, the voltage set so that it might become the output equivalent to 30% MVC of each test subject based on the reference waveform for output setting was used for each pulse component in each pulse group signal similarly to the said test 1. FIG.

(R1)
High frequency pulse component: frequency 200 Hz, unipolar (plus side) total 1 pulse Low frequency pulse component: frequency 20 Hz, bipolar (minus side-positive side) total 9 pulses (a2)
High frequency pulse component: frequency 200 Hz, single pole (plus side only) total 1 pulse Low frequency pulse component: frequency 20 Hz, single pole (plus side only) total 9 pulses (a3)
High frequency pulse component: frequency 200 Hz, single pole (minus side only) total 1 pulse Low frequency pulse component: frequency 20 Hz, single pole (minus side only) total 9 pulses

That is, the signal (r1) is the same as the signal (r1) in the above test 1, and is a known pulse group waveform having signals on the plus side and the minus side. The signal (a2) is the same as the signal (a2) in the test 1 described above, and is the proposed pulse group waveform having a signal only on the plus side. The signal (a3) is a unipolar pulse group waveform of the present proposal having a signal only on the minus side, contrary to the signal (a2).
As a result, the difference in the induced muscle contraction between when the unipolar pulse signal constituting the pulse group signal is on the positive side (a2) and when it is on the negative side (a3). evaluated.

[Evaluation]
As shown in [1] of FIG. 6, even when unipolar electrical stimulation signals (A2) and (A3) are applied, the induced muscle strength varies greatly depending on the direction of the polarity. I understood. That is, it has been found that the effect brought about by the electrical stimulation signal applied to the living body is greatly influenced by the directionality of the electrical stimulation signal. Then, the direction of the electrical stimulation signal is applied so as to advance from the central side of the living body toward the distal side as in the electrical stimulation signal (A2), so that a higher maximum muscle contraction force can be induced. confirmed. In the reverse direction, that is, when the electrical stimulation signal is applied so as to advance from the peripheral side to the central side of the living body (electrical stimulation signal (A3)), the bipolar electrical stimulation signal (R1) is applied. It was confirmed that the maximum muscle contraction force could be smaller than when applied.

The momentum shown in [2] is also the same result as the maximum contraction force, and by applying a stimulus so that the electrical stimulation signal advances from the central side of the living body toward the peripheral side, a higher momentum can be obtained. It was confirmed that it was obtained.
Regarding the pain evaluation, a simple comparison cannot be made because the difference in the maximum contractile force induced by each electrical stimulation signal is large, but the bipolar electrical stimulation signal (R1) and the unipolar electrical stimulation signal (A3) Then, although the difference was not large, the unipolar signal (A3) was more painful. This suggests that even if the direction of introduction of electrical stimulation into the living body is not appropriate, more effective current can be introduced into the living body by the unipolar signal (A3).
From the above, the known bipolar electrical stimulation signal (R1) can give a stimulus to a living body without being aware of its directionality, but to obtain a higher muscle contraction effect, it is a unipolar electrical stimulation signal. It was confirmed that it did not greatly meet (A2).

[Test 3]
Next, the depth of the undershoot provided in the pulse signal of the same signal (a2) as in the above test 1 is changed by 10% between (a2): -25% and -85%, and seven pulse groups Signals (a4) to (a10) were used. Other conditions were the same as in Test 1 above, and electrical stimulation signals (A4) to (A10) obtained by combining these pulse group signals were applied to the living body, and induced [1] maximum contractile force, [2 The momentum and [3] pain were measured in the same manner as in Test 1 above.
Each pulse component in each pulse group signal was a voltage set so that an output corresponding to 30% MVC of each subject in the output setting reference waveform.

Also, it is considered that applying the above seven electrical stimulation signals to the subject on the same day may result in fatigue and impair the reliability of the test. Therefore, (a4): −25%, (a5): −35%, (a6): −45% on the same day, (a6 ′): −45%, (a7): −55% , (8): -65% on the other same day, (a8 '): -65%, (a9): -75%, (a10): -85% on the other same day And evaluated together.

[Evaluation]
FIG. 7 shows the measurement results of muscle movement and pain induced by the electrical stimulation signal. Muscles induced by electrical stimulation signals (A6) and (A6 ′) with an undershoot depth of −45% and electrical stimulation signals (A8) and (A8 ′) with an undershoot depth of −65% As for the contraction mode, the measurement date was different, and a slight difference was observed in the result. However, between the electrical stimulation signals (A4), (A5) and (A6) measured on the same day, between the electrical stimulation signals (A6 ′), (A7) and (A8), and the electrical stimulation signal (A8 ′ ) And (A9), there was a tendency that [1] maximum contractile force and [2] momentum increased as the undershoot depth increased. However, both [1] maximum contractile force and [2] momentum tended to decrease when the undershoot deepened to -85% (A10).

In the evaluation of pain, the deeper the undershoot depth is between the electrical stimulation signals (A4), (A5) and (A6) measured on the same day, and the electrical stimulation signals (A6 ′) ˜ ( During A10), it was found that the pain caused by the electrical stimulation signal becomes smaller as the depth of undershoot becomes shallower. However, as a whole, when the depth of the undershoot is in a range shallower than −65%, there is not much difference. From the above, the depth of the undershoot is, for example, a depth shallower than −65% (for example, −20% to −20%) from the balance between [1] maximum contractile force and [2] momentum and [3] pain. -60%, preferably -25% to -55%, particularly preferably -45% to -55%). However, if it is desired to obtain a greater maximum contractile force even with pain, it is effective to make the undershoot deeper than −65%, for example, −65% to −85%, preferably −65%. % To -80%, more preferably -65% to -75%.

From the above, it has been found that the electrical stimulation device disclosed herein can efficiently induce muscle movement with a small current. It was also found that the pain due to such muscle movement is not significantly increased compared to the maximum contractile force obtained. In other words, it can be said that the electrical stimulation device disclosed here can reduce the load and act more effectively on the muscle contraction action of the living body.
As mentioned above, although this invention was demonstrated by suitable embodiment, such description is not a limitation matter and of course various modifications are possible.

DESCRIPTION OF SYMBOLS 1 Electrical stimulation apparatus 10 Signal generation part 20 Electrode part

Claims

A signal generator for generating electrical stimulation signals;
An electrode unit for applying to the living body the electrical stimulation signal generated from the signal generating unit;
With
The electrical stimulation signal includes a pulse group signal including a plurality of pulse signals,
The plurality of pulse signals in the pulse group signal are all unipolar pulse waves that rise on one of the positive and negative poles.
The electrical stimulation signal generated from the signal generator is N,
When an electrical stimulation signal including a pulse group signal composed of a bipolar pulse wave with a frequency of 20 Hz is M,
Parameters X N and X M indicating muscle output per unit peak current applied to the living body based on these electrical stimulation signal N and electrical stimulation signal M satisfy the following formula: X N ≧ 1.3 × X M ; ,
Here, the parameters X N and X M are respectively
Knee measured by applying the electrical stimulation signal N and the electrical stimulation signal M to the thigh of the living body at a voltage at which 30% of the isometric maximum muscle strength (MVC) is obtained. About muscle output during joint extension,
(1) An integrated value obtained by integrating the muscle output per one pulse group signal is defined as a total muscle output value,
(2) When the average peak current value obtained by averaging the maximum current values flowing through the living body from the one pulse group signal,
(3) Calculated by the following formula: X = (total muscle output value) ÷ (average peak current value);
The electrical stimulation apparatus according to claim 1.
The pulse group signal is:
High-frequency pulse components;
A low frequency pulse component oscillated after the high frequency pulse component; and
The electrical stimulation apparatus of Claim 1 or 2 containing this.
The electrical stimulation device according to claim 3, wherein the high-frequency pulse component includes a high-frequency pulse signal of 1 cycle or more and 4 cycles or less.
The electrical stimulation device according to claim 3 or 4, wherein the low frequency pulse component includes a low frequency pulse signal of 2 cycles or more and 20 cycles or less.
The waveform of the pulse signal is
A rectangular pulse that falls after rising from a reference potential,
Subsequent to the falling, and after further falling below the reference potential, comprising an undershoot that returns to the reference potential,
The electrical stimulation device according to any one of claims 1 to 5.
The electrical stimulation device according to any one of claims 1 to 6, wherein the intensity of the pulse-like signal is set to a stimulation intensity that induces other dynamic muscle output of 1 to 30% of the isometric maximum muscle strength. .
The electrical stimulation signal is:
Including a first stimulation signal having a plurality of pulse group signals across a first pause period;
The electrical stimulation device according to any one of claims 1 to 7.
The electrical stimulation signal is:
Including a second stimulation signal having a plurality of the first stimulation signals across a second rest period;
The electrical stimulation apparatus according to claim 8.
The electrical stimulation device according to any one of claims 1 to 9, wherein a time for applying the electrical stimulation signal to the living body is configured to be 1 minute or more and 180 minutes or less.
The electrical stimulation device according to any one of claims 1 to 10, wherein the electrical stimulation signal is configured to energize the electrical stimulation signal toward a peripheral side of the living body.