Patent Publication Number: US-2022226187-A1

Title: Apparatus, system, and method for testing and exercising the pelvic floor musculature

Description:
PRIORITY CLAIM 
     The present application is a continuation application of U.S patent application Ser. No. 15/618,104, filed on Jun. 7, 2018 U.S, which is a continuation application of U.S. patent application Ser. No. 14/009,429, filed on Dec. 11, 2013, which is a 371 Application of PCT Application No. PCT/NO2012/050058, filed Apr. 3, 2012, which claims priority to Netherlands Patent Application No. 20110524, filed on Apr. 5, 2011, with each of the above applications being incorporated herein by reference. 
    
    
     BACKGROUND 
     The present invention relates to an apparatus, system, and method for testing and exercising the pelvic floor musculature. 
     The pelvic floor muscles are a mind-controlled and layered muscle group which surrounds the urethra, vagina, and rectum, and which, together with the sphincter muscles, functions to control these openings. This musculature also serves to support the urethra, bladder, and uterus, as well as to resist any increases in the abdominal pressure developed during physical exertion. The muscle group includes both longitudinal muscles and annular muscles. 
     Training of the pelvic floor musculature has proven efficient in preventing and treating several conditions, e.g. incontinence. Numerous exercises exist for training the pelvic floor musculature. For a number of reasons, the effect of these exercises varies among people. Also, it is known that mechanical vibrations in a range below approx. 120 Hz applied to the tissue increase the training effect of such exercises. As the musculature becomes stronger, it will be possible to measure the training effect by measuring the ability of the musculature to retract. 
     Measuring Principle and Measurement Parameters 
     A stronger muscle can be expected to dampen an amplitude of oscillation applied thereto more than a weaker muscle. A first principle of measurement, therefore, may be to measure the amplitude dampening of an imposed oscillation. The measured amplitude can be described as A˜A0 sin(wt). A relative amplitude dampening is defined as: where 
       Δ A =( A−Ao )/ Ao    (1)
 
     A is the amplitude measured,
 
Ao is the amplitude imposed,
 
w is the angular frequency of the oscillation imposed, and
 
t is time.
 
     It is considered well known to a person skilled in the art that the output signal from an accelerometer may represent an acceleration which can be integrated to obtain a velocity and a second time to obtain a displacement or deflection. It is also well known that accelerations, velocities, and displacements of equal magnitudes and opposite directions have average values of zero, and that meaningful parameters hence must be based on absolute values such as maximum acceleration, velocity, or amplitude, for example. In view of the above, it is clear that the dimensionless attenuation ΔA can be calculated from displacements in mm, velocities in m/s, accelerations in m/s 2 , and/or electrical signals input to the oscillator and output from the accelerometer. In any case, the attenuation ΔA can be expressed in dB, calibrated to display the force in Newton (N), etc. according to need and in manners known for persons skilled in the art. 
     During exercise, the volume of the muscle cells increases and the skeleton of the cells becomes more rigid. In another model, therefore, the pelvic floor musculature can be regarded as a visco-elastic material, i.e. as a material having properties between a fully elastic material and an entirely rigid and inelastic (viscous) material. For example, a slack or weak muscle can be expected to exhibit relatively “elastic” properties, whereas a tight or strong muscle can be expected produce more resistance and thus relatively “viscous” properties. Formally:
         stress is the force acting to resist an imposed change divided by the area over which the force acts. Hence, stress is a pressure, and is measured in Pascal (Pa), and   strain is the ratio between the change caused by the stress and the relaxed configuration of the object. Thus, strain is a dimensionless quantity.       

     The modulus of elasticity is defined as the ratio λ=stress/strain. The dynamic modulus is the same ratio when the stress arises from an imposed oscillation. When an oscillation is imposed in a purely elastic material, the elongation measured is in phase with the imposed oscillation, i.e. strain occurs simultaneously with the imposed oscillation. When the oscillation is imposed in a purely viscous material, the strain lags the stress by 90° (π/2 radians). Visco- elastic materials behave as a combination of a purely elastic and a purely viscous material. Hence, the strain lags the imposed oscillation by a phase difference between 0 and π/2. The above can be expressed through the following equations: 
       σ=σ 0  sin(ω t )   (2)
 
       ε=ε 0  sin(ω t−ϕ )   (3)
 
       λ=σ/ε  (4) where
 
     σ is stress from an imposed oscillation (Pa)
 
ε is strain (dimensionless)
 
ω is the oscillator frequency (Hz)
 
t is time (s),
 
ϕ is the phase difference varying between 0 (purely elastic) and π/2 (purely viscous), and
 
λ is the dynamic module.
 
     Biomechanically, this may be interpreted as that a stronger muscle increases the force resisting the oscillation and thereby “delays” the vibrations measured by the accelerometer. This is equivalent with that a strong muscle is stiffer or “more viscous” than a slack, gelatinous, and “more elastic” muscle. 
     A general problem in the prior art in the field is that measurement values are often given in terms of pressure, e.g. in millimeter water column. As pressure is a force divided by an area, the pressure reported will depend on the area of the measuring apparatus, and hence on the supplier. Therefore, in the literature in the field, measurement values are often given in the format ‘&lt;Supplier_name&gt; mmH20’, for example. In turn, this results in that measurement values from different apparatuses are not directly comparable, and consequently a need exists for supplier independent measurement values in the field of the invention. 
     U.S. Pat. No. 6,059,740 discloses an apparatus for testing and exercising pelvic floor musculature. The apparatus includes an elongate housing adapted for insertion into the pelvic floor aperture. The housing is divided longitudinally into two halves, and includes an oscillator as well as a cut out and equipment for measuring pressure applied to the housing halves from the pelvic floor musculature. The apparatus indicates the force pressing together the two halves in Newton (N), and essentially measures the training effect on muscles acting radially on the housing. 
     A need exists for an apparatus which also measures and trains the musculature running in parallel with a longitudinal direction of the apparatus or pelvic floor opening. 
     The object of the present invention is to address one or more of the above problems, while maintaining the advantages of prior art. 
     SUMMARY OF THE INVENTION 
     According to the invention, this is achieved by an apparatus for testing and exercising pelvic floor musculature, the apparatus including an elongate housing adapted for a pelvic floor opening, the housing including an oscillator, characterized in that the housing includes an accelerometer connected to a signal processor configured for communicating signals representative of values read from the accelerometer. 
     The use of an accelerometer for measuring a response makes it possible to use a closed housing, simplify the remaining construction, and increase the accuracy of the measurements. It is also possible to calculate a relative amplitude attenuation, phase delay, and/or dynamic modulus in one or more dimensions. These parameters, combined or individually, can be used for characterizing the musculature in a more accurately and detailed manner than is possible with the prior art. 
     Also, imposing oscillations and/or measuring responses along several axes allow the adaptation of training and testing to specific muscle groups in the pelvis floor. 
     In another aspect, the present invention relates to a system using such an apparatus with a controller configured for controlling the frequency and/or amplitude of the oscillation. The system is characterized in that it further includes a control module configured for determining an oscillator parameter within at least one time interval, and for providing the oscillator parameter to the controller; a data capturing module configured for receiving a response from the accelerometer and calculating a result as a function of the oscillator parameter and the received response; an analysis module configured for calculating at least one group value based on a series of measurements of oscillator parameters and the results thereof; a data storage configured for storing and retrieving at least one data value from a group consisting of the oscillator parameters, response, calculated result, and group value; and communication means configured for conveying the data value between the modules and the data storage. 
     In a third aspect, the present invention relates to a method for testing and exercising the pelvic floor musculature, wherein an oscillation is imposed on the musculature, characterized by measuring the response from the musculature using an accelerometer and characterizing the musculature based on the response to the oscillation imposed. 
     Suitable measurement parameters, such as the relative amplitude attenuation, phase delay, and/or dynamic modulus, may indicate, among other things, force and/or elasticity of various muscle groups in the pelvic floor. 
     In a preferred embodiment, the musculature is imposed an oscillation of a frequency equal or close to the maximum response frequency during training of the musculature. The maximum response frequency is assumed to change over time, and may be, inter alia, displayed and/or logged in order to document training effect, alone or in combination with one or more other parameters. 
     Additional features and embodiments will be apparent from the attached patent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described in more detail in the detailed description below with reference to the appended drawings, in which: 
         FIG. 1  is a longitudinal schematic section of an apparatus; 
         FIG. 2  illustrates alignment of a triaxial accelerometer in the apparatus of  FIG. 1 ; 
         FIG. 3  (prior art) shows the principle of an oscillator; 
         FIG. 4  (prior art) shows the principle of an accelerometer; 
         FIG. 5  is a schematic illustration of a system according to the invention; 
         FIG. 6  is a schematic depiction of the functions of the system; 
         FIG. 7  is a flow diagram illustrating a method according to the invention; and 
         FIGS. 8A-8D  illustrate a more detailed embodiment of the signal processor according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a longitudinal schematic section of an apparatus  100  according to the invention. The apparatus is comprised of an elongate, cylindrical housing  101 , which can be made of a relatively rigid plastic material. Advantageously, an outer casing  102  made of medical silicone can be provided on the outside of housing  101 . The size of the housing is adapted for an opening in the pelvic floor. 
     Housing  101  includes an oscillator  120  able to oscillate along one, two, or three axes, and an accelerometer  130  able to measure the acceleration along one, two, or three axes. Preferably, the accelerometer axis or axes is/are aligned with the oscillator axis or axes, for the following reason: 
     Assume that oscillator  120  effects an oscillation of the apparatus along an axis x, and that the response is measured along an axis x′ forming an angle a with the x-axis. If a response along the x-axis is B, then the response along the x′-axis B′=B·cos α. B′ has a maximum for cos α=1, i.e. with α=0 and the x′-axis parallel with the x-axis. Correspondingly, B′=0 when the accelerometer axis is perpendicular to the oscillation (cos 90°=0). Thus, by arranging the x-axis of accelerometer  130  in parallel with the x-axis of oscillator  120  we expect the largest possible signal and hence the greatest sensitivity possible. The same is true along the y- and/or z-axes when apparatus  100  has more than one axis. Also, the level of crosstalk between the measured signals is minimized when the axes are perpendicular to each other, e.g. as shown with the x, y, z coordinate system of  FIG. 1 . 
     From  FIG. 1  is can also be seen that oscillator  120  and accelerometer  130  are offset relative to each other along the longitudinal axis of the apparatus, i.e. the z- axis. Strictly speaking, therefore, they have separate axes in the x direction, e.g. x and x′. However, this has no significance as long as the axes are parallel to each other, cf. the previous section. Hence, for convenience, the x-axes of the oscillator, accelerometer and apparatus are referred to as one axis, “the x-axis”. The same applies for the y- and z-axes. 
       FIG. 2  illustrates a triaxial accelerometer  130 , having its axes x, y, and z parallel with the axes x, y, and z of the apparatus shown in  FIG. 1 . In a preferred embodiment, the frequencies of the oscillations, and optionally also the amplitudes, can be controlled independently of each other along said x, y, and z axes. This makes it possible to measure the strength of a muscle or muscle group running in parallel with the main axis of the apparatus, the z-axis, independently of muscles or muscle groups acting radially on the apparatus along a combination of the x- and y-axes of  FIG. 1 . 
     In the following, parameters of one, two, or three dimensions are denoted with boldfaced characters, and the component of a parameter along the x, y, and/or z axis is indexed with x, y, and z, respectively. For example, the frequency ω=(ω x , ω y , ω z ). In some embodiments, the three frequency components may have different values, and one or two of the components can be zero, i.e. one or two oscillators could be eliminated. The same applies for a response or out signal a from accelerometer  130 , calculated results ΔA, φ.A, and so on. Components along the x, y, and z axes are measured and calculated independently of each other, e.g. as indicated in eqs. (1) to (4). 
     The oscillator  120  can be controlled to vibrate with a specific frequency, preferably within the range of 15-120 Hz, by a power supply  110 . Alternatively, the oscillator  120  can be driven by a battery  111   a , shown with broken lines in  FIG. 1 . 
     The output signal from accelerometer  130  can be passed to a signal processor  140  and thence to a computer  200  (see  FIGS. 5 and 6 ). Alternatively, the entire or parts of the signal and data processing can be performed by a unit  200   a  inside the housing  101 . 
     Oscillator  120 , accelerometer  130 , and signal processor  140  are commercially available products, and it is within the ability of a person skilled in the art to select models suited for the particular purpose. It is understood that  FIG. 1  is a principle drawing, and that the connections between the components may include several channels, e.g. one input channel per oscillator axis and one output channel per accelerometer axis. In some applications, accelerometer  130  and/or signal processor  140  may be driven by electric power supplied through a USB connection, for example. In other applications, it may be necessary or convenient to have a separate grid-connected transformer  111  in the power supply  110 , as shown in  FIG. 6 . 
       FIG. 3  illustrates the principle of a possible oscillator  120 . The oscillator shown includes a permanent magnet  126  arranged in a coil  125 . When an AC voltage Vx is applied to the poles and a current is driven through the coil, a variable magnetic field is induced which drives the permanent magnet  126  back and forth in a reciprocating motion. The permanent magnet  126  is attached to a weight  122  which hence also moves back and forth. When the oscillator is attached to housing  101 , the apparatus  100  will oscillate along the x-axis. 
       FIG. 4  illustrates the principle of a typical accelerometer. A piezoelectric disc or bar  133  is fixedly clamped within a housing  131 . The disc  133  retains a seismic mass  132 . When the housing is moved back and forth along the x-axis, the disc will be acted on by the mass  132  and an electric charge is produced, typically a few pC/g, on the disc  133  by the piezoelectric effect. For frequencies below about one third of the resonance frequency of the accelerometer housing, this charge will be proportional with the acceleration. The output signal is illustrated schematically as a x  in  FIG. 4 . Commercial vibrational testing accelerometers of this type typically have a frequency range from approx. 0.1 to above 4 kHz, i.e. far outside the range of 15-120 Hz preferred in the present invention. 
     The present invention does not rely on any specific types of oscillators or accelerometers. For example, eccentric weight oscillators may be used instead of the type shown schematically in  FIG. 3 . A design of the type shown in  FIG. 3  can also be used as an accelerometer: In such a case, weight  122  is moved in dependency of the applied forces. This induces a movement of permanent magnet  126  inside coil  125 , and a current is induced that can be read at the poles at Vx. 
       FIG. 5  illustrates a system in which a computer  200  controls an oscillator of apparatus  100  through a power supply  110 . The computer  200  can be of any design. Suitable computers have a programmable processor, and include personal computers, portable units (PDAs), etc. Computer  200  can be connected to a display, printer, and/or data storage in a known manner for displaying and/or logging measurement results. 
     Signals from an accelerometer ( 130 ,  FIG. 1 ) of apparatus  100  are amplified and/or processed in a signal processor  140 , and transferred to computer  200  for analysis and/or logging. The connection between apparatus  100  and the box  110 ,  140  may include several channels for controlling oscillators along several axes independently of each other as well as for measuring responses of a uniaxial or multiaxial accelerometer. The same applies for the connection between box  110 ,  140  and computer  200 . This connection may be a US8 (2.0 or the like) connection, and, in some applications, electric power may be supplied from the computer through the US 8  connection. 
     In some embodiments, signals may be transferred wirelessly (not shown), e.g. by way of radio signals, infrared light, or ultrasonic signals. 
       FIGS. 8A-8D  show another embodiment of the system, and in particular a more detailed embodiment of signal processor  110 ,  140 , according to the present invention, in which the power supply  110  and signal processor  140  can be embedded into a separate unit or box  110 ,  140  accommodating at least one rechargeable or replaceable battery or battery package  113  ( FIG. 8D ). 
     Signal processor  140  may also include: a CPU including the appropriate software; electronic circuitry programmed with suitable algorithms for managing and controlling the oscillation frequency and optionally the oscillation amplitude; input(s) for at least one EMG sensor (EMG=Electromyography); and input(s) for at least one force sensor. 
     The stand-alone unit or box  110 ,  140  can include a charge input. Additionally to the charge input, or in an alternative embodiment, in which the battery or batteries or the battery package  113  is to be replaced or charged at another location, the stand-alone unit or box  110 ,  140  may include a cover  114  which can be opened and closed, or the casing (housing) of the unit or one half of the unit or box  110  may be arranged so as to be easily opened and closed (i.e. without the need for using a tool). 
     The wire  115  from apparatus  100  may be permanently connected  115 A to the box  110  of signal processor  140 , or, alternatively, may be arranged so as to be pluggable  1158  (by means of a plug  1158 ) into the input port or connector  116  of the unit  110 ,  140 . 
     Signal processor  140  may further include a loudspeaker and/or display  118  for the instantaneous or immediate biofeedback on muscle activation as observed through the dampening of oscillations and/or force read from the apparatus  100  and/or EMG activity in the muscle acting on apparatus  100 . Display  118  may have a suitable shape adapted for the requirements of functionality and placement. An octagonal (eight-sided)  118 B, six-sided or round  118 A LCD or LED display  118 , having about 40 segments  119 , for example, could be used. The unit  110 ,  140  may also include an on/off button  117 . In addition, or alternatively, the electronic circuitry of signal processor  140  may be configured so as to switch off after a predetermined time interval of inactivity, e.g. from one to a few minutes of no active use. 
     Additionally, the stand-alone unit or box  110 ,  140  may include a CPU device and/or calibration means including at least one of a CPU device and various sensor means to allow, among other things, the calibration of a new apparatus  100  in the system. Unit  110 ,  140  may also transfer, e.g. wirelessly, real-time data to computer  200  of various reasons. 
     Apparatus  100  may include an integrated triaxial gyro sensor which, together with the triaxial accelerometer  130 , allows the data or signal processor  140  or computer  200  to calculate the 3D orientation of the apparatus  100 . 
       FIG. 6  is a schematic depiction of components of the system illustrated in  FIG. 5 . 
     A control module  230 , e.g. hardware and software in the computer  200 , determines an oscillator parameter, i.e. frequency and/or amplitude, for oscillator  120 . When the apparatus is being used for the first time, the control module  230  could set the frequency ω to a fixed initial value and then increase the frequency in predetermined increments Δω. On subsequent use, control module  230  can use previous results for selecting other initial values and/or frequency intervals. This is described in more detail below. The same applies for the amplitude settings. Alternatively, oscillator parameters could be determined in a binary search which is ended when the values of two consecutively calculated values are closer than a predetermined resolution, e.g. Δω x =5 Hz. 
     Both frequency and amplitude may be adjusted along the x, y, and z axes independently of each other by means of controller  112 . In  FIG. 6 , controller  112  is connected to a power source in the form of a transformer  111  connected to the grid voltage V 1 , delivering a power P with the desired current and voltage. As shown in  FIG. 1 , in the alternative, the power source could be a battery  111   a  located inside the housing  101  of the apparatus. For example, the controller  112  may control the amplitude A x  and frequency ω x  of the oscillator by controlling the current, voltage, and frequency of the signal supplied at the poles Vx of  FIG. 3 , and in a similar manner for oscillators oscillating along the y and/or z axes. 
     The oscillation is imposed on tissue surrounding apparatus  100 , and the response is measured by accelerometer  130 . 
     Signals from accelerometer  130  of apparatus  100  are passed to a signal processor  140 , which is provided as a separate box including an array of accelerometers. Accelerometer  130  may include a preamplifier, and unit  140  may include a pre-amplifier. Other configurations are possible as well. The output signal from signal processor  140  is shown as a, and may represent, for example, acceleration along the x, y, and/or z axes at a measurement point at which the imposed oscillation was ω i . 
     A data capturing module  210  process the signal further, and may, for example, integrate an acceleration to obtain a velocity and once more to obtain a displacement, measure a phase difference, etc. Said integration of acceleration, measurement of phase difference, etc. may be carried out at several locations in the signal path using feedback operational amplifiers, firmware, and/or software, for example, in a known manner. Note that the signal path of  FIG. 6  is exemplary only. 
     Output data from the data capturing module  210  are shown schematically as a measurement point ω, R, at which a result R is measured or calculated at an applied frequency ω. The result R may represent one or more of: acceleration a, velocity, displacement, relative amplitude attenuation ΔA, phase shift, stress, strain, and/or dynamic modulus as discussed above. In some applications, the oscillator amplitude may also be varied. Advantageously, the data capturing module can store a measurement sequence including a series of measurement points each representative of an oscillator parameter ω or A and a measured or calculated result R. As used herein and in the claims, the term “data values” is understood to mean any parameter value and/or the components thereof along the x, y, and/or z axes. 
     A data bus  205  carries data values between various components and modules of computer  200 . For example, a measurement series with a sequence of measurement points (ω i , R;) can be temporarily be stored in a data storage  201  before the measurement series is further processed in an analysis module  220 . In another embodiment, the measurement points (ω i , R;) could be passed to analysis module  220  at a later point, and the processing results, represented by (ω r , S), could be stored in data storage  201  and/or displayed on a display means  202 . 
     Analysis module  220  is a module processing one or more measurement series to characterize the musculature and the development thereof using one or more parameters deemed suitable. 
     In a preferred embodiment, a maximum response frequency ω r  is obtained for each measurement series. The maximum response frequency ω r  is the value of the imposed frequency for which the measurement parameter selected indicated a maximum response from the tissue surrounding the apparatus, such as the maximum amplitude attenuation, minimum amplitude measured, largest dynamic modulus, etc. This is discussed in more detail below. 
     In principle, analysis module  220  may calculate any desired group value and/or carry out statistical analysis of the acquired data, such as statistical distributions, mean or expected value, variance, maximum values, and trends in the development of the measured and calculated results described above, for example. 
     In one embodiment, for example, the group value S may represent a subinterval of the range of 15-120 Hz within which the maximum response frequency ω r  is located with a given probability. This interval may be calculated as a confidence interval from earlier measurement series using known statistical methods, and is expected to become smaller as the number of measurement series increases and the variance hence reduces. The purpose of calculating such a subinterval is to avoid superfluous measurements. 
     An exemplary trend analysis is the development of the maximum response frequency ω r  over a few days or weeks, which may provide information on training effect. 
       FIG. 7  illustrates a method according to the invention. 
     In block  710 , the musculature is imposed a first oscillation represented by ω r . In practice, this can be accomplished by introducing an apparatus as described above into a pelvic floor aperture and supply the oscillator  120  with electric power. The oscillation may be imposed along one or more mutually orthogonal axes (x, y, z). At the first use, the initial value could be about 15 Hz, for example, along each axis. After the apparatus has been used one or more times the initial values may be based on previous results and analyses. 
     In block  720 , the response a i , from the musculature is measured by means of an accelerometer  130  having axes oriented in parallel with the oscillator axes x, y, and/or z. 
     Block  730  illustrates that a result R i  is found from an imposed oscillation ω i  and its response a; as measured in a predetermined time interval. The measurement point (ω i , R i ) may be part of a measurement series in which i=1, 2, . . . n, and each index i represents a separate time interval. Both the imposed frequency and the measured or calculated result have distinct values along the oscillator axes. Results suitable for characterizing the musculature may be the relative amplitude attenuation ΔA, dynamic modulus λ, and/or phase shift ϕ between the applied and measured signals. The values may be measured and/or calculated as set out above in connection with eqs. (1) to (4), and independently of each other along the axis or axes x, y, and/or z. The measurement point (ω i , R i ) can be stored or logged as part of this step. 
     In block  740  an oscillation frequency for the next measurement point is calculated, and in determination block  750  a determination is made whether the measurement series has been completed. 
     In a first embodiment of the method, the imposed frequency is incrementally increased in block  740 , for example according to ω i ,=ω0+i·Δω, where Δω denotes a desired resolution for the measurement series, such as 1 Hz or 5 Hz. In this case, the loop ends indetermination block  750  when the new frequency Δω i +1 exceeds a predetermined threshold, e.g. 120 Hz, along the axis or axes. 
     In an alternative embodiment of the method, the objective is to find a maximum response using the smallest number of measurements possible. This may be carried out efficiently by way of a binary search. For example, assume that the result R from block  730  increases with the response of the musculature to the imposed oscillations, that a first interval is 15 Hz to 120 Hz, and that the desired resolution is 5 Hz along each axis. In this case, the binary search can be performed by bisecting the interval, rounding the frequency down to the nearest integer frequency divisible with the resolution, and compare the results of block  730  for each of the two frequencies in the upper and lower parts of the interval, e.g. R 1  at ω 1 =15 Hz and R 2  at ω 2 =50 Hz. If R2&gt;R1, ω 3  is selected as the center of the interval 50-120 Hz in block  740 , otherwise ω 3  is selected as the center of the interval 15-50 Hz in block  740 . Similar bisection of the intervals is repeated in this alternative embodiment until determination block  750  indicates that the next interval is narrower than the desired resolution, e.g. 5 Hz along each axis. 
     If the responses along the axes are independent of each other, a binary search in the interval 15-120 Hz with a resolution of 5 Hz along each axis will be able to find an approximate maximum response frequency using at most  6  measurement points, whereas a sequential search in the interval 15-120 Hz with a resolution of 5 Hz would require 21 measurement points. 
     If determination block  750  indicates that the measurement series has not been completed, a new iteration is performed in which block  710  imposes an oscillation with a new frequency Δω i +1, etc. When determination block  750  indicates that the measurement series has been completed, the process proceeds to block  760 . 
     In block  760  one or more measurement series is analyzed as described for analysis module  220  above. In a preferred embodiment, the maximum response frequency ω r  is calculated for each measurement series. By definition, this is the frequency at which the musculature responds most strongly to the imposed oscillation. In practice, the maximum response frequency can be rounded down to the nearest integer frequency which is divisible with the resolution, i.e. 
       ω r =Δω·round(ω r   ′lΔω ),   (5)
 
     where 
     ω r  is the practical value of the maximum response frequency, 
     ω r ′ is the theoretical or ideal value of the maximum response frequency, 
     Δω· is the resolution chosen, e.g. 5 Hz as in the above example, and 
     round( ) is a function which rounds down to the nearest integer. 
     Block  770  has been drawn with dashed lines to illustrate that the method may, but does not necessarily, include controlling the oscillator to impose the practical value for the maximum response frequency while a user performs pelvic floor exercises as described in the introductory section. Hence, in a preferred embodiment, the resolution Δω should be selected so that the difference between the practical and actual values is of little or no significance. For example, if it turns out to be a telling difference between training with an imposed oscillation of 62 Hz as compared to 60 Hz, Δω in the above example should be reduced from 5 Hz to 1 Hz. 
     The method may further include storing and/or displaying one or more oscillation parameters, measurement values, calculated results, and/or group values. Each data value may be stored in a data storage  201  and displayed on a monitor  202 . It is also possible to log parameters by printing them on paper. Hence, a printer (not shown) may optionally be used instead of or in addition to data storage  201  and display  202  (e.g. a monitor) shown in  FIG. 6 . 
     The method described above may further include analyzing the measured and calculated results using known statistical methods. In one embodiment, the development of the maximum response frequency and/or other results over time, for example, may document the training effect. Also, in the present or other applications, a confidence interval for ω r  can be estimated which is smaller than the entire measurement interval, e.g. 15-120 Hz, but still large enough for the probability p that the maximum response frequency is located within said interval to be larger than a predetermined value, such as p&gt;95%. 
     This may reduce the number of measurement points in the next measurement series, which may be recorded one or a few days later, for example, and stored in data storage  201  ( FIG. 6 ). Data storage  201  may store several such measurement series recorded during a time period, e.g. one measurement series per day for 1-4 weeks, and/or only the particular frequency ω r  within each measurement series which resulted in, for example, the maximum amplitude attenuation or phase shift. 
     Naturally, statistical analysis, trend analysis, etc. may be performed on one or more measured or calculated results, not only on the frequency as described above. The expression “calculating group value”, as used in the patent claims, is intended to include any known types of statistic analysis, trend analysis as well as other forms of analysis performed on one or more measured or calculated results, stored, for example, as measurement series of measurement points (ω i , R i ;) in data storage  201 .