JP2007135782A - Body fat measuring instrument using conductivity measurement and height estimation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an instrument suitable for measuring the amount of body fat of persons in need of carers or assistances who are obliged to lie in bed or rest in bed for a long period due to senility or diseases in particular in a body fat measuring instrument capable of easily measuring the body water content, the amount of body fat and a body fat percentage. <P>SOLUTION: This body fat measuring instrument measures the body fat by applying measurement electrodes whose terminals are exposed to the outside to the ankle and the wrist of the right or left half body. This instrument finds the body height from the front arm length by using an estimate value. In estimating the amount of the body fat, this instrument determines a coefficient by a multiple regression method using samples of 1,000 or more persons. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a body fat measuring device that can easily measure body water content, body fat mass, and body fat percentage, and is particularly necessary for long-term bed rest or floor rest due to old age or illness, It is an object of the present invention to provide a suitable device for measuring the body fat mass of those who need support (hereinafter referred to as “helpers etc.”).

  When measuring the degree of obesity, many simple methods such as comparing height and weight have been adopted. However, this method merely evaluates the body type, and it cannot be said that the degree of obesity is accurately evaluated. Therefore, “obesity” is defined as a state where body fat is excessively accumulated, and the degree of obesity is determined by measuring the body fat percentage.

  Body fat percentage is measured indirectly, and the typical method developed so far is the underwater weight weighing method. There are a caliper method, an ultrasonic method, a near-infrared method, a BI (Bioelectrical Impedance) method, and the like (see Document 1).

  In particular, the BI method is a method in which a weak alternating current is passed between the limbs to measure the bioelectric resistance, and the body fat percentage is estimated from the measured value. This method is inexpensive, has no need for special techniques for measurement, and has high accuracy.

  In addition, in the past, measurement was performed with electrodes attached to the hand and foot, but a method for estimating body fat percentage by measuring bioelectric resistance between hands and feet from bioelectric resistance between both hands has also been developed. (See Patent Document 1).

Bulletin of Osaka Prefectural College of Nursing, 129-137, Vol. 13, No. 2, 1991 JP-A-6-1114024

  In the conventional BI method, in order to measure the bioelectric resistance, the electrodes are brought into contact with each other by adsorption, sticking, gripping, and riding. However, a special adsorption electrode and gel are required for adsorption, and a special electrode is necessary for attachment. Also, methods such as gripping and riding cannot be used without a standing posture and physical ability to grip.

  However, it is not possible to use a person who does not have the ability to stand by himself / herself, such as a person who needs assistance. Moreover, it is necessary to know weight and height as essential parameters for estimating body fat percentage. However, although the measurement environment is complete, such as measuring the weight of each bed, it is not easy to measure the height of the person requiring assistance.

  Body fat percentage can be an important factor in deciding how much to administer, so it is of great value for people who are bedridden in hospital beds. Because there are drugs that dissolve in water, drugs that dissolve in oil, and drugs that dissolve in water and oil. This is because it is possible to select the appropriate medicine.

  However, at present, the body fat percentage measuring device is not an easy-to-use device for the person requiring assistance. The present invention has been conceived in view of such problems.

  The present invention measures bioelectric resistance by applying electrodes to the left and right hands and feet of the body, and estimates body fat percentage using the height estimated from the forearm length and the actually measured weight as parameters.

  Since the height of a person who needs assistance is estimated from the forearm length, the body fat percentage can be estimated by measuring the body weight, and the body fat percentage can be estimated even by an unconscious person.

Measurement electrode In order to measure the body fat percentage, it is necessary to attach an electrode to the body part. This is often the case with conventional electrodes for adsorption. In the present invention, as shown in FIG. 10, an electrode whose electrode terminal is exposed is used. The length between the electrodes is 3 cm, and a good conductor having a diameter of 10 to 15 mm is used for the electrodes. By using this electrode, measurement can be performed simply by pressing the electrode against the skin of the subject.

  The reason for using this electrode is that the body fat percentage measuring device of the present invention is intended for persons requiring assistance. These people are expected to have weak skin, and the conventional adsorption electrode may damage the skin.

  The validity of the measurement using this electrode is compared with the measured value of the conventional suction terminal. FIG. 1 shows the relationship between the resistance (Y-axis) of an electrode for adsorption (Y-axis) and the resistance (X-axis) of the electrode of this apparatus, which have been frequently used so far, for 13 adult men and women.

  For the measurement site, the lower limb was measured from the voltage electrode at the center of the inner and outer cavernous projections, and the current electrode was measured from the site 3 cm away from the voltage electrode to the fingertip side. The black circle (●) is measured with the electrode directly applied without any treatment. White circles (O) are measured after wiping with rubbing alcohol.

  The resistance of the Y axis was measured after wiping with a disinfecting alcohol on the measurement site and pasting the electrode gel as before. As a result, between the resistance due to the electrode for adsorption (Y axis) and the resistance due to the electrode due to this device (X axis), r = 0.903, when measured directly without any treatment, alcohol for disinfection After wiping, it was found that r = 0.991 was significantly (p <0.001) highly correlated.

  That is, it can be said that the value obtained by the conventional method can be estimated (replaced) with high accuracy by using the electrode attached to the apparatus. Therefore, it means that the value of the bioelectric resistance measured with the electrode attached to this apparatus can be used for various data using the conventional adsorption-type electrode.

Principle of Measurement The measurement method of the present invention obtains an estimated value from actual measurement data of a large number of people. Hereinafter, the calculation method of the estimated value derived | led-out from these data and data is demonstrated.

Measurement of body density To estimate body fat percentage, first, body density is obtained. Table 1 shows resistance (Z: unit is ohms), height (Ht: unit is m), body weight (Wt: Wt: measured after wiping the measurement site with disinfecting alcohol using electrodes attached to this apparatus. The coefficient when the body density is obtained from the multiple regression analysis method using the variables of Kg) and age (the unit is “years”).

対象は、6歳から94歳までの健康な男性540名、女性718名の計1258名である。体密度の妥当基準である基準体密度は、水中体重秤量法による値を用いた。同法に必要な残気量は、ヘリウム希釈法から測定した。
表１中の「合計」は年齢層毎の係数を使わない場合の係数を表す。年齢毎の推定値は同じ年齢層の人間を比較する場合は有効であるが、同一個人の経年変化を推定する場合は、年齢層毎の推定誤差が入るため、より一般化した「合計」欄の係数を用いて比較することができる。用いるバラメータに違いがあるわけではない。

The subjects were 1258 people, 540 healthy men and 718 women from 6 to 94 years old. A value based on an underwater weight weighing method was used as the reference body density, which is an appropriate standard for body density. The amount of residual air required for this method was measured by the helium dilution method.
“Total” in Table 1 represents a coefficient when the coefficient for each age group is not used. The estimated value for each age is effective when comparing people of the same age group, but when estimating the secular change of the same individual, an estimation error for each age group is included, so the more generalized “total” column Can be compared using the coefficients of There is no difference in the parameters used.

The regression analysis is expressed by the following formula.
Y = reference body density ± aX ₁ ± bX ₂ ± cX ₃ ± dX ₄ (1 set)
Here, each variable represents the following.
Y: body density (g / ml),
Reference body density: intercept,
a to d: constant (according to Table 1),
X ₁ : Z (ohm) / Ht ² (height m ² ),
X ₂ : Z (ohms),
X ₃ : Wt (kg body weight) / Ht ² (height m ² ),
X _4: age (years)
Z is the resistance value measured using the electrode terminal exposed electrode described above.
In the equation, “±” indicates that a plus sign is used when the value in Table 1 is plus, and a minus sign is used when the value in Table 1 is minus. For example, when the value of c is “−0.003767” in one equation, the term “± cX ₃ ” is “−0.003767X ₃ ”. The same applies to formula 6 described later.

From the body density determined as described above, the body fat percentage (%), the body fat mass (kg), the lean body mass (kg), and the body water content (kg) can be determined as follows.
Body fat percentage = (4.570 / body density-4.412) x 100 (2 formulas)
Body fat mass = body weight x body fat percentage / 100 (3 formulas)
Lean mass = body weight-body fat mass (4 formulas)
Body water content = lean body mass x 0.732 + body fat mass x 0.10 (5 formulas)

  2 and 3 show the relationship between the body fat percentage based on the estimation formula according to the present invention and the body fat percentage based on the weight weighing method in water. The subjects were 1258 people, 540 healthy men and 718 women from 6 to 94 years old. FIG. 2 shows a male and FIG. 3 shows a female. The body fat percentage according to the deduced estimation formula shows a significantly high correlation between male r = 0.786 (p <0.001) and female r = 0.817 (p <0.001). That is, the estimated value according to the present invention can be highly correlated with the actually measured value.

  4 and 5 show the relationship between the lean body mass using the estimation formula according to the present invention and the lean body mass by the underwater weight weighing method. The subjects were 1258 people, 540 healthy men and 718 women from 6 to 94 years old. 4 shows a man and FIG. 5 shows a woman. There was a very significant correlation between the lean body weight using the estimation formula and the lean body weight by underwater weight weighing method, with male r = 0.985 (p <0.001) and female r = 0.954 (p <0.001). It was.

Height estimation Next, the height is estimated from the forearm length. The forearm length is a measured value that can be measured even when the forearm is still on the bed, and is easily obtained. If the height value estimated from the forearm length can be used for the estimated body fat amount, the body fat amount can be estimated more easily.

  Table 2 shows the coefficients of the estimation formula for obtaining the height from the forearm length on the non-dominant hand side. The estimation formula is as follows:

対象は、6歳から94歳までの健康な男性540名、女性718名の計1258名である。非利き手側から推定式を考案した理由は、利き手側に比べて、運動による影響の可能性が少ないと考えたからである。前腕長は、尺骨の手首側突起と肘側突起の末端をノギスで測定した。 Y = constant ± aX ₁ ± bX ₂ ± cX ₂ ... (6 formulas)
Here, each variable represents the following.
Y: Estimated height (cm),
a to c: Variables (according to Table 2)
X ₁ : Forearm length (cm),
X ₂ : Age (years),
X ₃ : Sex (male 1, female 2)

The subjects were 1258 people, 540 healthy men and 718 women from 6 to 94 years old. The reason for devising the estimation formula from the non-dominant hand side is that it is considered that there is less possibility of the influence of exercise than the dominant hand side. Forearm length was measured with calipers at the ends of the ulnar wrist-side and elbow-side processes.

  FIG. 6 shows the relationship between the height estimated from the forearm length and the measured height. The subjects were 1258 people, 540 healthy men and 718 women from 6 to 94 years old. The BMI was a value obtained by dividing the weight (kg) by the square of the height (m), as in the WHO evaluation.

  As a result, a very high correlation of r = 0.945 (p <0.001) was observed between the two. Moreover, there was no significant difference between both values, and it was recognized that it was almost the same value. Therefore, it can be said that the height estimated from the forearm length can be obtained with high accuracy even if the subject cannot hold a standing posture due to bedridden or injured.

FIG. 7 shows the relationship between the measured standard weight (Y axis) and the estimated value of the standard weight estimated from the forearm length. The subjects were 1258 people, 540 healthy men and 718 women from 6 to 94 years old. The standard body weight (SWt, kg) indicates the body weight (Wt, kg) with the lowest prevalence against the height (Ht, m) and is calculated as SWt = Ht ² x 22 (Matsuzawa et al., 1990).

  There was a very significant correlation between the two, r = 0.941 (p <0.001). From this result, it can be said that the standard weight can be obtained with high accuracy by substituting the value of the forearm length into this estimation formula.

  FIG. 8 shows the relationship between each body index (BMI: X axis) obtained from the height and weight estimated from the forearm length and each body index (BMI: Y axis) obtained from the measured height and weight. . The subjects were 1258 people, 540 healthy men and 718 women from 6 to 94 years old.

  A very high correlation of r = 0.951 (p <0.001) was observed between the two. From this result, it can be said that the obesity level can be evaluated even for a subject who cannot maintain a standing posture due to bedridden or injuries. By the way, the degree of obesity in terms of standard weight and BMI can be evaluated as shown in Table 3 (Japan Obesity Society, 1993; WHO, 2000).

Specific Embodiment FIG. 9 shows a conceptual diagram of an apparatus for carrying out the present invention. The apparatus 10 of the present invention includes an input unit 12, a control unit 16, a display unit 14, a control unit 16, an A / D conversion unit 18, a resistance measurement unit 20, and an electrode unit 22.

  There are at least two electrode portions 22, each having an electrode terminal (221 to 224). The electrode unit 22 and the resistance measuring unit 20 are connected by an electric wire, and current application and voltage measurement are performed by the electric wire. Details of this part will be described later.

  The voltage observed at the electrode unit 22 is converted into a voltage value by the resistance measuring unit 20 and output as a biological voltage value Vsig. The biological voltage value Vsig is converted into a digital signal Sv by the A / D converter 18. The A / D conversion unit 18 may be built in the control unit 16 or the resistance measurement unit 20.

  The digital signal Sv is sent to the control unit 16. The control unit 16 includes an MPU that performs calculation, a fixed memory, a clock, and the like, and operates according to a program in the ROM. In addition to the biometric digital voltage value Sv, the control unit 16 receives data on weight, sex, age, forearm length or height from the input unit 12. Based on these data, estimation calculation such as body fat percentage is performed. This calculation is performed based on the above formulas 1 to 6. The control unit 16 displays the result on the display unit 14. The control unit 16 has a control line 24 for controlling the resistance measurement unit 20.

  The input unit 12 is provided with input means including a numeric keypad. Then, the forearm length is input together with the weight, sex, age, and height. Individual identification information such as a name may be input. The control unit 16 calculates the body fat percentage and the like from data such as bioelectric resistance, body weight, and forearm length, and sends the result Sd to the display unit 14. Note that the input unit 12 is not limited to a numeric keypad, and the data may be input from an external storage medium or a device that generates data.

  FIG. 10 shows details of the resistance measurement unit 20 and the electrode unit 22. The resistance electrode unit 20 includes at least a constant current generation unit 201 and a voltage measurement unit 202. The constant current generating unit 201 and the voltage measuring unit 202 are connected to the control line 24 from the control unit 16. And it is controlled by the control signal Cs from the controller 16. The constant current generator 201 generates an alternating current (I + and I−) of 50 kHz and 800 μA (microamperes). This AC voltage is supplied from the electrode terminals 221 and 223 of the electrode part 22.

  The electrode part 22 is brought into contact with a remote part of the human body. The electrode terminals 222 and 224 are connected to the voltage measuring unit 202. The voltage measuring unit 202 measures the voltage difference between the voltages V + and V− at both ends, and outputs it as a biological voltage value Vsig.

  The electrode mounting position is always constant. This is because the bioelectric resistance value often causes an error in the measurement method. In the present invention, the electrodes are attached to the wrist and ankle on the dominant hand side. The wrist is equipped with an electrode 221 for passing a constant current between the radial process and the ulnar process on the fingertip side and a voltage measuring unit 222 for measuring voltage on the forearm side. In addition, the ankle is attached with an electrode 223 for passing a constant current between the external and internal protrusions on the fingertip side and an electrode 224 for measuring voltage for voltage measurement on the tibia side. Regarding the measurement of the body composition, inevitable errors are included, and the range of about 5 to 7% is within the range of the estimation formula. The errors related to these measurements are also introduced in the following documents.

  Vol. 18, pp. 193-224, 1990. (Translated by Kiyoji Tanaka and Fumizo Nakajo): Richard N. Baumgarter, Wm. Bioelectrical impedance method as an evaluation method of body composition (produced by Sekisui Chemical Co., Ltd.), all methods of body composition cannot be avoided even when applied appropriately, that is, the inherent nature of the method There is a disclosure that there is a typical error and the error is about 1 to 3%.

  Alex F. Roche, Steven B. Heymsfield, Timothy G. Lohman (Editors): Human body composition. Human Kinetics, pp. 89-90, 1996. It is disclosed that there is about 1 to 2% of the error in impedance measured by a person with a stable weight on different days.

  Nakatsuji, F .: Body composition evaluation of Japanese adult women using bioelectrical impedance method. Academic doctoral dissertation (Osaka City University), 1991. As a result of measuring 3 times / day, a total of 9 times), it is disclosed that the variation (error) by the underwater weight weighing method was 3.4% and the variation (error) by the impedance method was 2.5%.

  FIG. 11 is a flowchart showing the basic operation of the control unit 16. When the operation starts (STEP 1000), the control unit 16 performs preprocessing (STEP 1100). Here, the measurement person is allowed to input identification information, weight, age, sex, and forearm length of the person to be measured. At this time, the instruction regarding the input item may be instructed by the control unit 16 displaying it on the display unit 14.

  When the input of data to be input in advance is completed, the control unit 16 instructs the measurement subject to wear the electrode unit 22 (STEP 1200). The electrode section 22 is attached by a measurer. When the electrode section 22 is attached, a measurement start signal is sent to the control section 16 through the input section 12.

  Upon receiving the measurement start signal, the control unit 16 starts measurement (STEP 1300). The control unit 16 instructs the constant current generation unit 201 to apply a current through the control line. When the constant current generating unit 201 passes a current and the bioelectric current is stabilized, the voltage measuring unit 202 is instructed to measure the voltage between the electrode terminals 222 and 224. The bioelectric current is stabilized when the measurement voltage of the voltage measuring unit 202 is measured at regular intervals and the change is reduced. The measurement may be performed after a certain period of time.

  The measurement may be one-point measurement, or is not particularly limited, such as measuring several times to obtain an average value. These measurement values are transmitted to the control unit 16 as the measurement voltage Vsig. The control unit 16 converts the ratio of the current flowing through these data into a resistance value to obtain a bioelectric resistance. Note that the voltage measurement unit 202 may perform conversion into a resistance value.

  The control unit 16 that has obtained the value of the bioelectrical resistance estimates the height from the forearm length, and estimates the body density using the estimated height and weight, sex, age, and bioelectrical resistance. Thereafter, body fat percentage, body fat mass, lean mass, body water content, etc. are calculated based on the body density (STEP 1400). For these calculations, formulas 1 to 6 are used. These calculation results are displayed on the display unit 14 (STEP 1500), and the process ends (STEP 1600).

  FIG. 12 shows an example of displaying results. An input value of the name, age, sex, weight, height, forearm length of the person to be measured, and an estimated value obtained from the measured bioelectric resistance value and the input value are displayed. A bioelectric resistance value may be displayed. The above display may be limited to only a part of the display. Also, personal information such as age and weight may only indicate that it has been input, and the actual value may not be seen unless another operation is performed.

  Also, although there is an input field for height, measurement may be possible if either forearm length or height is input. When the forearm length is input, calculation is performed from the above formulas 1 to 5 using the estimated height estimated from the forearm length. If the actual height is known, the actual height may be used for calculation.

 According to the body fat percentage measuring apparatus and the measuring method of the present invention, bedridden elderly body fat can be measured relatively easily, and useful body fat percentage and body fat amount are presented as prior information at the time of medication. can do.

The figure showing the correlation of the measured value of the electrode of this invention, and an adsorption electrode. The figure showing the correlation of the body fat rate and the estimated body fat rate by a male underwater weight weighing method. The figure showing the correlation of the body fat rate by an underwater body weight weighing method of a woman, and an estimated body fat rate. The figure showing the correlation of the fat-free rate by a male underwater weight weighing method, and an estimated fat-free rate. The figure showing the correlation of the fat-free rate by a female underwater weight weighing method, and an estimated fat-free rate. The figure showing the correlation between the estimated height using the forearm length and the actual height. The figure which shows the correlation of a standard weight and an estimated standard weight. The figure showing the correlation of the estimated BIM calculated | required using BMI and the estimated standard weight. The figure which shows the structure of the measuring apparatus of this invention. The figure explaining the bioelectric voltage measurement part of this invention. The flowchart showing operation | movement of the measuring apparatus of this invention. The figure which shows the example of a display of the measuring apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Body fat measuring device 12 Input part 14 Display part 16 Control part 18 A / D conversion part 20 Resistance measurement part 22 Electrode part 24 Control line

Claims (5)

A body fat measurement method for obtaining body fat percentage or body fat mass by estimation calculation based on parameters including body weight, forearm length, and bioelectric resistance. A bioelectric resistance measurement unit for measuring bioelectric resistance;
An input unit for inputting weight and forearm length;
A controller that calculates body fat percentage using the input body weight and forearm length and the bioelectric resistance measured by the bioelectric resistance measurement unit as parameters;
A body fat measuring device comprising a display unit for displaying the calculated result. The body fat measurement device according to claim 2, wherein sex and age are further input. The controller is
Calculate the estimated height from the input forearm length by one formula,

Calculate body density based on two formulas from the input weight, age, sex, bioelectrical resistance, and the estimated height,

Calculate body fat percentage from the body density based on equation 3,

Based on the four formulas from the body fat percentage and the body weight,

The body fat measuring device according to claim 3, wherein the display unit displays at least one of the body fat percentage and the body fat amount. The controller is
Calculate the estimated height from the input forearm length according to equation 5,

The body density is calculated based on the inputted weight, age, sex, bioelectrical resistance value, and the estimated height based on the six equations,

Calculate body fat percentage from the body density based on equation 3,

Based on the four formulas from the body fat percentage and the body weight,

The body fat measuring device according to claim 3, wherein the display unit displays at least one of the body fat percentage and the body fat amount.

Images