You’ve seen body-weight scales at stores, online, in gyms and at the doctor’s office that utilize bioimpedance analysis. These scales can be expensive and wondered what is bioimpedance analysis and is it worth the price?
Bioelectrical impedance analysis may sound complicated, however, BIA devices use today’s technology. It measures the rate at which low-level electrical current is run through the body. Based on the rate that it travels, algorithms are used to measure fat-free mass, along with other data, such as height, gender, and weight measurements to determine your body fat percentage.
There are different types of devices, but each device requires two points of contact.
Handheld devices use two points, which are the hands (called hand-hand BIA).
Typical BIA scale uses the feet (called foot-foot BIA).
You place each foot on a pad and the current travels through your body between the feet.
There are also hand-to-foot BIA devices.
There are many brands that make different types of BIA scales (also called bioimpedance scales)
Newer models link with a smartphone app so you can track your progress.
Prices of a BIA scale depend on the sophistication of the equipment.
Some scales use multiple frequencies and more advanced algorithms, as well.
Some provide segmental fat analysis, which means, you can get body fat measurements for each arm, leg, and belly.
There are reports that segmental fat analysis (utilizing hand-foot BIA) are more accurate because hand-hand devices focus on measuring the upper body.
Foot-foot scales primarily measure the lower body.
These devices are considered safe for most people. Except:
Bioelectrical impedance analysis should not be used by anyone with an electronic medical implant, (e.g. heart pacemaker).
Not e used by pregnant women.
Studies have shown that bioelectrical impedance analysis is an accurate method for measuring body fat.
But these studies generally do not test the scales from the store.
Experts agree the accuracy of the measurement depends on the quality of the equipment.
Parameters
(R) Resistance
Resistance and reactance are terms from physics, which are part of the field of materials and the effects on electricity. In reality, resistance and reactance are easy to understand.
Resistance is the ratio of electrical potential (voltage) to the current in a material. Put simply, a material with high resistance needs a high potential to generate a given amount of current in the material. A material with low resistance requires a low potential to produce the same amount of current in the material.
The easiest way to remember is:
Material with low resistance conducts well.
Material with high resistance conducts poorly.
When material conducts, it releases energy in the form of heat.
The resistance of a material is related to the material�s ability to dissipate energy.
Units of resistance are called ohms.
In the human body
Low resistance is associated with large amounts of fat-free mass.
High resistance is associated with smaller amounts of fat-free mass.
The Case
Primary conductor in the human body is ionized water.
As the percentage of body weight that is water increases, the conductivity of the body increases.
Body water is contained solely in fat-free mass
Conductivity of body is proportional to amount of fat-free mass.
The potential required to generate the current is measured.
The ratio of potential and current along with a process called correlation and integration are used to determine the resistance and reactance. NOTE: This alternating current resistance is not the same resistance that can be measured by a standard store ohmmeter.
(X) Reactance
Reactance: the effect on an electrical current caused by a material’s ability to store energy.
A time delay between applied electrical potential and current.
Material that stores energy easily causes high reactance, and causes a large delay in the current.
Material that stores energy poorly has low reactance and causes a small delay in the current.
Example: Water poured onto top of a sponge will flow out of the bottom after a delay.
Large sponge will cause a large delay in the flow of water out the bottom
Small sponge would cause a small delay.
Current flows in material the same way.
The delay flow of current from storage is the reactance.
Units of reactance are ohms.
In the human body:
High reactance: large amounts of body cell mass (intracellular mass).
Low reactance: small amounts of body cell mass.
The Case
Cell membranes consist of a layer of nonconductive lipophilic material interposed between two layers of conductive molecules.
Behave like tiny capacitors and store energy.
Reactance in the body reflects the strength of capacitance.
Intact cellular membranes contained primarily within body cell mass
Reactance of the body is proportional to the amount of body cell mass
Reactance is Measured�by
Small current is applied through the body.
The potential required to generate the current is measured.
Ratio�of potential and current along with process correlation and integration used to determine the reactance.
(Z) Impedance
Total impedance (Z): The vector sum of effects of resistance and reactance on a current in the human body.
Technically, impedance is the ratio of potential (V) to current (I) and is used in bioimpedance analysis.
How R, X, & Z Relate
Mathematical relationship between Resistance (R), Reactance (X), and Impedance (Z) are: Z = sqrt (X2+R2) X = Z * sin (?) R = Z * cos (?) phase angle = arcsin (X/Z) phase angle = arctan (X/R)
Example:
(?) Phase Angle
Phase angle is indicator of cellular health and integrity.
Research has shown the relationship between phase angle and cellular health is increasing and nearly linear.
Low phase angle: Consistent with inability of cells to store energy and
Indication of a breakdown in cellular membranes.
High phase angle: Consistent with large quantities of intact cell membranes and body cell mass.
Phase angle reflects the ratio of body cell mass to fat-free mass.
Phase angle is proportional to the ratio of reactance and resistance (proportional body cell mass to fat-free mass.)
Phase Angle Increase
Increase in body cell mass relative to fat-free mass.
Increase in fat-free mass relative to body weight.
Improved hydration of fat-free mass
Phase Angle: Useful For Comparing
Reactance along with the patient’s weight indicates an absolute amount of body cell mass (BCM).
Reactance is best applied when comparing test results in a single patient at different times.
Two patients with exact reactance (X) can have different amounts of BCM, depends on patient’s weight.
Any patient with a higher phase angle will always have a higher proportion of BCM than patient with low phase angle.
Phase angle indicates number of intact cell membranes.
Phase angle is direct measurement of relative amounts of intact cellular membranes.
Phase Angle Works How?
A bioimpedance analyzer applies 50-kilohertz alternating current to the body.
Phase angle is delay in time between the electric potential and current.
Oscilloscope connected to the body appears as delay between the voltage waveform and current waveform.
The period of each wave at 50 kilohertz is 20 microseconds. If, for example, the time delay is ten percent of the
period, then the time delay is 2 microseconds.
When expressed in units of time, it is said that the phase delay is 2 microseconds.
Time delay can be seen as percentage of entire wave period in degrees.
Complete wave period consists of 360 degrees. If time delay is one-tenth the total period of the wave, it is equivalent to 36 degrees.
When time delay is expressed this way (in degrees of total wave period),
This is the phase angle.
When electrical potential and current are depicted sweeping around a circle
Instead of moving over time
The relationship between reactance, resistance, and phase angle is easier to see.
Shown below
Range of phase angle in the human body is 1 to 20 degrees.
Phase angle is the arctangent of (X/R)
References:
Kyle UG, et al. Fat-Free and Fat Mass Percentiles in 5225 Healthy Subjects Aged 15 to 98 Years. Nutrition, 17:534-541, 2000.
Mattar J, et al. Application of total body bioimpedance to the critically ill patient. New Horizons 1995, Volume 4, No, 4: 493-503.
Ott M, et al. Bioelectrical impedance analysis as a predictor of survival in patients with human immunodeficiency virus infection. Journal of Acquired Immune Deficiency Syndrome and Human Retrovirology 1995: 9:20-25.
Bioimpedance Analysis (BIA) is defined as the analysis of resistance and reactance in the human body.
Energy dissipation is called resistance (R).
Energy storage is called reactance (X).
Units of resistance and reactance are called ohms.
Resistance and reactance taken together create impedance (Z).
Fat-free mass in the human body is proportional to its resistance.
Body cell mass is proportional to its reactance.
A bioimpedance analyzer is a device that contains a highly precise frequency meter, a processor, and a printer. The meter is called an impedance meter. It measures resistance and reactance.
The microprocessor computes the size of the fat-free mass and body cell mass along with all subsequent calculations.
A bioimpedance analyzer measures resistance and reactance, computes fat-free mass, body cell mass, total body water, and intracellular water.
To measure resistance and reactance, the bioimpedance analyzer generates a small electrical current to the body.
Measurements
Bioimpedance analysis is an assessment of change in electrical tissue conductivity, which indicates altered body composition.
The following electrical characteristics are measured and used to evaluate body composition.
Impedance (Z)
Impedance is a measurement of a medium to conduct current. It is a ratio of voltage injected current in a conductive medium and has two components: resistance and reactance.
Resistance (R)
Resistance is the component of impedance related to the dissipation of energy.
Reactance (X)
Reactance is the component of impedance related to the storage of energy.
Phase angle is a time delay between stimulating current and the voltage generated by an alternating current. The phase angle is expressed in degrees.
Electrical characteristics and their relation to each other?
The time relationship of voltage, current, and phase is shown below.
The Circuit
Water is the body’s conductor and determines the resistance.
Electrolytic fluid in fat-free mass consists of water and charged ions that conduct electrical current.
Extracellular fluid (water and ionized sodium Na+) provides a low-resistance pathway.
Intracellular fluid (water and ionized potassium K+) provides a low-resistance pathway.
Fat mass is non-conductive because there is no water.
Cell membranes within intracellular mass determine reactance.
The cell membranes consist of a layer of nonconductive, lipophilic material interposed between two layers of conductive molecules. They are tiny capacitors that store electrical charge.
Extracellular pathway (which is sodium ionized water) is represented by single resistance.
Intracellular pathway (potassium ionized water and cell membranes) is represented by resistance and reactance.
Total resistance is proportional to the amount of fat-free mass.
Reactance is proportional to body cell mass (intracellular mass).
The meter reports total resistance and total reactance to the microprocessor.
Equation for Regression
Bioimpedance analyzers use algorithms to compute amounts of fat-free mass, body cell mass, body water, and intracellular water.
What is the regression equation?
This equation is a mathematical formula that predicts the relationship between two or more variables based on the analysis of data.
For example, total body water�regression�equation
(TBW) = form:
TBW = a * Ht2 / R + b * Weight + c * Age + d
The terms are Ht2 / R, Weight, and Age.
The weighting constants are a, b, c, and d.
Resistance, height, weight, gender, and age are supplied for each subject. A computer then generates an algorithm which best describes the relationship between TBW, resistance, height, weight, gender, and age.
This is called Regression Analysis.
How do you use regression equations?
Once the bioimpedance analyzer measures the resistance and reactance, the results are sent to the microprocessor to perform the calculations. All the equations, (FFM, BCM, TBW, and ICW) are encoded into the analyzer’s software.
Diagram
Fat-Free Mass
Fat-free mass is derived by applying a small alternating current to the body.
The resistance of the body is measured using the measured resistance (R), the analyzer estimates the fat-free mass.
Body Cell Mass
Body cell mass is derived by measuring both the resistance (R) and reactance (X) of the body. With this measurement, the analyzer estimates body cell mass.
Total Body Water
Using the measured resistance, the analyzer estimates total body water.
Intracellular Water
Using the measured resistance and reactance, the analyzer estimates intracellular water.
Body composition analysis is becoming a standard tool that is being used by fitness experts, coaches, and healthcare professionals.
In 2019 we can�discard reliance on body mass index (BMI)�as a means to measure health.
Other than our appearance, there is a list of diseases associated with obesity. This is what’s at the top of our minds. The list is long and includes heart disease, hypertension, cancer, joint problems, dementia, and diabetes.
Body composition analysis is defined as the clinical assessment of tissue and fluid in the human body.
Fat Mass
Fat-Free Mass
Body Cell Mass
Extracellular Mass
Total Body H2O
Intracellular H2O
Extracellular H2O
Normal distribution of tissue and fluid is associated with immunity, high function, and longevity.
However, not being able to have detailed insight�into your personal body composition can�lead to critical errors�in understanding what’s going on, along with recommendations. This can hinder the�ability to reach a specific fitness goal.
Body composition analysis is utilized in preventative, therapeutic, and research applications.
Nutrition
Anti-Aging
Physical Performance Assessment
Weight Management
Geriatrics
Lifestyles Assessment
Athletic Performance
To perform body composition analysis, mass and fluid are modeled, measurements taken, and results analyzed.
Bioimpedance (BIA) body composition analyzers measure body composition electronically. However, they do not, diagnose disease, or calculate treatment options. Only qualified health care professionals can diagnose and recommend treatment options.
There are concerns that affect everyone, which is why knowledge of body composition is important for your health in 2019 onward.
Model Body
Look at the images below of six males, all of whom are 5′ 9″ and 170 pounds. There could be some envy from their 25.4 BMI, as the results are come up on the computer screen. However, looking at the actual patient or their scans using today’s technology, the results are pretty revealing.
Notice the difference in the midsection, where there is an abnormal accumulation of visceral fat.
This occurs in metabolic syndrome and what is known as Adiposity disease.
Fat Mass (FM): Total amount of stored lipids in the body and consists of the following types:
Subcutaneous Fat is located right under the skin. Subcutaneous fat functions as an energy reserve and as insulation from the cold.
Visceral Fat is located deeper in the body. This fat serves as an energy reserve and as a cushion between the organs.
Fat-Free Mass (FFM), aka Lean Body Mass (LBM): Total amount of nonfat (lean) parts of the body.
Consists of approximately 73% water, 20% protein, 6% mineral, and 1% ash.
Fat-free mass divides further into body cell mass and extracellular mass:
Body Cell Mass (BCM): All the metabolically active tissues (cells) of the body, which include muscle, organ, blood, and immune cells.
BCM includes the “living” portion of fat cells, but not fat lipids.
BCM also includes H2O inside living cells. This water is called Intracellular Water (ICW). The main electrolyte is potassium.
Extracellular Mass (ECM): All the metabolically inactive (non-living) parts of the body, such as bone minerals and blood plasma. ECM includes water contained outside living cells. This water is called Extracellular Water (ECW). The main electrolyte is sodium.
Composition & Body Health
Body composition correlates directly to maintained proper health, that range from mortality/morbidity to immunity, longevity, high function, and athletic performance.
Body composition analysis’ purpose is to monitor and improve function.
Healthy patients analysis of fat-free mass and body cell mass helped maintain function, productivity, immunity, physical performance, and longevity.
Every case is different but through body composition analysis, people can have a better understanding of their body, what options are available to them, and most importantly do not have to be on medication/s for the rest of their lives.
References:
Kyle UG, et al. Physical activity and fat-free and fat mass by bioelectrical impedance in 3853 adults. Medicine and Science in Sports and Exercise, 2001;33:576-584.
Mattar JA, et al. Application of total body bioimpedance to the critically ill patient. New Horizons, 1995, Vol 4., No. 4; 493-503.
Ott M, et al. Bioelectrical impedance analysis as a predictor of survival in patients with human immunodeficiency virus infection. Journal of Acquired Immune Deficiency Syndromes and Human Retrovirology, 1995; 9:20-25.
The way a person walks, their gait, can be very telling. It can reveal problems in the feet, ankles, knees, and hips � even in spinal alignment. A problem with gait can indicate pain in a patient as well as serious conditions like diabetes and arthritis. It, is a diagnostic tool for many conditions, injuries, and syndromes including autism. When it comes to chiropractic care, a patient�s gait can offer critical clues regarding the root of their complaints, allowing for a more well-rounded, whole body approach to treatment. If you think that the way you walk or moves doesn�t matter, think again. It most certainly does matter.
What is Gait Analysis?
Gait analysis is a set of tests that are designed to provide a comprehensive evaluation of a person�s gait. It is a systematic study of human motion that involves observation as well as the use of instruments that measure body movements, muscle activity, and body mechanics.
It is intended to be used as an assessment tool and provide insight into devising a treatment plan for people who have conditions or injuries that affect their ability to walk. It is often used in sports biomechanics to aid athletes in more efficient movement and to identify problems with movement or posture, particularly those with injuries.
During the analysis, the patient may walk in a prescribed pattern or on a treadmill, that is often connected to a computer, while the chiropractor observes them from various angles. Often cameras are used, places at multiple points to capture different views including the anterior, posterior, and sides.
The patient may have markers applied to specific points on the body such as the knee, ankle, pelvis, and other areas. As they move, the computer captures specific data of the movement, providing a three-dimensional calculation of each marker. It then applies a model to assess the movement of the skeletal structure, resulting in a detailed analysis of each joint�s movement.
Factors that Affect Gait Analysis
Certain factors affect a person�s gait, and that information must be included for the gait analysis to be accurate. The gender, age, height, and weight of the person is vital because men and women move differently and as a person ages their structure changes.
Excess weight or they physique can affect a person�s posture and their gait. The individual�s shoes (or lack of shoes) is essential, as is their clothing, the terrain they are walking on, and anything they may usually carry, such as a purse. Other factors include:
Physiological factors such as body proportion
Psychological factors such as their state of mind, emotions, stress level, and personality type
Pathological factors such as neurological diseases, psychiatric disorders, trauma, and musculoskeletal anomalies
It will also measure and factor into the analysis data that includes the patients:
Getting a gait analysis can be very advantageous because it can provide invaluable insight into how your body is aligned and how it moves. It is an excellent diagnostic tool for identifying health issues related to the gait, spine, and feet and can also help provide early detection of health issues before the onset of symptoms.
If your chiropractor recommends that you get a gait analysis, it could be that he or she suspects that something is going on, or it could simply mean that they want to examine you to provide optimal care more thoroughly. If you have any concerns, you should sit down with your chiropractor and ask them any questions that you have before undergoing the analysis. Stress and anxiety can put tension on the muscles and body, affecting the results.
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