Phase Angle - PhA (F) - reflects the integrity and function of cell membranes. Healthy cell membranes maintain optimal electrical properties, allowing for efficient exchange of ions and nutrients between the intracellular and extracellular environments. PhA is measured using Bioelectrical Impedance Analysis (BIA) on a device such as the InBody 970 that we use at Regenesis. BIA provides an estimate of body composition by measuring the impedance of biological tissues to electrical currents. Impedance consists of two components:
Reactance (X): Opposition to the flow of alternating current due to capacitance (Xc) and inductance (Xl) effects in tissues.
Resistance (R): Opposition to the flow of electrical current due to the resistance of tissues, fluids, and cell membranes.
Resistance is the property of a material to oppose the flow of electrical current. It is measured in ohms (?). The conductivity of a material is inversely related to its resistance. Materials with low resistance have high conductivity. For example, the resistance of 12 gage copper wire is 0.0016? per meter while the resistance of 12 gage aluminum wire is 0.0026? per meter.
In the human body, low resistance is associated with large amounts of Lean Body Mass (LBM). LBM is the total weight of organs, skin, bones, body water, and muscles within a human body. LBM represents entire body weight minus body fat.
Body water containing charged ions readily conducts electrical current. Both extracellular water or ECW (water and ionized sodium Na+) and intracellular water or ICW (water and ionized potassium K+) provide a conductive pathway. When a person has high levels of lean body mass (LBM), their body has high conductivity of current and low overall resistance. It’s also worth noting that resistance in the body is proportional to one’s LBM because water is contained solely within your LBM.
Reactance gauges the ability of cells to store energy. A body has high reactance if its cells can store energy easily and it has low reactance if it stores energy poorly. “Healthy” cells that have intact cellular membranes and high reactance hold an electrical energy charge “longer.”
For this reason, your body reactance is proportional to both the proportion of healthy cells in your body and the health (reactance) of these cells. Like resistance, the unit of measurement for reactance is ohms.
Impedance is the sum of resistance and reactance. When evaluated trigonometrically, the relationship between resistance and reactance creates a ratio: F=arctan XcR , this ratio is your PhA and is expressed in degrees.
To measure bioelectrical impedance, the InBody 970 body composition analyzer (BCA) sends minute electrical currents between skin contacts located on the foot platform and in the hand grips. The InBody 970 tracks the flow of these currents to assess body impedance and cell membrane health. In humans, 50 KHz is considered ideal alternating current frequency (AC Hertz) to maximize reactance and determine the point where cells are strongest at resisting the flow of current (thus creating the highest PhA).
The chart below provides comparative PhA data for adults in terms of the population median and mean.
By locating your age, you can find the healthy PhA range for your age. This table also provides Interquartile Range (IRQ) and Standard Deviations (SD) for the median and mean. IQR represents the range of phase angle scores that fall between the 25th and 75th percentiles of the distribution. SD (for a normally distributed population) provides the interval above and below the mean in which 68% of the population lies (95% of the population will lie between the mean plus and minus two standard deviations).
By way or an example, a 67-year-old male with F=5.8o has a PhA that is 2.67 SD above the population mean. This would put this individual in the 99th percentile of people his age. This means this individual has cellular health and nutritional status that is better than about 99 percent of people his age. As such his health prognosis is much better than typical of individuals his age and is more typical of someone thirty years younger.
Phase Angle (PhA) measures cell health and nutrition status using BIA. Higher scores mean better cellular function and overall health.
