Tool overview: Bioimpedance scales range from simple home use setups to laboratory use setups. What changes can be the areas of the body that are assessed, and the companys’ way of calculating what to do with the results. In the simple home use scales you are usually sending an imperceptible electric current from one bare foot to the other and therefore analyzing the body composition of the lower body only. In laboratory setups at least 2 body segments are assessed and sometimes more. The formulas used may be more or less accurate depending on the type of person being measured. Accuracy is not the main reason to use bioimpedance scales. Many studies have found that the formulas used to determine a person’s body leanness and fatness are off by large percentages. What bioimpedance is good at is speed. It takes less than 1 minute to take a measurement which makes it an attractive option for busy people.
Best way to use this tool: Try to always take bioimpedance measurements at the same time of day, preferably first thing in the morning after using the washroom. You should also aim to keep your hydration level the same each measurement because if you are more dehydrated than the last time you got measured your results will not be comparable. Females who menstruate are advised to take note of which day in their cycle the measurement is taken to address an additional water retention factor. The follicular phase (the time after bleeding, often 1 to 2 weeks) may be the most water stable. During the luteal phase (the time before bleeding, often 2 weeks) many women experience water retention.
How often to use this tool: You can use bioimpedance every morning along with body weight to track hydration levels. To track changes in body composition I would not use it more than once a month. Females might even want to wait three months between measurements if their menstrual cycles are not regular. It is also really important to note that you are not tracking true body composition you are tracking the changes between one time you measure and the next time you measure so if you just measure yourself 1 time your results are not really that useful.
Introducing The Laboratory “High” Tech
Occasionally high level athletes will get the opportunity to have potentially highly accurate testing done to determine their body composition. They get to use what we call in scientific studies the “Gold Standard”. These are tools that are considered so accurate that other tools are compared to them. These tools are found at many universities and in many sports institutes. Mostly they get used in research when a high degree of accuracy for body composition measurement is required. As you can imagine, they are expensive machines and this is one of the reasons they are not used more often for all athletes.
DXA. Otherwise known as Dexa. This machine has the subjects lie down on a scanning bed and a low dose x-ray is used to measure bone density and tissue thickness. The formulas then predict how much of the body weight is made up of bone, muscle, body fat, etc. It is not something that is advised to be done very often because of the exposure to x-rays (less than 1 time per year). This tool is really great for assessing anyone at risk of having low bone density.
Bod Pod. This pod machine, which is reminiscent of a spaceship, has very scantily clad subjects sit in the pod for a series of measurements each lasting a couple of minutes. Then formulas use the change in air pressure readings to determine the body composition of the person. It is one of the simplest ways of getting an accurate body composition analysis and it is a measurement that can be repeated as often as caliper testing or tape measure testing.
Pearle Nerenberg, MSc., R.D. is Canada's leading expert on hockey nutrition, and author of the book The Nutrition Edge for Hockey Performance. She co-founded and chairs the Hockey Nutrition Network, an international non-profit organization dedicated to linking hockey players with top sports dietitians who have an expertise in hockey nutrition.
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