What's the Best Way to Assess Your Body Composition?

What's the Best Way to Assess Your Body Composition?

The pros and cons of four common measurements.

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Whether we’re runners or “recliners,” many of us are concerned about how our bodies “should” look and feel – their size, weight, how much muscle they have and, more frequently, how much fat they have. There’s also a concern with how, or if, these things can change over time – and how much effort it will take.

If you’re a runner, these concerns are more than aesthetic – they can influence your running economy, or the ability to go faster or longer while exerting less energy. Excess body fat, less-than-adequate muscle mass and a higher body weight are three factors that can make you less economic as a runner. So how can you assess where you stand in these areas – beyond just stepping on the scale? Here are four options:

1. Body Mass Index

BMI was first developed in 1832, when it was known as the “Quetelet Index.” It was named after its creator, Adolphe Quetelet, a Belgian mathematician and statistician who was mostly concerned with developing a practical index of growth and development rates. More than a century later, Dr. Ancel Keys rediscovered the measure and adopted it for his landmark Framingham epidemiological study, renaming it body mass index. This was the first time it had been used as a measure of overweight and obesity, and we haven’t looked back since. You can calculate your BMI with an online calculator or by dividing your weight in kilograms by your height in meters squared.

  • Pros: BMI is very easy to use. Despite the seemingly high number of reported examples of BMI misclassifying people as overweight or obese when they really just have a lot of muscle mass, such cases are uncommon when we consider the population as a whole. In fact, when measuring large groups of people, strong links have been reported between BMI, obesity and health risk.
  • Cons: BMI has been criticized, repeatedly, from almost every angle. The main issue is that the measure does not differentiate what a person’s “mass” consists of. Consequently, people with high levels of muscle mass and low levels of fat – such as NFL players, some track and field athletes and body builders – fall in the overweight category, but are actually quite healthy.
  • Conclusion: While it does have some health-related value for the general population, BMI is not an appropriate measure for determining an individual’s running-related body composition.

2. Bioelectric Impedance Analysis

BIA involves running a light electrical current through the body. Since your muscles contain mostly water, they have less resistance to this electrical current than fat, which contains little water. Resistance to an electrical current is known as impedance; hence the name. In simple terms, the less the impedance to the electrical current, the greater the lean muscle mass, and vice versa.

  • Pros: BIA is easy to measure and can be done fully clothed. It provides rapid information about how much muscle mass and body fat you have. BIA devices range from relatively simple hand-held units that use only one small electric current to more complex free-standing units that provide greater accuracy by using use multiple electric currents at different frequencies.
  • Cons: One of the assumptions of a valid BIA assessment is that the body is adequately and consistently hydrated. However, in reality, hydration levels vary widely over time, even within the same day, and this will cause wide variations in results. For example, if you are dehydrated, BIA will report your percent body fat as higher than it would if you were normally hydrated or overhydrated.
  • Conclusions: BIA can provide running-relevant information about muscle and fat content. However, great care must be taken to maintain a consistent hydration level at each measurement time.

3. Skinfolds

In this test, also called a pinch test, a trainer or other professional lifts folds of skin and subcutaneous fat (or skinfolds) away from the underlying muscle at specific sites on the body with his or her thumb and forefinger and measures them with specially designed calipers. The thicknesses from all sites are added together and the resulting sum is used to estimate percent body fat.

  • Pros: Skinfold measures can be taken in shorts and T-shirts, and many health clubs provide this service as part of a fitness assessment. The whole process takes less than 10 minutes and the results can be rapidly obtained from commercially-produced tables or web-based programs. Skinfold calipers are widely available, ranging from under $10 for the simpler models to over $200 for the scientific models.
  • Cons: Skinfold measures are deceptively hard to take accurately and reliably. You need to be able to grasp the skin at precise sites and use precise methodologies to maximize accuracy and reliability. It’s very hard – even impossible at times – to lift an ideal skinfold. Factors such as sweat, body lotion and even ticklishness can produce inconsistencies in measures – regardless of the tester’s expertise.
  • Conclusions: Skinfolds can be a good measure of muscle and fat, as long as the tester is experienced. However, caliper measurement errors are, again, near-inevitable among some people.

4. Ultrasound

Research suggests that this is one of the most promising techniques for assessing body composition. It uses the same body site locations and prediction equations as skinfolds. However, ultrasound technology enables the thickness of the subcutaneous fat layer to be measured directly.

  • Pros: Ultrasound methodologies do not need to pinch folds. Rather, a tester places the ultrasound probe firmly and comfortably on the surface of the site to be measured, and can view results on a screen within seconds. Unlike skinfolds, sweat, body creams and lotions have no effect on accuracy. Portable and affordable ultrasound devices are now available that can be plugged directly into a tablet or laptop. More and more health clubs are offering this service. Most importantly for runners, and unlike the other measures, ultrasound technology can also detect fat inside the muscle. The more fat contained inside the muscle, the less healthy it is, the less powerfully it’s able to contract and the more it will reduce running economy.
  • Cons: The biggest obstacle is finding a club, physician or physical therapist that uses this device.
  • Conclusions: As I’ve seen in my work as chief science officer at MuscleSound, ultrasound technology can provide runners with immediate, actionable information that will enable them to unlock their muscles’ full potential, improve their running economy and enhance their performance.

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Whether you enjoy the attention of one-on-one private training, or the excitement of a group fitness class, Balance Massage & Core Fitness Studio has the right training options to help you meet your fitness, physical therapy, and relaxation goals.

Balance Massage and Core Fitness Studio

Address
233 SE Washington Street, Suite 103
Hillsboro, Oregon 97123

Phone: 503.352.9685
Email: info@balance-mf.com