Skinfold Assessments – why we use them and you should too

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Trying to gain muscle mass or reduce your fat mass? Looking at the number on the scales won’t tell you much about your body composition because it doesn’t distinguish between what’s fat, muscle, bone or fluids, it just tells you your overall mass. There are a variety of measurements that tell you a lot more information about your body than simple weight measurement does, for example DXA scans, Bod Pods, BIA and surface anthropometry (skinfolds). These types of measurements all come with their own unique set of errors and benefits with their estimation of physique. See the table below for a summary of the accuracy and reliability of different body composition assessments that can be undertaken:

At Precision Athletica, we primarily assess skinfold measurements. Skinfolds are a robust technique that is relatively cheap, convenient and efficient, and does not require any fasting beforehand, compared to other methods which are more expensive and can give variable results based on the time of day, meals eaten and hydration status.

In a skinfolds assessment, 8 anatomically defined sites on the body (triceps, subscapular, biceps, iliac crest, supraspinale, abdominal, front thigh and medial calf) are marked to then assess subcutaneous fat (fat below the surface of the skin) using skinfold callipers.

The sites are chosen to account for individual variations in body fat distribution and the results are given as a sum of the 8 sites (some sports will only measure 7 sites, leaving out the iliac crest measurement). Skinfolds only measure subcutaneous fat, not visceral fat, which is the internal fat surrounding organs, however this is not usually an issue for athletes.

In general, an increase in skinfolds is associated with an increase in body fat, while decreased skinfolds is associated with a reduction in body fat stores. Skinfolds are typically assessed in conjunction with your body mass, to offer an insight into changes in both fat and muscle mass (i.e. increased weight with reduced skinfolds could reflect increased muscle mass). Equations used to estimate a body fat % from skinfold measurements are usually inaccurate, as the equations were derived from non-athletic populations so offer little insight into absolute body fat stores.

See the table below for an example of how your skinfolds can be interpreted to assess changes in body composition:

As with many types of measurements, there is a margin of error associated with skinfold assessments. You will be given a sum of your 8 (or 7) skinfold sites, but this should also be presented as a range to allow for measurement error. When you have a subsequent skinfold measurement, if your skinfolds sum is not in the range of the previous measurement, then you know there has been a true change in fat mass, however if it falls within that range then it can be viewed that skinfolds have remained stable. Frequent ongoing measurement of your skinfolds will be a valuable tool in helping you monitor body composition over time. We recommend every 4-6 weeks depending on the athlete and sport.

When using your body weight to compliment your skinfold assessments, remember to weigh yourself at the same time every time you weigh yourself as weight can be influenced by the time of day or month (for females) and hydration status (lighter if dehydrated).

Who should have their skinfolds done?

Anyone can have their skinfolds done. If you have a goal of increasing your muscle mass, assessing skinfolds will show you whether increases in mass are due to increases of muscle, fat mass or both. Likewise, if you are aiming to reduce fat mass, assessing your skinfolds regularly will assist you in determining how well you’ve maintained muscle while reducing fat mass.  

In sports, skinfolds are another tool used to assess the effectiveness of your training. Some sports have certain physique traits associated with them, such as gymnastics or diving. In endurance sports such as marathons and cycling, lower body fat levels enhance efficiency and heat dissipation. In other sports with weight classes such as rowing or boxing, lower body fat levels will help enhance power to weight ratio compared to smaller, less muscular opponents. In team sports such as rugby, different positions on the field have different roles requiring different body compositions to effectively be able to achieve their roles.

Ongoing skinfold assessments are the most effective tool for monitoring body composition changes over time, and as an athlete, are just one of your tools that you can use to assess your progress in performance.

If you are interested in knowing more about skinfold assessments, having yourself assessed, or genrally interested in getting a strategic nutrition plan to support your training and lifestyle goals, contact our Sports Dietitian Kelsey Hutton, who will be happy to help.

Kelsey can be contact by email at: kelsey.h@precisionathletica.com.au or you can book to see her for a one-on-one below.

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