Bodily evaluation: skinfolds or bioimpedance

Before starting bodybuilding or any other physical activity, it is important to do a physical assessment to analyze how your body is doing and understand what needs to be changed. Only then can objectives and goals be set.

Especially for those who want to have a healthy body, low fat and a good amount of muscle mass, having a professional follow up is essential. Because, before deciding if your goal is hypertrophy or weight loss, you need to understand what your body needs.

If the goal is gain muscular mass but your fat percentage is too high, for example, it may be more convenient to focus first on fat loss and then work on gaining lean mass. This will depend on what your dietitian recommends.


Before any initiative we have to understand that each body is a body, that is, each person has biotype, genetics and different physical performance. This is why it is so important to do the physical assessment and have a professional follow-up.

But there are so many types of physical assessment, which is the best to define body composition, considering amount of fat and muscle? The best known and most widely used types in gyms involve skin folds and bioimpedance.

Main types of physical assessment at the gym

Many people ask which best type of physical assessment thinking about the goals: skinfold or bioimpedance. The answer is: it depends! Both are scientifically proven, and work differently.

The most efficient method will vary according to some conditions. See a little about each:

Skin fold

This assessment method, also known as adipometry, basically measures body fat rate from a device called adipometer. This instrument “pinches” two layers of skin and calculates the adjacent subcutaneous fat between them.


The method may seem inaccurate because it only measures the folds of the skin; however, there is a direct relationship between subcutaneous fat and the total body fatTherefore, the sum of multiple skinfolds can be very efficient in defining total body fat.

There are several skin prediction protocols to calculate the amount of body fat. Each protocol is an equation that considers specific or generalized population groups. They take into account factors such as age, ethnicity, gender and physical fitness.

In Brazil, the equation of Jackson and Pollock It is the most used. It considers three or seven folds of specific body regions, and involves healthy adult men and women – some exceptions are black, oriental, and obese.

It is very important to consider the protocol established before the evaluation, as the conditions are fundamental so that the test result is not false.

Look at the regions that the 7 and 3 skinfold protocol of Jackson and Pollock is based on:

middle axillary;

The equation changes for men and women, and both consider age in the formula. Through folds sum, it is possible that the professional follows the athlete's training and diets, being fundamental to achieve the goals.

Bioimpedance (BIA)

bioimpedance assessment

Bioimpedance is a method used to evaluate the body composition through a low-intensity electric current through the body.

THE impedance It is basically the body's resistance to this flow of electric current, which is relative to the type of body tissue. For example, muscle is a good conductor of energy due to the high water content, while fat is a bad conductor.

Thus, the greater the amount of fat, the greater the resistance, ie the higher the impedance. The result is calculated based on the device software.

For this method to be effective, it is essential that some criteria be taken prior to the assessment, such as hydration level, food etc. Here are some examples of precautions that must be taken for the impedance to give a true value:

Urinate at least half an hour before;
At least 4 hours fasting before the test (without eating or drinking);
Do not exercise until 8 hours before;
Do not drink alcohol 48 hours before;
Not being in the menstrual period;

The result may be false if these and other criteria are not considered. Also, as with folding, the result depends on a protocol that considers age, gender, etc.

Which is better: skinfold or bioimpedance

Before arguing which is better, it is important to note that both are scientifically proven, so both work very well. However, as has been seen, they are very relative – the ideal result can be easily changed, it all depends on the protocols of use.

There is no better or worse type of test, both have complementary characteristics. In this sense, the best is: complement the two methods! That's right, as each of these devices can have biases, the ideal is to use both, for a more accurate result.

So if you are looking for a professional accompaniment To analyze your physical makeup and set new goals, it may be a good idea to be with someone who works with both equipment.

So, do you have any questions about this? We hope we helped!

If you enjoyed this content, keep following our blog and check out our posts – there's a great tip for you to improve your physical performance in your bodybuilding workouts.

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