The Science Behind the Skulpt Aim®

The Science Behind Skulpt®

The technology behind Skulpt® is called electrical impedance myography or EIM. ‘Myography’ literally means “The description of muscles.”

The Basic EIM Model

To best understand the concept, let’s start with the basic make-up of a very simple EIM device (see figure). In this basic version, there are only 4 electrodes (unlike the Skulpt Chisel, which has 12).


When applied to the skin, a very weak current passes between the outer two electrodes. This current is high-frequency and alternating in nature. As the current moves through the skin, the subcutaneous fat, and the muscle, it loses a little bit of energy due to the resistance of the tissue and this change is then measured by the two inner electrodes.


In addition, the muscle fibers briefly store and release the electrical charge, and this confers a short time delay on the measured voltage on the inner electrodes. Thus, EIM measures two separate features of the tissue: its resistive properties and its capacitive properties.


Basic EIM Model

Skulpt & EIM

The Skulpt Chisel is more complex in that it measures electrical current flow in different directions and it can measure the flow at different depths (the further apart the electrodes, the deeper the electrical current will penetrate).


By combining these multiple electrode configurations with multi-frequency electrical measurements, and by using a variety of algorithms, the Skulpt Chisel can separate out the condition of the muscle from the amount of fat in a region in just a matter of seconds.


Aim EIM Model

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Important Features to EIM

There are two other important features to EIM. The first is that the electrical current can be applied at a range of frequencies and that the different tissues (muscle, fat, bone, etc) are sensitive to the frequencies in unique ways. In other words, some tissues have a greater effect on the electrical current at one frequency and not at another. This is an important feature since it allows us to separate effects of fat from those of muscle.

The second feature is that electrical current flows more easily along the muscle fibers than across them. This feature also allows us to discriminate muscle from other tissues, since fat, skin, and bone do not have this unique characteristic, called anisotropy.

Getting From EIM to MQ and Fat %

So how do we get you those two values: the percentage of fat over a specific region and the condition of the muscle via the MQ? The more fat overlying the skin and within the muscle, the greater the muscle’s resistance. Thus we are able to get a measure of the amount of fat by evaluating the resistance.

Fat and MQ Comparison

For the MQ, we rely on measurements of the preferential current flow in certain directions and the effect the muscle membranes have on the time delay between the applied current and the measured voltage. With muscle, the bigger the fibers, the greater the electrical charge storage capacity, the greater the time delay, and the more fit the muscle.

Evaluating Muscle Condition with EIM

Alterations in the muscle condition can also affect the electrical impedance of the muscle. For example, muscle injury will produce edema in the muscle, which will alter the electrical conduction of the muscle, and so EIM can be sensitive to muscle overuse and also to disease, the original use for which it was created.


EIM technology was initially developed to measure the muscle health of patients with neuromuscular disorders, such as ALS. After 16 years of development and research, and 6 years since the technology was successfully adopted by the medical space, Skulpt re-introduced EIM with the Chisel.