It can be hard to see progress when you're trying to get fit. Pounds don't fly off in a week, and massive muscles don't appear overnight. But a company called Skulpt wants to make it easier for you to see the fitness hurdles you've already jumped. Its $99 Skulpt Chisel is a brick-like device that uses "electrical impedance myography" to assess muscle quality and fat percentage all across the body. Think of it as a tracker for your fitness tracker, if you use a fitness tracker—the Chisel can assess if your workouts are actually working for you. Even if you don't use a fitness device, it can show you which parts of your body need improvement and how you've gotten stronger over time.

How it works: Feel the currents

Design and features go hand-in-hand with the Skulpt Chisel. It's a white, rectangular device that's slightly taller than a deck of cards, with a thin light ring around the edges. The front of the device is just the Skulpt logo, but the back is where all the technology is. That's where you'll find small electrode strips covering most of the surface, along with four small nodes that fit into its charging base. Those electrodes measure muscle quality and fat percentage on different parts of the body using electrical impedance myography, or EIM.

Skulpt's website explains how the technology works: EIM electrodes send weak electrical currents through your skin and through the different layers of your body. The electrical current loses energy as it moves through muscle and fat. That loss of energy is then measured by some of the electrodes. While current simply passes through fat, muscle actually absorbs and releases a portion of that electricity, allowing the device to measure resistive and capacitive properties of your body's tissue.

Many EIM devices only have four electrodes, but since the Chisel has 12, it can measure the flow of the electrical currents in different directions and at varying depths. After a few seconds of the electrodes pressed against your skin, Skulpt's algorithms interpret the device's measurements to give you a muscle composition reading as well as fat percentage.

Valentina Palladino

Valentina Palladino

Valentina Palladino

Valentina Palladino

Valentina Palladino

Valentina Palladino

Valentina Palladino

From Aim to Chisel: How Skulpt's technology evolved

Let's put the Chisel into context quickly: it's actually Skulpt's second device. Skulpt's first EIM device was the Skulpt Aim, a similarly-designed black brick with a small screen that displayed your muscle and fat results. It also used the Skulpt app to target specific muscles. Both the device and the app have been redesigned over the past couple years.

The idea began when co-founder Dr. Seward Rutkove, a neurologist at Harvard Medical School, wanted to create a device that could analyze muscle mass without needing a roomful of medical equipment. A few years later, co-founder Dr. Jose Bohorquez joined in and used his electrical engineering background from MIT to figure out a way to shrink all that technology down to a consumer-friendly size and price.

Skulpt prides itself on a device rooted in science. Researchers were using electrical impedance myography to examine skeletal muscle in animal tissue as far back as the 1950s. Subsequent experimentation has led doctors to use EIM to assess the composition of tissue in healthy humans and even those suffering from neuromuscular diseases.

While the Chisel's EIM technology remains largely the same as the original Aim, Dr. Bohorquez says that changes have been made based on user feedback. The Skulpt app now gives you personalized advice on what exercises you should be doing and what foods you should be eating in order to reach your goals. Dr. Bohorquez says this feature is slowly rolling out and will provide even more specific advice as you use the Chisel.

"Say that you indicated that you enjoyed running," Dr. Bohorquez told Ars. "And [the app] observes that your quads, the front part of the legs, are a lot stronger than your hamstrings, which are the back side of the legs. Those types of asymmetries over the long term could result in knee injuries... Giving people those types of insights is helpful, and then we can go one step further and say, 'Here's an exercise that's really effective and can help you improve that.'"

Living with Chisel and the Skulpt app: Mapping and assessing the body

The Skulpt app is basically a body diary. The homepage's anatomical diagram of the human body highlights the muscles you can measure in blue. Between the front and back views of the body, you can monitor every major muscle you'd want to focus on in the gym: biceps, hamstrings, calves, back, shoulders, and more. They're also separated into left and right side muscles, making it a truly accurate photocopy of your physiology—you might find that your left lower back is weaker than your right lower back (as I found, which is understandable considering a past back injury).

To measure a muscle, tap it on the diagram, and the app will automatically search for your Chisel. Then the app will show you exactly how to place the device on your body. After pressing the Chisel against your skin for a few seconds, the device's edge light glows green while it takes your measurements.













After the reading, the app brings up your scores. The muscle quality score measures how strong the scanned muscle is compared to its mass while the fat percentage score is relative to muscle mass. Getting the Chisel's placement right during each measurement is important. Moreso than insufficiently wetting the electrodes, improper placement can result in an inaccurate reading. This happened to me when I measured my right quads one morning—I didn't put the Chisel exactly where the interactive diagram on the app told me to, and I got a much lower muscle quality result than normal. Shifting the Chisel up slightly and re-measuring got a more accurate number.

In case you're wondering, the Chisel is not affected by your hydration levels. Dr. Bohorquez explained that since the Chisel measures muscle directly below the skin, the readings won't change if you haven't had a drink in a few hours because changes in hydration manifest deeper in the body, in your blood and organs.

Once you measure a few muscles on your body, the app starts to generate personal exercise and nutrition plans based on your goals (when signing up for the first time, you can tell the app if you have a goal to be healthier, lose weight, or get stronger). These reports are pretty revealing: my goal is to get healthier, and after my first full-body analysis, the app told me I should devote 50 percent of my exercise time to strength training, 40 percent to cardio, and 10 percent to stretching.

The Skulpt app also suggested a nutrition plan of 30 percent protein, 45 percent carbs, and 25 percent fats. Currently, the app only integrates with Apple Health (and that's only if you give it your permission). But Dr. Bohorquez told me that down the line there could be room for integration with workout and health apps like MyFitnessPal. That would make sticking to Skulpt's nutrition routine much easier since all your tracked food information could be shared via MyFitnessPal.

In order to get updated personalized reports, you have to measure your muscles at least three times a week. On average, it took me 15 to 20 minutes to complete a full body measurement, which isn't bad once or twice a week. More than three times is a bit much—especially when I wasn't seeing much difference in my muscles from day to day. I also didn't get new reports after completing a full-body measurement three times. The reports seem to generate randomly, possibly when there's enough change in your physiology for the app to recommend a change. But after getting the first few insights, I wanted more advice more frequently.

A meter for progress

Instead of tracking steps, runs, or heart rate, the Skulpt Chisel attempts to do what other fitness trackers only do as an afterthought: analyze progress. Many trackers offer tidbits of advice on how to get better and achieve your goals fast, but the Chisel can almost follow you along the way, providing an immediate assessment of how far you've come while also suggesting ways to improve.

It's hard to judge the accuracy of the Chisel, since there are no other consumer devices available now that specialize in EIM. However, you can do things to make sure the Chisel easily measures muscles accurately: spray the electrodes with enough water to activate them, and, most importantly, place the device properly on your body for each muscle. I can say that the muscles I work most frequently at the gym (biceps, triceps, glutes, and quads) consistently showed higher muscle quality when measured by Chisel than other muscles in my body, which makes me more confident about its accuracy.

The electrical impedance myography used in the Chisel is indicative of what we could see if more medical devices become consumerized.That's an exciting prospect for fitness technology and health tech in general. While I do wish the Chisel's personalized fitness and nutrition advice wasn't so limited right now, Skulpt has plans for the device to tailor its advice to each user's unique physiology. Overall, the $99 Chisel is a promising and unique product. The fitness tracker market is saturated with devices that do mostly the same thing. Skulpt's Chisel isn't trying to be one of those devices, and it's not trying to render them obsolete either—rather, it complements them. And it could complement your workout routine even if you don't use another fitness device already.

The Good

Quickly measures muscle quality and fat percentage on each muscle region.

Compact size makes it easy to take anywhere.

Rechargeable battery lasts a long time; it's enough for four full-body scans and more.

The Bad

Takes a while to complete a full-body assessment.

Currently the personalized fitness and nutrition reports are limited and delivered sparsely.

The Ugly

The ugly truth comes out when you think all those squats have been paying off... but realize they haven't.

Listing image by Valentina Palladino