The Best App to Track Muscle Groups Depends on How It Counts

Hevy, StrengthLog, Fitbod and Adonae all colour in a body map after a workout, but they count assisting muscles, old sessions and weekly targets differently. What each one does, where each falls short, and a one-session test for any app.

16 October 2026 · 9 min read

The best app to track muscle groups is the one whose counting you can check, because every app that shows a body map is answering a slightly different question and most of them do not say how they got there. Hevy, StrengthLog, Fitbod and Adonae all colour in muscles after you log a workout. They disagree about what a bench press did for your triceps, whether last Monday still counts, and who decides how much is enough. Those three choices decide what the picture tells you, so this post compares the apps on exactly those, Adonae included, with the places it loses.

What Does "Tracking Muscle Groups" Actually Mean?

Underneath the coloured diagram, an app is doing one of two jobs.

The first is a tally: how many sets each muscle got this week. That is the number the research on training volume is written in, which is why it is worth having. A review of fifteen studies grouped people by weekly sets per muscle (under five, five to nine, and ten or more) and found gains in muscle size rising with the number of sets (Schoenfeld and colleagues, Journal of Sports Sciences, 2017).

The second job is a freshness reading: how recovered each muscle probably is right now. That is a different question with a different shape. A tally only goes up during the week; a freshness reading drops after a session and climbs back over the following days.

Neither is wrong. They just answer different things, and an app built for one will feel odd if you wanted the other.

The Bench Press Test: What Happens to the Triceps?

Here is the choice that matters most, and the one app pages rarely mention. A bench press is a chest exercise, but the triceps and the front of the shoulders do real work in it. So when you log four sets of bench, how many triceps sets is that?

There are three common answers. Zero, because the triceps were not the target. Four, because they moved every rep. Or somewhere in between. The gap is not small: over a week with twelve sets of pressing and no direct arm work, the triceps read as untouched under the first rule and as twelve sets under the second, which is more than the ten that the 2017 review used as its top group.

The largest analysis so far tested this directly. A 2025 meta-analysis of 67 studies and 2,058 people counted each assisting set three ways, as a whole set, as half a set and as nothing, and half a set fitted the results best (Pelland and colleagues, Sports Medicine, 2025). Its authors concluded that separating direct sets from assisting ones appears essential for predicting what a program will do.

So an app that counts assisting sets as whole sets will flatter your arms and shoulders. One that counts them as nothing will nag you about muscles that are getting real work. Most apps do not publish which they chose. That is the first thing worth finding out before you trust a body map, and the test at the end of this post takes one session.

Hevy: Set Counts on a Body Diagram

Hevy is a workout log for iPhone and Android with a large exercise library and a social feed. For muscles, it shows a body diagram of what you trained in the last seven days, and a body distribution view that reports volume per muscle group as total sets for the current calendar week, according to its own feature pages. There is also a monthly report that breaks volume down by muscle.

The fuller muscle charts, including set counts per muscle group over longer ranges, are part of its paid Pro tier at the time of writing; the free tier keeps the seven-day view. Hevy's pages do not say how an assisting muscle is credited, and they do not describe a weekly target you are measured against. What you get is a clear count of what you did, which you then judge yourself.

That suits somebody who already knows roughly what a week should hold and wants the numbers in front of them.

StrengthLog: A Body Map With a Target You Set

StrengthLog, also on iPhone and Android, has a muscle map that turns each muscle a deeper red as its weekly set count rises, going fully red at ten sets a week by default. You can change that goal, for every muscle at once or for each one separately, according to its help pages. The map is a premium feature.

The adjustable target is the thing StrengthLog does best here. If your calves need fewer sets than your quads to hold where they are, you can say so, and the map stops shouting about them. Its help pages do not say how assisting muscles are counted.

Fitbod: Recovery, Not Volume

Fitbod answers the second question. After each workout it estimates how much every muscle group was worked from your sets, reps and load, then shows a recovery percentage per muscle on a heat map, and uses those numbers to build your next session around the fresher muscles. It can also read sessions from Apple Health, Health Connect, Fitbit and Strava so outside activity moves the map.

Fitbod does not publish the formula behind the percentages. That is a reasonable product decision for an app that writes your workouts for you, but it means you are trusting the number rather than checking it. Fitbod is a paid subscription after a short trial. If you want an app to decide what you lift today, it is the strongest option on this list for that job.

Adonae: Working Sets Against a Target, With Its Workings

Adonae counts working sets per muscle, across thirteen muscles shown as six areas, and fills each muscle's bar against a weekly target set by your training goal and what you are eating for. Warm-ups never count. Its muscle shares are written out exercise by exercise in its muscle balance view: a bench press is a full chest set plus a fifth of a set each for the front shoulders and triceps; a row is a full back set plus a fifth each for the traps, rear shoulders and biceps.

A fifth is deliberately less than the half that fitted the 2025 meta-analysis. At half, a chest and back day put a full extra set on the arms every two exercises, so somebody who had not done a curl in a fortnight watched their arms fill up on pressing alone. Whether a fifth is the right trade is arguable, and it is stated openly so you can argue with it.

Two other rules shape the bar. Each muscle is capped at its own target before its area is added up, so nine sets for the lats and nothing for the traps reads as half a back week rather than a full one. And a set counts in full for four days, then fades to nothing by day ten, so the bar drops on the days you would be training that muscle again. Tap an area and it lists every set that fed it, with how much of each still counts.

Where it loses: you cannot set your own per-muscle target the way StrengthLog allows. There is no iPhone app, only Android and a web app that runs in any browser. And exercises you add yourself are matched to muscles from their name, which is cruder than the written-out library.

Side by Side

"Not stated" means the app's own help and feature pages do not say, not that the app gets it wrong. Features and tiers change, so treat this as a snapshot of October 2026.

How to Test Any App's Muscle Count in One Session

You do not need to take anyone's word for how an app counts, this post's included.

Start a fresh week, or a test profile if the app allows it, and log three sets of bench press and nothing else. Then open the muscle view and read the triceps. Three means assisting sets count in full. One and a half means half. Zero means only the target muscle is credited. Anything else, such as 0.6, means a smaller share. Repeat with three sets of rows and read the biceps and rear shoulders.

Then check the clock. Look at the same view four days later and again a week later. If nothing has changed, the app keeps a plain weekly tally. If the numbers have dropped, it is modelling freshness or fading old work, and it is worth knowing which.

One session and two check-ins later, you will know more about the app than its listing tells you.

What No Muscle Map Can Tell You

A set count is a measure of what you did, not of what changed. Two people can log identical weeks and get different results, and nothing on a body map knows which one you are. The research above describes averages across groups of mostly young men, and its own authors found returns shrinking as sets go up, more sharply for strength than for size.

The other limit is the exercise list. Every app here maps the exercises it knows about. Log something unusual, or name an exercise yourself, and the muscle credit is a guess at best. If your training leans on a lot of custom movements, check how each app handles them before you rely on the map.

For the by-hand version of all this, the piece on how to tell if a workout split is balanced walks through counting a week on paper, and how many sets a week a muscle needs covers what the target numbers are built from.

Which One Fits

Fitbod is built for somebody who wants the app to choose today's exercises. For clean set counts you will judge yourself, Hevy does it well, and its free tier covers the last seven days. And if you already know your own per-muscle targets, StrengthLog is the only muscle group tracker app here that lets you set them muscle by muscle.

If what you want is a tracker that reads the log back to you rather than filing it, with the counting rules written down so you can check them, that is what Adonae is for, and its workout tracker works before you create an account. If you want a written plan to follow, it is the wrong app and one of the others above will suit you better. Get it for Android.