Brighter means more mapped work.
In Body Map, brighter areas received more training from the lifts and working sets in the selected window.
Learn: Muscle Heat Maps
What the Colors Mean
What data do muscle heat maps actually show?
A muscle heat map shows mapped training work by muscle group over a chosen time window.
It can help you see what your workouts covered, but it should not be confused with soreness, recovery, pain, or confirmed muscle growth.
Inputs
The map starts with the lifts you log.
In Via Fortis, muscle coverage starts with your workout history: the lifts you selected, the working sets you logged, and the time window you are reviewing.
Each exercise is mapped to primary and supporting muscles. A targeted lift may light up one area more directly. A compound lift may contribute across several areas at once.
Dimmer means review the pattern.
A quiet area does not automatically mean a problem. It means that muscle received less mapped work in that window and may be worth reviewing.
Logged Work
Exercise mappings create the coverage.
The app uses the exercise you logged and its muscle mapping to estimate which areas were trained directly or supported by the movement.
Time Window
The same lifter can see a different story over 7 days, 14 days, 1 month, or 3 months.
Short windows show recent training. Longer windows help reveal whether a missed area is a one-off or a recurring pattern.
Interpretation
Coverage is context, not a command.
The map gives you a clearer view of the work. You still decide whether the pattern fits your goals.
What It Does Not Show
A heat map is not a recovery score.
Muscle coverage does not claim to measure soreness, readiness, fatigue, injury risk, or whether a muscle grew. It shows how your logged work mapped across muscle groups.
That makes it useful as a review layer: a way to see the shape of your training before deciding what to keep, add, or adjust.
FAQ
Muscle heat map data questions, answered plainly.
What data does a muscle heat map use?
It uses logged exercises, working sets, exercise-to-muscle mappings, and the selected time window.
Does a heat map know how sore I am?
No. It shows mapped training coverage. It does not measure soreness, pain, recovery, or readiness.
Why do some compound lifts affect many muscles?
Large movements usually involve primary movers and supporting muscles. A good heat map should reflect that instead of treating every exercise as if it only trained one area.
Turn your log into clearer coverage.
Download Via Fortis on iPhone, or try the free audit first to preview muscle coverage from a two-week snapshot.