BodyAtlas
A muscle atlas, on iPhone

See where you’re cooked.Train where you’re fresh.

BodyAtlas is a fast strength logger fronted by a per-muscle recovery heatmap. Logged sets deposit fatigue; muscles cool on their own half-life. Open the app, glance at the map, decide what to train.

Platform
iPhone
Sync
iCloud
Pricing
Lifetime, under $10
Plate 01 · Front
fig. 1.0
Recovery stateT+18h since last session
Cooked
Fatigued
Mid
Cooled
Fresh
The hero screen

Two views of the same body. One honest snapshot of where you stand.

Swipe between front and back. Every muscle group is tappable for a drill-down: which exercise hit it last, when it’ll be fresh again, projected hours to full recovery.

9:41●●● ●●
Last workout18h ago
Fresh groups7 of 12
Heatmap
Workout
Log
Settings
Front view · post pull day
  • Recovery 0–25%Cooked

    The muscle worked hardest in your last session. Don’t train it today.

  • Recovery 25–50%Recovering

    Still actively repairing. Cardio or accessory work is fine. Heavy compounds, hold off.

  • Recovery 50–75%Mid

    Could push it. Diminishing returns vs. waiting another day.

  • Recovery 75–90%Cooled

    Near baseline. Safe to load.

  • Recovery 90%+Fresh

    Ready to be the focus of today’s session.

What’s in v1

Built for lifters who want the heatmap without the subscription.

  • Per-muscle recovery heatmap

    Front and back anatomical views. Every logged set deposits fatigue weighted per exercise. Muscles cool on their own half-life: large muscles 48–72h, small 24–36h.

  • Two-to-three-tap logger

    Last session's weight and reps pre-fill every new set. Warmup, working, failure flags. 1RM estimate (Epley + Brzycki). PR detection inline.

  • HealthKit, both directions

    Writes every workout to Apple Health as a strength session. Reads your last 30 days of strength and cardio on first launch, so the heatmap is populated day one.

  • PR tracking with history

    Per-exercise history view with set-by-set trend, PR markers, simple trendline. No social leaderboards. No streaks. Just your numbers, sorted.

  • iOS-native through and through

    SwiftUI. SF Symbols. Dynamic Type. VoiceOver. Liquid Glass on the nav layer. Same-user iCloud sync. iPhone and iPad, one purchase.

  • Your data, on your device

    Local SwiftData persistence. Optional iCloud private-database sync. No accounts. No server. No analytics on what you lifted.

The math behind the colors

Honest recovery, modeled.

Every logged set deposits fatigue onto its target muscles, weighted by exercise. Each muscle recovers on an exponential curve with a half-life tuned to its size. The heatmap is just a render of that number.

Fig. 2 · Recovery vs. timer = 1 − e−t / hl
CookedRecoveringMidCooledFresh0h24h48h72h96h0.00.50.91.0
Large muscle · 72h half-lifeSmall muscle · 36h half-life
Fatigue depositexercise.muscles[m] × sets × reps

Each exercise maps to a weighted muscle set. A bench press deposits 1.0 into chest, 0.5 into triceps, 0.4 into front delts. Sets × reps gives the intensity proxy.

Recovery curverecovery = 1 − exp(−hours_since / half_life)

Standard exponential. The half-life is the only knob.

Half-lives, by muscle sizelarge: 48–72h · small: 24–36h

Back, chest, quads, glutes get the longer curve. Biceps, calves, abs, forearms get the shorter one. A muscle reads “fresh” once recovery > 0.9.

Pricing

Lifetime, under ten dollars.No subscription. Ever.

One purchase. No item limits. No category paywalls. No pro tier hiding the heatmap. The hero feature is what you bought; we don’t hold it hostage.

AppPriceModelHeatmap?
BodyAtlasLifetime, under $10One-time
Fitbod$12.99/mo or $79.99/yrSubscriptionBehind sub
Strong$4.99 lifetimeLogger only, no heatmap
Hevy Pro$2.99/mo or $74.99 lifetimeLogger + social, no heatmap

Competitive pricing surveyed against the 2026 strength-app market.

In development

Built for lifters who payonce, not forever.

BodyAtlas is being built now. iPhone only. iOS 18+. Lifetime purchase under ten dollars. Coming to the App Store.