Why Your Workout Data Is Trapped (And What To Do About It)

February 5, 2026·5 min read·By Viktor

You've been tracking your workouts for two years. Every bench press PR, every squat session, every random hotel gym workout when traveling. 500+ logged sessions. Your entire lifting history in one app.

Now you want to switch to a different app. Or share your program with a friend. Or just back up your data somewhere safe.

Here's the problem: you can't.

Well, you can screenshot your workouts. Or copy-paste them into a note. Or manually type everything into a spreadsheet. But your actual workout data - the structured information that an app can read and use - is trapped.

Welcome to the walled garden of fitness apps.

The Walled Garden Problem

Every major fitness app operates as a closed ecosystem:

(•́ ᴖ •̀)Strong stores your workouts in Strong's format
(｡•́︿•̀｡)Hevy stores your workouts in Hevy's format
(๑•̀ᗝ•́)૭Fitbod stores your workouts in Fitbod's format

These formats are proprietary. They don't talk to each other. A workout you created in Strong cannot be imported into Hevy. Your three years of lifting history in one app is worthless in another.

(╯'□')╯︵ ┻━┻The current reality is embarrassing

Want to share a program with a friend? Screenshot each workout, send 15 images. Want to switch apps? Start from zero, lose all history. Want to back up your data? Hope the app doesn't shut down.

Compare this to other areas of your digital life:

ദ്ദി(ᵔᗜᵔ)Music: MP3 plays anywhere. Export Spotify playlist, import to Apple Music.
◝(ᵔᵕᵔ)◜Documents: .docx, .pdf work everywhere. Share with anyone.
٩(ˊᗜˋ*)وCode: Git, plain text. Copy, fork, modify freely.
(„• ֊ •„)੭Photos: .jpg works on every device, every platform.

Workouts? You're stuck with whatever app you started with.

What Data Portability Would Actually Look Like

Imagine if fitness worked like music:

Export your full workout history from any app
Import it into any other app instantly
Share a program by sending one file
Fork someone's program and modify it for your needs
Back up your data in a format that will work forever

This isn't a fantasy. It's just a file format problem.

※info

The reason you can play music anywhere is because MP3 became a standard. Before MP3, every music player had its own format. Sound familiar?

Introducing .trn — An Open Format for Workouts

We built TRN (Training Notation) to solve this problem. At its core is a simple idea: What if workouts were just text files?

Here's what a workout looks like in .trn format:

push-day-a.trn

workout: Push Day A
author: Viktor
created: 2026-01-15

exercises:
  - name: Bench Press
    sets: 4
    reps: 8-10
    rest: 90s
    notes: "Pause at bottom"

  - name: Overhead Press
    sets: 3
    reps: 10-12
    rest: 90s

  - name: Incline Dumbbell Press
    sets: 3
    reps: 12-15
    rest: 60s

  - name: Tricep Pushdowns
    sets: 3
    reps: 15-20
    rest: 45s

That's it. Human-readable YAML. You can open it in any text editor. You can understand it without documentation. You can modify it and send it to a friend.

٩(ˊᗜˋ*)وKey properties

Human-readable — You can read and edit it without special software

Machine-readable — Any app can parse it and import the workout

Portable — Send it via email, Discord, AirDrop, whatever

Future-proof — Plain text files will work in 50 years

Open — MIT licensed, free forever, no vendor control

What This Means For You

Your Data, Forever

With TRN, your workout history belongs to you. Not to an app. Not to a company. You can export everything, back it up, and know it will work decades from now.

No Lock-In Anxiety

Trying a new app doesn't mean losing your history. Don't like TRN? Export and leave. We're confident enough in our product to let you go.

Share Programs Easily

Found a great program? Export it as .trn. Send to a friend. They import it in 2 seconds. No screenshots, no retyping.

Fork and Modify

Your buddy's program is almost perfect, but you want to swap one exercise? Fork it, modify it, save as your own version. Like GitHub for workouts.

AI-Friendly

Because .trn is structured text, AI can generate workouts directly:

"Claude, create me a 4-day upper/lower split focused on hypertrophy"

Boom. Valid .trn file you can import immediately.

The Bigger Picture

We're not just building an app. We're building a standard.

Our goal is for .trn to become the MP3 of fitness - an open format that any app can support. We're starting with TRN (the app), but we hope other apps will adopt the format too.

※When that happens

Export from Hevy → Import to TRN → Export from TRN → Import to Strong → Share programs across any platform → Your data is truly free

Join the Movement

TRN is currently in development. The app is free, offline-first, and built for people who care about their data.

ദ്ദി(ᵔᗜᵔ)Unlimited workout tracking (free forever)
◝(ᵔᵕᵔ)◜Import/export .trn files
٩(ˊᗜˋ*)وLocation-aware progress ("What did I lift last time at THIS gym?")
(„• ֊ •„)੭No subscription required for core features

Join the waitlist to get notified when we launch.

Your workout history shouldn't be trapped in someone else's app.

Building TRN solo from Prague. Follow the journey on Instagram.