What is .trn?

A simple file format for workout programs. Like MP3 for music, but for your training.

Why does this matter to you?

Your program isn't locked in. Export it anytime. Move to a different app. Share with friends. It's just a text file.

Anyone can create programs. Coaches, influencers, AI tools, or you. No special software needed.

It's human-readable. Open the file in any text editor and see exactly what's in your program. No mystery.

What does it look like?

THE FILE:

push-day.trn

program: Push Day
author: @trainer_mike

exercises:
  - name: Bench Press
    sets: 4
    reps: 8-10
    rest: 90s

  - name: Overhead Press
    sets: 3
    reps: 10-12
    rest: 60s

  - name: Tricep Dips
    sets: 3
    reps: 12-15

WHAT YOU SEE IN THE APP:

Push Day

by @trainer_mike

Bench Press4 × 8-10

Overhead Press3 × 10-12

Tricep Dips3 × 12-15

How do I get .trn programs?

Download

Get programs from the TRN library, Reddit, or friends who share their files.

Ask AI

Tell ChatGPT your goals and ask for a .trn file. It understands the format.

Create

Write your own in any text editor, or modify existing programs.

Using AI to create programs

Share the format specification with ChatGPT, Claude, or any AI and describe what you want:

EXAMPLE PROMPT:

“Create a 4-day upper/lower split for hypertrophy. I have access to barbells, dumbbells, and cables. Output as a .trn file using the format from trn.fitness/format/spec”

View full specification →

Complete technical reference for AI and developers.

Open format, open future

The .trn format is open source under MIT license. Anyone can build apps that read and write .trn files. Your data is never locked into one app.

Read the specification →

Ready to try it?

Download the TRN app and import your first program.

Join the waitlist