About TRN

What is TRN?

TRN (Training Notation) is an open format for workout programs. Like Markdown for text or JSON for data, TRN provides a universal way to describe workouts that anyone can read, write, and share.

Why Open Format?

Most fitness apps are walled gardens. Your workouts are locked in their database, sharing means screenshots, and switching apps means losing your history.

TRN changes that. Workouts are simple text files (.trn) that you can:

• Write in any text editor
• Share via email, Reddit, Discord, anywhere
• Import into any compatible app
• Version control with Git
• Convert with AI tools

Our Vision

We believe workouts should be portable, shareable, and free from vendor lock-in. TRN becomes the standard format for workout interchange, enabling:

• Trainers sharing programs with clients
• Influencers distributing workout plans
• Communities building workout libraries
• Developers building compatible tools
• Power users scripting their training

The Name

TRN = Training Notation

But also: trn is Czech for "thorn" — symbolizing growth through challenge.