About IntervalBuilder.io

IntervalBuilder.io turns plain-language workouts into structured, export-ready intervals. Describe your session once, then review and refine outputs in seconds.

IntervalBuilder.io is designed for coaches and self-coached athletes who know that many of the ideas that drive good training are simple, but translating these ideas to modern tech platforms  can be fiddly and time consuming.

After generating a workout, edit in plain text or edit parameters globally. Currently, users can save outputs to a library or sync to their calendar or library on intervals.icu. Future development will support .fit file download and other platforms such as Garmin, Zwift, Wahoo, etc. 

Supported inputs include durations (min/s), repeats (e.g., 4x5), ramps, targets in %FTP/watts/zones, warmup/cooldown, rests, and common on/off microburst patterns. The model is sensitive to the context of your natural language and will attempt to intelligently structure you a work out that is consistent with widely accepted workout archetypes.  See Examples page for sample prompts and expected outputs.

Pre-Alpha Version. Nested sets, mixed workout types (e.g. threshold with sprints) or pyramidal structures (e.g. 3-4-5-4-3 work intervals) will likely be missed or throw an error. Rests and repeats in sprint and anaerobic intervals need also need tightening. Always review the generated structure before exporting. 
Currently only power targets in watts or percentages of FTP are supported. 
As always with AI tools, be sure to sanity-check outputs. 

Output data and user feedback is stored to refine the model and compiler