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Frequently Asked Questions

How does OpenSet compare to other workout formats?​

OpenSet is a prescription format: it describes what should be done (exercises, sets, intensity, rest) in a sport-agnostic, machine-readable way. It is not a logging format (no GPS tracks or sensor streams) and not tied to a single app or device.

Other formats often target one sport or one ecosystem. The table below summarizes how OpenSet relates to the most common ones.

FormatBest forHow OpenSet compares
Zwift (ZWO)Indoor cycling/running in ZwiftOpenSet can express the same workout (blocks → segments, series/sets → power/duration). Use power with unit %FTP for portable cycling workouts. Conversion is a tooling concern; see Interoperability.
ERG / MRCSmart trainers (time + power)Same prescription intent: duration, power (W or %FTP), rest. OpenSet models it as sets with duration, power, rest_after. ERG/MRC are time-series; OpenSet is set-based and semantic.
FHIR Physical ActivityHealthcare, referrals, goalsFHIR focuses on high-level plans (e.g. 150 min/week). OpenSet describes the actual workout structure. They are complementary: a CarePlan can reference or embed OpenSet for the detailed prescription.
Structured Workout Format (SWF)Cross-platform JSONSimilar ideas (sections, intervals, volume + intensity). OpenSet adds execution modes, exercise libraries, and multi-sport support. Conversion between the two is straightforward.
TCX / FITGarmin, devices, recordingPrimarily for recording and device targets. OpenSet is prescription-first; you can export from OpenSet to FIT/TCX for use on devices.

For a short interoperability note and links, see Interoperability and related formats in the spec overview.

What about Zwift (ZWO) workouts specifically?​

ZWO is Zwift’s XML format. A ZWO file has a single <workout> with ordered segments: <Warmup>, <Cooldown>, <SteadyState>, <IntervalsT>, <Ramp>, <FreeRide>, etc. Power is usually given as a fraction of FTP (e.g. 0.65 = 65% FTP), or in absolute watts when <ftpOverride> is set.

In OpenSet:

  • Segments → Use blocks (e.g. “Warm-up”, “Main”, “Cool-down”) and series with the right execution mode (e.g. INTERVAL for on/off intervals).
  • Power → Use the power dimension with unit: "W" for absolute watts or unit: "%FTP" for relative (same idea as ZWO/MRC). See Dimensions — Power.
  • Duration → Use duration (OpenSet uses seconds in the schema; you can use min in the unit string where appropriate).
  • In-workout messages → Use the optional x_cue extension for time- or distance-based cues.

OpenSet does not define Zwift-specific features (e.g. camera events, game UI). Those stay in ZWO or app logic. If you need to convert ZWO ↔ OpenSet, that’s done by tools (e.g. in tools/convert); the spec encourages such converters but doesn’t mandate them.

Can I use OpenSet for cycling only? Running only?​

Yes. OpenSet is sport-agnostic. You can:

  • Put "sports": ["cycling"] or "sports": ["running"] (or both) on a workout or program.
  • Use only the dimensions you need: e.g. power, duration, cadence for indoor cycling; pace, distance, duration for running.
  • Use power with %FTP for portable cycling workouts, or pace / speed for running.

The same document structure (workout → blocks → series → exercises → sets) applies to any sport.

Where do I get exercise definitions?​

OpenSet ships a default exercise library (openset-default) with 50 broadly recognized exercises. Workouts can reference exercises by exercise_id from that library or from custom libraries. For ad-hoc exercises you can use freeform name instead of exercise_id. See Exercise library and Workout library.

How do I convert free text or another format to OpenSet?​

  • Free text → OpenSet: Use the Conversion tool (LLM-based prompt) to turn a written workout description into valid OpenSet JSON.
  • Other formats (ZWO, ERG, MRC, SWF, etc.): Conversion is not part of the core spec. Implementations and tools (e.g. in the repo’s tools/convert or third-party apps) can implement import/export. The spec’s interoperability section describes how OpenSet maps to these formats conceptually.