HybridX Logo

Treadmill FIT & TCX Generator

Your watch lost the plot on the treadmill. Rebuild the session it should have recorded — define the intervals, paces and inclines you actually ran, keep your real heart rate, and export a FIT or TCX file that Garmin Connect and Strava read as a real running activity, splits and all.

Start from
Describe it, let AI build itPowered by Gemini

AI drafts the segments below into the normal editable builder — nothing exports until you review it.

Workout structure

Nothing here yet. Pick a starting point above, or add your first segment.

Session profile
Time
0:00
Distance
0 km
Avg pace
–
Climb
0 m

FIT imports into Garmin Connect as Treadmill Runningautomatically and is the most reliable format. Use TCX only for platforms that can't read FIT.

Add at least one segment

Keep your heart rate(optional)
Session details

FIT exports are tagged as treadmill running natively. For TCX, Garmin infers indoor vs outdoor from whether GPS points are present — this choice controls both.

The builder and file export run entirely in your browser — your workout and any attached file never leave this page (the AI “describe it” box is the one exception: that text is sent to Gemini to generate segments). Your draft is autosaved locally.

Now turn that number into a plan

Get a free, personalised 12-week Hyrox training plan built around your race date and ability level.

Get My Free Hyrox Plan

Why Treadmill Runs Get Mangled

Indoors, your watch has no GPS to lean on, so it estimates pace and distance from wrist movement. For steady jogging that's often close enough — but interval sessions break the model. Rapid changes between sprint and recovery paces, holding the handrail, or a treadmill calibrated differently from your watch can leave you with a recorded 6 km when the belt clearly read 10 km. This tool lets you rebuild the session from what the treadmill console actually showed, so your training log, weekly mileage, and pace trends stay honest.

How to Use the Generator

  1. Pick a starting template — time intervals, distance intervals, steady state — build from blank, or describe the session in plain English and let AI draft it (e.g. “40 min progressive incline, raise 1% every 5 min from 2% to 8%, then back down, steady RPE 6”). Add your easy-pace number alongside the description so effort language like RPE gets grounded to a real pace.
  2. Set each segment's duration or distance, pace, and treadmill incline. Use repeat blocks for interval sets.
  3. Optionally attach the GPX or TCX file your watch recorded: the heart rate and cadence stream is lifted out and re-timed onto the rebuilt session, while its wrong pace and distance are discarded.
  4. Check the effort profile and lap splits, set the session name and start time, then export — FIT is recommended, since it imports as Treadmill Runningautomatically; TCX is there for platforms that can't read FIT.
  5. Upload the file in Garmin Connect via Import Data(top-right cloud icon), or directly to Strava. Each segment appears as its own lap. On a phone, use connect.garmin.com in the browser — the Garmin Connect app itself doesn't support file imports.

Frequently Asked Questions

Will Garmin Connect accept the file?

Yes — the FIT export is built with Garmin's own FIT SDK and carries laps, trackpoints, speed, elevation, optional heart rate, and a native treadmill-running activity type. The TCX alternative is the standard Training Center XML format Garmin devices have exported for years. Note that manually imported activities don't count toward Garmin badges or challenges, and won't update device-computed metrics like VO2max.

Should I export FIT or TCX?

FIT, unless you have a reason not to. It's Garmin's native binary format: smaller, tagged as Treadmill Running automatically (TCX can't express a treadmill type at all), and treated as first-class by Strava, TrainingPeaks and most other platforms. Choose TCX only for older tools that can't read FIT.

Should I delete the original activity?

If your watch already synced the mangled version, delete it before or after importing the rebuilt one, otherwise your weekly totals will double-count the session.

Is my data uploaded anywhere?

The workout builder, watch-file parsing, and FIT/TCX generation all run entirely in your browser — your attached watch file and finished workout never leave your device. The one exception is the optional “Describe it, let AI build it” box: the text you type there (and the reference pace, if you add one) is sent to Google's Gemini model to turn into segments. Skip that box and build manually or from a template if you'd rather nothing leaves your browser.

How accurate is the AI-generated workout?

It's a starting draft, not a final answer — it lands in the same editable builder as every other segment, so nothing exports without you seeing it first. Ambiguous instructions (like an incline ramp that doesn't divide evenly into the stated duration, or effort language with no reference pace attached) get resolved with a reasonable assumption, which is listed under the generate button so you can check and adjust it before exporting.

How is incline handled?

Each segment's incline drives the elevation written to every trackpoint, so a hill session shows real climb in Garmin Connect and Strava. Total ascent appears in the session profile as you build.