🏋️‍♂️ Lyfta × Garmin Data Merger and Visualization Tool

Merge Lyfta workout set data with Garmin activity heart-rate data to get set-level physiological insights—including per-set HR curves, averages, peaks, and a full workout timeline.

This tool is designed for people who track sets/reps/weights in Lyfta, track heart rate & activity data using Garmin and want per-set heart-rate analysis.

Set-wise heart rate data can be used to track peak heart rate for each set and analyze how heart rate response changes across successive sets. Faster or higher HR spikes for the same exercise and load can indicate accumulating systemic fatigue or insufficient recovery between sets. By examining heart rate recovery during rest intervals, this data can help determine whether rest periods are adequate and identify the optimal rest duration needed to sustain performance.

Additionally, trends in set-wise heart rate over multiple workouts can be used to assess conditioning and recovery status. Lower heart rate responses for the same workload may indicate improved cardiovascular efficiency, and elevated responses may signal under-recovery or excessive training load.

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Live Demo (Hosted)

You can use the app directly here hosted using Streamlit Community Cloud (no setup required):

https://lyfta-garmin-data-merger.streamlit.app/

The demo also includes sample data so you can explore the UI without uploading anything.

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Features

• Upload Lyfta CSV and one or more Garmin .fit files
• Automatically:
  • Match Garmin activities to Lyfta workouts by date
  • Detect active sets from Garmin (ignores rest sets)
  • Reorder Lyfta sets correctly when supersets are used
• View:
  • Full workout HR timeline with set regions highlighted and labeled
  • Per-set HR graphs (one graph per exercise set)
  • Per-set metrics:
    • Exercise name
    • Weight × reps
    • Average HR
    • Max HR
    • Sample count
• Supports multiple Garmin activities → select a workout and drill down

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Exporting Your Data

🔹 Export from Lyfta (CSV)

• In the app:
  Profile → Settings → Export Data
• Or directly visit:
  https://my.lyfta.app/settings/export-data

Export the data as CSV.

The app expects the standard Lyfta CSV format, including:

• Date
• Exercise
• Weight
• Reps
• Superset id (optional)

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🔹 Export from Garmin (.fit)

Garmin activities must be exported per activity as .fit files.

Steps:

1. Go to:
   https://connect.garmin.com/modern/activities
2. Open the activity you want
3. Click the ⚙️ settings icon (top-right)
4. Select Export File
5. Upload the downloaded .fit file

ℹ️ Bulk Garmin exports (via Garmin’s “Export Your Data”) do not reliably include all .fit activity files.
For now, the app supports:

• Single .fit uploads
• Or .zip files containing exactly one .fit

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How the Matching Works

1. Garmin activity date is extracted from the .fit file
2. The app selects the Lyfta workout on the same calendar date
3. Lyfta sets are:
   • Kept sequential by default
   • Reordered for supersets using round-robin
4. Garmin active sets are matched 1-to-1 with Lyfta sets
5. HR data is sliced per set window and analyzed

Note: The number of sets recorded in Lyfta and Garmin for that workout should be the same.

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Visualizations

1. Full Workout Timeline

• Continuous heart-rate curve
• Each set shown as a shaded region
• Exercise names labeled under the curve

2. Per-Set Drill-Down

For each set:

• Exercise name
• Load (weight × reps)
• Avg HR / Max HR
• Individual HR graph for that set only

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Current Limitations

• Garmin .fit files must be uploaded one activity at a time. The "Export All Data" feature that garmin provides does not give you a consolidated list of all .fit files from your activities from what I've seen. I may write a script to automatically download all .fit files from your garmin connect dashboard in the future.
• Only heart rate and numeric Garmin record fields are visualized
• Assumes one Lyfta workout per day

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Future Ideas

• Support Garmin bulk ZIP exports
• Add HR zone analysis per set
• Compare same exercise across workouts
• Export merged data as CSV / JSON
• Interactive plots (Plotly)
• Strength-specific effort metrics
• Implement set auto-detect based on heartrate peaks so that you don't need to constantly stop and start new sets on the watch while working out
• Integrate with the other major workout platforms such as Hevy and Strong and incorporate their export structures

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License

MIT License — feel free to fork, modify, and build on top of this.

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