🏋️ Workout × Garmin Set-Level HR

Merge Lyfta or Strong workout set data with Garmin activity heart-rate data to get set-level physiological insights—including per-set HR curves, averages, peaks, a full workout timeline, cross-exercise comparison, and exercise history across multiple workouts.

This tool is designed for people who track sets/reps/weights in Lyfta or Strong, 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://workout-garmin-data-merger.streamlit.app/

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

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Features

• Upload a Lyfta CSV or Strong CSV and one or more Garmin .fit files
• Automatically:
  • Match Garmin activities to workouts by date
  • Detect active sets from Garmin (ignores rest sets)
  • Reorder sets correctly when supersets are used (Lyfta: via exported superset IDs; Strong: via in-app configuration)
• Workout View tab — per-workout drill-down:
  • Sets table with exercise, weight, reps, avg HR, max HR
  • Download merged data as CSV
  • Per-set HR graphs (one collapsible expander per set)
  • Full workout HR timeline with set regions highlighted and labeled
  • Per-set HR graphs
  • 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 Strong (CSV)

• In the app: Settings → Export Strong Data

Export as CSV.

The app expects the standard Strong CSV format, including:

• Date
• Exercise Name
• Weight
• Reps
• Set Order

Note: Strong does not export superset information. The app provides an optional in-app superset configurator — assign the same integer group to exercises that were performed as a superset, and the app will reorder sets accordingly before matching with Garmin.

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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 workout on the same calendar date from the uploaded CSV
3. Workout sets are:
   • Kept sequential by default
   • Reordered for supersets using round-robin interleaving
4. Garmin active sets are matched 1-to-1 with workout sets in order
5. HR data is sliced per set window and analyzed

Note: The number of sets recorded in your workout app and in Garmin for a given workout should match.

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Tabs

Workout View

Select a Garmin activity from the dropdown. The page shows:

• Full sets table with HR metrics
• CSV export button
• Per-set expandable HR graphs
• Full workout HR timeline
• Cross-exercise summary table and bar charts for the selected workout

Exercise History

Select any exercise that appears across your uploaded workouts. The page shows:

• A table of every set logged for that exercise with HR and estimated 1RM
• Avg HR over time (line chart, one point per workout day)
• Estimated 1RM over time (line chart, best Epley 1RM per day)

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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 a consolidated list of all .fit files from your activities. A bulk download script may be added in the future.
• Only heart rate data from Garmin is used
• Assumes one workout per day per CSV source

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Future Ideas

• Support Garmin bulk ZIP exports
• Add HR zone analysis per set (time spent in each zone per set)
• Interactive plots (Plotly)
• Implement set auto-detect based on HR peaks so you don't need to manually start/stop sets on the watch
• Hevy and other workout app integration

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License

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