SmO2 Recovery Analyzer — Muscle Oxygen Analysis from FIT Files
Upload a FIT file with SmO2 data and automatically detect recovery intervals. Measure the time from minimum to maximum muscle oxygen saturation.
Upload FIT File with SmO2 Data
Drag & drop or click to browse. Requires a Moxy, Humon Hex, or Train.Red sensor.
Automatic Recovery Detection
The analyzer automatically finds recovery intervals in your SmO2 data -- periods where muscle oxygen rises from a minimum to a maximum. Adjust sensitivity with the smoothing and delta controls.
Interactive SmO2 Chart
Visualize SmO2, tHb, heart rate, and power over time in a single interactive chart. Hover for exact values at any point during your workout.
Export to CSV
Download your SmO2 time-series and detected recovery intervals as CSV files for further analysis in Excel, Google Sheets, or any data tool.
Frequently Asked Questions
What is SmO2?
SmO2 (muscle oxygen saturation) measures the percentage of hemoglobin in your muscles that is carrying oxygen. It is recorded by near-infrared spectroscopy (NIRS) sensors such as the Moxy Monitor, Humon Hex, or Train.Red devices. SmO2 data helps athletes understand oxygen delivery and utilization during exercise.
What is a recovery interval in SmO2 data?
A recovery interval is the period where SmO2 rises from a local minimum (high oxygen demand) back to a local maximum (oxygen re-saturation). The time it takes for this recovery reflects your body's ability to restore oxygen to the working muscles. Shorter recovery times generally indicate better aerobic fitness.
What FIT files contain SmO2 data?
Only FIT files recorded with a compatible muscle oxygen sensor contain SmO2 data. Common sensors include the Moxy Monitor, Humon Hex, Train.Red, and similar NIRS devices. The sensor must be paired with a compatible Garmin, Wahoo, or other ANT+/Bluetooth head unit that records the data into the FIT file.
How do I adjust the recovery detection settings?
Use the Smoothing Window slider to control noise reduction (higher values produce smoother curves but may miss short events). Use the Min Recovery Delta slider to set the minimum SmO2 change required to count as a recovery interval. Start with defaults and adjust based on your data.
Can I export the analysis results?
Yes. You can download the raw SmO2 time-series data as a CSV file, and separately download the detected recovery intervals with their timestamps, durations, and SmO2 min/max values. Both exports work directly from the results page.
Is my data private?
Completely. All FIT file processing happens in your browser using local JavaScript. Your file is never uploaded to any server. Your workout data and physiological metrics stay on your device at all times.
Your Privacy is Protected
Your FIT files are processed entirely in your browser. No data is ever uploaded to our servers. Your workout data and physiological metrics stay on your device.