Efficiency Factor (EF) Field surfaces your EF (power divided by heart rate) live during a run, instead of only after the fact from a Garmin Connect export. A rising or falling EF trend is one of the earliest readable signals of fatigue or overreaching. This field smooths it with a rolling average, colour-codes it against your own personal band (green in band, amber as an early warning near the edge, red once you're sustained below it), and gives a single vibration alert if you stay below band for longer than you've set, so you don't have to keep checking the screen. Features: • Rolling-average smoothing with a configurable window (default 30s) • Fully user-configurable band edges — set your own low/high EF thresholds • One-shot vibration alert on sustained fatigue, with a configurable trigger time • Handles sensor dropouts gracefully, holds the last valid reading rather than flashing zero • Exports the smoothed EF to your FIT file for post-run analysis Built for ultra and endurance runners who want an early, glanceable fatigue signal on-wrist, not just in the post-run report. My Garmin apps are 100% free and always will be. Fuel my next line of code with a coffee here: buymeacoffee.com/0094994 New device support policy: New Garmin device releases are assessed for compatibility within 1 month of launch, with support added as soon as the SDK allows.

v1.0.1- Fixed a display issue where the "EF" label could overlap the value when this field was placed in a smaller multi-field data screen (e.g. 5+ field layouts). The label and value now scale and stack cleanly at every field size, from full-screen down to the smallest grid cell.