Yes, the Garmin’s first, second and third generation optical heart sensor hardware produces results with lower values than the Chest HRM.
Why is Optical Heart Rate generally lower:
1.) Wrist movement
2.) loose watch fit
3.) poor sensor contact
4.) hair, sweat or dirt will affect the values too
5.) Garmin Software filtering
Why are the high heart rate (Peaks) and low heart rate (valleys) missing:
Garmin Software imposes additional filters (Fast Fourier Transforms, FFT) in Activity types Strength Training, Tennis, Soccer and flexibility, due to high wrist movement in these activities. These FFT filters (advanced math) reduce the recorded peaks and valleys of a heart rate and calories calculations. Calories are based on heart rate, age, weight, gender and time.
There are a few solutions to improve the optical heart rate values:
1.) Wear the watch tighter. Poor sensor contact will result in lower HR values.
2.) Reduce wrist hair under sensor.
3.) Reduce wrist movement when possible, high movement reduces sensor contact.
4.) Chest HRM Gives best results.
Garmin Video explaining the difference between Optical and Chest Heart Rate monitors.
Adds advanced menus at watch screen controls (Lap mode, screen lock, color theme, Pace/Speed select, auto scroll)
Adds touchscreen lock
adds new devices
Corrections when rest screen is activated
Adds lap points on map
Using CIQ SDK 3.1.7.Jan29.
Autolap By Set Detect: Detects short pause in arm movement at pool length for distance calculation. Approximately short 0.5 seconds – 1.0 second watch pause is needed to detect length distance. To complete Set, long watch pause (~4sec), Swim+ app will lap and start Rest Mode.
Autolap By Pool Length Detect: Detects short pause in arm movement. Approximately short 0.5 seconds – 1.0 second watch pause is needed to detect length completion and Lap.