Apple Watch HR Monitor vs BT Chest Strap Monitor Strength Training Workout
I have an Apple Watch Series 2 with watchOS 4.0.1. The Apple Watch heart rate monitor usually does a pretty good job of measuring heart rate except during active strength training sessions with wrist/arm movements. I will be pushing myself and look down and the AW either shows it's trying to get a HR measurement or the measure it shows is like 85bpm - about half my actual heart rate. I'm not sure what causes this as my arm doesn't get especially sweaty but it may have to do with my wrists when I lift the weights. The problem is after an intense session where I have worked my tail off, it's disappointing to check the stats, and it shows that the average heart rate is way below what I know it was and a low Active Calories.
To try to get around this, I purchased a Polar H10 Bluetooth Chest Strap to get more accurate readings, and it works well. Once connected to my AW there is no delay and heart rate readings are a lot more consistent. I can tell it's getting the reading from the chest strap because if I lift up the watch slightly, there's no green light from the HR sensor. With watchOS4 I have noticed a problem. If I start a Workout doing cardio on the treadmill or elliptical things go well until I add Strength Training. When I do this, the wrist heart rate monitor activates, and I am back to the same problems with flaky, inaccurate measurements when doing specific movements. I've checked in Watch Settings and the chest strap is still connected via Bluetooth but the green light under the watch is still on, indicating it's also trying to measure with the AW sensor.
Am I wrong in believing that if the chest strap heart rate monitor is connected that the internal heart rate monitor should NOT activate? Anyone else seeing this behaviour?
Apple Watch Series 2, watchOS 4.0.1
