I’m on my second replacement Rival, thinking it was a hardware issue.
Half of my workout for strength training, the HR is super low or N/A. I’ve tried multiple positions on the wrist, varied levels of tightness of the strap, cleaning the sensor, nothing. Same thing on the replacement.
I tried the stair climber and about ten times in a ten minute session, HR was N/A.
@dannyg. This link provides a good overview of the issues with wrist based measurement. As I noted in my earlier post it also varies person to person which is why I recomend using a chest HRM paired to the watch.
Anyway – the reason I like armband optical HR sensors such as the three compared here – is that they tend to be very accurate. That’s primarily because it’s an incredibly good place to measure your heart rate. Unlike your wrist, there’s usually a bit more ‘flab’ and ‘chunk’ for really good quality readings. Additionally, your upper arm tends to absorb the vibrations that your wrists don’t in certain applications, like riding. Further, for indoor hand-driven workouts (like weights), again, your wrist being strained also can produce issues with optical HR sensors like those in a watch. But upper arm? Very rarely an issue here, even when under strain in the gym.