I'm in the process of collecting data from a second hr to send to Garmin as proof the optical is shit.
I get varying issues. Here's a couple of examples, I did a 21km run the other week started at 5:20 pace and did descend pace till 3:50s apparently my heart stayed in the 130s the whole time. I'm either a weapon or the hr is wrong.
Last Monday I did hill reps on the bike they were 12 minutes up and about 5 down. My heart rate apparently didn't drop on the descents, it recorded as one solid line with a variance of about 5bpm.
This morning's ride. I wore another hr conmected to a 510 this showed how much my HR varied between surges and hills. The 735 apparently had me at 140ish bpm for 45 minutes then the final 20mins spiked and I held above 170 for the whole time. There's no fkn way I can stay above 170 on the bike for 20minutes.