Sense heart rate inaccurate during workout

[BugOperator]

Had the sense for about three weeks now. Worked fine the first week, now the heart rate is never correct when I work out. I’m measuring 150-170 on the machines I use, but the Fitbit never registers above 90. I clean the back of the device and my wrist area before I go into the gym AND while I’m working out on the bike or elliptical or rowing machine. I change the position on my arm. I change arms altogether. I even do a hard reset mid-workout. No change. Still registers at LEAST 50 bpm below my actual heart rate. And, naturally, this results in my workout always being 100% below zones despite busting my **ahem**. It’s incredibly frustrating and kind of demoralizing. I know never to expect it to be 100% accurate, but for the price, it should not be this inaccurate this often. Is my device defective or is this the norm?

[sawilliams]

I only use weights at the gym. I find that during squats it is usually really under, like 90 bpm when squatting 150+ lbs (my resting is 65), it should be 135-155, it  will jump up a few seconds after the set. This is probably 70% of the time, but, I've also started adding pullups between my squat sets and it's definitely accurate during a full superset. I sometimes will notice during pushups it goes down but as soon as I'm done, it peaks to approximately what I expect. It has to do with however my wrist is placed or bent, I found squatting on a Smith machine without holding the bar and letting my arm hang it read well (not that I'm going to do that regularly). (However, pullups and chinups end up counting towards my steps ...)