I wore my garmin 4s to my stress test to check the accuracy. It was very very close to the 11 tabs monitoring my actual heart rate.

I'd watch some of these videos and decide.

https://www.youtube.com/results?search_query=garmin+forerunner+heart+rate+accurate

I have a Garmin Forerunner which measures my heart rate on the wrist. On several runs, I've noticed a sharp increase in heart rate to the point where it matches my cadence? Is that what it's actually tracking?

I know chest strap monitors are more accurate, but I don't know what causes the sudden jump. Anyone else experience this?