That applies to most wearables unfortunately. I was thinking on buying a moderately priced smartwatch to track my BPM during exercise but correlation can be as

That applies to most wearables unfortunately. I was thinking on buying a moderately priced smartwatch to track my BPM during exercise but correlation can be as slow on 0.3 on some devices and with delay and never accurately reporting peaks and valleys due to aggressive exponential smoothing. Just bought a cheap ANT+ chest strap instead, does the job without requiring an app.