Heart rate with photo skiing from Peak 8 at Breckenridge to base - thought it would be higher!

[DownhillRacer]

[t.parker]

Without verifying it against a chest strap you won't know. Even assuming the HR readings are correct, you'll find plenty of sports for which HR is lower despite higher RPE (cycling is one of examples). That's why some watch manufacturers allow defining HR zones per sport.

[DownhillRacer]

Thanks that's helpful.  Peak 8 starts at 12,900 feet and I couldn't catch my breath most of the way down, thought I'd be 160 or higher most of the run. 

[t.parker]

Not being able to catch breath isn't an indication of increased heart rate. That's why I gave cycling as an example. Comparing cycling and running it's common that with samen level of effort the heart rate of cyclist will be lower. It gets even more lower for swimmer. So nothing uncommon. Yet, when it comes to Fitbit I usually question HR accuracy (my experience) but without reference data one can't tell (I always have 2-3 sources of readings during endurance activities). It may be both - bad HR and type of sport.