Time to revisit!
I decided to purchase Apple Watch 5, and, have been cycling and walking with it for about a month. I stated in prior posts that I'm interested in monitoring my heart rate during exercise periods without using my dedicated Polar watch/strap, just to avoid wearing multiple gadgets. Cycling using the Polar gave me a very good baseline for heart rate during exercise periods, I have a pretty good ability to know heart rate from how heavy I am breathing.
When starting to use the Apple 5, I assumed, incorrectly, that the Heart Rate app would be the primary training tool to use. Wrong! It samples the heart rate much too slowly, and, disappears into background quickly. It also takes a too long to measure heart rate when opening it. It's main benefit is storing heart rate data over an extended period of time.
The watch does have exercise apps built-in that offer a wide verity of dedicated workouts, including cycling and outside walking. These apps remain visible for the entire workout period and show active heartrate, the heart rate number is large enough to be readable even for my aging eyes that need reading glasses, not as easy as the Polar watch. Following the workout, all the data, HR, time, distance, avg speed, GPS route map is saved and viewable on an Apple iPhone. It also provides data about how long recovery to normal heart rate takes following exercise period.
Both my experience to-date, and, from YouTube reviews, indicate the watch does a very good job of monitoring heart rate in an acceptable level of accuracy. When cycling, we all learn intuitively what speed to ride at for extended periods, the Apple Watch matches my normal heart ranges from Polar levels. Perhaps most important to me is to know when my rate approaches 10 beats more than normal levels as this can only be sustained for a short period without too much long term fatigue. The watch does a good job of showing return recovery to normal riding heart levels. We all need to push during training rides. I should add that my typical ride is 15-20 miles on very, very flat roads, my enemy is the wind that blows off the ocean in my So. Jersey seaside community.
Another minor benefit of the Apple Watch, is the fitness tracker functions that monitor body activities throughout the day. If I go into "slug" mode, it tells me to get off my ass and get cardio done.
Don't get my review as an indicator that the watch is a good as a dedicated chest band device. If I were going to push into more extended rides, I would add a Bluetooth strap. For my needs, the Apple 5 (and 4 that uses the same optical monitor) does what I need.