I’ve used my Vivoactive 4 everyday for over three years…a nice feature is the ability to download music directly to the watch, so you can use wireless buds to listen to your favorite music, while exercising, without carrying your phone.

The Vivoactive 5 has a nice OLED display upgrade and is available on Amazon for under $200.

If you want to read about the ERASE trial, regarding HIIT exercise in a randomized clinical trial with men with localized PCa, here’s the link;
https://jamanetwork.com/journals/jamaoncology/fullarticle/2783273
ERASE was a relatively small study; but, as they say, “good things often come in small packages” 😉

I’m more than willing to share my latest running protocol and some of my more detailed research, if you send a DM…it’s probably more than what many may want to see on this thread.

All the best!