Apple watch heart rate monitoring during activity

Can the apple watch monitor and notify of a heart rate threshold during activity not just notify after 10 min of inactivity?

if you go to the apple watch app --> heart rate --> You can set the alert once the heart rate threshold reaches your set limit; however, this is only for 10 min of inactivity. I have several people in my gym in which they need to stay under a certain heart rate during their workouts. It would be very convenient if they didn't have to keep checking their watch every few minutes during their workout and the watch would just notify them when that threshold was reached.