Quote Originally Posted by OakLeaf View Post
I believe that the 310xt cannot give HR alerts unless you program a workout (which can be a very simple workout that says nothing but "maintain HR between X bpm and Y bpm). I'm not sure about this, since I use HR during the workout only when it's a multi-step workout I've programmed, but I seem to recall complaints about this on the Garmin forums.
The 310xt owner's manual says that in training mode it can notify you when your HR exceeds or drops below a specific number of beats per minute. I don't think you need to program a workout but I've never used this feature so I can't be sure.

btw, you can download all the owner's manuals from the Garmin website.