HR Zone Alerts - The Killer App

I love Runkeeper because it does almost everything I need in a running app. The one thing missing though is the thing that would make it perfect: heart rate zone alerts.

Runners should be training in the right zone, staying in the right zone is a real-time exercise, not a once-every-5-minutes thing.

I would like something simple to set a target zone for a workout (default from the previous one), maybe using a circular slider like the iPhone Sleep alarm setting.

Then, if a HR monitor is connected for the activity, a tone for over limit, a tone for under limit, and a nice bell or something when you return within limit. The voice feedback would be a bit ponderous.

Oddly, over ten years ago a simple digital watch offered this functionality. Now, I can get wonderful charts after the event but no real time feedback.

Please make Runkeeper perfect. None of your competitors currently offer this (I've tried). The nearest is Fitiv but they can't do some run-specific things you can.