Target heart rate during workout.

[qlambert-pro]

When running I would like the app to help me stay within a specific hear rate zone.

It would be ideal, if the app allowed me to set a target heart rate before my workout. The app could then send me an audio cue if my heart rate is above or below the target heart rate zone.

The audio cue in the app I am currently using include the current heart rate, and an indication to speed up or slow down.

This may relate to #185, at least in the target audience.