Going to try out the following regime. Idea is that you train at low intensity (i.e. maximize your bodies fat burning potential) for a few months (until your fitness level starts to plateau). Then you switch to high intensity training to develop that.
I done this for the first time tonight. Went well I think. My target HR was 152bpm, so I aimed to keep it between 145-150bpm (don't ask why, 147bpm - 157bpm would have made more sense). Done 5.19km in 41.10mins, which is an average pace of 7.55min/km (7.6kmph). Average HR was 147bpm.