Weight / Fat loss

This is brilliantly useful, thanks. After a couple of days I've realised I spend 98% of time in recovery, which I suppose is why I can run a marathon and ride for 200 miles in one go but never get any faster and am usually a stone heavier than I'd like to be.

You definitley need to push yourself into the higher zones if you want to get faster.

You're probably in a great fat burning zone though.

In my non-expert opinion. Pushing yourself via intervals etc, and getting faster. Makes for more effective muscles, which in turn demand more fuel. So like most things, its best to mix things up a bit.