Hello all, I first dipped into this thread in January but it's only over the last week or so that I have managed to read the whole thread from the beginning!
I have always struggled with the end of marathons and long training runs, usually producing some fearsome positive splits. Like Cybistrider I'm doing the Chester marathon in October, so HADD training seemed tailor made for me. I started running at 'less than' 75% which for me is 140bpm and started to see some improvement of about 30 seconds per km. Unfortunately, this year has been blighted by health problems. In February I was hospitalised with gall stones and a week and a half ago I had my gall bladder removed, fortunately keyhole.
I'm aiming to start back with some gentle running soon and then build the biggest base I can LT75% for the first half of the time available, then throw in a run a week at 80%, which I'm hoping is going to be somewhere around marathon pace. I'm aiming for sub-4hrs, I would be happy with 3:59:59, as previously I've only managed 4:09.
As you can imagine I'm itching to get back out running and hoping for some improvements on the same scale as I have read about on this thread.
I'm not sure why you would think that you would run faster if you ran farther.
As Deasy says if you want to run faster you need to do some shorter/quicker runs. In addition I would also say do some longer runs but slower than your current 3-4 mile pace (11 min miles plus). Increase your weekly mileage by adding these slow runs and faster runs, you should improve pretty quickly.