I've been running for about 2.5 years now, 2 marathons (Inverness and Edinburgh), 4 halfs, 3 10ks and 2 5ks to date (oh and two Mighty Deerstalkers which were both a lot of fun!). I tend to use the Runnersworld training programs and I use a HRM.
I went too fast in both marathons and paid the price. I think the lesson has sunk in now. Well, I hope!
Thanks for all the feedback. I think race predictor should have a health warning on it!
On a similar note, is it common to have a significant number of 'off form' races? By that I mean races where training has gone well, you feel fine but your HR runs higher than normal early in the race and you know it is going to be a bad one from mile 2. I noticed in the marathon my HR hit 80% much faster than in the half even though I was going 30 secs per mile slower. I've had the same thing happen in previous half marathons. On all occasions I've felt fine.
I'm really struggling trying to work out what my target marathon pace should be. My PB on the half marathon is just under 1 hour 37 (set at the recent Edinburgh Rock and Roll half). The run predictor says that equates to a 3 hour 20 marathon.
For the recent Edinburgh marathon I trained to the 16 week 3 hour 30 Runnersworld training program (and found it fine). For the marathon I kept to 7:50 min mile pace and my HR below 160 (80% of max) for the first half. However my pace started to slow from the half and then really drag from the 18th mile. Miles 22 to 25 slowed down to a walk/run. I came in around 4:04. I felt wiped out afterwards but didn't actually feel that sore the day afterwards.
Here is my Garmin record of it: http://connect.garmin.com/activity/182735758
Obviously Edinburgh was fairly hot. So I'm trying to work out whether I went out too fast or was it the heat?
What pace should I target early in the race to have a better finish? Thanks!