IM Run - Measure training by time or distance? (Page 2)

My run training is by distance. I've got a running/marathon background and distance is way more motivating and makes sense for me personally. I've done a handful of 15-16 mile runs so far, I'm doing 19 tomorrow and 20 next week and that's it for my IM training. If I knew I only had to run 3 hours, I'd likely do the slowest run of my life and hit way less miles. Like others have said they are intimidated by miles, I'm motivated by miles and in the end, races are measured by miles so it's also a confidence booster for me. I train with a coach as well so I'm not just winging it.

it is super easy... go out and run 1:15 hrs out and then turn around and head back. Still, since it is not only about time/distance but also intensity I always know what pace I'll do for a given run, that is, I have a goal for each session. On my long runs I usually go at a easy/steady pace and close the last 15-20 min at a moderate to hard effort and sice I know around where my paces for each intensity are I can easily know before a run how many miles on avg I'll cover during "x" amount of time hence planning is rather simple. Finally, training should be flexible and if you run 2 min less or 5 min more it shouldn't be that big of a deal hence if I miscalculate my pace and I am still a bit away from home I keep running or if I get back home faster than expected I just stop, for me it is not a biggy...

I trained by time with the longest run being 3 hours. I followed the Be Iron Fit program and I think he says somewhere in there that after 3 hours no matter what the pace you start doing too much muscle damage to recover from. I always run the first 30 then walk 1 minute out of every 10 for the rest of the time and if I'm still out when my time runs out I walk in. It's a good idea to practice walking and running again some because chances are you'll be walking at least some of the aid stations race day and your quads will freeze up big time when you start to run again if they aren't used to it.