No long runs for IM training?

I also know a guy who runs pretty fast marathons that did one cycle where he never ran over 13 miles, but ran double digits nearly everyday...sometimes even twice a day.

But, more importantly, how are you going to squeeze in your bike and swim training if you are running so frequently?  It's one thing to run 6-7 days a week, where 3-4 runs are in the 3-6 mile range...so you can easily get in a good bike or swim workout on the same day as the short runs...but I would imagine it would be very difficult to bike and swim on days you are also running 10 miles.  Might be doable for a week or two, but after that, I would get run into the ground...no pun intended.

Your feeling is not surprising.  The former (50-60 mpw with long run of 12-13) is in fact easier than 40-50 with long run of 16-18.  But if the former is an option for you (i.e., you have the time to hit that mileage and still bike and swim as needed), why not do 50-60 mpw with a long run of 16-18?  That option is probably better than either of the other two.  And remember:  an 18 (maybe 20-22 if you are fast enough and can recover) mile long run is your peak.  This is not necessarily  week-in-week-out regimen. 

Example.  A reasonable (tri-focussed) 60mpw with 13 mile long run might look like (Mon-Sun, ignoring intensity):  6-10-10-10-6-13-5.  (One could reconfigure to get a day off.  Two days off is going to be hard without doing a double.)  A reasonable 60mpw with 18 mile long run might look like:  OFF-6-12-12-OFF-6-6-18.  To my mind, the latter actually looks easier to build into a triathlon training program -- and more likely to allow you to stay relatively fresh -- than the former.

Sorry -- I was editing.  There are not (alas) 8 days in a week.  The second 'plan' should have been OFF-6-12-12-6-6-18.  Of course, it's just an example to illustrate the general point that if you are going to do 60mpw, a long run of 18 or so is probably both in the cards and better (for IM training) than a long run of 13, for most people.

I don't know much about this but from my experience in the three IM's I've done is I limited my training runs to 2.5 hours.  I've negative split the runs so endurance hasn't been an issue.

Going into next year, I plan to focus more on shorter interval workouts to build some speed but will continue to limit my long runs to 2.5 hours.  I believe the cardo from the bike training transfers over.  I'm only running 4.5 hour marathons so that certainly could also play into it.

Is 50-60 miles per week for IM training necessary?  I'm asking because I have no intention of doing that many for my IM training.....I don't think I can handle that without getting injured at my age.

My only experience is a marathon 1 month after a HIM....I never got above 40 miles per week running....but I was also doing 350 per month on the bike.

No... although I think quite a few folks ramp up their running mileage in the offseason for a marathon.  Then scale back to 4 days a week or so during a 20 week IM buildup.

If you're only trying to maintain your current fitness level you can get away with less, too.

It depends on what kind of timeline you're talking about.  Blocks where you focus on 1 sport are a good opportunity to get faster.

All I can relate is what I did.  I am not a coach but understand it is different for everyone.

For my first IM (number 2 coming up in Nov) I only ran a few long runs.  The longest run was 3.25 hours but that was only once and was 3 weeks before the race.  Other than that my longest run was 2.5 hours (2) and a few other 2 hour runs thrown in.  I don't have my plan with me so the times might not be exact. 

Coming from a running background I was worried that I didn't get enough running in.  I was used to running 6 days a week with a lot of long runs for a marathon.  But, it went fine.  All 4 of my splits for the run were within 3 seconds of each other so I kept the pace throughout.  Surprised me.

Again, no advice for you just wanted to let you know what I did.

enjoy

Duane 

No, it is not necessary.  Many people do it on less.  I was just commenting on the two very specific options mentioned by OP, on the assumption that both of them are live options for OP.

Have you ever run 50-60mpw for any length of time?  By your logs, it appears as if you've topped out ~40mpw.  I think you are putting the cart before the horse.

This has been my philosophy training for my IM later this month (my third...runs didn't go well the first two times...for different reasons).  Did a marathon in the low 3:30's in mid-March off training that peaked in the 50+ mpw range with two 20+ mile runs and then went into maintenance on the run for two months while I rebuilt my bike and swim fitness.  Just finished an abbreviated marathon rebuild (on top of peak bike/swim training) that got to 40+ mpw with one 20+ mile run...less total mileage and fewer very long runs than I would do for a standalone mary, but still enough to constitute legit prep for a marathon, IME.  I believe I'm also better prepared for the bike this time...blowing up on the bike killed my last IM run, so trying to avoid that this time.  We'll see how that all worked in a couple weeks.

I didn't do anywhere near that volume for my IM.  I think my biggest running weeks were maybe 35-40 miles.  Of course there was a lot of biking and swimming mixed in too.

Build up towards the longer run as you are able. It's being written as if it has to be a big jump right now. It's very good that you are listening to your body and not making the jump since you don't feel you're ready. But still work towards it as you are able.

Also, what was your race? Thought I saw IMWI somewhere, so you'd want to be extending out at this point, adapting to the distance more.