3+ hour runs

I think that you need to way the benefits of the extended long runs with the impact that they have on your regular training schedule.  If it takes you a week to recover from a 20 mile run would you have been better served to have limited it to 15 and been able to continue training.

I personally find the extended long runs to be overrated because of my history of aches, pains, and injuries.  Given that I limit my long runs I do push the intensity a little higher but still within a range that doesn't leave me limping the next day.

The BT plans usually limit you to something like 2  or 2.5 hours for a run.

I have read that this is because of the risk of injury increases significantly after that point.

"I have been reading and seeing that there are some recommendations to limit runs to no more than 2.5-3 hours."

I'm curious about the specific physiological reason why this recommendation may be made.

Any thoughts?

If I had to make a guess I would say that, especially in training for triathlon, most folks aren't running enough weekly volume to support a very long run (most especially folks that are running only 3 or 4 times a week).  At some point the risk of injury starts to outweigh the benefits of the long, long run.

I seem to always be training for a marathon these days and am now throwing in some ultra distances too so I do long runs of 15 or more miles two days a week. My suggestion is if it takes you more than two days to recover from your long run you should either slow your pace or cut your distance. You should really not be feeling all that bad the after your long run if your fitness level is high and you are not running too fast a pace. You should be able to do a short 2-3 mile recovery run the next day. You really should not split up your long run into two different runs that day if at all possible. The theory behind the long run is to get use to being on your feet and moving for an extended period of time. Good luck with the training.

I haven't read the studies but from what I understand it that supposedly that benefit of the long run occurs within 90 minutes to about 2.5 hours in terms of cardiovascular strengthening I guess you can say. After 2.5-3 hours, some articles say that you are putting a higher level of stress on your body. I guess the argument for limiting longer runs to 2.5-3 hours is the additional benefits gained from running longer are not worth the risks of increased injury. 

I have to admit I'm torn. I ran 12 today which took me right at 2 hrs and 10 mins which is like my fastest time ever for a longer run. I would like to get to 20 since that seems to be the usual pre-marathon distance. On the other hand, in order to do that I'm looking at multiple runs over 2.5 hours. In comparison, my husband will complete his 20 miler in 2.5 hours and would never think of running 4 hours just to prepare for a marathon. On the other other hand, I have to complete the distance no matter how long it takes me. On the other other other hand, I have other races between now and my marathon so I would prefer to still be able to race these races and really I'm just looking to complete my marathon as it is my first. I don't know, any slower runners out there train for a marathon based on limiting the time length of long runs?

When training for my first marathon, my longest run was 20 miles. It took me 3:45, and it was awful. I had GI problems going into it, nausea during it, I got a bloody nose, and I darn near melted in 80+ degree temps on Dec 31.

I'm SO HAPPY I did it. I ran two nights that week - then did Ragnar the following weekend. I felt recovered 2-3 days later (not fully, but back to a normal sort of tired). Worth it - and I face a lot of common race day issues and knew I could handle them. 

The 20 miler is pretty big mentally and physically. If you don't need large recovery periods (like 5-7 days) I recommend it.

I say stick with your plan. If it's time based, do the time. If it's distance based, do the distance. Marathon training and IM-distance tri training are two different animals.

Virtually all of the most popular stand-alone marathon training ( Higdon, Galloway, Pfitzinger) plans will have you doing at least one if not multiple runs of 20+miles. Recovery time that's adequate for most people is built right into the training schedules. These plans have worked for hundreds of thousands if not millions of people. If you stick with the plan, it'll get you to the starting line prepared.

My disclaimer is that blind trust is not a good thing. If you're injured or have a specific recovery issue, then you need to do what makes sense. Also, if you fall into a category (age, weight, injury history) that needs more recovery time, then you may need to adjust a "canned plan".

I am in the same boat, training for first marathon at the end of October and taking a long time to get in the 10-13 mi runs. My longest event so far has only been 3:20, and I am worried about the mental challenge of a longer event.  While I don't look forward to the 4hrs running by myself, I think I really must do the 20mi once or twice so I have a little more confidence about finishing the marathon.

I trained up to 26.2 for my first marathon (about 5 hours).  My times for the next three weeks were a wreck, but the marathon itself well relatively well fitness wise (I broke my foot at mile 16 via stepping on a rock, but my cardiovascular system and muscles were okay.)  I did not do this for my second marathon due to the shortened training for the foot recovery and I got lost doing my longest long run, and my time suffered.  I don't see why you'd cap runs at 3 hours for just running training since people do it all the time.

I couldn't imagine doing a 26.2 mid ironman training since my swim and bike times would go to heck from the three week recovery... but maybe the cross training time off the legs would make recovery go faster.  I'm still getting the hang of training for a half Iron and I haven't worked out the full training program yet, but I probably would fit in a full distance (half marathon/two plus hour run) run in there somewhere.  though it's much easier recovering from a 13 than a 26 mile run.  :/

I did 3 weeks of 20, 22, 20 mile runs during my training leading into my Marathon this past February. Honestly, a slow build up in the distances definitely helps...I will say though, you will get the physical basis to deal with the marathon, but the last 4 miles of a marathon were possibly the toughest thing I've gone through (to this point), then again the race that I did had us finishing over a long, slowly building bridge...not the easiest way to finish a race. Though, I am glad that I completed the marathon early in my training this year, as I am gearing up towards competing at IMFL for my first IM (and only in my 2nd tri-season...still learning LOTS).

For marathon training, I absolutely think you need to run 3+ hour runs, unless you're planning on finishing sub 3.  I typicall do anywhere from 3 to 5 runs over 3 hours when training for a stand alone marathon.  You've got to learn how it feels to keep running and stay on your feet.

IM training can be different, since you are putting in much more volume on the bike and in the pool, and you have to weigh all sorts of factors.