Marathon Training - what pace should I run long runs?

It depends on the purpose of your long run within your training. A general recommendation is to do them 10-20% slower than your goal marathon pace. It is said that running long runs too slow reinforces poor running style and does a bad job of stimulating the demands of a marathon.

Thats interesting. I don't doubt it, but slower than I would have expected. Is that just so that you don't dig too deep a hole on those runs so you can keep quality up in the rest of the workouts/runs?

Exactly. It's so you recover for other important sessions, and also so you don't leave your goal marathon on the streets in training.

Would suggest a few types of long runs to have in your arsenal as you go through the next 18 or so week build up:

1) Moderate Rhythm Long Runs - start at 16 miles and building up slowly to a max of 24 miles at 7:00-7:15 pace

2) Easy Rhythm Long Run with pick-ups - starting at 14 miles and building up to a max of 20 miles at 7:15-7:30 pace with a 1 x :30 pick-ups one per mile the second half of the run

3) Fast Finish Long Run - starting at 14 mile and building up to max of 20 miles, with the first 10-12 miles at an easy 7:20-7:40 pace and then running at goal marathon pace (6:25-6:35) pace the remainder. The first effort may be 10E/4MP and final effort 12E/8MP.

4) Tempo Long Run - start at 14 miles and building up to 20 miles - this run with would star and end with easy pace miles but with some marathon pace to slightly quicker work in the middle section in the form of a tempo run or tempo repeats. Example - 16 miles with first 4 easy (7:20-8:00 pace), middle 8 mile comfortably quick at 6:10-6:20 pace, and last 4 miles easy pace. Or 18 miles with 3 x 3 miles in the middle at 6:10-6:20 pace with 1 mile easy between them.

5) Steady State Long Run - starting at 14 miles and building to 20 miles done at 6:45-6:55'ish pace after easing into it the first 2 miles.

In the first half of the cycle when its still summer and pretty warm I'd stick mainly to the first 2 types (Moderate Rhythm and Easy Rhythm with pick-ups) as they are easier to manage in the warm weather. Alternating between the two and gradually ramping up he distances.

In the second half of the cycle, I'd alternate weeks between the Moderate Rhythm Long and one of the quality long runs (fast finish, tempo long run or steady state long run). This will continue to draw out your endurance and give you opportunities to get use to running at marathon type rhythm while the body is lower on glycogen levels. The steady state long run is a great one to work on fueling strategy with.

Good luck and happy running!

Having looked at this question for upwards of fifty years now I think that all that matters is that you're doing a long run. Ron Hill usually did his 20 mile runs at about 7:00 pace. Ian Thompson did his 20 mile runs at about 5:00 pace. Ron's best time was 2:09:28 and Ian's was 2:09:12. Yes, this is perhaps an oversimplification but it's consistent with all sorts of things I've seen over the decades. Just don't run it so hard that you can't do your normal runs the next day.

Really depends how you're structuring your training. 1:17 gives you a shot at mid-2:40s. If you don't have planned quality in a long run your normal easy pace, up to ~80% HR max, is fine. But you're probably going to do some work around 6:15-6:30/mile that will drive up average pace on those days. No reason not to float some long runs in that 7:00-7:30 range. You might average 6:45s for a run where you do 6E + 10 @ GMP + 2E.

Grfeat feedback here - much appreciated. I'm on it!

I went 2:41 last year after doing a half at about 78:30 2 months prior on roughly about 50-55 mpw (peak 63). Most of my long runs were done at 8:30 pace lol (ranging 20-22 miles). I would do a medium long run (12-14 miles) every week typically with a Tempo in it (for example 3-5 miles at 5:50-6 range). While during later in my training I started picking up the pace for long runs to 7-7:30s, those were only on runs 18 miles or less. While I certainly intend on having long runs where I do a lot more marathon specific pacing in my long runs this time around keeping things pretty simple and just getting a lot of easy 20+ mile runs in worked for me.

This is all to say I believe that if you stay consistent and healthy mid 2:40s should certainly be a possibility at your current volume.