I too was on a quest for a sub-70 so I hope this is the right place to post. I have throughly enjoyed reading this thread and have benefited from all the great info.
That goal is now gone and I am looking for help in the final weeks before my race.
Here is some background: I am 29, 5'11", 160 lbs. I don't have a long history of running. I did run in high school, but then took nearly a decade off before starting to marathon 2 years ago. I came off a decent, but not great Boston run of 2:47. I think I was in 2:40 shape, but weather, seed (coral 5 start), and perhaps inexperience(second marathon) prevented the sub 2:40. I live in New England and the training in the winter can be complicated, so I just put in miles without too many workouts. My real goal was to survive the winter with a solid base in order setup a really great spring and summer of training, which I believe I accomplished.
Once Boston was done and the weather was warmer (sidewalks and tracks open, roads not slippery, etc) I started working on speed and towards my goal of a sub-70 HLM. Everything was going great. My workout paces were dropping quickly.
In spring I was doing some of these workouts on consistent basis.
Tempo: 5 @ 5:35
Intervals: 8x1k @ 3:07
Long: 17-18 w 3x2m @ 5:30 mixed in (plenty of rest between the intervals)
Uptempo: 10 @ 6:00
My best week came at the end of May where I did:
92 miles, 34:34 10k on the track for LT, and the above long run.
After that I seemed to plateau. I felt like I couldn't recover between workouts and needed nearly a whole week before attempting my next one. I decided to stop doing workouts at 90mpw and do a couple weeks of high miles before bringing it back down to 90. The hope was to make 90 feel less stressful and thus be able to workout at that volume. It appeared to work. After I was done with a 100 and then 110 week followed by and easy week, I was able to do 2 workouts and a long run every week for the past 6 weeks. I am not 100% sure the high volume was the main factor though. The temperatures starting to drop again around that time. I am getting quicker now, but slowly. I am 3 weeks out from my target race in October and realize I don't really have any chance to hit the Sub-70. Here are my last few weeks of workouts:
SEP 3-9 - 89 miles
Wed: 9x1k @ 3:07 6min "Go's"
Sat: 3x3200 @ 10:51, 10:57, 10:53. 2 min rest
Sun: 17.5 @ 6:37
Sep 10-16 - 90 miles
Wed: Tempo - 5 @ 5:35
Sat: 4x3200 @ 10:51, 10:54, 10:54, 10:45
Sun: 17 @ 6:34
Sep 17-23 - 87 miles
Wed: 7x1k @ 3:05 6min "Go's"
Sat: 4x2 @ 10:33, 10:45, 10:49, 10:48. 2 min rest - Flat, mimicking course conditions
Sun: Course preview. 18.5 easy with a tour group
Sep 24-30 - 93 (projected miles), currently 55
Wed: 2x20 min @ 5:38 . A little over 7 miles total. 1 mile rest between the intervals. Moderate hilly course.
Sat: Planned long tempo on a flat course
Sun: Long run at whatever feels uptempo after the Saturday workout
With just a couple weeks left of real training before I should start the taper I have many confusing thoughts. My 4x2 mile workout makes me feel like I am in 72 shape, but then my longer tempos don't feel great at all and aren't that quick. I don't race often (with the plan of focusing on one big race), but I am realizing recently that might contribute to how not confident I am about what pace I should go out at. It is a goal race and I don't want to leave a lot on the table which means not going out too slow or fast. Sometimes 5:30 (72) feels too ambitious and sometimes it feels too slow.
With the long winded explanations above, here are the answers (free coaching) I am hoping to get out of this. 1) recommendations for my final weeks 2) race pace suggestions based on these workouts 3) a post mortem WRT to why I stalled all summer.
Any help is appreciated.