Tempo during marathon?

It does have disaster written all over it.  Studies have already been done.  There's a reason tempo and/or intervals are done in training and that's to stress your body.  You don't want to do that on race day.  A steady state effort will be less taxing on you physically than mixing in tempo/interval running.

Let's say you ran four miles.  Which one do you think took more out of you?

1. Two miles at 7:00/mile pace, two miles at 9:00/mile pace
2. Four miles at 8:00/mile pace

They both average 8:00/mile pace but option one will have a higher rTSS or tTSS.

14-16 miles wasn't long enough to test your theory.  Unless your MP is quite a bit lower than your ability, you'll suffer over the last 6-8 miles.  There's a reason people joke that a marathon is not the same as 2 HM...that 2nd half is a bugger.  Someone on here once said that you should feel fresh after the 1st half (say 35%-40% of your energy expenditure) and I'd say that's about right.

At least in my training, I do a LOT of MP miles, especially in my long runs.

BUT these miles are different than Tempo Runs. A Tempo run for me is something a bit faster than my Half Marathon race pace and my 15k race pace.

I use an HRM to dial in my MP during training (Hopefully over a similar course for my goal race) and target 88% of Max HR.  A Tempo Run on the other hand would be targeting 91-92% of max.

On Race day, I use a combination of HR and the paces I hit during training to manage my race.

Not sure what your plan will be but doing the 1st 8 Miles a bit slower than goal pace and then slowly increasing to MP over the next 12 certainly would not be a bad thing. The key is to be able to KICK at a point where you are confident that you have enough left to finish and finish strong. Unfortunately, you won't know if hitting your target is done until the final miles.

In my experience, running fast in the beginning and banking up a bunch of time then holding on for dear life in the end has never worked for me. Negative splits are by far and away the most rewarding way to  run a race.

Not sure if this helped you or not but best of luck  and let us know how it goes

How did you determine your goal marathon time? What have you key workouts looked like?

As stated already, that strategy has disaster written all over it unless you're actually trained up way better than your GMP. 

1:45 may be a little soft but it should put you solidly and comfortably on your 3:45 goal. I'd run it out to 20 and see how you feel. I'm guessing you'll feel pretty strong still so around then you can think about picking it up some and racing it in. Probably wouldn't mess with changing GMP at this point though. 

I went through something similar on my first successful BQ attempt. I had come off some pretty big volume and was probably more in shape to BQ -10, however, I was running with a friend and just wanted to qualify, not give it everything or bust. I negative split (1:35/1:33) and finished with zero issue. Could I have ran faster? Probably, but I didn't need to at that time and probably executed my best race ever. 

With only a week to go it'd probably best to just be ready for the race, but thought to mention that there seems to be a number of differences between what I've seen in Daniels work and what's being posted & logged here. I think it depends on the individual whether it's best to go over the plan again at this point or after the race. You have some big runs in to work with for this one and I also agree with running the more steady pace throughout.

The pace calculators are for best efforts. You can use a table from the book or an online calculator like this one to figure out the training paces. They are for current ability and tend to come from a recent race (or maybe workout) that best represents current fitness. I don't really see an obvious one for you. The 1:45 HM was a training run, but in using that, it comes up with a VDOT near 43. Your training paces for various workouts come from there. I'd guess it was a little faster still as this was not a race (which is why I rounded faster to 43 vs 42), but not sure how much more as I don't know how hard you really went. Or how much more you were capable of. The easy pace of 10 min/mi you mentioned is for a VDOT of 41 (or a 3:45 marathon). The 1:45 HM projects faster than that, even before considering training run vs a race. That's why the 10 min/mi seems slow. That's not where your current ability is.

Then for the amount of running, Daniels listed only 2 key workouts a week, but this can be very deceptive. He only specifies those two, but the rest is much more open and flexible in how someone fits it in. There should actually be a lot more running. Say 6-10 total runs a week (some days could be double runs). I'd have to read again to see his long run percent for a marathon, but it would be no more than 30% of the weekly total. And from elsewhere in the book he prefers it to be down in the 20's more at the high end. So what that means is in order to fit in a 20 mile long run, one should be running up in the 60's or more for weekly mileage.

One last thing is with the split decisions. Like 22 miles or 2:45 (think it's usually 2:30). Those types of decisions are always to do the lesser of those two. So in your case that would be 2:45 and the mileage is what you get. The 22 is for faster runners who would get that far before 2:45 at their easy pace, and remember that he'll work some *very* fast runners.

Be interesting to see how the race goes for you. the 1:45 HM projects faster than the goal, but the lower mileage (if logs are up to date) can hurt that as the race gets farther out. So it is possible to make, and also quite possible it will hurt to do so.

This is what concerns me:

Low mileage outside of the key workouts.

Running harder on what are supposed to be slower-paced long runs (which was made possible by lower overall mileage)

I'd stick to that goal MP.

I understood that. You said up to 5k on non-key-workout days.

I do not think that 6-10 mpw outside of the two key workouts is sufficient. You may prove me wrong at your race, though

I said in my first post "I'd stick to that goal MP"

Originally posted by jennifer_runs The thing about Daniels' plans that a lot of people don't realize is that lowering the overall mileage will make it easier to hit the paces of the key workouts. You can't really cherry-pick just the key workouts and get the expected results of the plan. So you're doing a low-mileage training-- 2 workouts plus 2-3 short runs of 5K each. I also worry a bit about this. I can't really predict how this will work out for you, but to me it seems like 3:45 is a stretch goal. Go for it, but expect it will be pretty tough. Then again, all marathons are tough.

Agreed

OP- if you weren't running to the entire plan then all bets are off. Go at the 3:45 and see what happens.