I am way impressed that this thread kept going, taking on a life of its own. Great to see many other people offering their own valuable advice. Thanks to everyone, I hope you all continue to chime in when possible. There are enough of us here to answer any question to do with running. Trust me, nobody died and made me the Oracle.
Some questions were specifically aimed at me, so I will offer some replies. Other questions were expertly dealt with already (thanks, "Michelle Blanche fan", Hodgie-san and others), and need little further input from me.
Mr ? (or Ms ?)
Your runner has done well with PRs of 18.45/5k, 69.00/10miles, 3.15/marathon and 8.02/50 miler. These are good, but with a little tweaking, could be much better. I always use these rules of thumb when I hear a runner's PRs, especially for women. They are not perfect, but they should only be off by a couple of seconds either way:
5k pace + 12 secs/mile = 10k pace
5k pace + 20 secs/mile = 10 mile pace
5k pace + 40 secs/mile = marathon pace
Note: these are what a runner should be capable of. It does not mean these will apply automatically to every 5k PR. You have to work hard on the LT to make these numbers work.
Applying them to her existing 5k time (note: she does not have to get "faster" at 5k to set whole new PR's at all other distances), your runner should be looking at 38.45/10k, sub-65.00/10 mile, 2.55/marathon
When it comes to making these happen... if I could just refer you back to the first post in this thread (by CBASS, in which he copied an earlier post of mine). Here's the relevant paragraph:
"To move your LT don?t just jump into so-called ?tempo? runs. These would be too fast/hard and not cause the effect you want. Begin from the ground up and work until eg: a 90 min is no longer ?long?. Then work until a once-or-twice-per-week 10-mile run at 5k-pace + 1 min is no longer hard (you could go round again, although you don?t). Then until a session of 3 x 20 mins @ 5k pace + 40 secs is not THAT uncomfortable (and you could do more)... and maybe only THEN begin to work at paces such as 5k-pace + 30 secs (2-3 x 15 mins) right on up... (eventually to 2000m repeats at 10k-pace). All the time being careful. You cannot rush this."
To get her used to moving a bit faster, you might want to try the 200/200s I discuss above. Get her to aim for something like 45 secs (fast bit) and 65 secs (slow bit), and maybe 10 laps continuous to begin. Most runners enjoy these. If she can hit the times, she can build up to 25 laps continuous once every two weeks. On at least one, or even two other days of the week, work on her LT as I mention in the quote. With her aerobic background, it should not take her too long to improve significantly. Remember Runergrl's advice though: keep the easy days easy.
I have used a number of tapering methods over the years and learned that one method will not work for every runner. Some like a day off before a major race, some claim to feel sluggish if they take a day off the day before. Some just like to run reduced easy distance in the final week with some strides (5 x 100m with 1 minute jog recovery) every second day. One of the more "complicated" ones I have tried goes like this:
5 days out from races up to 10 miles: 5 x 500m at 1 mile pace (NOT FASTER) with 5 mins jog recovery
4 days out: 4 x 500m at 1 mile pace with 5 mins jog
3 days out: 3 x 500m etc
2 days out: 2 x 500m etc
1 day out: 1 x 500m
All of these with only 10-15 mins jog warm-up, a few strides, and 10 mins cool down.
With these (and all tapers) you are doing at least two things: reducing mileage and increasing leg zip. Two or three of my runners swears by these for those "special" occasions. Good luck with whatever you choose.
This thing about activating motor neurons is something many of you will have already experienced if you have run far enough. Ever noticed that you can chat away at the start of an easy long run, but that there can come a time when the talking stops? To activate ST fibres usually requires a low signal from the brain. So low, it feels "effortless", and you do not even have to think about running in order to run. To access those larger more powerful FT fibres (either in a race or at the end of a long run) requires a much stronger mental signal and this tends to force the brain to concentrate more on what it is doing and will often not have extra energy for yakking away. Timothy Noakes wrote that he found this happening to him one time when he ran the Comrades Marathon (55 miles?). He found he had lots of leg energy left, having carbo loaded well, but that his "mental signal" was weak since his blood sugar had dropped. If I remember right, quaffing a couple of quick Cokes soon put that right.
Repeated activation of particular fibres reduces the mental signal required to activate them NEXT time, and needing less mental energy is a good thing. They find this a lot in weight training, people apparently improving very quickly. The improvement is not really in strength, but in ability to recruit the proper fibres at optimal tension. So it's a neuro-muscular thing.
Middle Distance Runner,
As you will know, 800s are around 50% aerobic and 50% anaerobic, with 1500s being approx 65% (aer) and 35% (anaer). So you do not want to become a total aerobic animal like a marathoner. If you are a gifted middle distance runner, it is unlikely you have the musculature to be one anyway. You should have a generous supply of FT fibres to enable you to generate large quantities of lactic acid and (thereby) speed. What you should do, and what I advise, is maximise your aerobic ability before moving on to the V02max and anaerobic work. Remember, you WANT to be able to build high lactate (because it lets you run faster than us slower marathon type dudes), but you also want to build the buffers so it does not cripple you. But before that you want to make sure your aerobic system is top notch so you do not have to call on your anaerobic speed before absolutely necessary.
Think of it like a Ferrari and a compact Subaru side by side at 60mph. Both are okay at that speed, but we all know the Ferrari has a ferocious amount of power in reserve.
You resting HR IS high at 52+. Are you sure that you are dealing with the high mileage okay? You can still overtrain on too many slow miles. Get enough rest, enough sleep, and don't forget the carbos and fats (have I mentioned peanuts?).
Note my quoted paragraph to ? above. I don't recommend running slow all the time. You should be building up to where you can run at 5k + 20 secs or 5k + 40 secs, two times per week. Depending on what they are aiming for, my runners easily handle: Sun - 2hrs+ : Tue - total of 10-12 miles at 5k + 40 pace (aka M-pace) : Fri - 2k repeats at 10k pace or total of 10k at 5k + 20 pace (aka 10-mile pace). The rest of the week, easy (and long-ish).
If I have urged caution to you, it is just for you to take time to build up to being able to do that with a maximised aerobic system and not with steadily rising lactate as you were used to doing.