Just checking to see if anyone currently lurking the Low HR Training group has experimented with Friel based training. I'm making this post to hopefully get some constructive feedback (good or bad) on this training method. I may or may not experiment with this (but probably will just for fun and to keep things interesting).
The concept makes a lot of sense to me for someone who wants to get faster. It somewhat reminds me of Hadd's approach which has been mentioned a few times on this forum.
The basic concept is to completely ignore equation age based zones and Max-HR. Instead, you do a field test to find your LTHR (lactate threshold HR) and base your zones entirely off of that. Re-do the field test every 6 weeks or so and adjust your zones.
Field Test Procedure:
Train to your race based on these zones. For example, if you're training for the marathon or trying to maximize your aerobic base building, run a vast majority of the time time in Zone 2 (Aerobic - Endurance building) and Zone 1 for Active Recovery. What is interesting about this is "supposedly" it maximizes the development of your energy delivery system.
There was a podcast on Endurance Planet recently (episode 246 - about minute 45) where they compare this to MaxHR training and MAF. They made a very good analogy as to why this works better than MaxHR training. The example was to imagine an out of shape person that suddenly encounters a grizzly bear. This person runs like hell to escape and hits 210 bpm. Just because this person's MaxHR is 210, they shouldn't be running their aerobic zone between 70-75% of 210 bpm. They would be running WAYYY too hard. Pretty extreme example but it makes sense.
Anyway, any thoughts or experiences to share on this anyone?
I can hear Lucho talking through the grisly story as I read it, and I hadn't listened to that podcast yet.
(I'm guessing it was Lucho anyway)
I really like Friel and have done all of my long distance training (Ironman) based on his books. With that said, I've been 'retired' for too long and now getting back into this game over the past few weeks.
Just checking to see if anyone currently lurking the Low HR Training group has experimented with Friel based training. ... There was a podcast on Endurance Planet recently (episode 246 - about minute 45) where they compare this to MaxHR training and MAF. They made a very good analogy as to why this works better than MaxHR training. The example was to imagine an out of shape person that suddenly encounters a grizzly bear. This person runs like hell to escape and hits 210 bpm. Just because this person's MaxHR is 210, they shouldn't be running their aerobic zone between 70-75% of 210 bpm. They would be running WAYYY too hard. Pretty extreme example but it makes sense.
Just checking to see if anyone currently lurking the Low HR Training group has experimented with Friel based training.
...
Life Goals:
#1: Do what I can do
#2: Enjoy life
I can hear Lucho talking through the grisly story as I read it, and I hadn't listened to that podcast yet. (I'm guessing it was Lucho anyway) I really like Friel and have done all of my long distance training (Ironman) based on his books. With that said, I've been 'retired' for too long and now getting back into this game over the past few weeks.
Haha, yeah it was a good listen. Glad to hear you are getting back into the game! Will you be doing the field test right away then to set your base building zones? I was reading a forum yesterday where Friel suggested doing it early in a training cycle.
The first calculator I found actually gives you both your cycling and running heart rate zones to train for the triathlon. The triathlon is one thing, the Ironman Triathlon is another level of training!
Training by zones is mostly foreign to me. Over the last 6 months or so, I just did a vast majority of my training between 115-129 bpm and would do the last 25% or so of my long runs near 85% MaxHR (175 bpm for me). This did result in dramatic improvements but everything that I'm reading/listening to is implying that I'm running at WAY too low of a heart rate to really maximize gains in speed which is really what I'm after.
I haven't done my first field test yet as I just learned about this a few days ago and I'd like to schedule the test with a few friends. The podcast actually suggested not doing it alone. They actually encourage you to "race" your friends during the test as it is supposed to be maximum effort (which can be difficult to do alone) to get a more accurate test result.
I lost my rama
The basic concept is to completely ignore equation age based zones and Max-HR. Instead, you do a field test to find your LTHR (lactate threshold HR) and base your zones entirely off of that. Re-do the field test every 6 weeks or so and adjust your zones. Field Test Procedure: Find a fairly flat area where you won't have to stop for traffic (probably best on a track) Warm up easy Run 30 minutes all out. Pace yourself so you run the farthest possible distance in the 30 minute time frame. Hit the the lap button at 10 minutes. Average HR over the last 20 minutes is LTHR. Plug LTHR into one of many online calculators to generate your unique, personalized training zones. Train to your race based on these zones. For example, if you're training for the marathon or trying to maximize your aerobic base building, run a vast majority of the time time in Zone 2 (Aerobic - Endurance building) and Zone 1 for Active Recovery. What is interesting about this is "supposedly" it maximizes the development of your energy delivery system.
I've adopted the Hadd methodology which differs from Friel in one major assumption. Friel assumes your LTHR doesn't change throughout the training cycle (if I understand it correctly). Hadd assumes it does change and quite dramatically. I suppose it's based on how one defines LTHR. Hadd defines it as running 10 miles at constant HR without any change in pace. Quite different from Friel's protocol.
I still like Hadd for a couple reasons: 1. Your training paces progress (get faster) as the training cycle progresses, unlike other popular training plans where paces are set at the beginning based on goal or fitness level and only the distances changes. 2. The Hadd mini-tests provide tangible evidence if/when your aerobic fitness levels progress. Here were my Hadd mini-tests results from 2015 prior to my Half PR (7:33 pace) which I have not beaten since.
You can clearly see the progression in pace vs HR. But everyone is different and I've read posts from many advanced runners who have not had success with Hadd. Guess we have to find our own ways.
3/17 - NYC Half
4/28 - Big Sur Marathon DNS
6/29 - Forbidden Forest 30 Hour
8/29 - A Race for the Ages - will be given 47 hours
I've adopted the Hadd methodology which differs from Friel in one major assumption. Friel assumes your LTHR doesn't change throughout the training cycle (if I understand it correctly). Hadd assumes it does change and quite dramatically. I suppose it's based on how one defines LTHR. Hadd defines it as running 10 miles at constant HR without any change in pace. Quite different from Friel's protocol. I still like Hadd for a couple reasons: 1. Your training paces progress (get faster) as the training cycle progresses, unlike other popular training plans where paces are set at the beginning based on goal or fitness level and only the distances changes. 2. The Hadd mini-tests provide tangible evidence if/when your aerobic fitness levels progress. Here were my Hadd mini-tests results from 2015 prior to my Half PR (7:33 pace) which I have not beaten since. You can clearly see the progression in pace vs HR. But everyone is different and I've read posts from many advanced runners who have not had success with Hadd. Guess we have to find our own ways.
I'd argue that any low heart rate training plan will result in your training paces continually getting faster (MAF, Hadd, Friel). I do much prefer this over most training plans which include set paces which may be too fast, too slow, or force you to push through the wind/hills/etc to hit said paces.
From what I read from Friel, he does assume that your LTHR changes dramatically as your fitness improves. That is why he has you frequently re-do the field test to reset your zones. So your paces will naturally improve as you go for 2 reasons. 1. You simply get faster within your zones at any given heart rate (I believe this is true with any method that actually works) 2. Your zones will keep readjusting to higher heart rates until you reach a physical limit. (Your LT simply can no longer get better).
"Hadd defines it as running 10 miles at constant HR without any change in pace." - I don't quite agree with that because I can run 10 miles at 130 bpm without any change in pace no problem. My LTHR is not 130 bpm. I can also run 10 miles at 160 bpm without any change in pace. This is also not my LTHR. Perhaps what he meant was that the Maximum HR you can run for 10 miles? But even then, you'd have to run that tons of times by experimentation to do actually find that value. Also, LTHR is widely accepted as the pace you can run for 1 hour without slowing down. I would agree with Hadd if that athlete's LT pace happens to be exactly a 6 minute mile (wouldn't that be sweet!).
What I really like about Hadd's training method the most is that it's constantly working the LTHR up (even if you don't know exactly what it is). The biggest difference I see between Hadd and Friel is the following:
The biggest issue I have about Friel is the LTHR test is obviously very, very difficult. But then again, it can be viewed as a good speed workout and is widely considered to be a very close approximation of LTHR.
I do actually prefer Hadd's test better than the MAF test as it shows improvement is occurring at all levels of effort and shows you a lot that you can learn from. I can learn a lot from the data you shared including about where your LTHR might be. Just looking at your data I'd say your LTHR was probably about 165 bpm as the 160 bpm portion of the test was no problem but you weren't able to push up 170 and hold it there without nearly all out effort. My guess is that had you set your aerobic zone as a percentage of 165 bpm, you may have been able to push that threshold up (in theory). From test 1 to the final test your LTHR doesn't appear to have improved at all but you did get faster at all levels of effort and showed a marked improvement in speed!
Regardless of how we train, I do think that knowing LTHR can be about the single most useful tool that you can have for racing. If I had to guess I would say your best possible race you can run given your current physical reality would be to stay just below threshold until the burn phase at the end where you just light it up.
Wow, thanks for the detailed and thorough feedback! You are right in that I left out a key point in Hadd's definition in LTHR... it's the maximum HR that you can sustain the pace for that distance. Also, since I'm not a 2:25 marathoner, 10 miles for me is a much different (harder) effort than 10 miles for someone cruising at 6 min/mi pace. Therefore, I did my LTHR runs by time vs distance (55 to 75 min). I admit that I don't know enough of Friel's method other than what's published online (not that there's a whole lot from Hadd ). But I agree, sticking with the basic principles will results in much the same performance improvements. As I enter each training cycle, I do more improvisation vs sticking to a plan lately, but adhere to the basic principles.
Here's the data from my best marathon performance (3:26:49). I pretty much nailed it in terms of pacing vs HR. I had to extrapolate HR data for a few early miles due to cadence lock.
Even the cardiac drift in the end arrived on schedule. And I got a 30 second negative split. Honestly, I don't think I will match these numbers ever again.
Thanks again for the feedback!
Wow, thanks for the detailed and thorough feedback! You are right in that I left out a key point in Hadd's definition in LTHR... it's the maximum HR that you can sustain the pace for that distance. Also, since I'm not a 2:25 marathoner, 10 miles for me is a much different (harder) effort than 10 miles for someone cruising at 6 min/mi pace. Therefore, I did my LTHR runs by time vs distance (55 to 75 min). I admit that I don't know enough of Friel's method other than what's published online (not that there's a whole lot from Hadd ). But I agree, sticking with the basic principles will results in much the same performance improvements. As I enter each training cycle, I do more improvisation vs sticking to a plan lately, but adhere to the basic principles. Here's the data from my best marathon performance (3:26:49). I pretty much nailed it in terms of pacing vs HR. I had to extrapolate HR data for a few early miles due to cadence lock. Even the cardiac drift in the end arrived on schedule. And I got a 30 second negative split. Honestly, I don't think I will match these numbers ever again. Thanks again for the feedback!
Wow, that is an expertly run marathon. Great work! Didn't miss a beat even with a pee break.
You mentioned that you ran your LTHR by "time instead of distance" at about 55 to 75 minutes. I guess if you think about it, even if you don't know the value of your current LTHR, running hard for that long will put your heart rate at some number less than LTHR. In fact, I have to wonder if doing runs like that for your speedwork was a major reason why you were so well prepared to run the marathon so well. I'm curious how often you did that type of sub-threshold run and how many miles a week you ran?
Do you plan on picking the Hadd training back up? Any future target races?
After reading this, some other reading and some thought; I think I'm going to take the following personalized approach and see how it works for me (it just sounds more fun really):
Wow, that is an expertly run marathon. Great work! Didn't miss a beat even with a pee break. You mentioned that you ran your LTHR by "time instead of distance" at about 55 to 75 minutes. I guess if you think about it, even if you don't know the value of your current LTHR, running hard for that long will put your heart rate at some number less than LTHR. In fact, I have to wonder if doing runs like that for your speedwork was a major reason why you were so well prepared to run the marathon so well. I'm curious how often you did that type of sub-threshold run and how many miles a week you ran?
Thanks! I wish I could point to any one thing that made a difference, but it was an accumulation of multiple things (including bad luck and good luck). First, I did a Hadd-based training cycle for my spring Half (16 weeks ~49 mpw). The Half was a complete bust. It was warm, I went out way too fast and blew up after 7 miles. Lesson learned.
However, since I already had a solid aerobic base, I wanted to do a Hansons Advanced plan for the fall Full. Yes, Hansons is almost a polar opposite plan from Hadd. But even Hadd says that if you already have a good pace relationship between race distances, then there's nothing he can offer and you should see a different coach. This is something most overlook with Hadd. His method takes you only so far. Since I already had a decent aerobic base, I wanted to work on VO2 and strength - so Hansons.
However, three weeks into Hansons I re-aggravated an Achilles injury from the speed work. Took time off to recover. From there it was all improvisation for the final 12 weeks and a very odd mixture between both a little Hadd and a little Hansons (talk about Jekyl and Hyde!). I only planned week to week.
Did some Hadd because I was doing all low aerobic running at the start, as you noted, it's a progression in building speed, but not at the start. No Hadd tests though - in the warm weather these tests are pretty much impossible to get any decent data, I have found. And I needed to mind my Achilles.
5 weeks building up to 50 mpw all low-end aerobic. 145-150 overall avg HR and 9:30 avg pace.
Next started a little Hansons with his weekly GMP runs starting at 8 miles, but I didn't start at MP, so back to Hadd I guess. Also, a bit of Hansons in that my LR didn't exceed 16 miles - mostly for injury prevention. This also meant a lot of 7 and 8 mile easy runs to keep the overall volume up. Only 3 16 mile LR's this cycle.
Next 2 weeks - 1 run per week for 8 miles @155 AvgHR (79% Max) - slower than eventual MP. I know I said I ran by time before, but by now I know the relationship between time and miles.
Next 3 weeks - 1 run per week for 9 miles at 160 AvgHR (82% Max). Still slower than eventual MP but the Hadd progression in HR and Hansons progression in miles. I started working in a long hilly runs for 10 miles during the week as well, which I think helped build strength.
Final 3 weeks prior to race week - 1 run per week for 10 miles (1 mile w/u prior) at 165-170 AvgHR (85-87% Max), which was my eventual marathon target HR and pace. Hansons has 10 mile GMP runs these final weeks. These 10 mile runs were the fastest paced runs the entire cycle. And I continued the hilly 10 mile runs during the week at slightly higher HR than easy.
The final 11 weeks prior to race week was 52 mpw average. 9:15 overall average pace, which includes both easy and faster runs. This was my slowest average training pace for a marathon training cycle, which resulted in my fastest marathon. An invaluable lesson learned.
Do you plan on picking the Hadd training back up? Any future target races? After reading this, some other reading and some thought; I think I'm going to take the following personalized approach and see how it works for me (it just sounds more fun really): Occasional tempo runs in the form of the Friel field test to "calibrate" my zones. Equally occasional Hadd Test Run in "Zone 2" as much as possible. When legs are tired, run in "Zone 1" or rest. Do occasional sub-threshold runs similar to what you just described in Zone 3. Fast Finish Long Runs on the weekend (last 25 - 50% in Zone 3).
I would do Hadd again if I had to re-build my aerobic base, but no plans to do so right now. No goal races for now (marathons or shorter that is). The only way I know to improve my marathon performance is to increase overall training volume and build VO2 max and strength. But I've gotten injured over and over again trying to achieve this. Therefore, I've switched to trying trail ultras. First 50K in a few weeks.
I like the idea of the occasional Friel test, because like you said, you're re-calibrating training paces. I think most runners pick a training pace too fast at the start vs letting it develop and progress over time.
Hadd tests are also a good workout, I've found. But for me they provide useless data when it gets warm - anything above 60 deg. Wind also plays a factor. Also, that last segment I only do 1600 vs 2400. Just too damn hard to sustain that effort for 2 more laps. Besides, the more important data are at the next two segments down as you've noted.
Yes, lots and lots of miles in Zones 1 and 2. I hate it when people call them junk miles. To me they're gold.
Personally, I'm not a fan of a fast finish LR. First, I can't do it (LOL) - I'm usually pretty trashed by then. Second, I like the idea of maximizing time on feet to help the body develop.
Anyway, sorry for the long response. This is really good stuff though. When are you starting your training cycle and when is your target race?
Bert-o,
That was one of the more enjoyable posts I've read here in awhile. Good detail!
Good luck in the 50K! That's going to be a big achievement.
I really like how you crept up your effort on the fast runs over the course of time (79% MaxHR to 82% MaxHR to 85% MaxHR and so on). That really appears to be a smart progression.
" I think most runners pick a training pace too fast at the start vs letting it develop and progress over time." -- This comment by you is probably the one of the single most important thing that most of my friends miss, no matter how much I try and communicate it. Everyone is sooo worried about their workouts looking too slow on Strava or MapMyRun feeds. Keeping the effort easy, even while going fast seems to be lost to most.
"Yes, lots and lots of miles in Zones 1 and 2. I hate it when people call them junk miles. To me they're gold." -- Brilliant! Definitely NOT junk miles. I think I've developed more high end speed out of Zone 1 and 2 running than anything else. I can't prove it but I'm reasonably certain of that.
"Personally, I'm not a fan of a fast finish LR. First, I can't do it (LOL) - I'm usually pretty trashed by then. " -- Ha! I hear you! This has become my favorite workout but it is definitely VERY hard. In fact, I'm not always successful. I will even name my workout on Strava "FAILED! - Fast Finish Long Run Attempt" and then put the details in the comments so I remember what happened. An example run would be something like 10 miles at super EZ effort (120-130 bpm or so) and then the last 5 miles at something like 85-90% MaxHR and completely ignore pace. Pace will likely be fast but not so fast that I can't finish the 5 miles at that effort. As soon as I see 90% MaxHR display on my watch I start to breathe heavy so that's basically my limit in a long run.
"When are you starting your training cycle and when is your target race?" -- Since I started low HR training last December I really don't do anything in cycles to be honest. Just running all year when I feel like it and resting when I feel like it. Target races are the Turkey Trot on Thansgiving (jog it with family), Marathon in Phoenix with some friends in February. 2018 NYC Marathon and 2019 Boston Marathon. I've got an automatic qualifier for NYC and significantly under my Boston Qualifier (I think 22+ minutes under will get me in? )
Wow, you're fast! Will 2018 be your first NYC Marathon? It's my hometown marathon which I've done 3 times (2014-2016). I didn't get in this year, so I ran Chicago instead and watched NYC from the peanut gallery. It's such a fun race, both as a spectator and a runner. I'll put my name in the lottery again for 2018. I'm waiting until I turn 65 before I'm fast enough to go after a BQ.
Regarding Zone 1 and 2, I definitely found increasing training volume here made me faster. And if/when I can do speed work the recovery time is much shorter too. Do you do any specific speed workouts (other than threshold or tempo runs)?
Too true about peoples' paces on Strava, etc. This summer I did 60% of my runs on trails - getting off the road really made a difference in injury prevention. My weekly "hard" run was 90 minutes on a fairly technical and hilly trail (it was more of a fartlek run). I could brag about 12 min/mi pace at 85% MaxHR on Strava. I don't recall where I read this, but I like the saying - Your body only knows effort and time. Pace and distance are only in your mind. (or something like that)
Thanks for the nice compliment on my prior post. Were you over in the RW forums before they got shut down?
Wow, you're fast! Will 2018 be your first NYC Marathon? It's my hometown marathon which I've done 3 times (2014-2016). I didn't get in this year, so I ran Chicago instead and watched NYC from the peanut gallery. It's such a fun race, both as a spectator and a runner. I'll put my name in the lottery again for 2018. I'm waiting until I turn 65 before I'm fast enough to go after a BQ. Regarding Zone 1 and 2, I definitely found increasing training volume here made me faster. And if/when I can do speed work the recovery time is much shorter too. Do you do any specific speed workouts (other than threshold or tempo runs)? Too true about peoples' paces on Strava, etc. This summer I did 60% of my runs on trails - getting off the road really made a difference in injury prevention. My weekly "hard" run was 90 minutes on a fairly technical and hilly trail (it was more of a fartlek run). I could brag about 12 min/mi pace at 85% MaxHR on Strava. I don't recall where I read this, but I like the saying - Your body only knows effort and time. Pace and distance are only in your mind. (or something like that) Thanks for the nice compliment on my prior post. Were you over in the RW forums before they got shut down?
This will be my first NYC Marathon. One of my friends also qualified with a half marathon so I won't be traveling alone. A few others are going to enter the lottery and hopefully get in.
Honestly, I don't do any speed workouts. The Friel Test and the end of the Hadd Tests that I plan on doing with my friends will be the first true speed workouts I've done in months. The only real speed workout that I've done in the last year was the Find MaxHR test. I was really, really surprised how fast I was able to run during that last 2 minutes where you go all out. Good fun!
I've also done some trail running and I think you are right about it helping prevent injury. I felt like working more muscle sets just made me feel stronger and less prone to injury. I don't care at all if I'm running 12 minute miles over those trails either because the trails are beautiful and it's really fun to run on.
Yes, focusing on Effort/Time was really when everything started clicking for me. Maybe not for everyone but definitely for me! Even in races.
No, I wasn't on the RW forums. I found this forum looking for information on low heart rate training after reading the Maffetone white paper. So glad I did too. I've learned a lot here and read some really interesting stories.
This will be my first NYC Marathon. One of my friends also qualified with a half marathon so I won't be traveling alone. A few others are going to enter the lottery and hopefully get in. Honestly, I don't do any speed workouts. The Friel Test and the end of the Hadd Tests that I plan on doing with my friends will be the first true speed workouts I've done in months. The only real speed workout that I've done in the last year was the Find MaxHR test. I was really, really surprised how fast I was able to run during that last 2 minutes where you go all out. Good fun! I've also done some trail running and I think you are right about it helping prevent injury. I felt like working more muscle sets just made me feel stronger and less prone to injury. I don't care at all if I'm running 12 minute miles over those trails either because the trails are beautiful and it's really fun to run on. Yes, focusing on Effort/Time was really when everything started clicking for me. Maybe not for everyone but definitely for me! Even in races. No, I wasn't on the RW forums. I found this forum looking for information on low heart rate training after reading the Maffetone white paper. So glad I did too. I've learned a lot here and read some really interesting stories.
I think everyone has a different NYC experience, but be sure to enjoy it. Let me know if you have any questions (re - logistics). Just getting to the starting line can be half the battle.
I think we're in the same boat re - speedwork. The Hadd tests were the fastest I ran during my 2015 spring cycle for my Half. But it's also pretty cool to let it go and see what you have!
There were some folks in the old RW forums who also trained by HR. The only one I see active in RA is Commander Keen. He hangs out in the sub 3:20 thread. I haven't been following him because... well, I'm not a sub 3:20 runner. I don't know if he still trains by HR, but when he was in the RW sub-3:30 group he nailed his training runs and nailed his marathon too.
I think everyone has a different NYC experience, but be sure to enjoy it. Let me know if you have any questions (re - logistics). Just getting to the starting line can be half the battle. I think we're in the same boat re - speedwork. The Hadd tests were the fastest I ran during my 2015 spring cycle for my Half. But it's also pretty cool to let it go and see what you have! There were some folks in the old RW forums who also trained by HR. The only one I see active in RA is Commander Keen. He hangs out in the sub 3:20 thread. I haven't been following him because... well, I'm not a sub 3:20 runner. I don't know if he still trains by HR, but when he was in the RW sub-3:30 group he nailed his training runs and nailed his marathon too.
Great thread. Thanks for all the datahol.
Both Friel and Hadd point to the lactate threshold being an important thing to know and in terms of training. I agree with that. I've experimented with Hadd, but found that it didn't produce the best results for me. I got to the marathon a bit overtrained and aerobically underdeveloped. I've tried all sorts of methods and found that training mostly at or below MAF, with just a brief period of tempos, is what got me there healthy and with great endurance. I think these running gurus complicate things (including Dr. Phil a bit). For example, Friel's LT test: how do I ascertain what is "all out" for 30 minutes? I can go outside and run all out and be spent in two minutes. And if I manage to run hard for 30 minutes, was it hard enough? Could I have run 40 minutes?
The simplest and most accurate thing is to get tested on a TM with a machine with software that measures your C02 output (RQ test). They'll tell you what your threshold is. I had it done once and it coincided with around 176 bpm or about 71% sugar/ 29% fat burning. After which there is a steep rise in sugar burning until I hit 100% sugar fairly quickly. From 189 bpm all the way to 198 MHR, it was 100% sugar. Below is a graph of that test:
One can see a clear definition of the MAF plateau (130-142 bpm) and deflection point (142 bpm, AKA my MAF), but a smaller definition with LT/AT. There's a bit of a plateau near the LT/AT that the software gave me. Though there is a change in my breathing around that point that always occurs no matter what shape I'm in. My breathing always gets remarkably more labored when I reach about 180 bpm.
Dr, Phil Maffetone has written and said often that there is no need to train above 90% MHR, as anything above it is unnecessary stress, and one gets the same workout on the anaerobic fibers at 90% as one does at 95% or higher. Those type 2 anaerobic fibers are kicking in extensively once you reach and pass the AT/LT. There are Type 2 fibers that kick in at the MAF, which are responsible for the increase in sugar burning. These fibers are probably the ones that can become more aerobic.
I've tried a lot of things over the years, and I've determined that for whatever reason, if my speed at MAF gets faster, so will my speed at LT/AT heart rate. For me, there is no need to do anything more complicated than train at MAF or below for a period, building volume , then bring in some tempo runs around the AT/LT for sharpening, then get to racing with nothing but MAF heart rate in between races. If running at MAF heart rate or below, my anaerobic speed (at LT/AT) gets faster, then there is no need for me to do any intensities between MAF and LT/AT, except for when it's time to sharpen with tempo runs (which help mentally as well) for a brief period.
I've also determined, for me, that a lot of training methods that include a lot of above-MAF training time work, until they don't. I'd suddenly run into sleep problems, overtrained legs, etc.
I think Friel and Hadd point to something important. If you know the general area of your AT/LT then you have a clue about what effort to train when one brings in tempo runs or intervals into training for sharpening.
There's something called a Conconi test that may or may not be accurate. The idea is to slowly build in intensity keeping track of the heart rate at each change of intensity, seeing if there is a plateau and deflection around 85-90%, supposedly indicating AT/LT. I've tried it awhile back and saw a small plateau around where my RQ test indicated it was. Also, in my own test that I created, I added in paying attention to changes in breathing and sensations. There is change around MAF--just need a little more air for some reason---it feels a tad more stressful. But there is a huge need for air once I hit and pass the LT/AT. Stu Mittleman, the great endurance runner, also urges athletes to become aware of the changes in their bodies as they increase intensity.
This long-winded post I hope isn't too complicated, as I'm sort of saying that I like it simple now. 95% of miles at MAF or below, bring in some tempo not exceeding the AT/LT heart by too much, and always listen to the body.
Man, this thread is really full of good information. I think jimmyb makes some excellent points.