Intervals
 

I have some questions about intervals as I have no real hills to speak of that are on a close ride.

1. How long should they last?
2. How much time should be in between each one?
3. How many?
4. What percentage of max should be a reasonable heart rate goal?

I am assuming that the ride has a warm up period and a warm down period when intervals are done.

The answers to your question depend a lot on what you're trying to do and where in your fitness you are.

For example, in my training program I might do high gear, slow cadence intervals on Monday and Thursday. 5 minutes for each interval, 5 intervals in an hour. (5 minute recovery between intervals) On Saturday, I will do a 20 higher cadence interval at ~86% of my max heart rate.

Later in my training, I might do a few 1-2 minute intervals at ~90% of my heart rate with 5 minutes recovery in between.

But these are only examples. It would be best to formulate a training plan made for you and your goals. There are some great books on the subject at the bookstore or library. Joe Friel, Chris Carmichael, and others. Or you can get a personal coach. Do a web search or go ask at the local gym.

Good luck!

Az

I hear an echo... ;)


The first step should be to find out your true max-HR. Equations are off by +/-10% which will be completely out of range for target zones unless you know your true max-HR. Do the two common tests, the treadmill-running test and the biking test. They are short efforts of less than 5-minutes with increasing intensity until you hit max-HR. Most people can get 2-5bpm faster on the biking test.

Once your true max-HR is determined, you should then find your LT-lacate threshold. This too needs to be dertermined by testing. The 2x20 test outlined above is a good procedure. Be aware that LT is a muscular limit based upon exertion level and measuring HR is just a proxy indicator. Kinda like using the tachometer on your car to indicate speed, it depends upon the gear you're in. But, finding an approximate HR where LT occurs is good enough for your for now.

Once you've found max-HR and LT, we can move on to intervals. There are many varieties and different interval workouts. The ones I've found to give most benefits are defined as follows (anaerobic intervals):

"An effort above LT, but below max-effort (sprint) of a fixed time-interval, such that HR maxes out by the end of the interval"

Obviously any effort above LT will result in a rising HR, if you can hold that HR, then it's below your LT. The most basic interval is a 1-minute interval. You'll be doing this at 95-98% of your max-effort (it'll be just below a 100% sprint effort). Something that you can hold for 1-minute at a steady constant pace, say... 25mph. During this minute, your HR will steadily increase until it hits max-HR by the end. The practice is to learn to pace yourself so that your HR maxes out at exactly the same time as the 1-minute interval is over. It may be 25mph, it may be 23mph, etc. depending upon your conditioning.

Then rest until HR recovers to 65-75% and repeat. Do 5 1-minute intervals, then go home.

Another type of interval workout is a pyramid set where you do 1-2-3-2-1 intervals. Start out with the 1-minute interval like before. After hitting max-HR, rest, spin-easy until you get down to 65-75% max-HR, then do the 2-minute interval. This will most likely be at 93-96% max-effort. Recover, then do 3-minute, which will be about 90-94% max-effort. Rest, then 2 then 1-minute intervals. Takes about 30-minutes, then go home.

There are other kinds of workouts above LT that are more appropriatedly called tempo or fartlek workouts. Aerobic intervals are done right at your LT and needs to be at least 20-minutes. Hillclimbs are good examples of this kind of interval. These workouts have different physiological goals such as recovery or stamina. Anaerobic Interval IMO, are to raise LT, the steady-state maximum you can hold for a long time that's the balance between muscular output and cardiovascular supply of oxygen.

DannoXYZ,

Yeah, I thought it really was a different question after I asked it and so I posted a new thread. It is really nice to have so many brains to pick and opinions to consider. I appreciate your input.

Thanks,

ho hum

You're welcome, good idea on making a new thread to not mix up the old one. :) Do a search here for "sprints intervals" and you should get all the details you need. Be careful of getting caught in no man's land of training... ;)

There are a number of things in your post that don't agree with the usual advice from cycling coaches. I suggest doing a lot of reading in the cycling training books (written by cycling coaches) you've recommended elsewhere and try some Googling about LT training.

First of all, virtually any good cycling coach now days does not plan training based on max HR. LT is the preferred basis, whether you're going by HR's at various levels of blood lactate, or percentage of power produced at LT (or something very similar to LT). MHR is a poor choice because one person's LTHR could be 80% of MHR, or 75%, or 90%, just as their VO2max could be at various % of their MHR. Other coaches will virtually ignore HR or lactate and go by the amount of power (watts) produced by the rider for various periods of time, e.g. max one minute power, max 5 minute power, max 60 minute power, etc. and then use these power levels to establish appropriate training intensities. The might say, do a 2 hour ride with 2x20 minutes at your 60 minute max power.

HR will almost never max out during an interval (especially during an interval as short as one minute), nor should it. It will reach a maximum number (maybe this is what you meant) but aiming at your actual MHR is pointless and counter-productive, mainly because this intensity is so high that the amount of training that can be performed at that intensity gets limited, and being that far above LT or VO2max generates a relatively small amount of training benefit. Possible exception might be during the last 2-3 weeks before championship events.

Recovery time can be to a pre-determined HR, but the better choice is to recover for a certain period of time because some of the (good) things happening during recovery lag far behind the decrease in HR. e.g. regeneration of creatine phosphate stores, decline in blood lactate levels to levels below LT, etc.

Pyramid intervals are best saved for peaking periods, or near peaking periods. Don't expect to use them for more than 6-8 weeks (one time per week) because you will hit a plateau. The usual recovery period for these intervals is to use the same amount of recovery time as the work interval, or a certain ratio of recovery time to work time. The recovery time has an influence on what you will actually be training during the work intervals. For example, if you want to get really good at one minute intervals then recovery times must be several minutes. (e.g. 3:1 to 6:1 ratios) If you are trying to improve ability at LT then the intensity during the work intervals will be +/- 10% of LT and the recovery periods would be kept relatively short. e.g. half as long as the work interval up to twice as long as the work interval.

Next, "tempo" intervals are done BELOW, or at LT, not above. Typical intensity is a HR 5-15bpm below LTHR, power (watts) would be 20-50 watts lower than LT power. These intervals are probably the most efficient use of time for improving ability at LT if a person is training say, more than 5 hours per week. If they're training less then that then the insitensity could be higher, but it would rarely need to go more than about 10bpm above LTHR, or watts more than 10-15% above power at LT.

You say that anaerobic intervals are to improve power at LT. This would be a relatively poor way of accomplishing this objective unless training time is less than 4-5 hours per week. (If training time is less than 4-5 hours then interval training near 110% of LT [approximately VO2max] will be a likely approach.) Better to focus on aerobic intervals in the "tempo" range described above. The total time for the work portion of the intervals could be 15-180 minutes, depending on your ability and/or objectives. The length of each could be as short as 6 minutes or as long as 30+. Rest periods don't need to be more than 3-4 minutes. Most racers will do some on the flats and some on hills to work on slightly different objectives.

Finally, your definition of LT is a bit misleading. You can do some searching/research that will show you that supply of oxygen is rarely a limiter of performance, particularly at intensities near LT. When you go up near your VO2max and beyond then it might be a limiter, but not at LT unless you're ill or trying to split hairs.

There are a few good definitions of LT available, but generally, it is the balance point where the amount of lactic acid (blood lactate) being produced is the amount of lactic acid (blood lactate) being consumed/reprocessed by the body. If you go a little harder than LT you are producing more lactate than your body can "consume" and you will start to feel the pain in your legs (or whatever muscles you're using).

The (statistically) average amount of blood lactate at a person'sLT is 4mmol, although some people (coaches, etc.) use 2mmol for their definition. Not a problem really, because they incorporate exercise intensities based on the different blood lactate levels and things come out about equal in the end. e.g. the person who uses 2mmol, would describe "tempo" training as 100-110% of LT, whereas the person using 4mmol would probably describe it more like 90-100% of LT.

It is important to understand this definition because it will help you better understand the appropriate training to improve your ability at, or near your LT. I know that folks with a background of training in gyms like to emphasize muscular strength and that's fine, but for improving ability at your LT, muscular strength is a relatively minor component.

For example, pro racers who can produce relatively high power at their LT for long periods tend to be rather weak when tested for muscular strength. Less accomplished racers can see improvements of 10%, or maybe even 30% in the power they can produce at LT as a result of training, but their muscular strength is often unchanged or even lower than it was before the improvement.

-Warren

Do you see now why I suggested that you start out with the simple method?

Sorry grammatical error on my part, I define intervals as anything above LT (I use 3mm/l). Anything below or at LT is what I would call a tempo or threshold workout. There are so many different ideas out there and we're really talking about different things. That's why I try to define my terms first.


Nope I never said that... ;) If anything, I say it's to improve and lengthen the time you can hold any particular amount of effort or power-output.


I never defined LT, I referred to the 2x20 test to find it. I just said that using HR to indicate LT is not accurate. Let's say we have someone reaching my definition of LT of 3mm/l and they're able to generate a 200w output. They can achieve this LT at 155, 160 or 165bpm depending upon gearing and cadence. Bigger gears/lower-cadences tend to reach LT at lower HR while lower gears/higher-cadences tend to hit LT at higher HR (on the same person). That's why I was saying that HR is only an approximate proxy-indicator of LT.

Cycling performance is always about balancing the muscular system with the cardio. In general, LT is the first limit and is below VO2-max using HR as an indicator.


In looking at the balance between muscular and aerobic systems, it will be different for a beginning rider vs. a seasoned pro. Ultimate max-power output is the gauge of the muscular system while watts-output at LT or VO2-max may be a better measurement of the balance. Now the max-power will be significantly higher for a racer or pro than an enthusiast. That's the purpose of my assertion for anaerobic intervals, to build and train the muscular system. This is a bigger limitation for beginners than pros, so the training focus must be different.

Increasing muscule strength won't make a big difference in watts-ouput at LT or VO2-max, but it does make a huge impact on stamina and endurance. McEwen or any of the pros that can put out max 1500-watts+ can cruise all day around their LT of 350-400w, or whatever that may be. A beginning rider on the other hand, who can only put out 400w max is not going to have much endurance while pushing out 200w at their LT. It's the percentage of max-power generated at LT that I find anaerobic intervals to be of primary benefit to the beginning riders as they are never really limited by aerobic capacity. By raising their max-power output, they'll be able to maintain LT for much longer periods and get more benefits from tempo workouts (done on some other day). Which then works on the other half of the balance, the aerobic system.

Using HR above LT to monitor intervals doesn't work well because it will steadily increase at steady muscular efforts above LT. You can't say, "Ride 1-minute at 10% above LT, 170bpm" because they'll start out fast and go slower and slower to maintain that same HR. That's why for the beginners, using intensity and time is a simple way to measure anaerobic intervals, you don't even need a HRM. Simple baseline intensity to gauge is an all-out 100% max-sprint effort. Then backing off that to 95%, 90% effort is an easy way to fit it into a timed interval. If you still have some juice after a 1-minute interval at 95% effort, then increase effort to 96%. I define the end of an interval as complete exhaustion where you can go no more (max-HR may actually occur after that). Practicing steady-pacing and managing intensity to time the point of complete exhaustion to coincide with a time-limit is an easy practice for beginners to pick up.

Here's a good article on LT and HIT: Am.J.Physiol - Effects of HIT on lactate and H+
J.AppliedPhysio-Response of VT and LT to continuous and interval training

Okay, I have a heart rate monitor. I am an old guy who lives in a flat place with lots of wind and 3 days a week I can spend riding 2-2 1/2 hours each day that I ride and still manage all that needs to be done. As much as I would like to do more, this is what I can do with the constraints of my life.

I don't have any idea what my LT threshold is. I know I can sustain a heart rate of 150 over three miles in 9:33 seconds and a second three mile at 'tempo' with the same heart rate of 150 in 10:10. These are done on the level with no wind to speak of and after I have warmed up a few minutes. I did this after reading Carmicheal's work. These rides are done at a cadence of 80-90 RPM.

So, today I started a little 'tempo' program. Here is what I did for my workout:

1 mile as hard as I could sustain it.

1 mile at an effort that was less than my max but one that I could sustain after the max effort.

1 mile at a 'pushing pace'.

I then repeated this three times today.

My warm up was about 3 miles and at a pace of about 65% of Max HR. My warm down was 3 miles with a quarter mile as hard as I could go at the finish.

I don't know that my heart rate monitor really helped. I could only go as hard as I could tolerate no matter what my monitor said. It seems that 150 was all I could sustain on the Carmicheal type test and that is all that I would sustain today.

Yesterday, I did one minute sprints. My heart rate only got up to 150 and I felt like I was pushing as hard as I could sustain.

A "tempo" workout would by most coaches' definition of tempo be much easier than what you did, with longer work intervals than what you did. What you did was more like VO2max training since that's pretty close to the intensity you were using.

If 150 is the HR for your 10' TT then your LT HR is probably about 0-5bpm below that-call it 145 for now. If you were super-fit then your LT would be even lower than 5bpm below the rate you could sustain for about 20 minutes-probably more like 5-8bpm.

Tempo training (medium endurance) is typically done at about 8-15bpm below your LTHR. So try using 145 for your LT, and tempo intervals at about 130-140bpm. Try doing 6' at this HR range, rest 4-5', repeat 2 more times. If you had no trouble doing this then and one more interval and next time out try 3x8' at 135-138'ish bpm. Gradually add time to the length of the intervals, and/or add more intervals.

Here's some things to remember, since you have a relatively long ride available with enough days between them for pretty much complete recovery you can go pretty hard in each ride. You can get benefit from doing VO2max intervals like you did, but as you found out, you'll only be able to do about 25-30'' of good training. You would accomplish more by utilizing some (work) intervals that you can sustain for (eventually) an hour and more of total time, so work at the (near) maximum intensity that you can for a relatively long period of time.

-Warren

Warren wrote: You say that anaerobic intervals are to improve power at LT.

Danno replies: Nope I never said that... If anything, I say it's to improve and lengthen the time you can hold any particular amount of effort or power-output.

Your exact words above were: "Anaerobic Interval IMO, are to raise LT, the steady-state maximum you can hold for a long time that's the balance between muscular output and cardiovascular supply of oxygen."

Looks to me like the same thing. Perhaps it will help if you define what you mean by "Anaerobic Interval" since any interval over 20" long will rely on some energy produced by the aerobic system and after a few minutes of these "anaerobic intervals" you will likely be generating a higher percentage of the energy used from aerobic sources than from anaerobic sources.


And again, your definition of LT is really not correct. One's ability to ride fast at LT is not only a result of "muscular output" and supply of oxygen is nowhere near a lmiting factor at LT. Do a google search on "lactate threshold" and you will find no mention of a description like yours. Instead, it will be something like, the maximum sustainable effort at a balance point where lactic acid production equals lactate consumption or resynthesizing.

The things that are limiting ability at LT have much more to do with one's ability to generate high power while buffering the effects of lactate (actually it's hydrogen and ph changes). When you really understand this difference you will probably have a better understanding of the most effective ways for a cyclist to improve their ability at their LT.

Danno wrote: "I just said that using HR to indicate LT is not accurate. Let's say we have someone reaching my definition of LT of 3mm/l and they're able to generate a 200w output. They can achieve this LT at 155, 160 or 165bpm depending upon gearing and cadence. Bigger gears/lower-cadences tend to reach LT at lower HR while lower gears/higher-cadences tend to hit LT at higher HR (on the same person). That's why I was saying that HR is only an approximate proxy-indicator of LT."

It's a straightforward thing to have a person testing for their LT to use their normal pedaling cadence and then the number seen during the test will in fact be a usable proxy for their LT in a steady state effort.

Danno wrote: In looking at the balance between muscular and aerobic systems, it will be different for a beginning rider vs. a seasoned pro. Ultimate max-power output is the gauge of the muscular system while watts-output at LT or VO2-max may be a better measurement of the balance. Now the max-power will be significantly higher for a racer or pro than an enthusiast. That's the purpose of my assertion for anaerobic intervals, to build and train the muscular system. This is a bigger limitation for beginners than pros, so the training focus must be different.

You have assumed too much about the ability of pros. Most road pros have relatively weak muscles. Most couldn't do a real squat of even 300 pounds. The main reason they can produce more power than amateurs is because of their ablity to produce relatively high power with less production of lactate (hydrogen and ph issues) and because they are superior at buffering its affects. They do this with aerobic training and most do very little specific strength training, and when they do, it is almost always done on the bike with many repetitions so the aerobic energy systems are being stressed at the same time. For example, a fairly "strong" guy like Tom Boonen does some of his strength training with intervals that use a large gear, on a hill, at cadence of 45-50 rpm's for work interval totals well beyond 25 minutes. But the real reason he's doing these intervals is to improve his ability to haul himself over mountains and for his sprint-not for his ability to produce more power at his LT.

Danno wrote: McEwen or any of the pros that can put out max 1500-watts+ can cruise all day around their LT of 350-400w, or whatever that may be. A beginning rider on the other hand, who can only put out 400w max is not going to have much endurance while pushing out 200w at their LT. It's the percentage of max-power generated at LT that I find anaerobic intervals to be of primary benefit to the beginning riders as they are never really limited by aerobic capacity. By raising their max-power output, they'll be able to maintain LT for much longer periods and get more benefits from tempo workouts (done on some other day). Which then works on the other half of the balance, the aerobic system."

Again, you've made some incorrect conclusions. Using your example of McEwen. Let's say he does have one of the highest max power outputs in the peloton. Then how come he's not very good at all when it comes to the TT's that indicate who can produce the most power at their LT? He doesn't climb all that well so he doesn't have high power to weight ratio at his LT. He doesn't TT well on the flats so he does not have good absolute power at his LT.

Now, who does do really well when it's time to show who has the most power at their LT? It is the guys with relatively low max power-guys like Armstrong who have max power fairly close to 900-1000 watts, not 1500 like McKewen.

Now if you have a beginner who's max power really is only 400 watts, then yes, do some strength training because that's abnormally low.


Danno wrote:I define the end of an interval as complete exhaustion where you can go no more (max-HR may actually occur after that). Practicing steady-pacing and managing intensity to time the point of complete exhaustion to coincide with a time-limit is an easy practice for beginners to pick up.

This is not good. For one thing, beginners shouldn't be going to failure. It's too hard for them and the amount of time they'll need afterwards to recover will inhibit further training. Aerobic training really needs to be done 4+ days/ week and that won't be possible if all intervals go to complete exhaustion. Aerobic training should not just follow protocols intended for muscular training in a gym because the volume, frequency, and intensity needs for maximum improvement over the long term are much different in the aerobic sport of road cycling.


Danno wrote: Here's a good article on LT and HIT: Am.J.Physiol - Effects of HIT on lactate and H+
J.AppliedPhysio-Response of VT and LT to continuous and interval training

Hint... never rely very much on studies of untrained people to guide you for the training of trained people because there are many important differences in their needs and optimal approaches for improvement over the long-term. Also, studies that take place over a short term like 8 weeks are not always applicable for people involved in training that continues for many months.

In these two studies high intensity training was used for improvements but a good cyclist knows that training like that described in those studies is not sustainable over the long-term and will lead to plateaus at levels below what one can reach with a more long-term approach to training. Appropriate training is intended to build over many months. Normally it is only during the last 4-6 weeks before a peak event (e.g. championship race) when the athlete will do maximum effort intervals several days per week. Do reading on "Periodized training for endurance athletes" to learn more on this.

-Warren

Okay, I've been thinking... I rode 60 miles on Thanksgiving day with a slight headwind on my hybrid because I'd broken my road bike. I did it in a miserable 4 hours and 30 minutes. My heart rate averaged 134 BPM for the day's ride.

I then rode 26 miles the next day on the old hybrid, felt good and had little soreness. Am I not pushing myself hard enough on my intervals and maybe need to push harder on my 3 mile time trial and see what I can get for a max heart rate? Given these numbers, I guess I am not doing too bad for a 260 pound guy.

What would you say, is my level of fitness poor, fair, good, excellent, superior?

I am just wondering as I live in a small place and there really isn't anybody to ride with and I've been invited over for a group ride in Las Cruces and I'm afraid of getting chewed up and spit out.

Very good point. 134 for 4 hours means your LT will probably be 15+bpm higher. It is quite possible that you didn't go all that well in your 3mile TT's and the HR number that resulted was a bit low, but if the effort was maximum then the number is what it is. Add a few bpm to the ranges I mentioned previously and see how that goes.


At the risk of not being diplomatic-takes too much time... 260 pounds is never excellent fitness unless you're a football player. I'm guessing that you haven't been training all that long and this is probably the reason why you couldn't push yourself (relatively) very hard during your TT tests. Try doing the tempo rides for 3-4 weeks, maybe do some 1 minute surges now and then when you're still feeling good in the last hour of your long rides.

Then repeat the test when you're well-rested and you've done a one-hour prep ride the day before. I think your HR will go much higher but the best training HR for your tempo intervals will probably still be around 140-143bpm.

FYI, training for hours a week at "tempo" pace will do great things for your fat-burning ability. A little caffeine before long rides would probably help this too.



Just make sure it's relatively flat, at least 2 hours long, draft as much as possible, and know how to find your way back to the car. :-)

-Warren

Warren,

Yeah, yeah.... always pickin' at the fat kid....:-)! I am 6'3", fried my knee in 2001, ruptured my patellar tendon. I have dislocated my knee cap 5 times on that same knee and dislocated the left one once while I was screwing around and wrestling with the old roomates. I've had three surgeries on it, a blood clot, a partial tear to my achielles tendon all on that same right leg. I don't run. I wear a pedometer at my work and walk 13 miles every day at work (I am a nurse) and yeah, I've only been riding hard since July, when I weighed in at 290. I am a big guy, played a little football, could break things and was told to get on a bike for the sake of my knees and type II diabetes.

I'll kill you (or myself) on a downhill!

Hey, I'm 211 pounds so it may come down to a test of aerodynamics!

WRT to other stuff, you're doing really well. 30 pounds since July is great! Doing it the right way too. Very good! 30 fewer pounds to carry around for 13 miles a day, I can only imagine how good that feels. 20 more by next July? Even better.

Considering your knee and weight, etc., if you haven't already, a proper bike fit with an expert may be helpful. Ask questions at GOOD bike shops in your area.

Don't overdo the intensity. Work up to about 2.5 to 3 hours per week (gradually) for that range 5-15bpm below your LT and by next July you might be asking people about the local weekly time trial races. :-)

-Warren

Hi warren,

Interesting post. I've got a couple of follow up q's... I'm no physiology major so dont tear me to pieces!

So the buffering effects you're referring to are basically anaerobic capacity? i.e. ability to transport blood lactate away?
If so, how would they improve this with aerobic training? I would have thought training above VO2 max would be the zone that would be most beneficial?

If oxygen isn't the limiting factor at LT, where does all the lactic acid come from?

Is it theoretically possible to raise the lactic threshold to the Vo2 max level? i.e. only oxygen uptake is the limiting factor?

and a couple of practical questions.. (thread probably hijacked by now, sorry bruv):
how do I measure power output on the road? I saw a bit about perceived effort in this thread, is that the way to go rather than HRM? Are there power monitors available (suppose you'd have to measure drag and friction somehow).

And finally (thread definitely hijacked):
As a beginner should I be concentrating on raising LT or vO2 max? or even these at submaximal levels..?

Thanks a bundle,

*cough,

Be my guest, I'm learning too!

ho hum

Yikes! It's 10:30p.m. and I'm racing tomorrow!

Lactate buffering occurs as soon as you start riding. Actually even when you're at rest. Even getting out of a chair produces some lactic acid but your body can buffer/absorb/resynthesize it without you even feeling it.

You have basically three typed of muscle fiber. Slow twitch (type 1), Fast twitch type 2a, and fast twitch type 2b. Type one is for endurance and efforts that are not too hard. 2a is essentially stronger and is called upon when the force or effort required exceeds the capacity of the type 1. Type 2b is mainly for max efforts less than 20" (approximately) in length. If you ride relatively easy you're using pretty much only type 1, A little harder and the 2a's kick. Go real hard and all three fibers are called upon, but the 2b's will fatigue fairly soon and leave the work to the other fibers. Then the 2a's get so fatigued they can't help much anymore and the 1's are left to do what they can. Think about some various intensities of efforts and try to relate it to this paragraph.

Type 1 produces almost no LA and does a good job of handling LA produced in other fibers. 2a produces some LA and can absorb some too. 2b produces lots of LA and can not help with buffering (it can in a small way but relatively speaking 2b is not much help).

The LT is basically the point where the level of LA is high, but handled by the 1 and 2a fibers. Any harder and they can't handle it alll and LA levels continue to rise until you're forced to stop the effort.

So, if you develop the ability of your 1 fibers to a relatively high level you can go fast without producing much LA. So called "base" training is key. Intensity levels at least 20bpm below LT. (don't just go real slow because you need at least a certain level of stress to cause the body to improve its abilities.) There are many things developing from this training like enzymes that help with certain processes, muscle fiber growth, increased density of capillaries, etc.

You can also develop your 2a's so that they can contribute to the efforts without producing excessive amounts of LA. The most effective way to improve these abililties is as much time spent as possible working these fibers. Therefore, you can go too hard or the time will be cut short. I never measure miles of training-only time spent at different intensities because it's the time at certain intensities that leads to improvement.

If you ride at level just below LT you're using 2b's and their lactate production will inhibit some of the good things you want to happen with your 1's and 2a's. Save this training (mainly) until after you've developed the 1's and 2a's to near their capacity, or you need to get ready to race in a month. Once you start doing lots of efforts above threshold your improvement of the 1's and 2a's will not be as rapid as before.

Lactic acid isn't produced by oxygen. Oxygen into your muscles is a limiting factor but this limit comes from an underdeveloped transport of the oxygen into the muscles, not because of a meaningful lack of oxygen in the bloodstream. There's plenty in your blood (until you get near VO2max). The trick is getting into the places in your muscles where it's needed. the blood in there also needs to help carry away waste products that inhibit the work you can do. 2b fibers have almost no blood supply in them compared to the relatively high amount of blood within type 1's and also 2a's.

Raising LT to near VO2max? no. But I don't really know the answer as to why this is. What we can do is develop our systems so that they can withstand efforts near VO2max for longer and longer periods of time. I do points races on the track and this is an important ability to have. I'm not the best at it but at events like the National and World Championships I've done 20+ minutes almost continuously (26 minute races) at a level (avg HR of 185-186, MHR of 199) not too far below VO2max and other guys are even better at this than me. During these races adrenaline masks amazing amounts of pain.
The training we do for this is very hard, must be done carefully, and only after many, many hours of efforts preparing for it.

Measuring power on the road has gotten very accurate, but it's still expensive. Essentially, the devices measure the force applied to the pedals (drivetrain) times the frequency of this force (pedaling cadence). Powertap, Polar, SRM, and ergomo are things you can google on about the devices. I use the Polar because it was only $300 more than just the HRM. Without measuring power, and even when measuring power, Perceived exertion (PE), and HR can be your guides. If you have some flat areas with minimal wind then speed can measure progress too. How you feel in races will tell you a lot too. I consider all 5 of these things to measure my own progress. An occasional lab test measuring blood lactate levels too.

Beginners... For general fitness you'll do best to concentrate on increasing your abililty at LT. Then again, maybe you just want to be able to ride longer but at easy pace so LT doesn't really matter. If you're going to try racing, LT is the best thing to focus on because that is what you'll rely on far more than anything else to get you to the finish feeling good enough to sprint. You don't get to sprint if you don't get to the finish.

Sorry about the typos. I'm tired.

-Warren