Training Specificity Part 1: crits and sprint metabolism

The capacity of sprinters?  It takes more than just a killer sprint to win a race (like positioning, but my power meter doesn't record that), we need to consider other factors.  I will do so by considering some interesting power metrics, but they'll tie back into well known exercise physiology, if not by the end of this post then in the next one.  Today we look at neuromuscular power.

As always, charts are from WKO4, build 260.  Unlike usual, I will mostly focus on my own data.  Not for ego, but because I coach no track racers with power data, I end up as the purest sprinter for whom I have data.  That is to say, I'm the only athlete whose WKO4 phenotype didn't change from "sprinter" to "all-rounder" during base training.  To be fair, I'm not even a great sprinter.  This is my power curve from 2015, a year in which I sucked at criteriums.

In crits, repeated accelerations are arguably the most important factor.  This year I started training that ability and it's paying off.  The following is the power readout from two criteriums last sunday (I doubled up).

The course was 0.6 miles with two gentle corners and two right angles.  In each race there was no more than 6 minutes of coasting.  I did over 90 laps of the course this day, and the routine went: turn, accelerate, gain position, repeat.  You can tell that to haul my 163lb bulk back up to speed I had to hit about 600-1000w repeatedly.  The 1200w peak in the first race was an attempt to establish a break, and in the second race it was snagging a prime.

The highest average power for 5 minutes was less than my FTP.  Since FTP can be held for an hour, 5 minutes isn't really a big deal.  I selected a random 20 minutes from the first race and looked at the normalized power: 285w, right near FTP.  Random 20 minute chunk from the second race: 275w NP.  This is where the training specificity principle comes into play.  In order to meet the demands of an event, you have to prepare for them in ways that replicate those demands.  Hence this workout:

Since races are about 45 minutes long at the non-elite level, that workout is 40 minutes of 10 second sprints, one every minute.  Besides matching the neuromuscular demands of a criterium, the normalized power of this workout was 297w, over FTP by a few watts.  Excellent criterium specificity.

I've been learning that one mark of a sprinter or pursuiter (besides the obvious) is the ability to create normalized powers well over their FTP.  If you're well steeped in traditional power analysis, you may be thinking that NP represents the physiological demand if you had been working at a steady state, and you're right.  This doesn't mean that if you can normalize a power that you can recreate it steady state.  Believe me, I've tried.  So let's get into why.

The metric I've been working with is 1 hour NP way over FTP, which really only applies to sprinters and pursuiters, and modestly to all-rounders.  How does this happen?  It comes down to stored energy.  As you can see from the sprints above, I'm pretty good (but not amazing) at recharging PCr stores in my muscles, hitting between 950-1050w consistently.  Were I any better at this I would have normalized a higher power, or perhaps there's an optimal rest-sprint ratio to maximize NP for the workout.  Doing 12 sprints in an hour also normalizes 300w for me while hitting about 1250w each time.

What's this have to do with stored energy?  Phosphocreatine is recharged from two molecules that have higher stored energy, phosphoenolpyruvate and 1,3-bisphosphoglycerate (PEP and 1,3BPG).  PEP is shunted off from the TCA cycle and 1,3BPG is a glycolysis intermediate.  As the reaction ADP+PCr->Cr+ATP proceeds for each sprint, we can safely assume that the PCr levels in a muscle cell are well below normal levels.  This increases the demand for PEP and 1,3BPG and thus the glycolytic and aerobic systems.  See here (page 5) if you're rusty on your standard free energies and why this works.

Glycolysis is probably more taxed in sprinters with good anaerobic power since glycolysis can create energy more rapidly than aerobic metabolism.  Looking at it another way, because the normalized power a sprinter can create is much higher than FTP (here representing the aerobic ability of the athlete), the difference must be made up by stored energy in the form of PCr and glycogen.  This ability to rapidly mobilize non-aerobic energy (during and while recovering from high intensity efforts) is why sprinters and pursuiters can't simply put out their normalized powers at a steady state.  It should be obvious that FTP is also important for criterium racing.  Greater demands on stored energy during the race means there will be nothing left for the final sprint.

Next post will look more closely at the ability of some sprinters and all pursuiters to chew through glycogen at rapid rates.  I'll also look more closely at a couple cases of 1 hour NP > FTP.

Race prep: off season training targets

There are a few different sides of a coin when it comes to early season training, which maybe makes it more like a die.  I like to pick two things for an athlete to work on at the same time, and not just to shore up the coin analogy.  Over the winter with lots of trainer time, the obvious priority is FTP (because I don't like to assign 4 hour trainer rides).  The other thing is dependent on the athlete and their goals.  This will go through the process for a few athletes as well as the results.  Any charts are from WKO4, build 255.

Athlete 1, CX focus.  Goals: FTP and force production

The first person we'll look at has been doing road training for about two months now, and after finally having gotten a power meter in late December, his needs are exactly what I expected they would be but there's not deep historical data to compare with so I can't show you any pretty graphs illustrating progression, but here's the graph of his weekly peak values.  The first set of points in the 12/28 week is the testing protocol to establish baseline maximal values.  He has not done a maximal 1 minute effort since, but I doubt the anaerobic power has much increased.

This athlete's main focus is cyclocross, so with half a year before that racing starts, there's a lot of time to work on many things.  His slim 70kg build and tendency to ride at high rpm indicate a lot of slow twitch fibers, so the goal is to increase his threshold and muscular power, even if it means putting on weight.  These improvements will be the foundations on which we'll build his high end power for CX, but right now he needs to improve his musculature and maximal force production.  For the last two months he's been doing almost entirely endurance and tempo riding with strength training on and off the bike.  His training weeks are about 13 hours, plus one 20 hour week.

This training alone has been enough to bring up his FTP from 240w to 270w and raise his Pmax by 150w.  In just two months the two training targets are improving dramatically, and he's on track for a great season.

Athlete 2, road/stage race focus.  Goals: FTP and muscular endurance

The next athlete is a 61kg road racer who excels at climbing.  She's been training since October and, like the previous athlete, has a naturally high cadence but felt a lot of muscular strain and fatigue while climbing steep grades.

The last couple months have seen her intervals build from 3x10' to 3x20' at threshold.  In addition there was a lot of strength work in the gym and low cadence climbing on the bike, but it was different from Athlete 1's program.  We focused on muscular endurance for climbing, but it had the benefit of increasing her anaerobic power as well since the lifting was similar in demands to a short anaerobic effort.  Here's the graph of her build since October.

We can easily see that she's natural athlete, able to maintain high workloads and recover well.  Whether doing endurance, sub-threshold, or threshold efforts, her FTP has built from 210w to 250w.  The purple dots are 20' maximal power values, and they show steady progression upwards.  Also worthy of remark is that she did no anaerobic work until December with her first 1' power test (450w) around 20 December, which was already a full 100w better than her 2015 best.  After some time off in January for exams, she spent most of February maintaining the weight lifting and reestablishing her endurance, and her 1' power is still the same.  In terms of meeting the goal of increased muscular endurance and power, she is able to handle VO2max hill repeats at low cadence (up to 40 minutes of climbing) and her Pmax increased from 680w to a high of 820w in December.

Athlete 3, road race focus.  Goals: w/kg and endurance

This last athlete went through a real transformation in the last couple months.  His goal was to excel in road racing, so his goals were increasing FTP and losing weight.  In October, he was 10kg heavier, with a 1400w Pmax, 700w 1 minute power, and 280w FTP (not shown in graphic).  His Pmax dropped to 1200w, but his w/kg at FTP went from 3.8w/kg to 4.7w/kg.  This is the power curve not normalized to weight (the w/kg graph is a bit muddy with several lines on it, but this is clearer).

For the long road races he'll be doing, this is what I wanted to see.  Would he have 10-20w greater FTP if he hadn't lost the weight?  Probably, but a 345w FTP at 80kg that would only leave him at 4.3w/kg.  Fortunately his Pmax hasn't suffered as terribly as I expected, and will serve him well in reduced bunch sprints.  We've done some 3' VO2max work, but no anaerobic or sprint work yet.  It's just been burning calories and increasing threshold, and this is reflected well in this graph.  In fact, despite regular rest weeks, he spent from October through Christmas with a negative TSB, having ridden 6000 miles.  There's been reduced workload since, but it's the foundation of a successful season.

Two types of CX riders: training analysis

Not many of the athletes I coach have power meters on their cyclocross bikes, but two who do have them are quite different riders.  What follows is an analysis of the metrics I used when determining their workouts within the scope of their goals for the season.  All graphs come from WKO4, build 204.

The first rider is a 6'1 male, ~190lbs, 1500w Pmax, 21kJ FRC.  We'll call him Winston.  It was his first cyclocross season and no big goal races, so we worked on his technical abilities to help with crits in 2016 as well as his steady state power, which would be a limiting factor for him in many races as he moves through the categories.  PD curve:

The other is a 5'11 female, ~130lbs, 730w Pmax, 11kJ FRC.  Let's call her Linda.  Her big goal is winning collegiate nationals, which is tomorrow.  PD curve:

Since these PD curves show the male as a decent all-rounder and the female as having a slightly better steady state power than high end power, I should qualify this and say these are best all time efforts.  Winston is a former lifter and has lot of natural power, so during cross (he only did September and October) we worked a lot on his steady state riding so he wouldn't so heavily rely on his anaerobic reserves during racing.  Linda has very good abilities riding steady state, so we worked on her ability to accelerate and recover as well as her anaerobic power.

It'd take too many graphs to make the next point about cadence, so I'll just tell you.  Winston naturally pedals at a low cadence, and his ability to produce large torque puts him at an advantage in a cyclocross corner where the speed delta into and out of corners is large and even if you shift down twice, you're still accelerating from 75rpm.  This also takes a lot of core strength, which is another thing Winston has thanks to his lifting days.  We didn't do a lot of drills to increase his strength on the bike, so a lot of his targeted workouts were steady state to get him more used to putting out power for 40 minutes as well as getting him used to the body English of riding off road.  A usual interval workout was 45' tempo, or 3x15' sweet spot with accelerations every so often.  A technical workout would be classic 30/30/30/30s (30" sprint, 30" rest, dismount and 30" run, remount and 30" rest), a few hours of riding singletrack, or a recovery day with lots of cornering.

There aren't a lot of graphs that show an improvement in a rider's technical abilities, and since Winston's power numbers stayed steady, what I can show you is an improvement in points: first couple races were low 500s to high 400s, and his last race was low 400s (from crossresults.com).  A good and steady improvement for a first time cross racer, and already with 4 upgrade points.  Regardless, this is the weekly MMP (highest average power for specified time) for his two months of cross.

Linda's much more of a high cadence rider, a practical all rounder in terms of build and abilities.  A lot of her steady state workouts on the road show her pedaling at 95-105rpm, but in cross races the average was about 80, and it took her a few seconds out of corners to get up to speed.  She's quite thin as well, and so doesn't have large muscular power or FRC to dig deep continuously, but her steady state power and technical abilities serve her very well and allow her to ride consistently throughout a race, especially on longer rhythm sections.  Because a lot of cross is coming out of corners at low cadence, she was losing some time.  Most of her drills were a combination of accelerating from low cadence, from steady state, and pure anaerobic power.  An interval workout she did frequently was low-ish cadence threshold intervals with periodic accelerations.  There were many anaerobic power workouts, from 30" intervals to repeated 15"-2' intervals with varying amounts of rest.

To give you an idea of how effective this approach was, here is a quadrant analysis from an early season race from Linda, before I started working with her.  Most of the scatter is relatively low torque and high cadence, but there is still a very large amount of high torque, low cadence.

Next is a late season race.  You can see how the cluster shifts up and to the left.  She's still doing a lot of high cadence, low torque pedaling because it's what she does naturally, but the low cadence, high torque efforts are more repeatable and common.

Another thing Linda's long season allowed us to do was bring her to a nice sharp peak for collegiate nationals tomorrow.  The following is the graph of her build to nationals.

What this graph doesn't show is how hard she worked through late November.  Those power numbers went up, but she was feeling a whole lot of fatigue.  Linda is a great communicator, and I regularly adjusted her workouts to include less volume and intensity as the fatigue went up, so we were able to keep her riding the edge of functional overreaching without burning her out.  Even better was that we knew she would have almost an entire month to rest and maintain fitness between her last regional race and nationals.  During this time she rested, did some low intensity, high volume road riding, and did the absolute minimum amount of high intensity intervals, just to keep the legs sharp.  We can see her hitting her best power numbers of the season the week before the holiday.  When I took this screen cap I didn't have her files after Christmas, but she's been maintaining well and becoming fresher every day.

Something you may notice about the MMP graphs is the 5" power getting progressively lower through both riders' seasons.  This is something I see a lot, but it's not cause for concern.  It reflects the fatigue that cyclocross has on a rider, especially with regular racing and trying to hit those high numbers repeatedly.  Being able to hit that peak at the end of a race matters a lot in road sprinting, where freshness matters.  But like Adam Myerson says, there are no sprinters at the end of a cross race.  It's the combination of technical riding, accelerating repeatedly, and being able to maintain a high pace between those hard efforts that makes a fast cross racer.

HIIT is not endurance training for elite athletes

It's been a month since I posted, and despite being quite busy, I'm going to type into the internet void.  High-intensity-intervals-as-endurance-training is all over my usual internet haunts, specifically r/science and r/velo.

As usual, the link goes to a news article rather than the study, though the study is linked at the end of the article--a practice I wish were more common.  From the article:

Short bursts of just a few minutes of exhausting physical activity [boost] the production of new mitochondria...which culminates endurance enhancement much like more time consuming endurance training.  High-intensity exercise triggers the breakdown of calcium channels as a result of an increased production of free radicals. The muscle cells thus have anti-oxidative systems for trapping and nullifying the radicals.

Moving backwards, all cells have methods to nullify unwanted radicals, but let's recall that radicals are not necessarily bad.  Here's a primer that's long and excellent.  So the ryanodine receptor type 1 (RyR1) and sarcoplasmic reticulum (SR) are disrupted by HIT, which causes radical generation that the cell recognizes as oxidative stress.  In turn the cell makes more mitochondria.

Popularly, this is hailed as hard evidence that HIT is just as good as low intensity training.  An astute observer from r/velo notes: "To me this reads like, train like a track sprinter and become the next TT world champ."  Indeed.  Clearly that never happens, so what's going on?

All we really need to know from the study to answer this question is in the abstract, which is publicly available.  It states that the main study was done on moderately active individuals, and that in elite endurance athletes "the measured transcript levels related to mitochondrial biogenesis and endurance showed a general decrease— rather than the expected increase—24 h after the HIIT exercise."  The explanation for this is simple.  Experienced athletes spend a good deal of time activating their muscles, and any easily fracturing RyR1 or leaking SR would be some of the first adaptations that take place in order to facilitate more exercise.  Because let's face it, if your calcium machinery isn't working properly, you're going to have serious problems with muscle contractions.  To confirm this, another quote from the abstract: "the same HIIT exercise does not cause RyR1 fragmentation in muscles of elite endurance athletes."

MLSS = FTP? Plus VO2max and 20' power variability

I've been sick and NOT racing Gloucester, so I've got more time on my hands than usual to think about these things.  I started with this question: is MLSS the true functional threshold of power which, by definition, equals the maximal one hour time trial effort?

What used to be here were two paragraphs of ranting about how lab tests can't inform our training and how what we use as cyclists doesn't relate.  Then, instead of assuming my logic was infallible here in my ivory tower (which I would have done ten years ago), I looked to confirm it.  Every single study I found that tested time to exhaustion at MLSS was 50-70 minutes.  Here is a fascinating study that shows that 90% of your MLSS velocity (not power because air resistance isn't linear blah blah), give or take about 5%.  Let's talk about it before we go on.

Four subjects actually do 38-40kph for a true 1 hour time trial (or as close as I'm willing to forgive based on no criteria).  The AVS column tells the whole story, showing velocity at MLSS and velocity in the 40k TT.  What I'm fascinated in is the variation of the 5km TT time.  I calculated 40kmh at around 8 minutes, so what we know as the long side of a VO2max interval and this we know to be variable among cyclists.  We can conclude from the table above is that while the average of 5km TT speed is about 92% of your MLSS speed, the variability is between 86-95%.  This is a very wide range, and let's make up some numbers.  Let's pretend briefly that power and speed are close enough to linear at these speeds, so 5% of 300w is 15w.  Over a long TT, if this overestimates your FTP, trying to hold the extra 15w is going to blow you up in short order.  Going under won't blow you up, but 15w can make a big difference over 30-60 minutes.

Real life example of short efforts being variable: last year with a 300w FTP I was doing 5' VO2max intervals at 380-400w, let's average it at 390.  My friend was doing 400w on the same 5' hill with an FTP of 370w.  That's 108% of his FTP and 133% of mine.  He now trounces me on any duration longer than 2 minutes, but this illustrates that I've got a larger amount of readily available anaerobic reserve.  This is going to greatly influence any efforts I do in terms of estimating my true MLSS/FTP.  Including 20' tests?  Yes.

I just equated MLSS and FTP, so, quickly: FTP is a reference defined as the power maintainable for one hour.  In many studies where MLSS has been held to exhaustion in various sports including running and cycling, the times I've seen were 50-70 minutes.  So for my purposes, equating the two will be close enough.  It's not precise, it's not scientific, but it's my way of relating commonly used training parameters to the existing body of literature.

Anyway, since I don't know any cyclist who sets their training zones based on speed, well go back to last post's study that some great variability in 20' TT performance when it comes to predicting MLSS.  My educated guess is that this comes from a high level of FRC involvement which will vary by individual.  I'm sad that the individual power data wasn't published because then we'd be able to perform some of our own statistical analysis.

It'd be nice to see is 20' power vs measured MLSS by rider type.  The hypothesis is that the variation in 20' test results is influenced by FRC, and in conjunction with the advanced metrics in WKO4, we'll be able to get a more accurate picture of where an athlete's FTP is in terms of %20' mean maximal power.  You're saying this is a very small point to harp on, and it is.  It's also reasonable, based on the analytic tools to want to be able to tell a rider his or her FTP is only 93% of a 20' test, or 97%, or wherever their phenotype puts the estimate.  95% is a pretty good estimate for people inside the bell curve, but for the people outside of it (speaking for myself and some athletes), it can be frustrating.

Lab tests, 20 and 90 minute time trials

There's frighteningly little literature on how lab tested variables relate to the standard field tests cyclists use.  There's more than I'll ever be able to read when it comes to comparing in-lab tests to other in-lab tests.  VO2max and peak wattage in a ramp test?  Got it.  Comparing MLSS, Dmax, CP, OBLA, or a certain % of VO2max?  Got loads of those.  I've been digging a lot to find some good studies that actually use things that cyclists do on a daily basis.

Enter exhibit 1.  20 and 90 minute time trials from elite and internationally competing cyclists were used to test a variety of previously defined in-lab LT markers.  It's got some very, very interesting data.  First, 20 and 90 minute TTs were not well correlated: r =0.66, p=0.54.  I would rather they had done a 60 minute test because of the relationship we always hear between a 20 minute maximal effort being 105% of your FTP, which is ostensibly the power you can hold for an hour.  But it's actually fine that they didn't use a 60 minute test, because a 90 minute test is going to be pretty close too, and I'll examine why.

We've seen of TTs that are well over an hour, like this year's Giro Stage 14 that was won by Vasil Kiriyenka (spoiler alert: he just took the world ITT title).  Second on the Giro stage, LL Sanchez, who also competed in worlds, was down 2:45 at worlds and only 0:12 down in the Giro.  I know, worlds and grand tour ITTs are different, but because Sanchez and Kiriyenka competed in the Giro, Vuelta, and worlds this year, so we can feel comfortable in comparing their performances.  As a side note, many other top finishers in the Giro TT were well known breakaway riders and long TTers, such as Sylvain Chavanel and dare I say Alberto Contador on the rare chances he can get away, like Stage 17 of the 2012 Vuelta.

Why'd I go over that?  Oh yeah, 20 minute power doesn't correlate well with 60 minute power, and most likely doesn't correlate well with 90 minute power.  In the graphic above, the x-axis is self explanatory, but the y-axis test went like this: 3 minutes at 50% VO2max (previously determined), then increasing the workload by 5% VO2max until voluntary exhaustion.  Highest wattage reached during this test was the Wpeak.  And how well did this correlate?  Compared to most other variables tested, very well.

All the variables tested here are lab things, nothing cyclists can generally do on their own.  They all require equipment that measures VO2max or blood lactate (though there are some semi-affordable ones of the latter) and occasionally a little graphical or mathematical inspection to find inflection points and tangential lines.

What I find particularly fascinating is the low correlation of VO2max and the TT powers.  This kind of thing shows that over longer periods of time (20+ minutes according to this study) the maximal oxygen transport that a body is capable of producing is limited by other physiological factors.  For instance, over a 2:10 marathon, an average of 80% of the fuel used is carbohydrates (source).  So we can conclude that a 60 or 90 minute time trial, though creating great aerobic stress, are still primarily glycolytic in nature.  A rider's muscle fiber makeup, VO2max, and other factors like fatigue will influence performance, and just how aerobic a 60 or 90 minute TT really is.  That's a fascinating paper as well as a classic, so I'll get into it more sometime later.

Now what can we conclude about a 20 minute time trial?  It uses a very, very large proportion of glycolysis as the primary fuel source.  I was always skeptical of the standard 20 minute test being preceded by a 5 minute maximal effort, but now it's a bit more obvious why it's there.  Burning through your first hard effort when you're fresh is a good way to get your 20 minute time trial to behave more like something longer.  For riders with high functional reserves and VO2max power, this is important.  This can set training zones at more reasonable targets so an athlete is able to spend more time in the target zones and reap greater training adaptations, especially since power from 20 minutes may fall off rapidly as it approaches the 60 minute mark, but again, this depends on the individual.

Postscript:
I spend a lot of time thinking whether we really should care about our MLSS values, VO2max, or such things to set training zones.  How long can we really spend at MLSS?  Can you really spend an hour at the FTP as set by a 20 minute time trial?  (In most cases no.)  What I've been seeing is that it doesn't matter that much, every rider comes with a different set of strengths and weaknesses at all power levels.

Although here's a study that offers a clue: these TdF riders (figures 2A and 3A) did way over 4.0mmol/L blood lactate in a 30 minute time trial, and several were well under.  Unfortunately this study was from 2006 and may very well be EPO tainted, hence I won't hold it in high regard.

Lactate intolerance

Growing up and doing martial arts I was always told I got sore because of lactic acid.  Acid? That stuff burns!  Makes total sense.  Many years later while learning metabolism from the one and only Hans Kornberg (discoverer of anapleurosis and writer of this lovely memoir), I started having some of those oh, this is how things work moments.  Since then I've been reading articles, both scholarly and semi-journalistic, on blood lactate accumulation and exercise.  This is the first of what I'm sure will be many posts.  This one is titled "Lactate intolerance" because it seems to be the villain molecule in amateur physiologists, like many cyclists and cycling coaches are.    But it's not, and is quite useful for many reasons.  Let's get into it.

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For a brief period, I studied the enzyme that catalyzes this reaction:

http://www.aaltoscientific.com/purifiedhumanproteins/images/lactate-dehydrogenase.jpg

Pyruvate is the end of glycolysis.  After pyruvate, the next step is rate determining (read: slow-ish, for enzymatic catalysis).  Pyruvate->acetyl-CoA happens more slowly than the reactions before it, so pyruvate can add up.  Other things that add up are NADH and H+.  During highly glycolytic times, NAD+ needs to be regenerated to be used in more glycolytic reactions.  And because the TCA cycle doesn't seem to be particularly fast compared to glycolysis, it can be slow regenerating NAD+.

Like many metabolic reactions at rest, lactate and pyruvate are kept in near equilibrium concentrations.  During exercise when glycolytic muscle fibers become engaged, pyruvate starts to pile up, and lactate dehydrogenase (LDH) regenerates NAD+ and mops up a spare H+ as well (it catalyzes the above reaction both ways, depending on the concentration of lactate and pyruvate).

Think of it like a bucket that has a divider in it.  As pyruvate piles up, it'll spill over into the lactate half.  Now they're both filling up.  Glycolysis is still happening because you're still exercising.  Now if lactate piles up too fast, so will pyruvate, which might fill up the bucket (bad metaphor, overflowing cells would be a serious problem) and back up all of glycolysis!  So now what do we do?  Throw out lactate.  Into the blood stream you go!

What happens to lactate in the blood?  Does it pile up?  It can, but it also gets taken up by other cells and converted back to pyruvate for aerobic metabolism.  One of the big lactate users during exercise is heart muscle, which is very, very aerobic.  When you eat heart, it's very dark meat because there's so much mitochondrial density, and the iron makes it dark.  Incidentally, aerobic training increases the density of enzymes that import lactate and pyruvate from the blood (MCT, monocarboxylate transporter).  And contrary to what you might read in some older literature, lactate itself is not oxidized, but is converted back to pyruvate.  Not that they were bad researchers, they just didn't have the tools that we have now.

Lactate appearance in the blood has several names, and they serve different purposes.  What most people say is "lactate threshold", researchers have defined as: the highest VO2 attained during incremental exercise before an elevation of blood lactate is observed; a blood lactate concentration 1mmol above baseline; blood lactate concentration 2.5mmol above baseline; &c.  Also there's onset of blood lactate accumulation (OBLA), the VO2 attained during incremental exercise corresponding to a blood lactate concentration of 4 mmol/L (source).  So if that's where your current understanding of LT is at, that study just cited as a source is about to blow your mind.

Category 2 and 3 cyclists' average steady blood lactate in a 20k TT is in the upper left hand graph.  In each graph the dotted line is one of the previously defined lactate threshold definitions.  Nuts, right?

It's fortunate for us as cyclists that we don't do physiological testing to define our training intensities.  A standard 20 minute test may well have some of us doing a steady 12mmol/L blood lactate.  Although if we did do such blood tests to set training zones, we probably would have figured out sooner that lactate isn't guilty of anything except being the most obvious blood molecule during exercise.

As it stands, the 20 minute test is generally not excellent at setting training zones, and how long an athlete can hold a certain % below or above the reference value indicates what the athlete is naturally good at.  I'm a sprinter/pursuiter, some people I know are good in a long breakaway but not so good in a short TT.  Incidentally, figuring out this stuff is another thing WKO4 does well (it's a feature I always pined for using trainingpeaks) as long as the athlete has good maximal power values all around, although it still takes a good eye to interpret the data and curves.

For the record, here's mine from WKO4.  You can guess what power zone I'll be working on next spring.  And just to make it easy, we can keep calling it lactate threshold.  And before you ask, there are many reasons I'm not an elite.  Like beer and cookies.