Lactate Clearance Intervals, MCT-1, Arrhythmias, and Why You Need Speed

EKG ImageA few weeks ago, I did some very short, high-intensity sprints in the middle of a zone two bike ride.  The sprints left me feeling exhausted far more than they should have, so I thought it was probably a good idea to do two things: get some more low-intensity aerobic training in and to simultaneously work on some really high intensity interval work.  This post explains why this might not be a bad idea after a couple of weeks of hard racing.

Need an Aerobic Break?

This first point isn’t the real focus of this post, but I thought I should talk about it and get it out of the way quickly.  The problem that I see often happening in race season is that we do a ton of tempo and lactate threshold work.  That’s fine, because it’s so darn specific to what we need in racing sprint and olympic distance races.  Arthur Lydiard was one of the first to notice, however, that high levels of training at lactate threshold had a deleterious impact on aerobic abilities.  This is certainly one of the reasons why it was avoided in the base phases of training.  After a few weeks of intense racing, therefore, it’s not a bad idea to take a week or two in the middle of the season to get an “aerobic break” and just keep everything in low zone 2.  For myself, I can tell when I’m hitting this point– I feel a little more on edge with a touch more tension.  I can also feel it physically– I get a tiny bit of tension around my ribcage and can feel a little tightness around my temples.

And Maybe a Touch More Lactate as Well?

Let’s get back to the problem that started off this article– the inability to recover quickly after a short hard sprint.  A related problem comes up in races when one is moving well and riding on that razor’s edge of going too hard.  Suddenly there’s a hill or someone makes an attack and there’s a surge to keep up.  Shortly thereafter, the wheels start coming off the truck and the race just falls to pieces.  Alternatively, we start a race with a much-too-hard effort (just like what happened to the guy who blew by me in the opening minutes of my last time trial) only to have the walls irreparably come crashing down later in the race.  Sound familiar?  This is usually a problem of having insufficient lactate clearance and tolerance.

Building Lactate Clearance/Tolerance the Old Fashioned Way

Lactic acid is an unfairly maligned little critter.  We tend to think of it as a nasty chemical that chokes our performance and turns our happy blood vessels into a corrosive, acidic soup.  While it is a metabolic by-product, it is in turn a valuable fuel source for our muscles and, in particular, our cardiac muscles.  In reality, it’s other metabolic by-products that are created in the same process as lactic acid (in particular H+ ions) that really do cause the problems that we blame lactic acid for.  It just so happens that the proportion of lactic acid and H+ ions is relatively constant, so we tend to measure lactic acid levels when we’re really trying to estimate nasty H+ ions.  Think of it as chemical “guilt by association.”  Either way, our goals are two-fold in dealing with lactic acid.  On the one hand, we want to be able to tolerate a really high level of lactic acid (and hence our ability to withstand a lot of H+ ions) in our workouts.  On the other hand, we want to be able to clear as much lactic acid (and H+ ions) out of our system.

crossroads of fixing or toleratingNow for a little more confusion.  When you look up lactate tolerance workouts, you find a bunch of workouts that have short hard bursts with long recoveries– exactly the kind of workout to teach our bodies how to clear a bunch of lactate.  And similarly when you look up lactate clearance workouts, you find much more sustained efforts that hold the body at a highly acid level (i.e. the ability to tolerate lots of lactic acid).  Both are needed– it’s just that the naming of the workouts seems quite backwards.

Let’s talk about the longer workouts first because these are the more common type of high-intensity lactate workout that most folks do.  These are typically harder tempo efforts that alternate between slower and faster elements or tempo efforts that throw in an occasional short hard surge.  To me, these are also the most hellish workout I can do; my tempo runs are already at a really hard pace– and throwing in a few hard surges will leave me shot for the rest of the workout. I think this is a terrible option for a coach to throw at an unsuspecting athlete without some build up (which we’ll talk about next).

A Better Way to Build Lactate Clearance

First things first.  The workout that I just described above really teaches the body how to tolerate acidity over a fairly long period of time.  Whether you call it a “lactate clearance workout” or a “lactate tolerance workout” doesn’t really matter– the waters are so muddied already.  Yes, it does teach the body how to clear lactate but you’re asking an athlete to tolerate a ton of acidosis to get there.

leaky bucketNo matter what you call the workouts, the important point to me is this: before you can expect someone to tolerate lots of lactate (and H+ ions), it first makes sense for them to practice how to clear lactate out of their systems.  Think of it this way.  Suppose you have a bucket of water (your body) that is being filled by a spigot (lactate produced by your working muscles).  Thankfully, your bucket has a few holes punched in it (your lactate clearance ability) so it doesn’t overflow (i.e. you blow up).  Suddenly, you turn up the spigot.  If you still want to prevent the bucket from overflowing, you either have to turn down the spigot (i.e. reduce your speed) or punch a few more holes in the bucket.

Well, it turns out that much brighter people than me have already figured out a better way to start off accomplishing this task.  None other than legendary coach Renato Canova created so-called “blend” workouts, which I think are a much more humane way to segue into the harder sustained efforts described above.  Steve Magness does a great job at giving examples of these blend workouts, but the basic pattern is to do workouts that combine the following elements into a set:

  • Run 1 mile at about 5-K pace
  • Jog for 2 minutes
  • Run 400 meters at an even faster pace
  • Jog for 4-5 minutes

Then repeat this set about 3-4 times.  The beauty of this workout is that the opening mile does a great job of lifting lactic acid levels up to a high level.  It’s known that lactic acid levels typically rise for a while (usually 2-3 minutes) for most individuals after a really hard effort is finished.  So while lactic acid levels are still rising super-high, hitting it with a really hard 400 meters will make lactic acid levels soar.  Then a gentle 4-5 minutes will let those lactic acid levels come back down.  It’s that recovery time where all the magic happens because you’re teaching your body to clear out a ton of lactic acid (and the associated nasty H+ ions).

Science Suggests an Easier Way (Mostly for Cycling)

All of these coaching ideas are all well and good, but is there any hard science behind any of it?  After all, we can talk abstractly about clearing lactic acid, but do we know what’s really going on the body?  And, if science can teach us something about our bodily responses, can we learn how to optimize those responses in our training to get the most “bang for the buck”?  Well, as it turns out, there is some “hard” (okay, let’s just call it “harder”) science behind all this “lactate clearance” mumbo-jumbo.

I first learned about this back in 2004.  It turns out that when lactate is produced, it can either float around our muscle cell waiting to be picked up by the mitochondria (i.e. little power plants) inside our cells or it can be released into our bloodstream and eventually picked up by another cell (and then its mitochondria).  But lactate can’t enter a cell or even a mitochondria without being pulled in by a protein called a “monocarboxylate transporter” (MCT).  It turns out that there are four kinds of MCT proteins– three of them are pretty bland and unaffected by exercise, but one of them (MCT1) turns out to be highly-trainable.  Back in 2004, there were about a half-dozen studies all showing the same result– a few sets of high intensity short intervals with relatively decent recoveries hugely improved MCT1 concentrations and dramatically improved resistance to fatigue.  For instance, the most practical study (in terms of workout routines) had cyclists do 3-5 sets of (2 x 30 seconds and 3 x 60 seconds) with each 30- or 60- second interval “full out” and a generous 2-minute recovery between each effort.  After eight weeks, MCT1 levels rose 76%!  If you’re interested in reading about MCT1, order a copy of the November 2004 copy of Running Research News and look for the article, MCT1s are Performance Markers.

I personally wouldn’t feel comfortable prescribing one or two minute all-out running intervals to a bunch of older age-group athletes (because of injury risk)– except for potentially on a long hill and after a good warmup.  Even then, I wouldn’t want them doing more than 8-10 of them in total.  On the other hand, I would have absolutely no problem telling the same group of athletes to do 30- or 60-second all-out efforts on a bike (especially on an indoor trainer).

A Possible Build

Okay, down to brass tacks.  How would I construct a plan to boost lactate clearance and when would I do it?  First, I think that it is important to have a really solid lactate threshold base before embarking on lactate clearance.  Using the bucket analogy, it’s better to first have a more efficient spigot before punching holes in your bucket.  This means that I would put this kind of work into Phase 3 of a build— ideally as the interval workouts in a typical week that also has tempo workouts.  For the run, I might start with some weeks of 60 second super-hard hill sprints with a good 2-3 minutes rest after each effort (to make it fun, I might even make it a handicap start with runners starting at different points of the hill so they each race to “catch each other” and cross the finish line first).  I might alternate these workouts with the one-mile/400m workout described above.  After about 4 weeks, I would start introducing the old-fashioned varying tempo effort described above.  For the bike, I would have no problem starting with 30-second all-out sprints, then moving to 60-second all-out sprints, each with double-time recoveries.  I might even throw in some Tabata-style intervals in a format like 3-4 sets of 4 hard 30-second efforts and 15-second recoveries (I’d give a generous 5 minutes of recovery between sets).  The Sufferfest has a couple of great videos arranged around short intense efforts, such as Revolver, Violator, and especially the new Half is Easy videos.  As I find it really hard to motivate myself to throw sprints into an already very hard tempo effort voluntarily, I would either evolve this initial effort into a hilly sustained tempo ride or (preferably) riding the Hell Hath No Fury video with my watts turned up 5-10% higher than my FTP (and then seeing if I could hold on for dear life).  If using the Sufferfest videos, I would use the more sprint-oriented videos on a plain old magnetic trainer and ride the Hell Hath No Fury video inside of PerfPro Studio on a computrainer.

So What Does this Have to Do with Arrhythmias?

A few years ago, I started noticing heart rate spikes in my heart rate downloads.  My heart rate would be going along fine at about 160 beats per minutes and then BAM! it would hit 200 beats per minute (the highest maximal heart rate I could achieve was about 180).  I knew that these events weren’t entirely random as I would recall feeling a combination of being extremely winded with an unshakable sense of dread.  My cardiologist also confirmed these same anomalies using a full EKG machine and concluded that I had occasional (and thankfully harmless) PSVTs (paroxysmal supraventricular tachycardia), which is a fancy term for “heart rate spikes” (thanks doc).   Sadly, this is an increasing common problem for endurance athletes as we get older– in other words, if you don’t have this now, remember you read this post.   After about six months, I was able to mostly shake these PSVTs by eliminating caffeine from my diet and by dramatically increasing my magnesium intake.  In total, I saw four different cardiologists each for a different aspect of this problem (one doctor referred me to the next).  The last one I saw was an exercise cardiologist.

Guess what exercise protocol the exercise cardiologist recommended I use to treat PSVTs?  That’s right, a lactate clearance workout.  She recommended a bike workout using one-minute full-blast intervals with two minutes rest.  At the time, I wasn’t in a place where I could do that workout– and then I discovered the caffeine/magnesium connection (thus mooting the need for painful intervals).  Her theory was that high lactate levels can also trigger PSVTs and so improving the ability to clear lactate is a very good thing.  So it seems that my journey has come full circle– whether I like it or not, I’ve got to do these damn things.

Master Runners Need High-End Speedwork More than Our Younger Counterparts

We all get slower as we age.  Most of us hate this fact, but like to think that we can still win a race against our younger competitors because our endurance is so much better.  Nice try.  It turns out that, when you compare how much world record times change in different age groups, it’s the longer events that get hit more than the shorter ones.  In other words, sprinters slow down less than marathoners as they get older.   Also, in any older age group, the ones who can sprint faster usually can run faster at the longer event too.  So if you want to run fast– and keep running fast versus your age group cohorts– you had better introduce some high-intensity speed work into the mix.  An interesting article in Runner’s World recently suggests how you can keep your speed.  In addition, another recent study showed that older sprinters did much better than older distance runners in a number of measures, most notably bone density.


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