No Zone Training: Part 3

In my first post on this subject, I first tried to measure the "No Zone" for myself using lab and race heart rate data. This resulted in too wide a swath of intensity to avoid; in effect the information was useless. In the second post, I addressed some of the support of the Polarized Training Model. In this post, I'm going to resume with a summary of the argument in favor of this model and contrast that with some arguments in favor of threshold training.

A Brief Summary of the Case For The Polarized Training Model
Stephen Seiler et al make the following points in a variety of different articles:

1. Elite endurance athletes in a variety of sports independently converge on a polarized training intensity distribution, with ~80% at relatively low intensity with remaining ~20% at either threshold or between 90-100% of VO2max
2. Research shows the benefits of high intensity training (~90-100% of VO2max )
   But the benefits of high intensity training are limited in frequency; increasing number has no extra benefit.
3. Research shows the benefits of low intensity training (below 2mmoles of lactate)
4. Research shows benefits from training at or near lactate threshold, however that research used untrained and/or elderly subjects
5. Some research shows the benefits of polarized training over threshold type training
6. And finally, time-constrained athletes tend to converge on threshold intensity too much of the time.

All in all, it seems like a well-researched, cogent and logical series of arguments (and I'm not doing them justice with this summary).


What's Good for the Goose is Good for the Gander? 
If you're paying attention, you'll notice the seeming contradiction in points 1 and 6. To paraphrase Seiler et al:

1. elite endurance athletes through experiment and innovation naturally converge on a polarized training mix.
2. Time-constrained athletes naturally converge on a "training error" of too much--lactate threshold. He writes: "We can call it falling into a training intensity “black hole. It is hard to keep recreational people training 45-60 min a day 3-5 days a week from accumulating a lot of training time at their lactate threshold."

It seems odd that one group would naturally converge on productive polarized training to optimize their training effect, while the other group would naturally converge on an unproductive single mode of too much threshold training. Seiler writes that, for elite athletes:

any consistent pattern of training intensity distribution emerging across sport disciplines is likely to be a result of a successful self-organization (evolution) towards a “population optimum.” 

If true, why wouldn't the same be hold for time-constrained athletes: couldn't they too be demonstrating self-organization toward some optimum strategy?

This really begs the question: assuming all of Seiler's (and his fellow authors') points to be true, does it necessarily follow that training at threshold is a bad thing? Moreover, if  you have plenty of time for recovery, e.g., several days each week like many recreational (and even competitive) masters athletes, then maybe, in fact, threshold training is the optimum training strategy for time-constrained people. Given a finite amount of time, would you want to go for the most bang for the buck. Unfortunately, as Seiler points out, it's hard to find threshold training research that isn't about the untrained.


The Evidence Against Training at Threshold for Time-Constrained Athletes
In Intervals, Thresholds, and Long Slow Distance:  the Role of Intensity and Duration in Endurance Training cites a personal communication from researcher Esteve-Lanao about a study of recreational athletes showing that the polarized model worked better than more training at threshold intensity. I've searched for this study and have not found it published anywhere (Pubmed's list of Esteve-Lanao's research).

The Evidence Against Training at Threshold for Sub-Elite Athletes
Removing the training time consideration and moving along the recreation-elite spectrum,  Seiler and Lanao, et al, compared two training programs in sub-elite runners. In Impact of training intensity distribution on performance in endurance athletes, they had one group train using a polarized program and one with more threshold intensity. The polarized group performed significantly better than the threshold training group, "supporting the value of a relatively large percentage of low-intensity training over a long period ( approximately 5 months), provided that the contribution of high-intensity training remains sufficient."

More Evidence Against Threshold (or for Polarized Training)
Seiler continues to seek empirical data that the polarized model works while too much threshold seems to hinder. In Lactate profile changes in relation to training characteristics in junior elite cyclists published in Sept 2010, he and A. Guelich studied the training of 51 German junior cyclists and found that "training at <2 mM blood lactate appears to play an important role in improving the power output to blood lactate relationship. Excessive training near threshold intensity (3-6 mM blood lactate) may negatively impact lactate threshold development."

The Case for Threshold Training
1. Researchers
On the other sides of the aisle, one researcher and athlete who seems unabashedly in favor of threshold training is Andrew Coggan. He depicts a variety of benefits accruing from training at or near threshold (level 4 in his schema) in this pdf (see Table 2). Not surprisingly, one of the benefits cited is increased lactate threshold. In other words, train at threshold, benefit your threshold. While this seems intuitive, this publication and the subsequent "Training and Racing with a Power Meter" don't cite specific research in favor of this concept.  Coggan and fellow author, Hunter Allen, do cite a study of fiber recruitment: around threshold is when fast-twitch muscle fibers start being recruited. While that is interesting and may be important, it doesn't really constitute the research we would like to have in support of threshold training.

Another researcher (and author with Seiler) who has been a proponent of threshold training is Jack Daniels. In Threshold Training: Finding your T-pace, he writes: "Threshold or Tpace running is one of the most productive types of training that distance runners can do." Daniels describes this intensity as "equal to a pace they could race at for 50 to 60 minutes."

2. Research Findings
According to one training website "There is a substantial body of research that shows training at or close to the lactate threshold increases the intensity at which it occurs." This statement is accompanied by a list of published research (see below). However, if you read these studies (check out the abstracts) you will see the participants consist mostly of untrained, elderly. This presumably makes them less relevant to trained athletes, masters or otherwise. The studies that use trained athletes seem to support high intensity training, not training at the lactate threshold.

3. Anecdotal
Many athletes including cyclists, runners, rowers and cross-country skiers have been doing considerable threshold training and reporting excellent results. Many cyclists are performing 2 x 20-minute intervals at threshold pace; this has been one of the more popular workouts of many of those who have adopted cycling power meter training.

In fact, Stephen Seiler, himself used to row 3 x 20 minute intervals at friendly club race pace as part of his training. One can only assume this was harder than low intensity, but too easy to be high intensity training. Maybe he wouldn't do that any longer, however.

Definitions or What is Threshold Intensity?
In the first post, I began with the calculation of threshold intensity based on the definitions, as offered in the Outside Magazine article "Beware the Black Hole". Below is the a re-formatted table with those calculations.

Method and associated heart rate	Calculated "No Zone"
75-80% of maximum heart rate. Max = 200	150-160
Talking becomes difficult guesstimate = 165	165-175
HR at Measured Lactate Threshold = 178	178-189
HR during last 20-minutes of all-out 30-minute effort = 185	185-196

If my experience is representative, then identifying, let alone avoiding, threshold will be challenging.

Seiler, in many of his articles, uses a definition of 2millimoles of lactate for low intensity exercise and 4 millimoles as roughly threshold intensity exercise. So, to employ the polarized model, an athlete would aim to stay below 2mmol for 80% of training. For the remainder, the training would be at 4 mmol or considerably higher.  Avoiding training in the 2 to 4mmol area is the implication. Can you figure this out?

I can say for myself that that zone is easily avoided. As I mentioned in the previous post, in lab testing my blood lactate only reached 2mmol at a heart rate of 176, an intensity which I would consider a challenging effort, not low intensity, and definitely not something I would naturally settle into. I have to actively make myself exert up to this level. The exercise physiologist there described that as my lactate threshold.

Seiler, Coggan, Daniels and others seem to agree that threshold is roughly the intensity you could sustain for about an hour in a race. This is certainly hard. However, if you perform that intensity for 20-minutes or less at a time, it may be considerably more manageable, thus the idea of 2 x 20 minute intervals at threshold pace.

Conclusions

1. Seiler makes a strong case for the polarized model of training
2. The evidence against threshold training is not particularly strong, however
3. The case against threshold training for time-constrained athletes, based on private communication, seems weak
4. Ascertaining threshold efforts based on suggestions in Outside Magazine article seem flawed, at least based on my lab data
5. The evidence for threshold training is not particularly strong either.

This is most unsatisfying. The argument in favor of avoiding threshold doesn't seem strong. Based on nothing other than the principle of specificity, one would think that to improve lactate threshold, one could  train at or near that intensity. However, the evidence in favor seems minimal.

-------------------------------------------------------------
Research cited by the "Sport-Fitness" website in favor of training at lactate threshold to improve lactate threshold (their footnote numbers) and accompanied by my bold notes in parenthesis.


7) Yoshida T, Suda Y, Takeuchi N. Endurance training regimen based upon arterial blood lactate: effects on anaerobic threshold. Eur J Appl Physiol Occup Physiol. 1982;49(2):223-30 (college students, not specifically athletes)
8) Davis JA, Frank MH, Whipp BJ, Wasserman K. Anaerobic threshold alterations caused by endurance training in middle-aged men. J Appl Physiol. 1979 Jun;46(6):1039-46 (sedentary middle-aged males)
9) Belman, MJ, Gaesser, GA Exercise training below and above the lactate threshold in the elderly. Med Sci Sports Exerc. 1991;23,562-568 (elderly, not likely athletes)
10) Evertsen F, Medbo JI, Bonen A. Effect of training intensity on muscle lactate transporters and lactate threshold of cross-country skiers. Acta Physiol Scand. 2001 Oct;173(2):195-205 (athletes, but not clearly in favor of training at lactate threshold, may be case for higher intensity)
11) Weltman A, Seip RL, Snead D, Weltman JY, Haskvitz EM, Evans WS, Veldhuis JD, Rogol AD. Exercise training at and above the lactate threshold in previously untrained women. Int J Sports Med. 1992 Apr;13(3):257-63 (untrained women)
12) Acevedo EO, Goldfarb AH. Increased training intensity effects on plasma lactate, ventilatory threshold, and endurance. Med Sci Sports Exerc. 1989 Oct;21(5):563-8 (athletes, but a case for higher intensity, not training at or near lactate threshold)
13) Henritze J, Weltman A, Schurrer RL, Barlow K. Effects of training at and above the lactate threshold on the lactate threshold and maximal oxygen uptake. Eur J Appl Physiol Occup Physiol. 1985;54(1):84-8 (college students, not specifically athletes)

No Zone Training: Part 2

In the previous post on this topic, I briefly described the Black Hole training article in Outside Magazine and then tried out the accompanying "No Zone" calculation methods to figure out what training intensity to avoid. Using lab-generated data, I found that it was difficult to calculate a meaningful "no zone". Still, I know there is considerable thought and research underlying this brief article. Just because the quick magazine calculations don't work well [for me, anyway], doesn't mean that the principles on which they are built are flawed.

The Polarized Training Model

Training lots really easy, training some really hard, and training not much at all in between (the Black Hole) is known as the "polarized model" of training and has been the subject of several accessible papers by Stephen Seiler. Along with Carl Foster, Seiler is one of the researchers mentioned in the Outside Magazine article and is the co-author of a paper, with Espen Tønnessen, called Intervals, Thresholds, and Long Slow Distance:  the Role of Intensity and Duration in Endurance Training in which the "black hole" is referenced. In another paper, Quantifying training intensity distribution in elite endurance athletes: is there evidence for an‘‘optimal’’ distribution?, Seiler and co-author Glenn Øvrevik Kjerland find in the affirmative and make a case for a polarized training distribution.

Besides being a long-time exercise physiologist, Seiler has also been a competitive masters rower and many of the studies he cites in his papers are rowing related, which makes it all the more interesting for us. Moreover, he's been answering my sometimes stupid questions for almost a decade. Several of these questions have been on the topic of the polarized training model.

If we were to characterize the polarized training model in a graph of training volume and intensity, it might look a bit like this:

This is my simple rendering that hopefully captures the gist of the polarized model: lots of training hours (volume) at low intensities and some lesser, but still considerable amount of higher intensity hours, and not many hours spent around Lactate Threshold.

This polarized model is both descriptive (it's what elite athletes do) and prescriptive (it's what you ought to do), says Seiler. And, he marshals a wide array of research to bolster this claim in a variety of published articles. I lump his evidence/arguments into 2 basic categories:

1. "Best Practices" of Elite Endurance Athletes 
2. Research showing the benefits of low-intensity training

The Evidence for the Polarized Model: Best Practices

This argument suggests that whatever successful endurance athletes are doing is what we should do. Near the beginning of  Intervals, Thresholds, and Long Slow Distance: the Role of Intensity and Duration in Endurance Training, authors Seiler and Tønnessen suggest that elite endurance athletes figure out the best way to train, though innovation and success (the bad methods of training get cast aside). As such, they argue, we are better off studying them than we are paying attention to some research. To wit:

While arguments can be made that tradition, resistance to change and even superstition may negatively influence training methods of elite endurance athletes, sports history tells us that athletes are experimental and innovative. Observing the training methods of the world's best endurance athletes represent a more valid picture of “best practice” than we can develop from short-term laboratory studies of untrained or moderately trained subjects.

Coincidentally, when rereading this recently, I had just watched a video of a 2010 World Cup regatta in Bled, Slovenia. I was struck by how many of the rowers there were competing in seemingly identical boats. In the women's race, for example, it was pretty much a foregone conclusion that a yellow Empacher would cross the line first. This could lead to the conclusion that you must row a yellow Empacher to win.  I think this might fit better in Seiler's description of resistance to change or following tradition, rather than being innovative...

Experimental and Innovative or Lemming-like?

I think it's fair to say that competitive athletes are always looking for an edge and that can mean being innovative, but not necessarily.

Seiler goes on to say:

In today’s performance environment, where promising athletes have essentially unlimited time to train, all athletes train a lot and are highly motivated to optimize the training process. Training ideas that sound good but don't work in practice will fade away. Given these conditions, we argue that any consistent pattern of training intensity distribution emerging across sport disciplines is likely to be a result of a successful self-organization (evolution) towards a “population optimum.”

There's a Panglossian "best of all possible worlds" quality to this statement. If we're all doing the same thing, it must be the best thing. Several decades ago long, slow distance (LSD) seemed to be the mantra across a variety of sports (running, cycling, swimming, xc skiing, etc).  But it's hard to buy the argument that whatever we're doing at any given instant is the pinnacle of training up until this point because we're all doing it.

Still, let's try to suspend judgment and look at the evidence Seiler and Tønnessen marshal. It is considerable. They cite studies in swimming, cross-country skiing, marathon running and rowing. Since we're particularly interested in rowing, we'll look at a few of those examples.

Steinacker et al. (1998) (full study in PDF) described the training of elite German, Danish, Dutch, and Norwegian  rowers leading into a World Championship. Here's a graph of the Norwegian and Danish rowers depicting training intensity vs hours of training over a period of 40 weeks.

The key points in this study relative to Seiler's argument are:

• Rowing at higher intensities was performed only ~4-10 % of the total rowed time (slightly different that total training time)
• Extensive endurance training (60- to 120-min sessions at <2 mM blood lactate) comprised the greatest training volume. 
• German rowers spent virtually no time at lactate threshold intensity, but either trained below 2 mM blood lactate or at much higher intensities (in the 6-12 mM range).

OK. A bit of condescending digression here for folks like me who need a bit of clarification. Blood lactate is a by product of exercise that increases with an increase in intensity. A blood lactate of <2 mM (millimoles) is generally associated with a relatively low exercise intensity. However, it's clear that different athletes produce differing amounts of lactate. For myself in lab testing, my blood lactate only reached 2.0 at my measured lactate threshold and a heart rate of 176, an intensity which I would consider a challenging effort, not low intensity. Your mileage may vary.

Back to examples of polarized training in practice. Seiler and Tønnessen also cite a recent study, Gullich et al. (2009). This study, co-authored by Seiler, reported on World Class Junior rowers from Germany, showing that "95% of total rowing was performed at intensities corresponding to <2 mmol" and that when the competition period approached, they shifted to even lower intensity within that 95%, but the remaining 5% of rowing was performed at "near maximal oxygen consumption (VO(2max)) intensity".

Seiler was also an author of Training and performance characteristics among Norwegian International Rowers 1970–2001. This paper "quantified changes in training volume, organization, and physical capacity among Norwegian rowers winning international medals between 1970 and 2001." During that time, training at a low blood lactate (<2 mM lactate) increased from 30 to 50 hours a month and high intensity training ( 8–14 mM lactate) decreased from 23 to 7 hours a month, leading authors Fiskerstrand and  Seiler to conclude that:

The training organization trends are consistent with data collected on athletes from other sports, suggesting a ‘‘polarized’’ pattern of training organization where a high volume of low intensity training is balanced against regular application of training bouts utilizing 90%–95% of VO2 max.

At this point, we could review some of the cycling, marathon running, and other research mustered in favor of Seiler's argument, but I think we can accept, for the moment, that signficant numbers of elite endurance athletes are using some form of the polarized training model. This is not to say that successful endurance athletes aren't using other forms of training intensity distribution. We'll get to that in another post.

Why Are Elite Endurance Athletes Using the Polarized Training Model?

Besides suggesting that this training pattern is one that is by its nature, self-organizing,  the question doesn't lend itself to easy answers. Says Seiler:

Why has this training pattern emerged?  We do not have sufficient research to answer this
question, but we can make some reasonable guesses.

My own guess is that competitive endurance athletes (and their coaches) are compelled to do more and more training, the thinking being "if I train more than the next guy, I will prevail". If x hours is good, then x +10 is better. Training volume escalates, and if one makes the reasonable assumption that you can't train at higher intensity for the same number of hours, you will naturally settle on lots of low-intensity volume. Training lots of hours at low intensity also might look good in log books, bar charts and the like. Seiler seems to agree in a more scientific way:

Athletes may migrate towards a strategy where longer duration is substituted for
higher intensity to reduce the stress reactions associated with training.

This echoes some exercise physiology textbooks: "Generally, a longer exercise duration offsets a lower exercise intensity." (McArdle, Katch & Katch). However, this is a curious statement in the following sense: there is still a training stress associated with the long, low-intensity training. In another Seiler research article, Impact of Training Intensity Distribution on Performance in Endurance Athletes, he and his co-researchers used the TRIMP method of assigning training stress to different intensity/duration workouts to facilitate comparison.

Low intensity training may produce real physiological and performance benefits

Seiler and Tønnessen, proceed to the next step in their systematic case: demonstrate that low-intensity workouts have intrinsic physiological benefits other than just recovery. They cite several studies, one of which is a rowing one.

In Physiological and performance effects of low- versus mixed-intensity rowing training., Ingham et al, took 18 experienced rowers after a season-ending rest period of 25 days, randomized them into two training condition groups, one with low-intensity training and one with mixed-intensity regimen. Both groups trained for 12-weeks on the rowing ergometer. The low-intensity group trained at an intensities below that eliciting 75% VO2max, while the mixed-intensity group performed 70% of their training at the same low intensity as the other group and 30% of their training at an intermediate intensity (about half way between power at lactate threshold and power at VO2max. This 30% worked out to be about 3 days a week. The two groups performed very similar volumes of training. Remarkably, the results were very similar. Both groups improved 2000-m times, with 16 of the 18 setting personal records. Both groups improved VO2max by ~10% and power at various lactate levels. 

This is very impressive argument in favor of low intensity training having beneficial physiological benefits. On the other hand, the low intensity as defined in this study is not exactly an easy walk in the park. For some folks, an intensity eliciting 75% of VO2max may be close to their lactate threshold. For me, in one of my VO2max tests, this intensity would have been at heart rate of around 170 and my lactate threshold was deemed to be 178. In another test, 75% of VO2max occurs almost exactly at my lactate threshold, in this case at a heart rate of 176. So, for me, the upper-bound of the low-intensity group is right near my lab-measured lactate threshold.  

On the other hand...

Seiler and Tønnessen then cite a study with which, as a cross country ski racer, I am somewhat familiar. In Responses to training in cross-country skiers, Gaskill et al "evaluated whether cross-country skiers who did not respond positively to a training program consisting of high volume and low intensity would improve if high-intensity training volume was doubled during a subsequent training year." The important part of the study was this group of skiers increased their high intensity training (of lactate threshold and higher) from less than 17% of total training to more than 35% of training and reduced their low-intensity training volume by 22%. 

This higher-intensity, lower volume group of skiers increased VO2max by over 5% and increased lactate threshold by about 20%. And, their ski results improved. Gaskill et al's conclusion: 

Increased volume of high-intensity training may improve competitive results in cross-country skiers who fail to respond to increased volume of low-intensity training.

This study seems to contradict the polarized model, the "no zone" and the adverse consequences of the "black hole." At the very least, this study suggests for some athletes, increasing volume is not necessarily a good idea and increasing intensity might be.

Inconclusive

I've tried to be objective in reading the research offered by Seiler and colleagues, but I have to say that I am not persuaded by the case for the polarized model. On the one hand, I accept that many elite endurance athletes use the polarized model. On the other, I am not persuaded that it is the optimum training distribution. 

In the next post (or posts?), I hope to explore a bit further some of the challenges of an optimum training distribution, why the polarized model might not be right and what the case is for training around lactate threshold.