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:
- "Best Practices" of Elite Endurance Athletes
- 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.
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