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.

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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)