Friday, July 31, 2009

The Science of 'Steady'

On our Endurance Corner forum ( the following question was recently raised, regarding the emphasis Endurance Corner places on steady-state training:

“Help from the research literature gurus, please.
My involvement with Endurance Corner has generated plenty of great discussion at the cardiology practice I work in. Many of us in the practice pride ourselves on readily referencing the various studies that provide support for the diagnostic and therapeutic recommendations we make. If I can't reference a study, I am careful to qualify my position as being based on a theory or based on anecdotal experience.
Today I was making a case for endurance athletes spending a significant amount of the available training hours on 'steady" zone work. The very appropriate question came up, 'based on what research". My response "I'll get back to you'.


While there are a number of observational studies on elite swimmers, cyclists and runners that support a large percentage of training being spent in what we at EC would call the ‘steady’ training zone, i.e. at or slightly above the aerobic threshold, there are few controlled scientific studies on athletes that provide scientific validation. The reasons for this are multiple and more related to the difficulties in controlling the extraneous variables within an athlete’s life, coupled with the fact that most studies are, by their nature, short duration studies, and finally that it’s tough to convince an ethics board of the merits of ‘harvesting’ the athlete at the end of the study so that physiological adaptations can be investigated to their full extent :-)For this reason, we tend to turn to the rats to help to determine the training strategies that result in optimal physiological adaptation.

One of the studies that I referenced in reply to this athlete’s question was the landmark (rat) study of Dudley, Terjung and Abrahams (1982).

In the study, the researchers subjected rats to training protocols of varied durations and intensities over the course of 6 weeks ranging from 10mins/day at 116% of VO2max to 90mins/day at 50% of VO2max. They then looked at mitochondrial adapatation as a function of cytochrome c concentration in the 3 different fiber types – fast glycolytic, fast oxidative and slow oxidative.

While the optimal protocol for improving the aerobic capacity of FOG fibers was clearly maximized at 60-90 minutes per day of training just below the anaerobic threshold (~functional threshold pace/power), the slow twitch fibers exhibited a different pattern:

The aerobic capacity of the fiber is shown on the y axis (in the form of cytochrome c concentration) for the 3 different duration groups on the x axis (30, 60 and 90 minutes per day) for each respective intensity level.

In the first group – 10m/min or approximately 20% of the ‘athletes’ vVO2max, a very light level of intensity, only small improvement in aerobic capacity can be expected. Additionally, once the athlete is doing 60 minutes per day at this level, very little additional improvement can be expected with increased duration. In other words, there is little physiological benefit to ‘touring’ at very low intensities, whatever the duration.

This pattern continues for the second group (~40% of the ‘athletes’ vVO2max) albeit to a lesser extent. We may consider this ‘easy’ training, the type used for recovery or warm-up. This training is still quite limited in terms of the benefit to the aerobic capacity of the muscle fibers. However, 60-90 minute training sessions are still useful, though less so than 60 minutes of ‘steady’ which we’ll get to in a bit. But first…

The 40m/min protocol reflects a training level approaching the ‘athletes’ functional threshold. Clearly, this is not only a powerful stimulus for the fast oxidative fibers mentioned above, but also these slow twitch fibers. In fact, according to the data, 30 minutes of threshold training is more beneficial to the slow twitch fibers than 60 minutes of steady training.


The benefit of threshold training to the slow twitch fibers is ‘maxed out’ at ~60 minutes of training. Looking at the trend of the 30m/min curve (an intensity approximately equal to ‘steady’) it is clear to see that while 90 minutes of steady training only equals 60 minutes of threshold training, in terms of relative benefit, the ‘steady’ curve is still on the up and up.

In other words, we would expect continued benefit at 2hrs and potentially 3hrs and maybe even 4. In fact, this has been confirmed by a study by Harms and Hickson (1983) who found this near linear relationship existed through to 2hrs/day of steady training. However, despite the fact that we subject 10 year old swimmers to ‘2-a-days’ of 3-4hrs of training, we are yet to subject the rats to the same fate. So we can only guess on whether this trend will continue to 3 and 4 hours. Elite athletic practice would say yes!

In summary, the greatest aerobic benefit to your slowtwitch fibers will be had from the following sessions in order of importance:
- 2-4hrs of steady training
- 45-60 minutes of mod-hard to threshold training
- 30 minutes of threshold training
- 60 minutes of steady training
- 60-90 minutes of easy training

Of 4 intensity levels examined, only one offered continued benefit for the athlete willing/able to train for more than 90 minutes per day – steady. Not too easy. Not too hard. Steady is ‘just right’ :-)

Train Smart.



runtilyoudrop said...

Nice but rats aint humans. Do you think that science may be limiting the true athletic potential. Why have IM times at the sharp end not improved siginificantly in 20 years (in spite of the technology)? "Steady" may be more tolerable for all but may not give the best results, but I guess for most of us "steady" will give us our most achievable results.

Alan Couzens said...

I think coaches who look at science independent of best coaching practice may be limiting their athletes' potential.

Studies like this are interesting in that they help to provide the 'whys' of best (human) athletic practice but most worthwhile discoveries are made by coaches (first) then scientists (second) often with decades in between.



Unknown said...

Would you put "steady" in the Zone 3 (of 7), ie solid "tempo"?

Lucho said...

Hello Alan-
Renato Canova uses the term 'aerobic threshold' to describe the point at which you reach 2.0-2.3 mmol of lactate, which corresponds to marathon pace in a well trained runner. In recent tests I hit 2.0 mmol at 5:37 pace per mile. 2 hours per day at this effort would put me in the hospital after 2 days. What am I missing here?
Tim Lucho

mat jude said...

Hey AC, does this imply that we should rack up 60 - 90 min of "easy" per sport per day first then look to progressively convert that into "steady" training?

Also if steady is where it's at, what are the caveat's before progressing to "steady" zone?

If "mod-hard" and "threshold" zones provide the most stimulus for aerobic improvement what is the protocol for maximizing returns while not frying one's self?

I'm fishing for a good starting point for a novice athlete.

I'm assuming it all comes back that post you wrote on complex training: the principal of variety for multilateral development?

Cheers AC, keep the great posts coming!!

P.S. What are the requirements before prescribing Big Gear work on the bike?



Alan Couzens said...

Hey Kirk and Lucho,

The intensity zones that you're both referring to are closer to what Coyle would call the 'lactate threshold'. Training at this level has good benefit to the time limited athlete or the metabolically strong athlete.

My advice would be to fill the week with the bulk at level 2 (AeT to AeT+10) and determine your tolerance to it before adding a chunk of zone 3 training. Some athletes will tolerate a good chunk of it (particularly females and smaller athletes) but for large, male athletes, with weak meatbolic profiles, a lot of tempo training in the week will wreck them.



Alan Couzens said...

Hey Mat,

Generally speaking, in my way of thinking, steady trumps easy. IOW, I'd rather see an athlete do 60min of steady, than 'hold back' and do 90min of easy.

I'd probably rather see an athlete do 90min of anything than 30min of steady but if there is this big of a gap between easy and steady tolerance, I'd suspect steady hasn't been properly defined. So, no real caveats to progress to steady. Generally, I'm happy with a wide range of easy-steady in the first 4-6 weeks of the season before starting focused main sets.

I didn't add the FOG chart in the post but steady also helps threshold. There is decent carry-over. So, for the novice to int. athlete, little need to emphasize threshold.

BG training can start pretty early in the piece providing the athlete is structurally sound, but at steady intensity.

Thanks for the encouraging words.

All the best,


Unknown said...

Hmmm, maybe I'm thinking in terms of power (as opposed to heartrate):

Paul Fleuren said...

Nice post Alan,

I actually put my steady zone at -5bpm Aet to +5bpm. I think I got this fromKP. My aim is too hit 30-40% of my weekly volume in this zone. To me that is challenging.

I'm a flat 10hr IM athlete that puts in around 18-20hrs PW of training, if that helps.

Training in hte steady zone is easier for novice athletes, but once you gain some experience and can handle the volume training in hte steady zone upwards of 30% PW become quite challenging and requires careful planning.


Alan Couzens said...

Hey Paul,

Since muscle fibers are 100% aerobic up to AeT, I believe to challenge the aerobic system, AeT should represent the low end of the steady zone. Not to say that anything below this is wasted, esp if the session is long enough, but I believe the focus should be just above AeT for most main sets.

I think the 30-40% is a reasonable goal when factoring in warm-ups, cooldowns, maintenance of other physiological qualities and recovery training.

Thanks, as always, for the input.



Alan Couzens said...

Hey Kirk,

I think we're speaking the same language re power and HR. I just disagree with a Z3 emphasis. Sure, it may be optimal for an athlete training 10-12hrs/wk but most athletes will get even better performance by dialing it down 10 beats/20 watts, cutting the fluff from their lives and training 10 more hours each week.



Unknown said...

You may be correct, my own personal (n=1 (me) as a bike racer, UCI domestic level for 8+ years and n=50 of coached athletes) fitness went way up when I cut back on the volume and increased the intensity.

I do admit, not many of those above (aside from myself) were doing many races over 2 hours.

Alan Couzens said...

Hey Kirk,

For sure, intensity is needed and most athletes will improve when they 'cut back on the volume and increase intensity'. However, I firmly believe that those who wait longer before doing so will improve more - the hallowed concept of base.

I did not include other data from the study that showed that FOG fibers (which are better trained by tempo, threshold and VO2max) training have greater potential for improvement than ST fibers. However, tolerance to FOG training is largely dependent on how quickly lactate is removed from fibers, along with how quickly glycogen can be recovered, both functions of ST fibers. Therefore, when an ST 'fit' athlete decides to emphasize FOG training, the margin for improvement will be far greater than a novice athlete who does the same.