Why? If the cadence is low enough and the force high enough, the athlete would recruit previously idle fibers. But, would they then be available on race day at normal cadences and forces, or would they go back to sitting idly?

Many use PE or HR instead of pace to monitor exertion on the run.

On what kind of run? A footrace, an ultra run, or a mass-start AG triathlon?

I think the feedback strategy differs depending on what sort of event it is. A "pure" running race is typically paced by (1) those around you; (2) the watch; and (3) PE. In that order.

That's a pretty good argument for all race pace, all the time. Why not do that then?

I wasn't making that assertion (as you know) -- just asking about the value of the low-cadence, high force cycling. You seemed to indicate that you thought there was value in that workout. Is the overloading induced by that workout specific to our goal of high steady-state aerobic power? (I ask because I'm not sure; I'm skeptical, but I'm not really sure.)

"If a guy's FT is 300 watts, and he rides at 80 vs. 100 rpms, the recruitment pattern is immaterial. The dominating effect there is the tradeoff between efficiency (weighting to the 80rpm choice) and stamina (weighting to the 100rpm choice). The preponderance of the evidence points to the fact that a slower work-rest cycle is more metabolically efficient than a faster one, at a given average work rate. But the faster one can result in a given average work rate being maintained for a longer period of time. This curious, and its cause is not (to my knowledge) been firmly identified. Referencing the work of Taigen and Wells, Bernd Heinrich has hypothesized that the longer "pull" at a higher force (in a low cadence setting) can upset the equilibrium of CHO usage and replenishment, resulting in a more rapid depletion of CHO overall."

According to that, riding at the lower cadence results in a dependency on CHO vs. Lipids for energy production; otherwise one wouldn't deplete of CHO sooner at the same absolute work load. If it's not the difference in fiber type recruitment at low vs. high cadence, then what is it?

What is different when riding at 80 vs. 100rpms if it is not muscle fiber recruitment? You mentioned the work-rest cycle which obviously is different between the two. What else? Or is that alone responsible for the increase in CHO dependency at the same work load? I'm still not convinced that riding at the two cadences results in the activation of an equal percentage amount of type I and type II fibers.

Why would the slower cadence result in a greater dependency on glucose? I'm just asking, maybe AC could help out again :)

As far as I remember, two key enzymes that affect glycolytic flux are GP and PFK. Ca+ and increases in the concentration of metabolites (P, ADP, AMP) may also play a role in turning glycolysis on. So if it's not the difference in the percentage of fiber type recruitment, could the lower cadence disrupt any of those variables? There must be something about turning on glycolysis (to a greater extent) when riding at lower cadences, otherwise one wouldn't be as likely to deplete at lower vs. higher cadences (all relative).

AC we need your help again! :)

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�The greater danger for most of us is not that our aim is too high and we miss it, but that it is too low and we reach it.� -Michelangelo

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The hypothesis turns on the fact that power generation isn't continuous -- "work rate" is an instantaneous measure. We only take the average (integral) of these measurements over a period of time. When we say "I held 200 watts" we really mean, "I held an average of 200 watts."

Animal muscles are not continuous motors; they are reciprocal and periodic. Then, a given average work rate actually consists of very high work rates, followed by very low work rates. A lower cadence rate is therefore a situation in which the muscles are working harder, but resting longer, than when using a faster cadence at the same average work rate. So, it is at least plausible that the higher momentary power requirement of slower cadences results in a disproportionately faster use of glycogen, or, a disproportionately slower replenishment of same. Whether the cause here is this glycogen cycling or not, something seems to be happening in the "work harder, but rest longer" setting to accelerate fatigue in many cyclists (and animals).

It really depends on the duration of the race and where the threshold of activation of type II starts. This can happen by force or fatigue of type I. So activation of type II in training is helpful either you plan to go long and slow or short and fast.

"That's a pretty good argument for all race pace, all the time."

Paulo,

Seems to work for many Kenyan distance runners :)

Well maybe not all the time, but a significant chunk of their total training time

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Steve Fleck @stevefleck | Blog

Add:

The way it works out is that, assuming that the work in a pedal stroke is done over the same part of the circle whether at 80 or 100 rpms, the average power during that part of the circle is the same. If the "business part" of the circle is a 1/3 revolution, then a one-legged cyclist holds 900 watts for that short part in order to average 300 watts (to use a simplifying example).

But, he holds that effort for .25 seconds at 80 rpms, and .20 seconds at 100 rpms. Of course, he then gets a longer rest at the slower cadence. With a slower cadence, it's the same instantaneous work rate, but held for a longer period, followed by a longer rest. Which is better? Is it better to average 300, by doing 900 a third of the time, with long or short cycles?

Ah...got it.

One last stab at the cadence-recruitment question before I head home...

As many are probably aware by now, the pedal force-pedal velocity (or torque-cadence) relationship when cycling is essentially linear, i.e., as the velocity at which the pedal moves around the circle increases the maximal force that can be generated decreases (cf. http://home.earthlink.net/.../setraining/id1.html). As a consequence, the power-velocity (or power-torque) relationship is well-described by an inverted parabola, with a maxima at one-half of (theoretical) maximal pedaling rate (i.e., the X intercept of the pedal force-pedal velocity line). IOW, there is one, and only one, pedal velocity (cadence) at which you can generate maximal power. On the other hand, any isopower line is a right hyperbola, with that representing maximal power falling entirely above the pedal force-pedal velocity line except for one point (i.e., said power can only be reached at that optimal pedal velocity) (cf. http://home.earthlink.net/.../strengthvspower.gif). At any submaximal power (e.g., 300 W), however, the isopower line will be below the pedal force-pedal velocity for at least some portion, i.e., said power can be generated using a variety of pedal forces and pedal velocities, but if the pedal velocity is too low or too high, not enough force can be produced to achieve that power.

So what does this have to do with motor unit recruitment? This: since the the pedal force generated during a maximal effort at any pedal velocity presumably represents recruitment of all motor units, the point on the isopower line that is furthest from the linear pedal force-pedal velocity line at least theoretically represents the recruitment of the fewest motor units required to generate that power. At either a lower or a higher pedal velocity, more motor units must be recruited because the relative force required is closer to the maximum that the muscle can generate at that velocity. Although other factors are undoubtly also involved, this way of looking at things helps explain, e.g., why optimal cadence tends to increase with increasing power output, or why individuals with more type I motor units (and hence a steeper pedal force-pedal velocity relationship) tend to self-select a lower pedal speed (cadence). More specifically, it explains why Alquist et al. failed to see any discernable difference in fiber type recruitment pattern (based on PAS staining) in subjects pedaling at either 50 or 100 rpm, as both conditions were probably equally distant from the optimal cadence at that power output for these individuals, i.e., the one that results in minimal motor unit recruitment.

Paulo,

Seems to work for many Kenyan distance runners :)

Well maybe not all the time, but a significant chunk of their total training time

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To quote a world renouned Portugese coach, "Specificity is important, but it's not ALL about specificity."

The largest portion I've ever heard quoted for % of training at race pace (or faster) is 45%....that means at least 55% was under race pace.

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-----------------------------Baron Von Speedypants
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Dr. AC,

quick question: I have notice that if I am training at LT on the bike (judged by RPE and HR relative to previous tests) and drop the cadence but increase the resistance (and theorticaly keep the same wattage), my RPE stays about the same yet my HR drops by many BPM.

Am I likely still in the same "training zone" despite my lower HR....and is that a typical response?

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-----------------------------Baron Von Speedypants
-----------------------------RunTraining articles here:
http://forum.slowtwitch.com/...runtraining;#1612485

Why is the HR more accurate than the pace during the VO2 Max test (assuming we aren't using inclines). Or rather, running wattage if we are using inclines?
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I don't know if you are refering to only cycling or if you are including running. However, according to some discussions with Daniels, the MOST accurate way is to test the blood while exercising, 2ndly you'd want to look at percenatge of velocity (% of maximum pace at different distances...ie MaxV02 @ 11 minutes, LT @ 60 minutes), then RPE, and only lastly do you use heart rate as a guide.

There are too many factors that can affect HR that are not necessarily exercise related. IE, if a dog jumps out and scares you, your heart rate will jump however your legs will continue to operate just as aerobicaly as before.

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-----------------------------Baron Von Speedypants
-----------------------------RunTraining articles here:
http://forum.slowtwitch.com/...runtraining;#1612485

Mike,
I started using a PM in the spring of 2004 and stopped in Fall of 2006. During those 30 or so months I rode without one for about three months waiting for a replacement and 7 months when I was in Iraq. Others have certainly used one more, but I have a bit of experience, to include all the races in those years.

The PM is a useful tool, but I realized I had become a slave to the numbers and was judging my rides by what they said at the end of the day. I've been power-free for three months now and enjoying it.

Chad

[reply]
...As a consequence, the power-velocity (or power-torque) relationship is well-described by an inverted parabola, ... IOW, there is one, and only one, pedal velocity (cadence) at which you can generate maximal power ...

At any [i]submaximal[/i] power (e.g., 300 W), however, the isopower line will be below the pedal force-pedal velocity for at least some portion, i.e., said power can be generated using a variety of pedal forces and pedal velocities,

...this way of looking at things helps explain, e.g., why optimal cadence tends to increase with increasing power output, ....[/reply]

So is it possible to develop an individuals optimal cadence/power curve through a series of tests?

Maximal power and cadence is a single point. As you say submaximal at 300w could be achieved at a range of cadences, but could you run a series of tests, say time to failure @ 600w, 500w, 400w at a range of cadences and then plot the cadence at the longest time to failure (for example) vs. power and then project this down to 300w and 200w to predict optimal cadence at powers where testing time to failure is not practical.

Except that, as I put it, "...other factors are undoubtly involved..." in determining the optimal cadence during submaximal exercise. The most practical (and usually the most precise) approach is therefore to just throw away your cadence monitor and let your body tell you what cadence it prefers.