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(How To) Cardiac Drift - A Different Way of Looking at Indoor Training

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(How To) Cardiac Drift - A Different Way of Looking at Indoor Training

Old 02-12-19, 01:20 PM
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(How To) Cardiac Drift - A Different Way of Looking at Indoor Training

Please keep in mind that this thread is intended to merely introduce a few alternative metrics or ways of looking at metrics which may or may not prove valuable as an aid in helping ERG mode users to manage workout intensity, duration and frequency.

It is not specific to any event type and does not presume or prescribe any particular workouts, interval structures, training schedules, periodization, etc.

These things are all still up to you or your coach to determine according to your goals, events, circumstances, etc.


---

I base the determination of workout intensity, duration and frequency on three metrics:
  • Cardiac drift
  • MSI
  • Internal:external load ratio
Here's why, starting with cardiac drift, which is the metric I'd chose if I could only have a single metric:

Perhaps even more compelling than obvious physiological support and its use by successful coaching outfits, the relationship between cardiac drift, endurance and fatigue is reproducible/empirical.

Increase workout duration or frequency and cardiac drift goes up. Decrease them and drift goes down.

Better yet, there is a near-perfect association between cardiac drift and problems I have had with recovery in the past, even before I was tracking cardiac drift.

From a purely analytical perspective, cardiac drift provides additional insight into the distribution of heart rate over time than average heart rate alone.

And, at fixed power under controlled conditions indoors, otherwise confounding variables are more reliable and consistent within and between workouts.

MSI (maximum sustainable intensity) is obvious. You must continually challenge the body in order for it to adapt and MSI is nothing more than a fancy word for "challenging". MSI is the maximum power you can sustain across all intervals of an interval workout.

The most natural, intuitive and widely-used performance metric in the history of cycling is the internal:external load ratio, whether people know that they are using it or not. Indoors under controlled conditions, it merely becomes an even faster and more reliable indicator.

Here's how, again starting with cardiac drift:

If cardiac drift is < 5%, increase endurance workout duration. If > 10%, decrease duration.

If cardiac drift is increasing, decrease workout frequency, especially when there is a coinciding increase in RPE or decrease in average heart rate.

Perform interval workouts at MSI. If you have too much left in the tank at the end of a workout, increase the power of the subsequent workout.

Use the internal-to-external load ratio (I:E) to monitor whether your training is working, whether you received adequate stimulus, and to predict recovery requirements. A decrease in I:E is an indicator of improved fitness. This can happen in two ways; (1) You are able to more with the same effort or (2) you are able to do the same with less effort.

While possibly counter-intuitive, the ability to do more with less effort is a reflection of the effectiveness of prior workout and subsequent recovery. What this means is that, today's lessor internal load may have been inadequate since it was less than the prior workout internal load which produced the improvement.

Conversely, if improvement is indicated by today displaying a "more for the same" relationship, then, using the same logic, today's stimulus was likely good and calls for the same amount of recovery as followed the prior workout.

---


Please disregard the below as I'm just trying to save it temporarily until I can work the meat of these posts into this OP. Sorry for the inconvenience:

Last edited by fstrnu; 02-18-19 at 12:58 PM. Reason: Re-write
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Old 02-12-19, 01:47 PM
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Mod note: link to article on ERG

IS ERG MODE KILLING YOUR TRAINING?





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Old 02-12-19, 09:14 PM
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Old 02-12-19, 09:31 PM
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Originally Posted by fstrnu View Post
  1. When you reach the point at which you start looking forward to the end of the session, ride for 25% longer, e.g. if you start looking forward to the end of the session at 96 minutes then ride 24 more minutes for a total of 120 minutes
That would limit my indoor workouts to 6.25 min...
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Old 02-13-19, 02:07 AM
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Originally Posted by fstrnu View Post
[*]When you reach the point at which you start looking forward to the end of the session, ride for 25% longer, e.g. if you start looking forward to the end of the session at 96 minutes then ride 24 more minutes for a total of 120 minutes
[*]Rinse and repeat and keep me posted!
And that's why the great outdoors exists.

I have done 4 hours indoors, but really, anything over about an hour ... just not that interested.


I've asked before and I'll ask again ...


Why? For what purpose?

What is the goal that "implementing an indoor training program based on cardiac drift" strives to meet?

Last edited by Machka; 02-13-19 at 02:25 AM.
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Old 02-13-19, 07:09 AM
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This dude is a hydra. Call his b.s. out on one thread and two more pop up.
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Old 02-13-19, 07:37 AM
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  • What is cardiac drift? What is aerobic decoupling? What is EF?
Well, I would be nice if the OP answered these questions first? This newbie would like to know.....
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Old 02-13-19, 08:08 AM
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Intensity, duration and frequency (AKA programming variables)

Intensity, duration and frequency are what you manipulate when you decide when and how to workout. While these variables are in play at every level and both work and rest, the primary consideration is overall stimulus, progression and recovery between workouts.

As a self-regulating metric, maintaining 5-10% cardiac drift addresses all three of these components automatically.

By definition, fitness improvement changes the relationship between effort and power. As this relationship changes, power or duration needs to be progressed in order to continually challenge the body. If not, the body will cease to adapt. Incidentally, this decrease in stimulus will also manifest in a cardiac drift below 5%. This is due to the inverse relationship between power and time.

As a measure of endurance cardiac drift has obvious application to the duration of workout which will stimulate adaptation.

But it also informs power vs time trade-offs when workout time is limited. If the ideal workout for today calls for 120 minutes but you only have 90 minutes, then the goal is to work at a power which will produce a cardiac drift of 5-10%.

Frequency is also informed by cardiac drift, especially in conjunction with average work interval heart rate. A decrease in heart rate which coincides with a spike in cardiac drift is a sure sign of fatigue which causes a suppressed (lower than normal heart rate). This, in turn, skews the measurement of cardiac drift which is based on comparing first half average heart rate to second half average heart rate. The magnitude of such fatigue is also captured as suppression increases which allows accurate tracking of fatigue accumulation. Beyond 10% suggests the need to adjust workout frequency in order to achieve adequate recovery and adaption from training sessions.
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Old 02-13-19, 08:11 AM
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Go ride outside. Riding indoors sucks.
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Old 02-13-19, 08:11 AM
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So ... you're not planning to answer any questions. You're just planning to continue quoting from some textbook?
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Old 02-13-19, 08:11 AM
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I make this my next write-up. For now, check these out:


Originally Posted by Ald1 View Post
  • What is cardiac drift? What is aerobic decoupling? What is EF?
Well, I would be nice if the OP answered these questions first? This newbie would like to know.....
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Old 02-13-19, 08:31 AM
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The best part is, I put in a nice 67 miles yesterday and never thought about any of these "parameters" even once. So it can be done-- an individual can actually ride a bike for fitness and leisure without turning it into a High School science experiment.
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Old 02-13-19, 10:54 AM
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What is cardiac drift? What is aerobic decoupling? What is EF?

Cardiac drift refers to "the gradual rise in heart rate we see in our bodies toward the end of prolonged exercise despite the level of intensity remaining the same". Source:


Efficiency Factor (EF) = Normalized power / Average heart rate

EF is relevant for two reasons: (1) it is used in calculating aerobic decoupling (see below) and (2) it is "a measure of improvement in aerobic efficiency" (Training Peaks), the same as the internal-to-external load ratio which I will also be writing-up.

Aerobic decoupling attempts to estimate cardiac drift for outdoor rides by comparing first half EF to second half EF. EF is used instead of heart rate because of how power varies wildly outdoors.

Indoors using fixed power under controlled conditions, however, aerobic decoupling = cardiac drift and is much more reliable because there's no need to compensation for variability of power or conditions which can effect the relationship between effort and power, the measure of said relationship or things that effect the measure of said relationship.
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Old 02-13-19, 12:47 PM
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Log

Sat = Workout 1 of "endurance" block = 90 minutes with 10% drift and 129 bpm
Sun = Workout 2 of "endurance" block = 90 minutes with 5% drift and 133 bpm
Today = 90 minute "tempo" workout

Discussion:
.
  • Sat/Sun = Endurance block due because I couldn't fit in 90 minutes on either day
    • A side benefit of weekend endurance blocks is that they allow a pseudo 9-day microcycle which also aligns with calendar week
  • Sat metrics impacted by poor nutrition and much beer consumed Fri
  • Sun drift a bit lower than what I'd like to see so will increase power for next endurance block
  • No adjustments to power for today's session even though load indicators suggest drift may be low today ; If so, then will establish new baseline for this duration
.
Edit - I just noticed that drift only hit 10% once and that was with 50% less than normal recovery so I've decided to increase today's workout power, especially given load indicators

Edit #2 - Worth specifically pointing out that the 10% drift coinciding with a drop in HR, indicating suppression from fatigue.

Last edited by fstrnu; 02-13-19 at 01:18 PM.
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Old 02-13-19, 06:52 PM
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Well, I understand what you are getting at with Cardiac Drift, however it's not something I see as being something that must be within a range to ensure it's a quality workout for all zones. I did steady state intervals Saturday that sent my HR within a couple beats of my max for the end of the last set, then did a 2 hour ride Sunday with 1:20 in the middle of my endurance wattage and ended up with PWR:HR on Training peaks of -0.37 for the Endurance portion and I was pretty beat by the end of it. I would say from the sweat and heart rate, it was very solid work. I could not have got anywhere near 5%. For the Steady State ride Saturday, I was at 9.9 for the entire workout including warm up and cool down but 4.5 for the 3 intervals with rest between. So do you prescribe using the result from the entire ride or just the work portions?

Last edited by srode1; 02-13-19 at 06:57 PM.
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Old 02-13-19, 07:44 PM
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Yeah, that's why we don't do that. Too many confounders, plus I maybe do one workout/week where drift might even be a factor. That said, it is nice to see drift coming down to only a couple beats on the second 15' Z3 interval, but I'm certainly not going to mess with my weekly zone totals in order to inappropriately get tired when I'm going to need some ability later in the week.

Your Edit #2 : well not necessarily what you think it means. Frequently when one's HR is depressed for fatigue, one warms up to a normal HR for power after maybe 1/2 hour, depending on approximately one zillion confounders. Then drift goes up from there. OTOH, when one's HR is depressed, should one care about CD? Or maybe one should care much more about being ready for the next hard workout. All this planning is a lot harder than you think and flexibility is key. I was supposed to hit the indoor bike for an hour today, but my legs are saying, "Stupid, kid." I checked my TSB and week's projected CTL increase and see that I was overoptimistic about how much I could push the latter up this week. So I'm sitting here typing instead. I'll have a better couple of workouts tomorrow and be stronger on the weekend.

That's the advantage one has using TrainingPeaks - one can look ahead and see what one can profitably.do. And that's why I don't use power to plan my training. I'm tired from snowshoeing and Alpine skiing, but I can still see what's going on because I use hrTSS for everything.

I know you are interested in CD, but look at it as a tell, not to set one's program. Too many confounders and the generation of foolish workouts which no one will do is also an issue. It's like discovering sex. Yeah, we know it's interesting, but it's old news. And so far, I haven't heard a song about cardiac drift. In that way, a little CD education on BF is not a bad thing, but that takes one comment on one thread to accomplish, see, and you've already done that. Then one can bookmark that comment and give a link to it in future threads as appropriate.

You are talking to a tiny minority of nut-case training freaks here, and no one thinks that training by CD is a good idea, especially if it requires sitting on a bike indoors for more than about 45'. Give it up. Besides it doesn't mean what you think it means:
Cardiovascular physiologists suggest that cardiac drift is connected to an increase in core temperature and body water losses. When core body temperature increases a similar increase is seen in heart rate. Furthermore, when core body temperature increases the body responds by increasing skin blood flow to help control the temperature rise. The increase in skin blood flow occurs at the same time that the working muscles demand a large proportion of blood flow, which creates competition and demand from different parts of the body.

To understand the importance of fluid losses on cardiac drift, researchers looked at cyclists who cycled for 2 hours either with or without taking on extra fluids during exercise. The group of cyclists who didnít consume any fluids during their cycle experienced an increase in heart rate of 10%. When the group of cyclists who were able to consume enough fluids to match sweat rate completed their cycle their heart rate increased by only 5%. The study concluded that half the cardiovascular drift experienced by the cyclists could be explained by dehydration.
https://www.polar.com/blog/cardiac-d...t-on-training/

Thus during long rides, I use CD as a tell that I'm becoming dehydrated, not better trained! And it's not just dehydration, but also core temperature and who knows what else that they didn't monitorr. Carb consumption also affects HR vs. effort. It's a waste of time, other than using it as a tell for various things.
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Old 02-13-19, 08:15 PM
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I have looked at the research on CD and it is mostly about increases in core temperature. So what would change core temperature? Ambient temperature, body fat, clothing, air movement and CO2 concentration v O2. When I am indoors, ambient temperature and fan air flow rate dominate my cardiac drift. If I am skinnier then I get better heat regulation and lower CD. How about a closed room full of cyclists consuming O2 and breathing out CO2? Not good. Indoor cycling requires good ventilation of fresh air otherwise there is too much CO2 and that is our nemesis in power production...getting rid of CO2. Outdoors, we are constantly bathed in air that has constant O2/CO2 ratio. Hence the trainer is harder and CD an interesting variable that may have tertiary value at BEST. I consider HR in general a tertiary measure with too many unknowns to provide a lot of benefit. Relying on a derivative of a derivative seems dumb.

For a moment, let me argue the other side. CD is the new new thing in training and everyone should be indoors doing 120 minute workouts until CD is X. Assuming that is true, a workout is only of value if an athlete is willing to do it. I am not interested in 120 minute workouts on a trainer monitoring my HR. That is a non starter and I will do something else.

I do indoor workouts only when I have to and only when I am highly motivated. Also, I know that indoor workouts increase my mental fatigue more than the same TSS of an outdoor workout. So why would I do them? If I only wanted to ride inside to increase fitness, I would do a spin class, Zwift or Peloton and use their software. If I go to spin class, all I need is clothes and shoes.
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Old 02-14-19, 02:47 AM
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Originally Posted by Hermes View Post
I have looked at the research on CD and it is mostly about increases in core temperature. So what would change core temperature? Ambient temperature, body fat, clothing, air movement and CO2 concentration v O2.
I wonder how menopause factors into that.
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Old 02-14-19, 05:03 AM
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Originally Posted by Hermes View Post
For a moment, let me argue the other side. CD is the new new thing in training and everyone should be indoors doing 120 minute workouts until CD is X. Assuming that is true, a workout is only of value if an athlete is willing to do it. I am not interested in 120 minute workouts on a trainer monitoring my HR. That is a non starter and I will do something else.
The other issue for me is how to know when you have reached that CD target while riding. If there was a Garmin IQ app one could use to calculate it as you ride during an interval or set of intervals that would be something I could execute, otherwise how would you know? Seems it's a fairly complicated target to predict performance vs while riding a trainer.
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Old 02-14-19, 08:19 AM
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Originally Posted by srode1 View Post
Well, I understand what you are getting at with Cardiac Drift, however it's not something I see as being something that must be within a range to ensure it's a quality workout for all zones. I did steady state intervals Saturday that sent my HR within a couple beats of my max for the end of the last set, then did a 2 hour ride Sunday with 1:20 in the middle of my endurance wattage and ended up with PWR:HR on Training peaks of -0.37 for the Endurance portion and I was pretty beat by the end of it. I would say from the sweat and heart rate, it was very solid work. I could not have got anywhere near 5%. For the Steady State ride Saturday, I was at 9.9 for the entire workout including warm up and cool down but 4.5 for the 3 intervals with rest between. So do you prescribe using the result from the entire ride or just the work portions?
I assume you mean Pw:Hr/Pa:Hr and not PWR:HR. Nutrition, caffeine, hydration or variation in cadence could be playing a role and if this was outdoors all bets are off because there are too many confounding factors. Having said that, I have had negative drift but only a handful of times and without sufficient controls.

When I say all bets are off if you are riding outside, I don't mean cardiac drift is not useful outdoors ; just that I don't specifically advocate it because I am an indoor specialist. I see no reason you can't use cardiac drift outdoors and the more variables you can control and the more directional evidence you can establish via trend analysis the more reliable the conclusions you can draw from it will be. I consider Joe Friel's and Hunter Allen's advice around this to be both practical and genuine.

Using the whole workout will be easier for some and will suffice when warmup is similar to work, i.e. for lower intensity workouts, etc. but work intervals will be more precise. I only measure drift during work intervals. One thing to keep in mind is that an odd number of intervals will skew the calculation of cardiac drift higher because the first half of the workout will get HR lag from the middle interval while the second half will only get the higher HR from the middle interval.
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Old 02-14-19, 08:31 AM
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Originally Posted by Carbonfiberboy View Post
Frequently when one's HR is depressed for fatigue, one warms up to a normal HR for power after maybe 1/2 hour
...which, as I've said at least 100 times, allows CD + HR to give such reliable insight into both the presence and magnitude of fatigue.
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Old 02-14-19, 08:36 AM
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Originally Posted by Hermes View Post
I have looked at the research on CD
Look again:

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Old 02-14-19, 09:01 AM
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Originally Posted by srode1 View Post
The other issue for me is how to know when you have reached that CD target while riding. If there was a Garmin IQ app one could use to calculate it as you ride during an interval or set of intervals that would be something I could execute, otherwise how would you know? Seems it's a fairly complicated target to predict performance vs while riding a trainer.
This is an excellent question (keep them coming) as it allows/reminds me to point out a few things and introduce some nuances/concepts. Firstly, I MIGHT use such an app, however, while it may sound counter-intuitive, I might not use it to stop a workout at the right time. Why? The first reason is that I can learn from analyzing why CD is below or above 10%. Also 5-10% is a range/rule of thumb so what number would you pick? Would you stop at 5%? 7%? 10%? 11%? I like to monitor and understand the relationship between fatigue accumulation and recovery. For example, I can watch fatigue accumulate from 5% to 7% to 10% and drop back down to 7% from an extra recovery day. And I can reproduce this with near perfect precision. See the 3 x 3 x 3 test discussed in the PB Science video I posted above. It allows me to play with intensity, duration and frequency at multiple levels to tune my training according to my ability to handle load at both the microcycle and block level. For example, I might find that I can handle more overall load with a higher ramp rate but more frequent rest weeks...or vice versa.

You can't go wrong using the 5-10% but this is also a range for the purposes of guidance based on a lot of internal data so your magic number might be 4 or 11 or 8. Or maybe there is no single magic number. The point is to open your eyes and begin the process of learning about how your body individually is responding to training and the more data you accumulate the more you will know yourself.

Another thing to consider is that deliberately allowing fatigue to accumulate before dissipating it is a valid approach to training.

My prescription is designed to get people started but is not even close to fully leveraging the power of cardiac drift and longitudinal analysis.
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Old 02-14-19, 09:02 AM
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Originally Posted by fstrnu View Post
I assume you mean Pw:Hr/Pa:Hr and not PWR:HR. Nutrition, caffeine, hydration or variation in cadence could be playing a role and if this was outdoors all bets are off because there are too many confounding factors. Having said that, I have had negative drift but only a handful of times and without sufficient controls.

When I say all bets are off if you are riding outside, I don't mean cardiac drift is not useful outdoors ; just that I don't specifically advocate it because I am an indoor specialist. I see no reason you can't use cardiac drift outdoors and the more variables you can control and the more directional evidence you can establish via trend analysis the more reliable the conclusions you can draw from it will be. I consider Joe Friel's and Hunter Allen's advice around this to be both practical and genuine.

Using the whole workout will be easier for some and will suffice when warmup is similar to work, i.e. for lower intensity workouts, etc. but work intervals will be more precise. I only measure drift during work intervals. One thing to keep in mind is that an odd number of intervals will skew the calculation of cardiac drift higher because the first half of the workout will get HR lag from the middle interval while the second half will only get the higher HR from the middle interval.
My understanding of the Training Peaks Metrics that what is displayed on the screen for analysis of a workout as Pw:Hr is indeed Aerobic Decoupling or Cardiac Drift, so I think we are on the same sheet. All my rides right now are indoors on a trainer, so that would include both I mentioned, also not using Erg Mode. Good point on the inflation of odd number intervals which is what I typically do for Steady state (3X Something), so result from the Saturday SS I used as an example is inflated somewhat.
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Old 02-14-19, 09:06 AM
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wphamilton
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I did glance at the video, skipping to 22:25 where she gives a basic explanation of "decoupling" and spends some time on the simple calculation. She then says in a very general sense that looking at decoupling over a large period of time, if she sees "excessive decoupling" she can infer that there is too much fatigue (particularly, she says, when you can't finish a workout). I didn't hear anything I'd think of as "research" nor, frankly, more than a very basic description of what you mean by cardiac drift and one or two of the several factors which contribute to it.

What are you referring to as research in that video, relating to cardiac drift/decoupling? How do you justify, with this video or presumably other research that you're aware of, your use of instantaneous cardiac drift to modify individual training sessions? Apparently the entire rationalization is to train approximately at or near threshold, and in that case why not just train at threshold? Using CD as one of several measures to determine cumulative training stress.
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