Physiological Aspects of TSS

jsocia said:

[font=Arial]I'm curious if anyone knows or understands the physiological training effect that is represented by TSS. I understand that TSS represents a measure of one's ability to train long/hard day after day and how much recovery time is needed for both intervals sessions and racing, as well as the amount of time one can spend at or above FTP... but specifically in a physiological sense, what is the training effect? I would guess that it is at least partly due to one's increase in capacity for glycogen storage, but are there other training effects?[/font]

It's a good question but it's a bit "forest and trees".

The specific training effects to a large extent depend on the nature of training that make up the TSS, and particularly the intensity side of the TSS equation.

FTP is what it is. You can spend ~ 1 hour at FTP. If you can go substantially longer at a given power, then it is highly likely your FTP is higher than that given power.

Uh... TSS can't really predict adaptations, I think the motivation of TSS was to quantify a workout's calories - so to speak. Alex is right - you need to know composition before you start considering what will happen next.

I eat 300 calories. That doesn't give the whole story of the composition of the calories - fat, carbs, protein, etc... So who knows how my stool will turn out [effect of digestion/effect of TSS score].

If I say I ate 4000 calories in a meal, regardless of the composition - everyone knows I'm full. Much like TSS - if you scored 500 - everyone, including the athlete - knows they are spent.

Now - start to pick out from the TSS - time above/below/at FTP - now we get into composition [fat/carbs/protein] - so we can get a better idea of how your stool will turn out [too much protein - you get bad stool].

I hope that analogy brings some light.

[font=Arial]Thanks for the responses, but I just realized my goof on the part of how I phrased the question: wrong acronym usage. I was actually questioning the meaning of CTL.

To reiterate the question with the original intent:

[font=Arial]I'm curious if anyone knows or understands the physiological training effect that is represented by CTL. I understand that CTL represents a measure of one's ability to train long/hard day after day and how much recovery time is needed for both intervals sessions and racing, as well as the amount of time one can spend at or above FTP... but specifically in a physiological sense, what is the training effect? I would guess that it is at least partly due to one's increase in capacity for glycogen storage, but are there other training effects?[/font]

Thanks again for your feedback!
[/font]

Ahh... ok.

CTL is pre-set @ a 42d constant [your 42 day average TSS score]. Why? I have no clue... 🙂 😄 I know someone in these forums does.

High CTL can come in many different forms [I consider 120TSS/d OR 840TSS/wk high]:

~15h/wk of pure L2
[840/(.75)^2/100] = 14.93 h

~10h/wk of L3/L4 [SST training]
[840/(.9)^2/100] = 10.37 h

~8.5h/wk of racing
[840/1/100] = 8.4 h

So again, the theme of composition appears. Someone who is doing L2 for 15h a week will not have significant adaptations comapred to the SST athlete or the racer. You can't tell if someone has gained any adaptations by looking at their CTL number. You need more information. Not to mention if someone works hard for 42 days and then stops - their CTL is skewed and is not indicative of what's really going on.

Training effects in particular "levels" appear here:
cyclingpeakssoftware.comlevels.aspOpen ↗

Note that "levels" is a loose term - and you can get L3 adaptations while doing L5 work and vice versa. The levels were meant to identify the "best" level for "maximal" adaptation of a particular physiological effect.

What is important is that intensity be significant enough [higher than L2] to stir up the body but not TOO high [L6/L7] for FTP adaptations.

jsocia said:

[font=Arial]Thanks for the responses, but I just realized my goof on the part of how I phrased the question: wrong acronym usage. I was actually questioning the meaning of CTL.

To reiterate the question with the original intent:

[font=Arial]I'm curious if anyone knows or understands the physiological training effect that is represented by CTL. I understand that CTL represents a measure of one's ability to train long/hard day after day and how much recovery time is needed for both intervals sessions and racing, as well as the amount of time one can spend at or above FTP... but specifically in a physiological sense, what is the training effect? I would guess that it is at least partly due to one's increase in capacity for glycogen storage, but are there other training effects?[/font]

Thanks again for your feedback!
[/font]

FTP = how fast you can go
CTL = how long you can go fast

Somewhat tongue in check, somewhat seriously ... you choose 😄

simplyred said:

....CTL is pre-set @ a 42d constant [your 42 day average TSS score]. ....

It's actually a 42 day time constant in an exponential averaging function so it technically includes every workout you've ever recorded but practically represents your average for the last 3 to 4 months. As to the why I'd look into the time course of training adaptation where estimates like 6 weeks to adapt to an increased training load come up pretty frequently.

But yep, CTL and TSS don't tell the whole story. They don't tell you the makeup of your training. They only tell you how much and in the case of CTL how consistently and to some extent, for how long you trained. But as you point out, CTL viewed in isolation could be really misleading and can actually lead folks down the big slow miles training path as that will rack up a lot of TSS but may not produce the desired fitness gains.

Fitness requires:
- Sufficient intensity targeted to desired adaptations
- Sufficient volume
- Sufficient training frequency

AP, NP, IF, etc. do a good job of quantifying the intensity portion. CTL, ATL and TSB do a pretty good job of quantifying the latter two. Sure you could track volume with Calories burned, hours on the bike, mileage or other metrics but TSS and from it CTL do a really nice job of accounting for real world non-isopower riding and racing. Straight kJ might lead you to believe a L6 or sprint workout wasn't all that hard since the average power (and hence total energy) isn't all that high with rest periods. NP, TSS, CTL, ATL, and TSB all take into account the way that bursty workouts are harder than their energy expenditures would lead you to believe.

Specific physiological adaptations, that's tough since it depends so much on what you did to earn that CTL. But I think most riders realize that there's a volume component to training. If not we'd just do Tabata sets all year and go out and race long road races. CTL gives you a way to track that volume component.

-Dave

daveryanwyoming said:

It's actually a 42 day time constant in an exponential averaging function so it technically includes every workout you've ever recorded but practically represents your average for the last 3 to 4 months. As to the why I'd look into the time course of training adaptation where estimates like 6 weeks to adapt to an increased training load come up pretty frequently.

Thanks for the correction Dave. I didn't know that...

I am - by virtue of my time on these forums - still a noob. 😉 😄

While I made the forest and trees comment, I'm not sure we've completely answered the question. I kinda figured it was CTL that was meant, since it's expressed in units of TSS/day anyway.

I still think it's a good question worthy of more discussion.

Alex Simmons said:

...I still think it's a good question worthy of more discussion.

Agreed, I tend to think of CTL in rmur's terms, as a way to estimate how flat your MMP might be for longer durations and as a way to estimate how well you'll bounce back from a hard ride or race and be ready to train or race again.

But the low level reasons aren't as obvious as the benefits of accumulating a reasonably high CTL.

I was out on a long solo ride today and thought about this a bit. Sure my thoughts were influenced by the fact I was doing a long ride and probably trying to justify the benefit. Here's a couple of those random mid ride rationalizations:

- CTL in part tells you how long you sustained a certain workout (as in total minutes accumulated at reasonably high level) and or how frequently and consistently you do such workouts. Sure as everyone has pointed out you still have to consider the individual workouts, CTL doesn't say much about that when viewed in isolation. But anyone who's used the WKO+ Performance manager to track CTL during a build cycle realizes how CTL drops like a stone when you take a day off and how slowly it climbs once your CTL gets fairly high. If you do great well focused and well chosen workouts but take every other day off your CTL won't get very high. If you find a training blend that targets the right systems and addresses your particular needs, do those workouts well but don't kill yourself with each workout so that you can train on subsequent days with minimal rest days your CTL will climb much higher. So in a way it helps you keep track of how well you've found the balance between individual workout intensity and the need to workout many times a week and for many weeks or months to see progress. A single "perfect" workout won't lead to noticable fitness gains, many such workouts might and CTL helps keep track of the "many" aspect.

-My other thought around hour five of today's long ride was that muscles get fatigued. And if you try to hold focused intensity from start to finish on a longer ride at some point you're either stressing your muscles relatively harder for the same IF because they're getting really tired or you're recruiting additional muscle fibers or muscle groups to share the load as your primary muscle fibers or groups get tired. Yeah, no science behind this thought, but fatigue isn't a particularly well undestood phenomena yet we all experience it. It seems to me there's training value in working out at reasonable intensity after some accumulated fatigue, no not every day, but from time to time it seems to make you dig deeper and perhaps get some training adaptations that are hard to come by with shorter rides. If so, CTL in part tracks that longer term load that equates to training prefatigued muscles. It might be day after day of steady work or the occasional longer ride but either way CTL or maybe TSB provides insight into how often you trained tired or trained long enough to work tired muscles.

Yeah, just random unscientific thoughts during a longer than usual ride but that's what popped into my head.

Feel free to throw darts at my hallucinations, I'm not heavily invested in these ideas but thought they were interesting at the time.....

-Dave

Some results of high CTL that I think are happening:

Chronic use of metabolic pathways at high frequencies - so they are activated more frequently than sedentary people.

Whether or not this action stimulates adaptations, no clue - but I'd imagine your body figures out ways to better distribute red blood cells, remove/use lactic acid quicker, the muscle fibres become more "specific" to a particular neural activation, oxygen consumption decreases for a particular power [ie. increase in power @ VO2max], typeIIa convert to typeIIb [fast-oxidative-glycolic], type I become more "efficient", body position on the bicycle becomes more natural - so blood pathways become accustomed to pumping around your torso - so to speak, umm... that's all I can think of for now...

This isn't so much an adaptation, but more so a condition of the training but I'd guess there's the possibility of adrenal gland overuse and low blood pH.

jsocia,

I think this website should answer some of your questions:
home.hia.noexphys.htmOpen ↗

It's quite the popular website [almost 2mil hits!!]
Assume that the adaptations and increases in efficiency are spurred by high CTL.

Also - I made many errors in my above post - please disregard. I should've waited till morning to post something rather than post something before going to bed...

simplyred said:

Some results of high CTL that I think are happening:

Chronic use of metabolic pathways at high frequencies - so they are activated more frequently than sedentary people.

Whether or not this action stimulates adaptations, no clue - but I'd imagine your body figures out ways to better distribute red blood cells, remove/use lactic acid quicker, the muscle fibres become more "specific" to a particular neural activation, oxygen consumption decreases for a particular power [ie. increase in power @ VO2max], typeIIa convert to typeIIb [fast-oxidative-glycolic], type I become more "efficient", body position on the bicycle becomes more natural - so blood pathways become accustomed to pumping around your torso - so to speak, umm... that's all I can think of for now...

This isn't so much an adaptation, but more so a condition of the training but I'd guess there's the possibility of adrenal gland overuse and low blood pH.

To be more detailed about it. Training (at proper levels) causes adaptations in the cardiovascular system, muscles and associated neurology.
Generally speaking, adaptations are intensity driven with higher intensities inducing adaptation in a shorter training duration. As such, training is very much a "top-down" endeavor. Therefore, high-intensity training, with the exception of very short duration sprint intervals (i.e. 10 seconds) will induce adaptations that provide multi-zone performance increases. For example, 30-second interval training with increase both AWC and FTP.

Specific adaptations include: increased muscle mitochondria, capillary density and aerobic enzyme activity, increased plasma volume, left ventricular hypertrophy, conversion of Type IIB muscle fiber to Type IIA muscle fiber.

Keep in mind that among groups of people who experience identical training, due to genetic differences there will be responder (significant improvement), non-responders (little improvement) and the entire range between. For example, the genetics that dictate high VO2 max tend to limit efficiency.