# What does a higher FTP but lower LTHR than previous test mean?



## digita6 (Sep 29, 2012)

Greetings!

After two months of hard indoor training, and recently completing the tour of Sufferlandria, I did a 20 min test today on Trainer Road (last one was almost 2 months ago). The result is that I gained 60 watts of FTP from 233 to 293 (awesome), but the recommendation for LTHR was to lower it from 168 to 158. I am wondering how this could be the case? Is it possible that it is telling me I could have worked much harder on the 20 min test?

Incidentally, I went for a group ride on Sunday, and I've never felt this good on the road. Hills that used to bother my just seem to melt away into the distance behind me now.

Thanks for any insight!


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## adam_mac84 (Sep 22, 2010)

increased power at lower HR is like the definition of improvement


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## woodys737 (Dec 31, 2005)

If you tested the same way it means your kicking ass. 60W in 8 weeks is huge. In no way do I want be debbie downer but is there a chance you sucked on the test 2 months ago?


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## digita6 (Sep 29, 2012)

I remember the previous test, and even took notes to review, and have an exercise/diet log. Everything seems to be pretty close to the same, including time of day, and all equipment and settings were identical (including rear wheel/tire/tire pressure).

I gained about 10 FTP since joining TrainerRoad in late Nov 2012 through the end of Dec (about 4 weeks). I feel like I *really* busted my hump over the past 8 weeks, however, and have used the regular metrics generated through TR as a sort of motivation.

I also only just returned to cycling last September after dropping about 90 lbs through diet and regular exercise. Perhaps the fact that I had a pretty low starting point allowed room for more drastic improvement?


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## woodys737 (Dec 31, 2005)

digita6 said:


> I remember the previous test, and even took notes to review, and have an exercise/diet log. Everything seems to be pretty close to the same, including time of day, and all equipment and settings were identical (including rear wheel/tire/tire pressure).
> 
> I gained about 10 FTP since joining TrainerRoad in late Nov 2012 through the end of Dec (about 4 weeks). I feel like I *really* busted my hump over the past 8 weeks, however, and have used the regular metrics generated through TR as a sort of motivation.
> 
> I also only just returned to cycling last September after dropping about 90 lbs through diet and regular exercise. Perhaps the fact that I had a pretty low starting point allowed room for more drastic improvement?


Well that is awesome! Congrats!

Big gains can be made from little fitness so those you observed are probably ligit. However, the LTHR of 168 to 158 is strange as I would think under similar conditions (rest, hydration, temp, etc...) if you tested the same way LTHR would actually go up. 

You definitely know your improving when you hold power constant and HR is lower. I used power and HR for a while then figured the HR data was more or less useless to me. I'd recommend just focusing on power. JMO.


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## digita6 (Sep 29, 2012)

Thanks! It feels great to be able to just get out and ride. Cycling has long been the only real athletic pursuit I've been drawn to. I use the HR data primarily to get a more accurate calorie count, but that is becoming less important to me than other metrics.


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## Alex_Simmons/RST (Jan 12, 2008)

adam_mac84 said:


> increased power is the definition of improvement


ftfy.


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## Alex_Simmons/RST (Jan 12, 2008)

digita6 said:


> Thanks! It feels great to be able to just get out and ride. Cycling has long been the only real athletic pursuit I've been drawn to. *I use the HR data primarily to get a more accurate calorie count*, but that is becoming less important to me than other metrics.


Your power data will be far more useful than HR data for calorie metabolism estimation. Calorie metabolism estimators based on HR can be notoriously inaccurate.


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## IKnowYouRider (Jul 1, 2003)

Alex_Simmons/RST said:


> Your power data will be far more useful than HR data for calorie metabolism estimation. Calorie metabolism estimators based on HR can be notoriously inaccurate.


Alex,
Sorry for the threadjack...but regarding hr, you've always been a clear proponent of power as the single most important training metric, with very little to be gained from paying attention to heart rate (a view I share). Recently it seems people (Friel) have been paying more attention to heart rate drift or decoupling as a metric for aerobic fitness. Is there any merit in this? Thoughts?

TIA
-w


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## digita6 (Sep 29, 2012)

Alex_Simmons/RST said:


> Your power data will be far more useful than HR data for calorie metabolism estimation. Calorie metabolism estimators based on HR can be notoriously inaccurate.


It is strange that most of the apps out there seem to use HR for calorie estimation then. What is HR data useful for then? It is interesting to see that I'm able to sustain greater power output at a lower HR.


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## woodys737 (Dec 31, 2005)

digita6 said:


> It is strange that most of the apps out there seem to use HR for calorie estimation then. What is HR data useful for then? It is interesting to see that I'm able to sustain greater power output at a lower HR.


Until Alex clears the air with his knowledge, a PM can measure kilojoules. As I understand it the relationship of KJ to Kcal is roughly 4:1. So knowing KJ is a more objective way to estimate cal as it's based on actual work done. Someone correct if I'm wrong. A little out of my element.

I think Iknowyourider hit on why HR is a useful tool in that if you know what you are looking at you can measure decoupling and determine a level of aerobic efficiency you are achieving. Looked at another way if you start a ride at a constant 200 watts and a HR of 130 BPM and after 3 hours you should see some elevated HR at that 200W. The difference of BPM (cardiac drift) can be looked at as some measure of your aerobic efficiency (IIRC). Meaning, the more efficient (fit) a rider is the less that cardiac drift will drift over time for a constant effort.

I alluded to it in a post above. When I used both HR and power (when fit) my HR at 200W was much less than when unfit. Or the real measure to me was for a certain HR my power was higher such as LTHR to FTP relationship.

edit...just wanted to add that I pretty much stopped with monitoring HR simply because it's so affected by rest, hydration, general health etc...as a family, career guy I just felt it much too variable to give me any useful data beyond what power was showing.


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## Alex_Simmons/RST (Jan 12, 2008)

IKnowYouRider said:


> Alex,
> Sorry for the threadjack...but regarding hr, you've always been a clear proponent of power as the single most important training metric, with very little to be gained from paying attention to heart rate (a view I share). Recently it seems people (Friel) have been paying more attention to heart rate drift or decoupling as a metric for aerobic fitness. Is there any merit in this? Thoughts?
> 
> TIA
> -w


Well when you consider that the circumstances needed to derive consistent data involve very steady state, significantly sub-threshold riding for long periods, when everything else such as environmental conditions (e.g. temperature) and hydration/fuelling etc status are precisely controlled, then it has very limited practical use IMO.

Even if you are able to precisely control such things, its value is debatable. Once a ride become "normal" and involves varying power output, decoupling isn't much more than a random number generator.

Put it this way - what _actionable intelligence_ is it providing that you can't already reliably ascertain by tracking changes in your power output?


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## Alex_Simmons/RST (Jan 12, 2008)

digita6 said:


> It is strange that most of the apps out there seem to use HR for calorie estimation then.


Well on the basis that far more people have had access to a HR monitor than a power meter (given the cost ratio is < 1:10) and for longer then I'm not surprised.



digita6 said:


> What is HR data useful for then? It is interesting to see that I'm able to sustain greater power output at a lower HR.


If you have power measurement, then not much.

If you do not have power measurement then HR can be used as a guide to intensity for general sub-threshold aerobic level riding, but as long as people realise its utility becomes increasingly limited when rides are more variable in nature, and when intensity exceeds threshold power levels. 

And importantly, HR is simply a measure of how fast your heart beats and is NOT a measure of fitness. It's not even a measure of cardiac output (which would be more interesting, although of still fairly limited usefulness wrt to tracking performance and determining what training one should do).


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## Alex_Simmons/RST (Jan 12, 2008)

woodys737 said:


> Until Alex clears the air with his knowledge, a PM can measure kilojoules.


A HR monitor records the rate your heat beats. Any estimate of energy metabolism from HR will be a guess using some population based formula. It's not unusual to see calorie estimates from HRMs to be double actual.

A power meter is recording the rate of mechanical work (energy) being done.

Now mechanical work done is still not a measure of how much energy you have metabolised, because apart from our body converting fuel and oxygen into work done at the cranks, it's also generating heat and doing a few other things (but mostly generating heat).

As an example, typically for every watt we generate at the cranks, we are also generating about 3.5 watts of heat.

We use a term - Gross Mechanical Efficiency - which is a measure of how much energy reaches the cranks as a proportion of total energy metabolised.

For trained cyclists, this ratio is typically in the range 19-23%.
e.g. one hundred watts for one second = one hundred joules. But we would have metabolised at total of 100J / 22% = 454J (or 0.45kJ). 

Since 1 Calorie ~= 4.2kJ, and typical GME is roughly the inverse of that ratio, then as a good first order approximation, you can assume the kJ of mechanical work recorded by a power meter will equal the number of Calories metabolised. It's probably more like 1.05 - 1.1 times but that's just a first order approximation.

To get a better estimate you need to know your individual GME, which you can have measured in a lab - it requires measurement of oxygen utilisation and power output.

Of course there are things that will acutely and to some extent chronically impact your GME, but overall this is the most reliable means to determine actual energy metabolised during training/racing.


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## nhluhr (Sep 9, 2010)

digita6 said:


> I remember the previous test, and even took notes to review, and have an exercise/diet log. Everything seems to be pretty close to the same, including time of day, and all equipment and settings were identical (including rear wheel/tire/tire pressure).
> 
> I gained about 10 FTP since joining TrainerRoad in late Nov 2012 through the end of Dec (about 4 weeks). I feel like I *really* busted my hump over the past 8 weeks, however, and have used the regular metrics generated through TR as a sort of motivation.
> 
> *I also only just returned to cycling last September* after dropping about 90 lbs through diet and regular exercise. Perhaps the fact that I had a pretty low starting point allowed room for more drastic improvement?


ahhhh that explains it. There's basically no way a rider who has been consistently training will be able to gain that amount of power in such a short time. Nice work getting 'back' to that level


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## stevesbike (Jun 3, 2002)

Since heart rate/power output variation isn't random, in principle there should be information from variances that could be meaningful training metrics - both inter-session variations and intra-session variations. I train with both and use lower heart rate/power as an informal indicator of fatigue, which I believe has been validated by some studies. Has there been any systematic attempts to run regressions on these data to see first just how correlated they are and what information could be extracted from variations?




Alex_Simmons/RST said:


> Well on the basis that far more people have had access to a HR monitor than a power meter (given the cost ratio is < 1:10) and for longer then I'm not surprised.
> 
> 
> If you have power measurement, then not much.
> ...


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## aussiebullet (Sep 26, 2005)

stevesbike said:


> Since heart rate/power output variation isn't random, in principle there should be information from variances that could be meaningful training metrics - both inter-session variations and intra-session variations. I train with both and use lower heart rate/power as an informal indicator of fatigue, which I believe has been validated by some studies. Has there been any systematic attempts to run regressions on these data to see first just how correlated they are and what information could be extracted from variations?



Maybee in a controlled enviroment with identical workouts which in the real world is rare, but my hr for 20min ~95% at the start of a ride vs at the end of 2hrs tempo is miles apart and never consistent 
then add in the huge temperature swings here over 12mths, below zero in winter and up to 45deg plus in summer means the roads never cool down in summer 35deg in the am and that 20min at 95% at the start of a ride feels more like the same 20min done at the end of a 2hr tempo ride 
Then trying 20min at 95% and the end of a 2hr tempo ride with temps in the very high 30's is more akin to the last 20min of a 40km tt, hr is not depressed so am I fatigued? sure feels like it even if training load is low and hr is high...
Then there is all the temp swings inbetween summer and winter and we havn't even touched other variables like did I have a coffee before hand, still digesting food etc.
Hr is a poor measure of anything except in all but the most controlled environments and even then...


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## Alex_Simmons/RST (Jan 12, 2008)

stevesbike said:


> Since heart rate/power output variation isn't random,


It's not random, and there is a correlation, but if you plot a chart of HR v power, and split the indoor rides where the environment is pretty controlled, from the outdoor rides, then you'll probably get a linear correlation* with an R^2 of 
~ 0.8 indoors, and
~ 0.6 outdoors

Don't know about you, but I don't think that's really good enough to reliably use for the tracking of training stress.

Now granted what I don't know so much about is how one can interpret HR _variability _data and whether it can be a more reliable indicator of anything. Even if it was an indicator or correlated with something, the issue is whether it's better than existing information, such as actual performance (i.e. power), perceived exertion, mood, feelings of tiredness, heavy legs and so on.


* I just quickly grabbed some data from one of my athletes that still bothers with a HR strap. This is from his rides over the past month or so. I ditched any rides where I didn't have both power & HR, and where it was obviously erroneous data.


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## stevesbike (Jun 3, 2002)

thanks for posting the plot - I noticed there's an app for measuring heart rate variability (at rest) for assessing recovery - would be interesting if anything is to be gained by examining this variability under steady state training load.

ithlete Heart Rate Variability Monitor (HRV) - Training & Recovery App


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