# Power meter with heart rate monitor?



## Newnan3 (Jul 8, 2011)

I have a power meter en route and I was wondering if how beneficial it would be to continue to use my heart rate monitor...

Or does the PM essentially tell me everything I need to know?


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## DaFlake (Sep 25, 2012)

Power meter tells you how much power, the heart rate monitor will tell you heart rate. Not sure what your question is as they are two different things.


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## Srode (Aug 19, 2012)

I use both. The PM is what I use for pacing and training primarily but the HR helps me keep in touch with how hard I am pushing when varying efforts are required like a bunch of shorter hills in a row, VO2max and higher efforts up followed by low effort down hill. The HR also helps me keep track of how I am doing with Joe Friel's Aerobic decoupling metric on training rides.


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## Alex_Simmons/RST (Jan 12, 2008)

Srode said:


> I use both. The PM is what I use for pacing and training primarily but the HR helps me keep in touch with how hard I am pushing when varying efforts are required like a bunch of shorter hills in a row, VO2max and higher efforts up followed by low effort down hill.


?
Power is what tells you how hard you are working.

Indeed the utility of HR as an indicator of intensity declines significantly once efforts get beyond threshold power level, and when effort becomes more variable.



Srode said:


> The HR also helps me keep track of how I am doing with Joe Friel's Aerobic decoupling metric on training rides.


Personally I think being able to put out more power is far more useful as an indicator of fitness.

For the OP - when you have power measurement, HR is essentially redundant, and quite often just plan misleading. The one situation I'd recommend keeping it is if you have a medical reason for doing so.


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## DaFlake (Sep 25, 2012)

Alex_Simmons/RST said:


> For the OP - when you have power measurement, HR is essentially redundant, and quite often just plan misleading. The one situation I'd recommend keeping it is if you have a medical reason for doing so.


Okay, I will bite. Can you explain how it is redundant? The power meter measures how much is coming out, the heart rate is going to tell you how hard your body has to work to get there (input). So, if you combine the two, you can get a better understanding of how much work it is taking for your body to produce that power. Where is the redundancy?

Not trying to be snarky, just want to learn. :wink:


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## Alex_Simmons/RST (Jan 12, 2008)

DaFlake said:


> Okay, I will bite. Can you explain how it is redundant? The power meter measures how much is coming out, the heart rate is going to tell you how hard your body has to work to get there (input). So, if you combine the two, you can get a better understanding of how much work it is taking for your body to produce that power. Where is the redundancy?
> 
> Not trying to be snarky, just want to learn. :wink:


Unfortunately, your characterisation that HR is a measure of the body's work (or input as you say) is simply incorrect.

HR is simply a measure of one of the responses of the heart to the work being done. It is also subject to vary as a result of many things that are unrelated to how hard you are working.

HR also lags actual work rate by a considerable delay, such that using it as a guide for work is a bit like driving by looking in the rear view mirror. By the time HR hits "the red zone" it's too late, you've already been there too long and the damage has been done (in terms of being able to maintain the effort). As I said before, this particularly applies when efforts become harder and/or variable in nature.

As for redundancy, there is no insight about your training, fitness or performance that can be obtained from having HR data when you already have power data.

Ratios of HR to power are not measures of fitness. Being able to sustain more power for durations of interest is (and honestly, if you can put out more power, who gives a toss what the heart rate response was?).


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## DaFlake (Sep 25, 2012)

Alex_Simmons/RST said:


> Unfortunately, your characterisation that HR is a measure of the body's work (or input as you say) is simply incorrect.
> 
> HR is simply a measure of one of the responses of the heart to the work being done. It is also subject to vary as a result of many things that are unrelated to how hard you are working.
> 
> ...



Makes sense, thanks!


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## Newnan3 (Jul 8, 2011)

Alex_Simmons/RST said:


> As for redundancy, there is no insight about your training, fitness or performance that can be obtained from having HR data when you already have power data.
> 
> Ratios of HR to power are not measures of fitness. Being able to sustain more power for durations of interest is (and honestly, if you can put out more power, who gives a toss what the heart rate response was?).


This is what I was thinking....thanks for the helpful response!


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## anotherguy (Dec 9, 2010)

What about decoupling/cardiac drift?


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## Srode (Aug 19, 2012)

anotherguy said:


> What about decoupling/cardiac drift?


that's what I use it for when training - below 5 is supposed to be pretty good aerobic shape, above that and more base building is needed according to Joe. I typically run below 5, more like 2 on an hour and a half ride with 50% threshold or above. Perhaps meaningless when not working on base building though? 

I understand that power is a better measure of effort but going up and down short hills with substantially variable power required seeing that I am running at the upper end of Threshold or beyond is what I use to tell me to let up a little on the climbs. It is probably too late to fully recover but don't know how to do that with power alone. Thoughts?


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## Alex_Simmons/RST (Jan 12, 2008)

Srode said:


> Thoughts?


Learn to train _with _power, not _by _power. That's a paradigm shift that takes are little while for those so used to the HR paradigm.

IOW, power _is _ naturally variable, and how and when one should be concerned about that is the issue. Often it's not something to be overly concerned with. That's why we have ride assessment tools like Normalized Power to help makes sense of such things.


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## anotherguy (Dec 9, 2010)

Srode said:


> I understand that power is a better measure of effort but going up and down short hills with substantially variable power required seeing that I am running at the upper end of Threshold or beyond is what I use to tell me to let up a little on the climbs. It is probably too late to fully recover but don't know how to do that with power alone. Thoughts?


You may already do this, but I have a screen on my garmin that displays my current power zone as a decimal number (e.g. Zone 3.2), a 3 second rolling average power and a 10s avg power, I find that the combination helps me do a better job of pacing longer efforts since it cleans up the stochasticity quite a bit.


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## Srode (Aug 19, 2012)

My normal screen riding has 3 second power, HR, cadence and speed. I'll try a screen set up like you suggest and see how it works for pacing, thanks.


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## iliveonnitro (Feb 19, 2006)

If you have both hooked up to the same bike computer (ie, you can look at HR and power from the same ride on the same graph, like in WKO), use the HRM for a couple months to play around with the data. Then ditch it, as it's not worth a lot after that.

After you start training with power, HR mainly is used for measuring your resting HR or doing recovery rides...and even then, recovery rides are done just as well with a power meter.


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## stevesbike (Jun 3, 2002)

I started training with HRM in 1985 (before wireless HRM) and power in 2007 or so. I still use my HRM with power - I find variations in their relationship useful (fatigue, reaction to environmental stressors such as heat, etc.). Since I don't have power on my TT setup, I also use HR for pacing, so seeing their relationship on my training rides regularly helps with that. My heart rate usually only varies 5 BPM across a TT effort, so it's easy to use for pacing.

I've never bothered doing any regresssions to examine their correlation, but I'd guess an R2 would be very high. In fact, my Strava's 'suffer score' which is based on an HR TRIMP model is almost always within a few points of WKO's training stress score - so much so that I use the suffer score to manually fill in TSS when I train without a PM.


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## Alex_Simmons/RST (Jan 12, 2008)

The correlation between HR and power is variable, and for outdoor riding the R^2 is typically in the 0.6x range and for for indoor trainer riding it's in the 0.75-0.85 range.

Of course some will have a closer correlation than others, and that will partly come down to the nature of training/riding/racing you do. Greater variability and short range supra threshold efforts will see that correlation drop.

In terms of fatigue and reaction to environmental stressors, I use the power I am capable of under such conditions to tell me that, along with perceived exertion which is IMO more effective and reliable than HR.

Pacing longer TTs with HR is possible, provided you understand the initial lag and gradual rise of HR over such an effort, and that often comes from learning to pace well by using power to start with.

The following chart demonstrates what I mean about HR response at threshold and at supra threshold:


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## stevesbike (Jun 3, 2002)

thanks for the info re HR and power correlation. My interoceptive ability is pretty bad (at least cardiac awareness), so HR seems better for me that perceived exertion (I had thought perceived exertion also 'drift's during a workout - gets worse later). 



Alex_Simmons/RST said:


> The correlation between HR and power is variable, and for outdoor riding the R^2 is typically in the 0.6x range and for for indoor trainer riding it's in the 0.75-0.85 range.
> 
> Of course some will have a closer correlation than others, and that will partly come down to the nature of training/riding/racing you do. Greater variability and short range supra threshold efforts will see that correlation drop.
> 
> ...


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## Alex_Simmons/RST (Jan 12, 2008)

stevesbike said:


> I had thought perceived exertion also 'drift's during a workout - gets worse later.


Yes, I'd agree with that, if an effort is well paced at least.

e.g. the initial minutes of a TT often seem ridiculously easy, even though the power might still be over target. and squeezing out the power in those last minutes can seem like hell.

Then there is the PE during an individual pursuit. Final laps. Get. Ugly. That's an event you really need to practice pacing for.

Another element in the difference in power and PE in a TT is when there are variable gradients. While good pacing sees power a little higher than average on inclines and a little lower than average on declines, in PE terms the sensation is the opposite, i.e. it feels like you don't go so hard on inclines but need to PLF on the declines.


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