Power Meters and Pedaling Effectiveness

[ric_stern/RST]

Thanks, Ric. I understand how and why HR will vary from day to day and based on temp, alt, caffeine, etc. But, I neutralized those variables by doing my cadence tests on the same day at the same altitude, temperature, and wind. My purpose was to explore the relationship between cadences at a given power level and effort, represented by HR as the best available proxy (I don't have a CO gauge on my bike at the moment -- know where I can get one?). So, I would naively assume that I would experience fatigue earliest at a cadence that produces the highest HR (113 in my test) and latest at a cadence that produces the lowest HR (84 in my test). Where am I going wrong?

I have to be brief as it's late here, but quickly... measuring cardiac output would be a highly invasive procedure...

to confuse matters, the most efficient cadence (i.e., the one that requires the least amount of energy and could be as low as ~ 60 revs/min depending on the actual power output) may not be the most optimal as your muscles maybe fatigued at a greater rate. The least efficient cadence may also not be the best, and the most *efficient* cadence will also increase (or decrease) at higher and lower power outputs.

In short, the most *optimal* cadence is the one that is most likely self-selected and is the one that allows you to produce the highest power over the duration concerned, under the conditions that you are riding.

In other words i wouldn't worry about either cadence or HR too much, just aim to generate the greatest sustainable power over the duration concerned

ric

 

[RapDaddyo]

I have to be brief as it's late here, but quickly... measuring cardiac output would be a highly invasive procedure...

to confuse matters, the most efficient cadence (i.e., the one that requires the least amount of energy and could be as low as ~ 60 revs/min depending on the actual power output) may not be the most optimal as your muscles maybe fatigued at a greater rate. The least efficient cadence may also not be the best, and the most *efficient* cadence will also increase (or decrease) at higher and lower power outputs.

In short, the most *optimal* cadence is the one that is most likely self-selected and is the one that allows you to produce the highest power over the duration concerned, under the conditions that you are riding.

In other words i wouldn't worry about either cadence or HR too much, just aim to generate the greatest sustainable power over the duration concerned

ric

Thanks, Ric. I was just kidding about the on-bike CO gauge. I started to put a 'just kidding' note after that comment, but I figured you would know that I wasn't being serious. Anyway, I gather that HR isn't a good predictor of fatigue. Maybe I'll have to do longer tests at a constant power and different cadences and see if there is a difference in when I 'blow up.'

 

[acoggan]

I designed a test that should have resulted in equal power. I have a nice long, relatively constant grade hill here. I did four 5-minute climbs (with 10 min. easy pedaling after each) in four consecutive gears, with cadences computed to maintain the same speed. The cadences were 113, 100, 91 and 84. My HRs were 150, 148, 145 and 143 respectively at the end of each 5 minute climb. Interestingly, the cadence that 'felt' the best was 91, even though I am most comfortable at about 100 on the flat. So, the feel and the HR were at odds with each other. Now, I would assume that HR is a predictor of fatigue and that I would have more endurance at the 84 cadence, even though I felt better at 91. Is HR a predictor of fatigue?

If it felt easier to pedal at 91 rpm instead of 84 rpm, you should pedal at 91 rpm - period. Your body has numerous sensors to determine just how stressful (actually, strainful) a particular activity or exercise might be, all of which are integrated to result in your perceived exertion. By contrast, HR is just one number, i.e., the rate at which your heart is beating - heck, it doesn't even tell you how much blood your heart is pumping!

(If I had a nickel for every misconception that has developed as a result of the widespread use of HR monitors, I'd be a rich man many times over.)

 

[RapDaddyo]

If it felt easier to pedal at 91 rpm instead of 84 rpm, you should pedal at 91 rpm - period. Your body has numerous sensors to determine just how stressful (actually, strainful) a particular activity or exercise might be, all of which are integrated to result in your perceived exertion. By contrast, HR is just one number, i.e., the rate at which your heart is beating - heck, it doesn't even tell you how much blood your heart is pumping!

(If I had a nickel for every misconception that has developed as a result of the widespread use of HR monitors, I'd be a rich man many times over.)

Thanks. Actually, my test results were kind of interesting, not so much that my HR was lower with lower cadence at a constant speed (and power), but that I was so uncomfortable at 113. Now, I go 113 on the flat all the time with no problem (even though I am a little more comfortable at about 100). But, with the added stress of climbing, I just couldn't believe how hard it was to push the cadence up to 113 and keep it there. I just kept looking at my countdown timer thinking, "God, isn't this over yet?" Likewise, I was kind of surprised that I wasn't more comfortable at the 84 vs. the 91 cadence. I kept looking at my HR monitors (one on the bike and one on my wrist), not believing that my HR was a couple of beats lower than at 91, yet I felt less comfortable. Interesting.

 

[Smartt/RST]

Anyway, I gather that HR isn't a good predictor of fatigue....

Without going into a serious exercise physiology discussion, perhaps it would be helpful to think of things in this way: a lot of research has gone into discerning the cause(s) of fatigue (which is the inability to maintain a power output specific to the circumstances of just what is being tested - eg: 4.5W/kg to fatigue) during endurance performance; although no one variable can be singled out as "the cause", there are many to consider....one that most people are familiar with is muscle glycogen availability; so, given that fatigue is a multi-factoral phenomena, no one variable that you monitor will give you the whole story (and as mentioned, heart rate is not even one of those variables anyway). This is one reason why training with power is so advantageous...you are measuring performance directly, not indirectly via a physiologic response (which is always confounded by other physiologic responses). End result...preempt as many causes of fatigue as you can, then "i wouldn't worry about either cadence or HR too much, just aim to generate the greatest sustainable power over the duration concerned".

 

[RapDaddyo]

Without going into a serious exercise physiology discussion, perhaps it would be helpful to think of things in this way: a lot of research has gone into discerning the cause(s) of fatigue (which is the inability to maintain a power output specific to the circumstances of just what is being tested - eg: 4.5W/kg to fatigue) during endurance performance; although no one variable can be singled out as "the cause", there are many to consider....one that most people are familiar with is muscle glycogen availability; so, given that fatigue is a multi-factoral phenomena, no one variable that you monitor will give you the whole story (and as mentioned, heart rate is not even one of those variables anyway). This is one reason why training with power is so advantageous...you are measuring performance directly, not indirectly via a physiologic response (which is always confounded by other physiologic responses). End result...preempt as many causes of fatigue as you can, then "i wouldn't worry about either cadence or HR too much, just aim to generate the greatest sustainable power over the duration concerned".

I accept everything you say. But, from a practical standpoint, I find it hard to believe that I can generate the greatest sustainable power over the duration concerned at a cadence of, say 100 on the flat and 90 climbing one day and the next day it is 110 and 80 respectively. Yes, I can see that HR may be all over the place, but I can't get my mind around the notion that my optimal cadence is going to be all over the place from day to day. I have limited things I can monitor and manage on the bike and cadence at a certain power output is a big one. Do I have to start every ride thinking, "Gee, I wonder what my optimal cadences are today?" I've picked gears to get me to a target cadence given the situation since the first day I rode. That'll be a hard habit to break.

 

[RapDaddyo]

If it felt easier to pedal at 91 rpm instead of 84 rpm, you should pedal at 91 rpm - period. Your body has numerous sensors to determine just how stressful (actually, strainful) a particular activity or exercise might be, all of which are integrated to result in your perceived exertion. By contrast, HR is just one number, i.e., the rate at which your heart is beating - heck, it doesn't even tell you how much blood your heart is pumping!

(If I had a nickel for every misconception that has developed as a result of the widespread use of HR monitors, I'd be a rich man many times over.)

Dear Mr. Coggan, thanks again for your input. I wanted to send you an email on a non-cycling exercise physiology question, but can't do that from this site. Could you please send me an email and let me know how I can contact you?

 

[Smartt/RST]

I accept everything you say. But, from a practical standpoint, I find it hard to believe that I can generate the greatest sustainable power over the duration concerned at a cadence of, say 100 on the flat and 90 climbing one day and the next day it is 110 and 80 respectively. Yes, I can see that HR may be all over the place, but I can't get my mind around the notion that my optimal cadence is going to be all over the place from day to day. I have limited things I can monitor and manage on the bike and cadence at a certain power output is a big one. Do I have to start every ride thinking, "Gee, I wonder what my optimal cadences are today?" I've picked gears to get me to a target cadence given the situation since the first day I rode. That'll be a hard habit to break.

If it helps, the research fully supports your issue of performing better at one cadence one day and another the next. That's not to say that one is cadence better then the other, quite the opposite. Efficiency and performance are typically only effected by very large changes in cadence: eg when comparing 60rpm to 100rpm or more. So, I would suggest that if you saw any noticeable differences in performance, it was because of other factors rather than cadence.
And just to muddy the waters some more, "optimal cadence" (depending on how you want to define that) can chance within a single ride as muscle fibers fatigue.

 

[ric_stern/RST]

In other words, all you really need to do is aim to generate the most power over the duration concerned, and don't worry about your HR or cadence.

ric

 

[RapDaddyo]

If it helps, the research fully supports your issue of performing better at one cadence one day and another the next. That's not to say that one is cadence better then the other, quite the opposite. Efficiency and performance are typically only effected by very large changes in cadence: eg when comparing 60rpm to 100rpm or more. So, I would suggest that if you saw any noticeable differences in performance, it was because of other factors rather than cadence.
And just to muddy the waters some more, "optimal cadence" (depending on how you want to define that) can chance within a single ride as muscle fibers fatigue.

Well, that settles it then. Cycling is too complicated! I'll have to take up swimming.

 

[beerco]

Well, that settles it then. Cycling is too complicated! I'll have to take up swimming.

Now that's funny! I hear golf is a no brainer too.

 

[RapDaddyo]

Now that's funny! I hear golf is a no brainer too.

Well, it is for now. Now, you just hit the ball and take pride in a good ball flight to your target. But, just wait until they come up with a swing analyzer you can wear on your wrist. Then, we'll be saying, "Oh, no! I was 2 degrees off my swing plane at the top and my clubhead speed was 2MPH slow. What a lousy shot." Maybe we're getting too enamored with data. I mean, look at the times in the Tour de France. Power meters were introduced in the late 1980s. The winner of the Tour in 1988 (pre-power meters) won in 84 hours and 27 minutes. Last year, Lance Armstrong won in 83 hours and 36 minutes. I mean, he didn't even take an hour off the 1988 time for riding around France in the middle of the summer. Go figure.

 

[beerco]

Maybe we're getting too enamored with data.

Maybe You're getting too enamored with data. All the advice to you I've read here is to "just push on the damn pedals". You're the one who's trying to turn it into an issue.

I brought up golf because golf and swimming are both very very very technique oriented.

 

[RapDaddyo]

Maybe You're getting to enamored with data. All the advice to you I've read hear is to "just push on the damn pedals". You're the one who's trying to turn it into an issue.

I brought up golf because golf and swimming are both very very very technique oriented.

If data doesn't matter, why have a power meter? As to what I'm trying to do, I thought I was just trying to understand the relationship between different observable variables. I'm glad you cleared up my intentions. And, I'm really glad to learn technique doesn't matter in cycling. One less thing to worry about.

 

[ric_stern/RST]

If data doesn't matter, why have a power meter?

To know how much power you are producing... using this for visual feedback when training and post ride/race analysis and goal setting.

ric

 

[ric_stern/RST]

And, I'm really glad to learn technique doesn't matter in cycling. One less thing to worry about.

Generally, cycling is a gross motor control sport, where your legs are constrained in the sagittal plane and they don't have much option but to go round in a circle. As Beerco points out this is somewhat different to e.g., golf which requires fine motor skills (although i would imagine that e.g., rifle shooting in the Olympics requires even finer motor skills).

Ric

 

[RapDaddyo]

To know how much power you are producing... using this for visual feedback when training and post ride/race analysis and goal setting.

ric

Actually, I fully understand and appreciate the value of a power meter for training and goal setting. I was reacting to Beerco's suggestion that I was too focused on data. What I am not yet ready to do is to declare HR and cadence as useless feedback information and unplug those from my bike computer. You know, it hasn't been all that long since some pretty credentialed people like Dr. Edmund Burke advocated the usefulness of HR in training. Is he a nut? You sure can't tell it from his resume. As I said in my original posting, power meters appear to be one of the most significant advancements in cycling in the past 20 years. The value of knowing precisely how much power one is delivering to the cranks is huge. My objective is to determine the benefits of power meters beyond the obvious and whether the different products available differ in any significant way.

 

[ric_stern/RST]

Actually, I fully understand and appreciate the value of a power meter for training and goal setting. I was reacting to Beerco's suggestion that I was too focused on data. What I am not yet ready to do is to declare HR and cadence as useless feedback information and unplug those from my bike computer. You know, it hasn't been all that long since some pretty credentialed people like Dr. Edmund Burke advocated the usefulness of HR in training. Is he a nut? You sure can't tell it from his resume. As I said in my original posting, power meters appear to be one of the most significant advancements in cycling in the past 20 years. The value of knowing precisely how much power one is delivering to the cranks is huge. My objective is to determine the benefits of power meters beyond the obvious and whether the different products available differ in any significant way.

If you have a power meter, then yes, i feel that HR and cadence info isn't that useful. I'd take a HR monitor for training prescription versus nothing at all (i think, and i hate to speak for others, that this maybe different to AC...?). Hopefully, AC will chime in on that aspect and maybe about EB.

I believe that the SRM and PT don't significantly differ from each other in most respects - i recommend both of them - although they each have pros and cons.

Ric

 

[RapDaddyo]

Generally, cycling is a gross motor control sport, where your legs are constrained in the sagittal plane and they don't have much option but to go round in a circle. As Beerco points out this is somewhat different to e.g., golf which requires fine motor skills (although i would imagine that e.g., rifle shooting in the Olympics requires even finer motor skills).

Ric

I agree with you about cycling being a gross motor control sport, with the athetic action (pedaling) being constrained. But, some would say that cycling technique matters and that techniques can be learned. I read somewhere that Lance Armstrong worked a lot on his pedaling technique in his earlier years because he didn't feel that he was smooth. There is an entire discussion here about pushing up vs. pushing down. SRM has gone to the trouble of developing and marketing torque analysis data collection and analysis. Polar has a power balance feature in their power module software. In the last TdF, I was struck by LA's high cadence up the steepest stages, both on and off the saddle. I sort of doubt that he was born with that technique. We have choices about how we peddle, when and where we push, whether we attempt to push symmetrically or not, position on the bike, cadence. I consider all of this technique. Whether the techniques are different from golf is irrelevant. What I have in innate athletic ability is, unfortunately, locked in. But, I have a brain and (with today's technology) I can choose to process a lot of information about my performance and I can choose to experiment with different techniques to see which allows me to generate the maximum performance for a sustained period of time. Or, I can decide that none of that matters and ride a bike the way I did at age 5 or whenever it was that I first could balance one. Personally, I choose to collect data, use it intelligently and work to improve my technique.

 

[ric_stern/RST]

I agree with you about cycling being a gross motor control sport, with the athetic action (pedaling) being constrained. But, some would say that cycling technique matters and that techniques can be learned. I read somewhere that Lance Armstrong worked a lot on his pedaling technique in his earlier years because he didn't feel that he was smooth. There is an entire discussion here about pushing up vs. pushing down.

from the data that is available using force instrumented pedals and iEMG, it appears that better cyclists tend to push down more and pull up less, that less good cyclists who push down less and pull up more.

SRM has gone to the trouble of developing and marketing torque analysis data collection and analysis. Polar has a power balance feature in their power module software.

as far as i'm aware the Polar left right balance doesn't *measure* this as you'd need force instrumented pedals to capture such data accurately. Nonetheless, people do change the amount of force that goes to each pedal and this can alter each time you ride. This perhaps one reason why i found the Ergomo i tested to be not very accurate (as it just doubles left power).

In the last TdF, I was struck by LA's high cadence up the steepest stages, both on and off the saddle.

where have you been for the other five TdF's ;-)

I sort of doubt that he was born with that technique. We have choices about how we peddle, when and where we push, whether we attempt to push symmetrically or not, position on the bike, cadence. I consider all of this technique.

and other riders who have won 5 TdF or other races may or may not pedal at super high cadences

bike position is something else, and wasn't what any of us were including while talking about pedalling

ric