Has anyone used a bike trainer to detemine your best cadence based on heart rate, and power output. Can you explain how you figure this out. Thanks
I did this as a fun experiment with the most basic of equipment, a HRM and the bike computer as I had no way to measure power output. I would pick a given kph speed and shift different gears to be mashing or spinning on the trainer but maintain the same speed. I tried to determine at what cadence my heart beat was the lowest. Did this so long ago that I can’t even remember the results.
Not sure what relevence this sort of experimentation has to do with real world riding. I guess in theory that if you could find your most effecient cadence on the trainer based upon the HRM reading , then just try to ride in that cadence range as much as possible on the road by shifting gears appropriately.
“Has anyone used a bike trainer to detemine your best cadence based on heart rate, and power output.”
one can arrive at false results using heart rate as a measuring tool. that cadence that–at a given power output–produces the lowest HR or oxygen consumption is not necessarily (or even usually) the desired cadence for a shorter distance bike ride (shorter distance being, say, half-IM or shorter, and perhaps even up to IM distance). this is especially the case if one must run afterward, but is even the case for standalone bike races.
“Has anyone used a bike trainer to detemine your best cadence based on heart rate, and power output.”
one can arrive at false results using heart rate as a measuring tool. that cadence that–at a given power output–produces the lowest HR or oxygen consumption is not necessarily (or even usually) the desired cadence for a shorter distance bike ride (shorter distance being, say, half-IM or shorter, and perhaps even up to IM distance). this is especially the case if one must run afterward, but is even the case for standalone bike races.
This might even be more true for long distances. Assuming HR is pretty much proportional to O2 consumption and that the rider is putting power out at intensity levels well below VO2 max (i.e. O2 delivery is not a limiting factor), a higher ratio of HR (and therefore O2 consumption) to power output may indicate a higher level of glycogen sparing aerobic metabolism is going on. Creating ATP from fat requires much more O2 than creating the same amount of ATP from glycogen, so one could probably assume higher HR to power ratios would indicate less glycogen consumption and greater reliance on fatigue resistant, oxygen eating Type 1 muscle fibers. This would result in less neuromuscular fatigue and a reduced chance of bonking.
I think it’s kind of like how those who assume that lower cadence / higher pedalling force riding is more ‘efficient’ due to lower O2 consumption are probably making the wrong conclusion (for efforts not approaching VO2max intensity levels). O2 consumption may be lower, but if you’re well below VO2 max oxygen is free. If higher O2 consumption allows you to reduce fatigue and save glycogen you should be using your ‘aerobic engine’ to its fullest extent. I almost hate to bring this up, but how many ‘PowerCrank’ converts with PC training’s tendency towards lower cadences have bonked or had difficulty finishing races after making the switch to a lower cadence PC pedalling style?
“This might even be more true for long distances.”
you’ve got the mechanisms right, but i think your end conclusion is backwards. there is nothing wrong with pedaling more slowly in order to ride with more economy (using “economy” in the narrow, technical sense). burning less oxygen, riding with a lower HR, is good in theory. the problem is when you must do anaerobic work to reach the power requirements, and that’s not likely to happen at low-intensity levels.
in other words, if you’re riding at 12mph, you’ll be able to go longer, and ride easier, and burn less fuel, and less oxygen, at 70rpm. riding at 70rpm at 24mph might mean that you’ll burn less oxygen, but perhaps at the expense of recruiting gas-guzzling fast twitch fibers to do the work. yes, you’ll have a slightly lower HR during the ride, but you’ll be doing kona shuffle off the bike.
I know this topic was discussed at length some time ago, but this is the first time I actually understood it. Not sure if I am a bit slow or if this thread gave a great explanation.
“This might even be more true for long distances.”
you’ve got the mechanisms right, but i think your end conclusion is backwards. there is nothing wrong with pedaling more slowly in order to ride with more economy (using “economy” in the narrow, technical sense). burning less oxygen, riding with a lower HR, is good in theory. the problem is when you must do anaerobic work to reach the power requirements, and that’s not likely to happen at low-intensity levels.
in other words, if you’re riding at 12mph, you’ll be able to go longer, and ride easier, and burn less fuel, and less oxygen, at 70rpm. riding at 70rpm at 24mph might mean that you’ll burn less oxygen, but perhaps at the expense of recruiting gas-guzzling fast twitch fibers to do the work. yes, you’ll have a slightly lower HR during the ride, but you’ll be doing kona shuffle off the bike.
Not sure I agree that my conclusion is backwards. Oxygen is essentially free as long as you’re exercising well below VO2max. At those intensity levels it’s not a limiting factor. Folks think that because a low resting HR is indicative of fitness and high stroke volume, that low HR (and low O2 consumption) for a given, sustainable power output is also somehow better.
If someone who’s max HR is 190 is crusing along and putting out say 225 watts with a HR of 150, gears down slightly, spins a bit more, maintains the same 225 watt output but raises his HR to 155 or 160, he’s probably saving glycogen and using more fatigue resistant muscle fibers. The only real cost is using a bit more of something (oxygen) that at those intensities is essentially limitless and free.
If you’re not in the first few minutes of exercise or doing something like a non-sustainable finishing kick, you’re essentially ‘aerobic’. If you have to rely on anaerobic energy sources to reach your chosen power level, that level of power output won’t be sustainable - you’ll be on borrowed time anyway.
“Oxygen is essentially free as long as you’re exercising well below VO2max.”
it’s not exactly free. the more oxygen you burn, the more fuel you burn (as long as you’re below the effort lever required to recruit glycolytic fibers). you’d therefore be better off burning less of everything at a lower intensity.
i therefore don’t know that i’d call oxygen free. i’ll make an example, and this is probably not exactly fair, but (to take it to the absurd) let us say that you and i were to race each other in a 10k on the track. wouldn’t you consider it a handicap if i made you run two miles at 60% of your max heart rate before we started, and then without your stopping i’d just join on in after 8 laps and we’d commence our 25 addn laps?
i think that’s why the longer the distance, the slower the cadence. RAAM riders don’t ride 90rpm, they ride 65 or 70 on the average. and pursuit riders ride 110rpm. 40k guys ride 85-100. and so on.
“Oxygen is essentially free as long as you’re exercising well below VO2max.”
it’s not exactly free. the more oxygen you burn, the more fuel you burn (as long as you’re below the effort lever required to recruit glycolytic fibers). you’d therefore be better off burning less of everything at a lower intensity.
nice little dialogue going on on the topic here. really interesting!
I don’t quite agree with “the more oxygen you burn, the more fuel you burn”. This is true if the substrate (glycogen or lipid) remains the same. However, from my interpretation you are trying to compare lipid with glycogen utilization. As you compare the exchange ratios of lipid metabolism (.70) and glucose metabolism (1.0) you can see that the number of oxygen molecules utilized doesn’t correspond to the quantitiy of energy (joules, calories) used.
lipid metabolism:
C16O32O2 + 23O2 —> 16CO2 + 16H2O (overall yield 129ATP)
R= VCO2 : VO2 = 16:23 = .70
129ATP / 23O2 = 5.6 ATP per O2 molecule
glycogen metabolism:
C6H12O6 + 6O2 —> 6 CO2 + 16 H2O
R= VCO2 : VO2 = 16:16 = 1.00
6.3 ATP per O2 molecule
Fat utilization clearly requires more oxygen to yield the same amount of energy. But as *justcurious *mentioned before. This shouldn’t be a problem at intensities well below VO2 max.
Here is another variable that might play a role (thought of it the other day while riding up a pass). Since muscle contraction aids venous blood return through its pumping mechanism, especially where against gravity, ie. legs. Could it be possible that an unknown cadence “x” at HR “y” increases performance by aiding venous return? Just my thought. I still think that fiber type recruitment and fuel utilitation are more important, but who knows…
“Oxygen is essentially free as long as you’re exercising well below VO2max.”
it’s not exactly free. the more oxygen you burn, the more fuel you burn (as long as you’re below the effort lever required to recruit glycolytic fibers). you’d therefore be better off burning less of everything at a lower intensity.
Again I disagree. We’re talking equivalent power outputs. Therefore, the energy cost is essentially the same.
Assuming equivalent efficiencies when comparing the ‘spinner’ to the big gear ‘masher’, the spinner’s higher HR (and therefore probably higher O2 consumption) is an advantage even though the power output he’s putting to the pedals is the same as the masher. If power outputs and efficiencies are the same, I would think it would be safe to assume that the same amount of ATP per unit time is required to maintain the effort. Using fat (essentially an unlimited fuel source) to produce a greater percentage of the working muscles ATP requirements requires greater oxygen availability. When HR’s (and O2 availability) are lower, the body must use more of its less efficient, less oxygen dependent, and much more limited glycogen stores. It’s not necessarily true that “the more oxygen you burn, the more fuel you burn”. All fuels are not the same. The fat burning downside is a greater oxygen demand per unit of ATP produced and a dependence upon the availability of mitochondrially dense slow twitch muscle fibers. The upside of fat metabolism is its essentially unlimited supply and greater ATP yield per gram.
As long as O2 availability is not the ‘bottleneck’ in the whole process (as with efforts approaching VO2max), the more O2 that’s utilized for a given level of output the better IMHO. You’ll experience less fatigue and minimize your muscle glycogen utilization.
Am I missing something? I don’t claim to be a world renowned expert or anything, I just think and read about this stuff way too much.
Thanks for helping me explain something that’s very difficult to explain as simply as possible.
In response to your comments on venous return I thought you might find these comments by the controversial Dr. M. Ferrari of interest.
Training
High Pedaling Cadence
By: Michele Ferrari
Published: 10 Mar 2003
The Art of Spinning… Read about the concepts and advantages of having a high pedaling cadence while training/racing.
Pedaling at 60 RPM (revolutions per minute) or at 90 RPM during an uphill course: what are the effects on performance, tiredness and recovery?
At 60 RPM it takes 1.0 second for the crank to make a complete revolution (360º), at 90 RPM it only takes 0.66 seconds that is 34% less.
The contraction time of the muscles involved in pedaling, decrease thus of that same percentage.
During the muscle contraction phase, blood flow (and so the oxygen carrying) to the single fiber, especially the most profound ones, lessens because of the increased pressure within the working muscles.
Moreover, in terms of equal power output supplied by the cyclist, a cadence of 60 RPM requires a 34% more of applied force to each push on the pedals, compared to a cadence of 90 RPM. This means a heavier load for muscles, tendonds and lower limbs-lumbar joints.
It is easy to realize the advantages of a more “agile” pedaling cadence, especially when the rider is busy with an all-out effort, as soon as the oxygen carrying becomes the limiting factor of his performance.
Also the recovery between 2 or more efforts, within just one training session or race, or even within the next days, takes advantage from an agile pedaling cadence, whereas the risk of injuries or overworking lesions increases with lower RPMs.
A high pedaling cadence also improves the pumping function of skeletal muscles, the most important factor in defining systemic venous return of the blood to the heart.
This peripheral pump plays a critical role in circulatory functional
capacity, and can be viewed as a second heart.
In conclusion, high pedaling cadences are favorable to riders, as demonstrated by the examples of great champions such as Miguel Indurain and Lance Armstrong.
A very long training as well as specific sessions are needed in order to learn how to pedal comfortably and profitably at high cadences, particularly during climbs: but that is a different story.
“Am I missing something? I don’t claim to be a world renowned expert or anything, I just think and read about this stuff way too much.”
perhaps i don’t understand what you’re saying, but if i got it right then you’re advocating the opposite of what we see in practice – that RAAM riders ought to be pedaling at a faster cadence, just like shorter distance athletes do. regardless of the physiology involved, it would be interesting to see whether the long-distance cycling world would agree, en masse, to this flip-flop. and if it wouldn’t, one must go back to the drawing board and refigure what’s really going on during the pedal stroke.
there are at least dozens of studies that have been done on cadence, and up until the turn of the century most that i’ve read have indicated that good cyclists choose 90rpm, and that this is odd because 60rpm offers greater economy – that term describing lower oxygen consumption to do the same amount of work – and scientists consider this a good thing.
not until more recently has it been posited (through muscle biopsies during riding) that the recruitment of fast-twitch fibers during lower cadence and high work loads results in too much glycolytic respiration, causing skeletal muscles to run out of glycogen too quickly. but at lower work loads (RAAM), economy wins.
but maybe you’re right. maybe economy isn’t very economical.
Good point.
But the thing is, I think for RAAM type efforts they’re sort of ‘super economizing’ by minimizing both cadence and pedalling force. For those efforts they need to minimize both neuromuscular and cardiovascular stress. All I’m saying is that if a tradeoff is to be made at sustainable exercise intensities, it’s better to sacrifice cardiovascular stress to minimize muscular stress.
Average power to the pedals for the RAAM guys is probably surprisingly low. My guess is if a typical RAAM rider is told to give his best effort for the typical 4 to 6 hour effort that we ‘normal’ riders typically ride, he would increase cadence proportionally more than pedalling force to perform that effort (i.e. stress his HR/cardiovascular system to a greater degree than his skeletal muscles).
I still think the old adage holds, that preferred cadence pretty much increases proportional to power output… But when working in and around the rider’s preferred cadence range for a particular power output, I think spinning a smaller gear at higher cadence (even at the cost of higher HR & O2 consumption) has advantages as long as the rider is not approaching his aerobic limits.
Knowing some physiology and biomechanics, here are my thoughts (hypothesis) on the different cadences choosen at various velocities:
Cadence at “slow” velocity
- at low velocity, low power output is required, e.g 150W
- if you would divide the power output by the low cadence of e.g 60, you would get 2.5W/cadence
- if you would divide the power output by the high cadence of e.g 90, you would get 1.6W/cadence
- let’s say FT fibre recruitment of this individual begins at 3.0W/cadence
if all of the above are true, it could make sense that the individual pedals at the lower cadence. Both, the low and the high cadence require the same amount of energy as power output are equal. And both recruit the same percentage of ST fibres. Therefore, O2 consumption should be equal as well.
If you combine those thoughts with the comments by Dr. M. Ferrari (posted by michaelg), it would make sense because “During the muscle contraction phase, blood flow (and so the oxygen carrying) to the single fiber, especially the most profound ones, lessens because of the increased pressure within the working muscles.”
So why would you pedal at a higher cadence, if it recruits the very same muscle fiber type, but limits the oxygen and nutrient delivery to some extend?
Cadence at “high” velocity
- at high velocity, great power output is required, e.g 300W
- if you would divide the power output by the low cadence of e.g 60, you would get 5.0W/cadence
- if you would divide the power output by the high cadence of e.g 90, you would get 3.34W/cadence
- let’s say FT fibre recruitment of this individual starts at 3.0W/cadence
to spare glycogen at high velocity, one would have to use a greater amount of oxidative ST fibres. Since the treshold of FT fibre recruitment occurs at 3.0W/cadence (overlap as from ST → FTa → FTb), this individual would actually be more efficient to ride at a cadence of 90 due to the percentagewise greater recruitment of ST fibres. Even known the decreased recovery time eliminates the benefits of Dr. M. Ferrari’s theory, the ST fibre recruitment would probably outweigh those advantages.
Can you guys here what I’m trying to say? Would that make sense and be a possibility?
“I think for RAAM type efforts they’re sort of ‘super economizing’ by minimizing both cadence and pedalling force.”
yep. i think we agree.
“Can you guys here what I’m trying to say?”
yes, but you’re choosing the most convoluted, tortured way of saying it. pretty much everybody here agrees, including ferrari, that faster cadences are better at higher workloads. but his listed reason, and my reason, for the efficacy of pedaling at a faster cadence, are different.
the main issue is muscle fiber recruitment. ferrari’s theory that the rate of venous return changes when cadence changes may or may not be true. but everyone agrees that it’s better to pedal faster as the workload increases.
I actually participated in a study this fall at the local university testing oxygen utilization / power output / heart rate / rate of perceived exertion at different pedalling cadences. Your post reminded me that I haven’t seen the results yet, so I just emailed the grad student and will post when she replies. The test took place over 4 sessions (actually 5, but the first was simply a VO2 max test, weight, body fat etc - not sure how she used these variables in the test though) Each session was completed entirely at a given cadence (60, 80, 100, and finally 120) on separate days. (well rested) The protocol was to warm up for 10 minutes, and then ride at the given cadence (for that particular test) for 4 minutes at 100 watts, 200 watts, 300 watts, and then finally 360 watts. (There was a 2 min easy spin rest between after the 200 watt, and 300 watt intervals) I knew going into the test that I spin fairly high cadence, about 97-103 for a 40k time trial, and during the testing, I found the 100 rpm, and 120 rpm tests fairly easy, the 80 rpm test was very tough, and the 60 rpm test was an absolutely agonizing affair.
I will post her results and conclusions (with her permission) after she sends them to me.
The “muscle pump” is a myth.
Why do you say that? It’s well known that long periods of inactivity causes venous stasis and increased risk of thrombosis.
This has been a great discussion, but I’m still not sure why HR is not a good measure of optimal cadence. For a high exertion, I know that low cadence/high gear/increased fast-twitch fiber pedalling is not the way to go. It also seems like it would lead to a higher HR than spinning more aerobically at 90-100rpm. Wouldn’t there be an optimal cadence for a given power output where you have balance between biomechnical efficienct (lower rpm) and physiological efficiency (higher rpm, more slow-twitch fiber recruitment, etc.), and wouldn’t that be reflected by the HR?