gmatocha

Hi,

I recently started working out with a HR monitor, and decided to do a little experiment on my trainer. The results surprised me, and were different than I was expecting. I'd like to get some feedback.

Background:
I've been a strong recreational biker for the last couple of years. Early on I read about the importance of maintaining relatively high cadence, and took that to heart. Working out on the trainer, I'm comfortable spinning 90-100rpm, start "working" between 100 and 110, and am pushing it a bit to hold 120. The max cad I've hit on the trainer is 188, no bouncing. On the road I routinely ride 60+ miles at 18-19mph, maintaining an average cadence in the high 80s.

Based on all this, I felt that somewhere around 85 would be my most efficient cadence.

I'm 41, and have always had a fairly high HR, here are my base numbers:
Resting Heartrate 58
Max Heartrate 193
Working Heartrate 135


The Experiment:
I wanted to find out what cadence (gear ratio), would give me the lowest heart rate for a given power output. Like I said, I expected this to be somewhere around 85rpm.
I have a fixed load fluid trainer. I chose a speed which gave me a "moderate" effort, of about 80% perceived effort - 14.1 MPH. According to my trainers (difficult to decipher) documentation, this should be somewhere around 150-200 watts. I warmed up for 1/2 hour, then started the test. This consisted of soft-pedaling in a low gear (38/26) until my heart rate hit 155, shifting into the "target" gear, then adjusting my cadence to hold 14.1mph. I held that cadence for three minutes to let my HR adjust to the load, then took an average HR for the next two minutes. Then back to cool-down to 155 before the next test.

Here are the results:

Test Spd Cad Gear HR % MHR
1 14.1 107 38/23 175 86.4
2 14.1 96 48/26 168 81.2
3 14.1 85 48/23 167 80.4
4 14.1 74 48/20 163 77.4
5 14.1 63 48/17 157 72.9

Much to my surprise, as you can see, there is a direct relationship between my HR and cadence at this power level - the lower the cad, the lower my HR. I can definitely say the lower cadences were less "comfortable", with noticeable lactic acid build when turning 74 and even more at 63.

This countered my view of cadence efficiency.
What are your thoughts on this? Should I be training for long rides (centuries) at a lower cadence?

P.S. I have yet to repeat the test at a lower (or higher) load...that may change the results.

silversx80

A higher cadance, at the same resistance, will result in the same power produced, yet with less force applied to the pedals for a shorter duration. Your legs, however, have less of a chance to recover from each stroke. A lower cadance means more force for each stroke, and since the stroke is longer, the force is applied for a longer duration. You do, however, get a longer duration for each leg before the next stroke.

Relate it to the weight room. I can bench 200 lbs, from my chest to full extension, in one second. To do the same amount of power, I'll have to do 20 lbs, 10 times in one second, or 100 lbs, 2 times in one second, etc, etc, etc. Someone else may be able to do 20 lb, 10 times in one second, but not 200 lbs, once.

The point is, everyone is going to have an optimum.


Another point is that a higher cadance is taxing on your aerobic ability, while a lower cadance is more taxing on neuromuscular strength.


What you should train is up to you and what your goals are.

frankum

Nice work here, but really though I find that cadence is more about 'comfort' than trying to be 'efficient'. I feel that if I'm pushing a comfortable pace, around 100 or 110, I'm working pretty efficiently BECAUSE I'm comfortable. What I'm trying to say is that cadence and whether a higher or lower one is more efficient, it depends on what you personally find comfortable. But regardless, good work. We always hear debates on cadence and efficiency/heartrate...

jrobe

I don't think you can conclude too much from a 3-5 min test time. There are too many short term variables in heart rate with exercise. For example, I have seen times when my HR at a high cadence is quite high initially and then seems to drift back as my body adapts (at the same power output).

The best way to determine your optimum cadence (ie the cadence that gives the highest functional threshold power output) is to do a 20 min FTP test (or better yet, 60 min test) at different cadences preferrably with a powermeter. It is possible though that your optimal cadence is lower than you suspected.

Spreggy

My amateur, inexact science way of looking at it is this. One, your results were exactly what I would have predicted; the higher the cadence, the higher the heart rate.
Higher cadence places more emphasis on oxygen for fuel.
Lower cadence places more emphasis on glycogen for fuel.
Oxygen is pretty much limitless, whereas glycogen is finite.
Thus, higher cadence is more efficient.

umd

As others have said your test really has nothing to do with efficiency, as your heart rate is a byproduct not actually the thing that matters, per se. It has been well established that picking a cadence involves a tradeoffs between aerobic vs muscular capacity. Lower cadences work your muscles more and high cadences work your hear more. That's why there is the saying that if your legs are tired, go to a higher cadence, and if you are out of breath, decrease your cadence.

Also it's worth mentioning that trainers do not approximate the road well because they spin down too quicky without a massive flywheel.

gregf83 

As long as your long rides are 2 min or less . Try repeating the test using 20 min intervals instead of 2min. Generally, most riders find their optimum cadence increases with power output. Lower cadences are always more efficient because you don't waste as much energy lifting your legs up and down (which doesn't do anything to move you forward) but not necessarily optimal.

gmatocha

Thanks guys, this makes more sense now.

The error I was making is assuming that the most "efficient" cadence would produce the lowest heart rate. When in fact "efficiency" from a cardiovascular standpoint has little to do with it.

Spreggy's response makes a lot of sense - paraphrasing: the higher the cadence, the more aerobic cycling becomes, and aerobic activity can be sustained for a longer period of time.

So to digest all this and try to answer my own question - if I'm training for a fast century, it sounds like I should train at a cadence that puts me just barely under my anaerobic threshold...and I should ride the century at that same cadence?

Thanks again!

jrobe

You obviously are interested in educating yourself on proper training techniques. Good for you.

On the other hand, your last post suggests that you could still use some help (your conclusion makes no sense). Here is a good book that would give you lots of new information. It is only $13 and it would transform your training regimen. You don't even need a powermeter to use some of these concepts (they can be done with just a heart rate monitor.

https://www.amazon.com/Training-Racin...5246841&sr=8-1

JoelS

I think you would get more useful information out of that if you used a powermeter instead.