Heart rate & cadence for a given power


(Doug Jeffery R2S.CA YVR) #1

Something I’ve noticed while doing my structured workouts is the change in heart rate for a given power depending on cadence.

The training plan I am following often is calling for 6 or 7 minute repeats at 180W. I’ve been varying the cadence at this wattage and seen that if I am spinning faster (100-105) my HR is higher than if I am spinning slower (85-90).

In terms of getting the best training effect what cadence should I be using?


(Mark Hewitt) #2

Probably the one in the middle of that ;).

It’s a really big subject area in cycling, cadence vs heart rate and which is the most efficient, there have been dozens of books written just on that subject, not to mention power output etc.

But just as you’ve found spinning puts more stress on your heart & lungs* grinding puts more stress on your legs, finding the balance is key. 

 

*That’s why Armstrong rode with a high cadence, because his heart & lungs were, erm, artificially supported. But that doesn’t mean it won’t work for you too.


(Noel Nunkovich *USMES*) #3

As @Mark said, there’s all kinds of different opinions about cadence. That said, my coach has been advocating for me to increase my cadence for a pair of primary reasons.

  1. The physiological reason. This makes sense to me but I’m not a physiologist, I don’t don’t have the scientific background to make a judgment, and I didn’t sleep in a Holiday Inn Express last night. The reason is that higher cadences transfer more of the “load” to your cardiovascular system, thereby sparing the muscle glycogen supplies in your legs. Those supplies are limited and only replenishable via calorie intake and digestion. Your cardio system, on the other hand, is built to handle endurance loads. If you run out of fuel to power that system you have much, much bigger problems.
  2. The physics/practical reason. This one I have direct experience with. When riding or, especially, racing in groups, higher cadences allow you to respond faster to surges or attacks. That’s because if you are in a bigger gear, turning a lower cadence at a given wattage, it takes more time to spin that gear up. By the time you get the power down, get the gear spinning up and the bike accelerating, the group has had more time to gap you. Thus, you’ll spend more effort getting up to speed and then have to stay at speed longer to close a bigger gap. With a smaller gear/higher cadence, you can spin the gear up much faster and with less physical effort, the gap never gets as big, so you can back off sooner because you’re back in the draft.

So, while this is just one (or, I guess two counting my coach) man’s opinion, I can say that training myself over the last year or so to ride comfortably at 96-98 RPM as my “natural” cadence has been a plus for me.