Cadence and Heart Rate, a tale of two runs

Two things I don’t care about. Seriously, if you say ‘cadence’ to me while I am running I will be annoyed beyond belief. It would be like saying ‘watermelon’. I care about heart rate a little more because it can indicate if something is seriously wrong or if you can afford to push yourself a little harder.

To illustrate my point, I will use a tale of two runs. One run was an outdoor run and one was an indoor run. My outdoor run was baaaad according to Garmin, my cadence was too low and my heart rate was too high. Bad Cadence

Yellow is bad, green is good, according to Garmin. So I was in the green for only a little while.

My corresponding heart rate was also baaaaad, according to Garmin, somewhere around zone 8 or 9 (this is tongue and cheek).

Bad Heart Rate

Now on to my gooood run according to Garmin metrics. My cadence shows up mainly as green!

Good Cadence

The computer is much happier now. My heart rate is also better according to them. Good Heart Rate

Google “run cadence” and see the overwhelming amount of opinions on what the ideal run cadence should be. In fact, our coach insists that we pick up our cadence. I ask, however, “what scientific evidence have you that cadence matters?”. The honest answer is none. In fact, when it has been studied, it was found that coaching on run dynamics yields little benefit at all. There is a correlation that more efficient runners tend to have a higher cadence than less efficient runners. However, science is always conscience of the difference between causation and correlation. In other words, are the more efficient runners more efficient because of their cadence or is the cadence the result of something else, like higher levels of physical fitness.

So relax on the cadence, it will come (mine has gone up) as one becomes more fit.

On to the heart rate and “zone training”. The idea behind zone training is that your exertion can be measured in neat little boxes where you have a “fat burning zone” and an “anaerobic threshold zone”. heart-rate-zones1

This is why everyone and their mother wears a heart rate monitor now. When I was ripping off sub 7 minute miles in cross country I can’t remember my coach ever saying anything about heart rate zones.

Same question, “what science, have you, that backs up these findings”? There actually is quite a bit of science surrounding this (more than cadence) but, as always, it is much more nuanced than a simple box. The first nuance we have to be aware of is that at all times you are engaged in anaerobic respiration, (refer to earlier post) so it is disingenuous to make a zone called “anaerobic zone” as if it just kicks in at 160 bpm and your ATP production stops. My coach uses a term “lactate”, in reference to the time in which the amount of lactic acid produced by the cell’s fermentation process exceeds the cell’s ability to remove lactic acid from the cell.

The other disingenuous bit is the “fat burning zone”. There is no such thing. There is a zone that fat tends to be burned in, but that is more related to the fact that the average person can stay in that zone for a long time and therefore dip into their fat reserves for energy. A trained athlete will burn fat at any “zone” provided they are exercising long enough to dip into their fat stores. This is why sprinters and distance runners are both quite lean, even though their training hits much different intensities over different time intervals, they are both burning fat…and probably eating better than average.

I actually engage in a bit of zone training, I look at my watch to make sure I am not getting an abnormally high heart rate – but I don’t split hairs between 145 and 155, or even 145 and 159. At 160 I start paying attention, if the pace is good and and high and I feel OK, I let it ride out.

So back to my two ones, one run Garmin tells me I “overreached” and the other was “highly improving”. One was a 6.1 mile outdoor run on varied terrain, up and down hills, with a strong uphill headwind for the first mile. The other was a 3.2 mile treadmill run. Garmin says the treadmill run was the better one. I disagree, while my heart rate was high, the run was designed to make me run at a higher tempo than normal. More importantly, I was not sore at all the next day even though according to the chart I should have been in full bore lactic acid overload.

I don’t mean to bash coaching recommendations based on zone and cadence, in fact I use those metrics myself to evaluate my progress. The exercise industry is FULL of claims about certain products and techniques where very few have been tested to a scientific standard. More importantly, we should not reduce exercise to a video game (keep your heart rate here, keep your cadence here….now you are winning!). Consistency in training is king.

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