Quality in z2 by cadence

Fig1 : Power Output (W) vs FAT oxidation rate white from ISM paper

Was wondering if other riders notice this effect where you can actually feel the body wanting to creep out of z2.

If you look at the graph A (top) included above you can see that the rate of fat oxidation is roughly the same at 250 and 225 W being on either side of the vertex located at ~240. Of course the difference being that from 250 onward raising the power causes a quick drop off in fat oxidation as the energy system switched over. You might say that in the space between energy systems is highly unproductive in terms of fat oxidation.

However if you are out there for 2+ hours in zone 2 it can become extremely easy for the body to start raising the output to burn a bit of sugar for whatever reason be it to save fat or just to have a change up in the sensation in the legs.

This effect in particular got me thinking about those turns out of the saddle during a z2 ride and how they often tend to become more frequent towards the end of the ride and greatly reduce the RPE of the whole ride (and as a result likely diminish the effect). For example if you do a 3h straight z2 ride with no stops the last 15 minutes can be very uncomfortable, and while the correct thing to do is to rationalize by saying okay this is why I’m doing 3h to build up the fatigue to get to this part where I can now apply this unique stress to my systems, often I find myself wanting to get out of the saddle to make it more comfortable in a metabolic sense (sitting pressure aside).

My interpretation is that this is really quite bad as I mentioned above the whole point of doing a long ride is to create the opportunity for this accumulated stress so why would I then try to avoid it during the most cumulative part?

As an example I would list the following ride where I actually believe that the accumulation in a 3h ride was better than in a 5h ride, simply because the 3h ride was easier and thus required less out of saddle to complete. By that last hour of a 5h ride the quality I find does have a drop off for a number of reasons.

You can see in the cadence data where this is happening : here

So should I reduce the duration of these rides to get better quality ?

For me, changes in cadence do not show much. Or more precisely, cadence do not change at all, except every 10min 30-50sec out of saddle riding to break monotony.

For Z2 duration effectiveness I look at HR/power decoupling instead: not by first vs second half but when exactly it starts going above 0%. From that point, I’ll keep going for 30-60min more and adjust next week long Z2 accordingly. Intervals.icu has helpful chart “Activity Power” → “Power & Heartrate” for that purpose:

EDIT: seems I have missed before that this chart can be configured to overlay cadence on top of it as well. Might be helpful for you to analyse how it affects your trends :thinking:


The general rule is don’t worry if you go a bit above Z2 or bit below as long as it’s not a large proportion on the ride. Just go out for as long as you wish to spare within the context of your current volume and longest rides and be disciplined. My cadence is whatever feels natural on such rides, it will vary throughout the ride. I don’t have a single cadence like a metronome.

The beauty of the long Z2 ride is that you don’t have to overthink it. It’s a great time to unwind.

Physiology is complex, training is simple.


Volume is king. This is overthinking things.


Ride your bike for 3+ hours. Eat. Take breaks if needed. Don’t worry be happy.


Old me used to experience this. Have mentioned it in other threads. 160bpm? Could sit there for ages in blissful happiness. 145bpm (which is mid Z2 HR) would give me this annoying nagging feeling like a dull ache.

What cured it? Riding right there at that irritating intensity more.

This is from a 2015 strava comment chat I was having with someone about it:

It’s really odd. I managed less than 30mins out of 2hours today. Uphill is fine but on the flat, I seem to cruise along in the low 120’s. Anything higher and my thighs hurt. It’s like my body can’t fuel itself very well in that zone. Yet Tempo is fine- I can buzz along quite happily at 150-160. One of the pitfalls of self-coaching I suppose is that it’s hard to diagnose problems.

The only thing I got wrong perhaps is that 150-156 actually was in Z2 still.

The great thing about training to solve this problem, is that when you go back to the Z3 you were naturally good at, you’re even better at it with a bigger Z2 :grinning:

(Basically a +1 for don’t over complicate it- just ride more Z2 :rofl:)