Long Ride Zone 2 HR/POWER

Hi everyone,

On the zone 2 rides, in the sweetspot plan, you prescribe a target power for the duration of the ride. Im wondering what your opinion is on HR drift. Over time, especially if base fitness is low power and HR can get out of sync over a long ride (I believe the technical term is cardiac drift)

I like to ride at the prescribed power for as long as possible but will back off the power if my HR is drifting out of zone 2 and into zone 3, Once this starts happening I try to keep my HR in zone 2 while pushing as many watts as possible, so I look at both power and HR but HR ultimately dictates the pace.

As the TSS is prescribed using power, TSS may not be hit in the prescribed time due to decoupling of HR + Power. The easy way to overcome this is to extend the ride time until TSS is hit.

What are your opinions on this, how do you guys like to train on zone 2 rides? and would you consider this to be FTFP???!!!

I hope this makes sense!!


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One of the Velonews podcast episodes, around 21-ish min Stephen Seiler discusses doing the long slow rides/zone2 by HR rather than power. He argues the power is a measurement of what’s happening to the bike rather than the body and doing these by HR better achieves the goal of reducing cardiac drift over time.


Do any of the fascat coaches have an opinion on this?

I’m intrigued what Stephen Seiler said.

So I’ve always been one to stick with power and train the body to adapt to the effort. This way you are getting the physiological gains from riding in zone 2 power. Though if your heart rate is in zone 2 you are working. So it’s an interesting topic.

I guess it would be interesting to know when this deflection happens. Like if you are doing a 4 hour endurance ride is your heart rate up in zone 3 after only 2 hours, or in the last 30 minutes? Maybe if the latter you should start your zone 2 rides a little easier so it does not go up so much, so quickly. You might not match your TSS exactly like the plan but you will be riding in proper zone 2.

Also over time this shouldn’t be happen frequently if you are getting in your training and endurance rides. This is why we do a progression. Building from 2.5 endurance rides, to 3, 4 or more hours. If you are not getting these rides in maybe it is best to push it a bit on the ones you actually are completing.

This is a great way to test endurance as well. If you can find a good route where you can keep your power consistent in zone 2 and ride at the same power throughout. You can repeat this ride throughout the year and compare your heart rate and see when it increases, how long into the ride it increases and etc.