I am doing 40 to 60 minute tempo intervals by power, but end the interval if my HR gets above the tempo HR range. My thinking is that if my HR is too high, then is it really a tempo interval anymore? Is this a mistake? Should I just keep going with the planned tempo interval even if my HR creeps into the threshold zone? Usually my legs feel good enough to keep going in most instances, but I will stop if my HR gets too high. Any thoughts?
Thanks in advance,
Joseph
I do, but this is because I trained with heart rate (and RPE) before power. I think what you’re explaining is fine, in general. If I’m coming off a rest week or sickness my heart rate will be elevated across all power zones.
However, if this is a common occurrence I would either start to question how well-rested you are or whether or not your FTP is set inaccurately… and when you think you’re doing tempo you’re actually doing true threshold. Not an uncommon occurrence.
This is key. HR is about the only thing to measure internal stress, do pay attention to it; Specially because power based zones usually have a fair amount of measurement errors.
Yes, because it provides me with additional information. For example, how quickly does my heart rate recover after an interval? What is the average during the work interval or during the rest interval? That tells me whether e. g. I have been rested properly or not, how fit I am that day, etc. It can tell me when it is better to pull the plug or push through a hard workout. I find that heart rate is tremendously useful in that regard.
I suggest you research Aerobic Decoupling:
Thanks for responses. And special thanks for the article link, mtbjones. It was a great insight. I see that Pw:Hr in my workout data but never really knew what it was all about.
I record about every piece of data I can, and use about none of it for anything. Not sure what that means 
@Joe_Vdenne I regularly use a similar approach with hour long ‘threshold’ workouts…except if my 3min avg HR gets above ~92.5% observed cycling HRmax I will adjust the power down to maintain HR at less than that. My reasoning is similar to yours…if HR is that high it’s a VO2max effort not a threshold effort.
So I would recommend not just ending the interval. Adjust the power down by 5W. Wait 30 seconds. Adjust again if needed.
This. 
I always work on power and use heart rate as a marker just to how fresh/fatigued I am
IMHO if your ftp is set correctly then yes it is still a tempo effort. The point of tempo efforts is to increase muscular endurance, which is primarily about your METABOLIC fitness and NOT cardiovascular fitness. So make it muscular (metabolic) focused workout and don’t pay much attention to heart rate unless it is unusually high or low. Pacing by power is the correct approach. If you see high cardiac drift then maybe you need to do more aerobic endurance, or slice up the tempo intervals into shorter segments with some rest intervals. Again the point of tempo is to increase muscular endurance / metabolic fitness.
If your focus is autonomic nervous system stress (one of Seiler’s messages), then start with asking why you are doing tempo.
Depends on the interval. I generally ride longer race-pace efforts to HR- but I mainly race long course triathlon, so if I see my heart rate rising to the extent that I have to significantly decrease my power I’m probably not in a good place. I think the key there, though, is that those workouts are more focused on execution than a specific fitness outcome.
I don’t think I use any one metric to dictate effort, though- ideally i use all three to inform my own judgement, brain space allowing. That seems to scale pretty well though- at really high intensities I think they become less relevant.