[hbaastrup]

When I do longer Cycling Foundation or Run Foundation training, I often see my heart rate grow into to zone X, when I keep the power or pace constant within zone 2.
Example: The other day I did a CF11 workout (30 min Z1, 50 min Z2, 10 min Z1), when I started the zone 2 part, my heart rate quick stabilized around 135 bpm, I kept the power constant around 125 W for the whole 50 minutes I should stay in zone 2. Around 55 minutes into the session, half way through the zone 2 part, my heart rate entered zone X and it kept growing throughout the whole zone 2 part for end around 145 bpm.
I believe it is normal that my heart rate slowly grow throughout a workout with a constant effort.

Now my question is: Shall I keep my power effort in zone 2 and let my heart rate drift into zone X, or do I lower my power effort to keep the heart rate in zone 2 and eventually let the power effort drift down into zone 1, when I do Foundation workouts?

NOTE: My FTP is 190 W and my LTHR is 159 bpm on my Indore trainer, based on a 30 minutes test done in this month.

[David Warden]

H,

The phenomenon you are describing is called “cardiac drift” and is a normal part of using HR to measure intensity.

HR does tend to drift less with proper training. In fact, when you analyze a workout in TP that has both power and HR, you’ll notice a metric named Pw:Hr (or Pa:Hr on the run when using Pace and HR). Any value under 5% is considered a measure of a good aerobic base for rides of 2+ hours, and it really should be under 3% for rides of less than 2 hours. Athletes who have spend too much time at moderate intensity (athletes with a long history of not doing 8020 training) tend to have low Pw:Hr, but it gets better as you commit to low intensity.

This measure only works for endurance rides, not interval rids. Interval rides are not valid for Pw:Hr values.

The drift you are describing is a bit high, so I’d suspect you just need more time following the plan and committed to easy training 80% of the time.

However, having said all of that, if you use Power, just ignore HR altogether on these rides, and any ride. Using HR when you have Power is like watching a sports program on the TV and listening on the radio at the same time, and wondering why the radio program experience is so different than the TV. Why listen to the radio when you have the TV?

David

[hbaastrup]

Hi David,
Tank you so much for your answer, it was very useful, I like I have to keep the effort constant at a level I feel good going even my HR is going up.

I have another question on the HR drifting. I’m new to 80-20, but before I have used Phil Maffetone’s MAF at lot even with some frustrations, I have always had a problem with the 180-formula without any test. My HR has always drifted or when I tried to keep it constant, my pace has drifted. Any case I think my aerobic base is not that bad, but when you say that the HR drift should be under 3% for the ride I did, I think I’m a bit far off (my calculation tells me mine was around 7%).

My question is: Would the drift become bigger with the age (I’m 60 years old)?

By the way, are the numbers for the HR drifting the same for running?

Regards,
Henrik

[David Warden]

Hmmmm, I never thought of cardiac drift and age. I don’t know, and I would not want to even guess. There is probably some merit to that, but I have not seen that researched.

The values are the same for running, but the distance is different. Under 5% for 1.5 hours or more and under 3% for under an hour is a “good” target for running.

David

[winoria]

David,

Cardiac drift is an interesting topic and my understanding is/was that dehydration plays a major role. I thought that by dehydrating during an exercise, blood thickens and the heart is forced to work harder to supply the muscles with the oxygen/fuel needed to maintain the power output. Is this wrong?
Also, if it is correct, how much of the cardiac drift would be dehydration related and how much usually caused by an insufficient aerobic base?
Or is it even likely that the cardiac drift caused by dehydration can be neglected due to a very minor impact?

Thanks
Winoria

[hbaastrup]

Hi Winoria,

My personal experience is, on a hot day my heart rate is higher, for the same effort, than on a cold. I’m not so sure with the drift, but my sensation is the drift is higher too, maybe you David could confirm this?
I believe it has to do with keeping me cool on a hot day. If I do an one hour run, I’m always is well hydrated when I hit the trail, if it is a hot day I will bring a small bottle of water with me, on a cold I will run without hydration, in both cases my heart rate will drift, I do believe the hydration count, but not as much as the environment temperature.

In general I’m very much personal interested in how much age count in my training, as most study is done on much younger people than my age. Also I think there are ever more “aged” people there do sport at a certain level, so I find it a bit sad there is no more study on my age group and older.

Any case, if anybody is interested to follow how my heart rate drift will I go, while I go through my new 80/20 program, I’m ready to post it some place.

Regards,
Henrik

[David Warden]

Henrick, I’d be very interested to see you post your drift results here. It really only matters for rides of 2 hours or longer, and it really only matters when the conditions are similar. Temperature will absolutely impact drift.

Winoria, for sure dehydration impacts drift for the reasons you describe, but it won’t eliminate it. A well-hydrated athlete will simply drift less than a dehydrated one. I don’t know how to quantify how much dehydration impacts drift, but the solution would be to ensure adequate hydration for every workout, and then you have a baseline for which to compare.

David

[hbaastrup]

Hi David,

If we have to wait to I begin to do 2 hours rides, we have to wait well into April, as I’m still on the Level-0 program and plan to swift to the Level-1 program March 8, but I already have a clear drift in my 90 minutes foundation rides, the drift is rather linear over a ride, can’t they be used?

Any case I will post them here: http://hba.dynu.com/sport/workouts/

In this moment I do my bike workouts on an indoor trainer, so the environment temperature is rate constant on 20°C. My run workouts is done outside where the temperature vary a lot in this moment, even the drift is there too with a constant pace.

Henrik

[David Warden]

A couple of thoughts here:

– Don’t get caught up in the Pr:Hr number. Yes, I know I pointed it out, but don’t treat that value as the end-goal, it is just one of many, many indicators. For example, if your FTP is 400 watts, and you can hold 80% of that for 4 hours, who cares what your Pw:Hr is?

– Yes you can use the 90-minute rides, even a 1-hour ride. The drift should be about 5% or less for 2 hours and should be less drift for less time and a bit more drift for more time. 2 hours/5% if the “polestar” and you can estimate how good you rare doing from any other ride from 60 minutes to 6 hours using that baseline.

– It takes about 3 years to fully develop an aerobic base using proper training. I don’t want to discourage you, but between now and April your base is not going to change much. Sure, 50% of your gains will take place Year 1, then 30% of gains Year 2, so a lot of improvement will happen this year, but give it time. It’s a long-term investment

– Again, just use Power. Don’t worry about your HR drift. If you follow the 80/20 system, your aerobic base is absolutely going to improve. If you just focus on following the plan and using power, you don’t have to worry about much else.

David

[hbaastrup]

Hi David,
First thank you for taking the time to look at this.

A little about me: I have been running for more than 10 years, for the last couple of years I have spend lot of time on building my running aerobic base. I started to take up triathlon for around 1 1/2 year ago, and began to road biking – of course, so biking is rather new to me. My running aerobic base is, after my own opinion, not that bad, and I expect some of it would spill over to my biking, so I would not expect to wait for years to have some reasonable aerobic base on the bike too. I might be naive 😉

I did an analysis on the latest Foundation ride I did, where I tried to keep the power constant, and got the following times in the different zone (see below), after my opinion there is something wrong here. I believe I should have spend the main time in the HR zone 2, as is – I spent a third of the time in zone X. This can after my opinion not be very 80/20 correct.
I see your point with using the power instead of HR, as the power is instantly, while the HR always will be delayed, but in the end, it is the HR there tells what my body actually did, especial over a longer time.
I also agree I should not be so fixed on all the measurements, but I use them to setup a feeling on what and where I should be when I do a workout, and HR has really helped me in my run workouts. To return to my age, things change and again I believe these measurements can help out, also I find it interesting to see how my body responds to all this.
I begin to suspect my indoor trainer power meter is not very accurate, I do not have a power meter on my bike, so I use what my trainer can gives me, maybe it is better to use my HR in my workouts until I can find a way to check or calibrate my trainer.

Heart rate zones:
– Z1: 30 min
– Z2: 29 min
– ZX: 29 min
– Z3: 5 min

Power zones
– Z1: 45 min
– Z2: 48 min

If I should describe the workout above using the RPE description, I would no way describe it as a Light workout, but something between Somewhat Hard to Hard. The end of the zone-2 part of the workout, I would definitely described as Hard.

Henrik

[David Warden]

Henrik,

Great questions, a few observations and comments:

– HR and Power Zones will only line up if you capture FTP and LTHR within the same test. If you capture FTP and LTHR separately, they are unlikely to line up.

– Even if you do perform the FTP and LTHR test at the same time, it may increase the chances that HR and Power line up, but HR is so influenced by external factors that it will often not line up. Sleep, stress, temperature, time of day, when you last ate, indoor or outdoor, all will change HR for a given power by up to 30 beats.

– Pick one measure or the other, don’t try and mix them. It just will cause confusion in your training. I recommend Power.

– Aerobic base for running does not translate very well to cycling. It does a little bit, but they are separate sports. Additionally, if you have been training improperly on the run (too much high intensity) then you still need up to 3 years of 80/20 training on the run too!

– “but in the end, it is the HR there tells what my body actually did…” This is not correct and a common misconception of training. HR is an indicator of how your body is responding to training, it is not an output. If I sneak up behind you and say “boo!” your HR will jump to 140bpm. It does not count as a workout. If you run on a treadmill at 14kph at 70 degrees F your HR will be 160. If you run at the exact same speed at 90 degrees F your HR will be 180. Your recovery and fitness gained will be no different between the two.

– Any time we call for Zone 2 in a workout, you can use Zone 1. The division between Zone 2 and Zone X (the threshold between low and moderate intensities) in the 80/20 system is empirical. The division between Zone 1 and Zone 2 in the 80/20 system is an estimate. Matt and I just made a best guess on where Zone 1 ends and Zone 2 starts. There is no empirical data for “low intensity” and “really low intensity.” Therefore, high Zone 1 is still low intensity, and qualifies in the 80/20 system the same way as Zone 2. Feel free to hover in Zone 1 when Zone 2 is called for, and as you get stronger that Zone 2 won’t feel so hard.

David

[hbaastrup]

Hi David,

Gosh – My running fitness does not translate into my cycling fitness – now I have to sit on that bike for years to come, and me there thought it would be a piece of cake to start biking 😉

Without to be a doctor or biologist, I will still argue for the HR is a better indicator for what goes on inside me, than the power output I read on my power meter. Power tells me how much work my body does in the very moment, how much energy I transfer to the bike, seen from the bike. HR tells me something about my metabolism over a time period. Yes – the HR change all after how I am that very day, but I still will argue it is an expression of my metabolism: If I’m stressed, run on a hot summer day, or an evil coach sneak up behind me and say “boo!” so I almost got a heart attack, they are all cases where I have a higher metabolism. My question now is: If my metabolism goes up, do I risk to go out of my aerobic zone?
If I keep my power the same on a cold or hot day, stressed or relaxed day etc. my HR is different, it is right my muscle did the same work, but did I get the same benefit to build up my aerobic base, if my HR entered zone-X on the hot stressed day?
I think that is the base in my first question, what I observed was exactly this, my HR was in zone-X, third of the time when I should have worked in zone-2, while my power output was in zone-2 all the time, was this beneficial to build up my aerobic base?

Now I have analysed and posted my latest foundation run, it was around an hour long. It is clear my pulse drift up until it hit a ceiling, just on the limit of my zone-2 HR, but the drift was from 132 to 148 BpM = 12%, so I asked myself do I calculate this right? I have used the start value just when I switched my effort (pace) from zone-1 to zone-2, would it be more correct to use a value 10 minutes into the zone-2 run, like we do when we do our threshold tests?
To re-formulate the questions, which start value should I use to calculate the drift? The HR drift the whole time from I start running until it hits the ceiling or I stop.

I think I understand the whole zone system as such, but have some problem to see how to merge the power I see on my bike with the HR I expected, but as I wrote, it might be a problem with the instrumentation I use.

I know for most people the right effort it should be a feeling, and I think I have that feeling in my run sessions, but not in my bike sessions, I build up that feeling for my run sessions by using a heart rate monitor. I also have an other problem, as a data engineer I just love data and I can’t stop myself to collect them, analyse them, and try to understand them.

Henrik

[David Warden]

Henrik,

Heart Rate as a measure of intensity has been used successfully by millions of athletes for decades. Despite it’s disadvantages and risks, it’s still a great way to train. I do think Power is better. I also think trying to serve the two masters of power and HR will just drive you crazy. The real advise I hope you’ll follow is not necessarily to use Power instead of HR, but my strong recommendation is don’t try to juggle both.

Also, your heart rate for a given power will start to drop as you continue to cycle more. That delta will probably naturally start to decrease. Consider ignoring HR for a month and just use Power. Collect the data, just don’t read it for a month. Most athletes who committ exclusively to power never go back.

In my opinion, “work” in the very literal interpretation (W=Fs) is a better measure of stress introduced to the body than heart rate.

Cardiac drift is actually measured by taking the ratio of HR to Power (or Pace) for the first half and dividing it by the same ratio for the second. For example, if your average power for the fist half was 180 and average HR was 138, that’s a ratio of 1.3. If your average power for the second half was 180 and HR was 148, that’s a ratio of 1.22. 1.3/1.22 is 1.065%, or 6.5% cardiac drift.

Anyway, the subject of this thread is “Should I use power/pace or heart rate when I do Foundation training?” We’ve com a long way since then, but the short answer is I recommend Power, then Pace, then HR.

David

[hbaastrup]

Hi David,

Yes it is true, we have come a long way. Maybe my preference for HR is, I have used it so much in my running. Under all this comes, I do not have a power meter on my bike, in less than a month I hope to start to bike outside, so no power from my indoor trainer, and if I do not find a very good offer for a power meter, it will not be the first thing I buy, they are terribly expensive.

Any case, your input has been interesting, very useful for me and I really appreciate it. I will continue to follow the 80/20 program, I have started on, and hope it will build up my bike aerobic base and help me to get some more speed out of my run, my swimming is still on survival level, but I hope I soon can apply the program there too.

I don’t know if you had a look at what I have posted in the site above (http://hba.dynu.com/sport/workouts/), but if you still are interested in how the HR drift change, for a 60 year old man, while I progress through your program, I will continue to post.

Thank you,
Henrik

[David Warden]

Henrik, your website tracking is amazing! Who needs TrainingPeaks when you can journal your own results and workout history?

I see you’ve already updated your tracking to include the correct cardiac drift calculations.

David

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