Meaning of average intensity based on heart rate

jbruced

I recently got the Map My Ride upgrade and one of the things it shows is average % intensity based on the recorded heart rate during the bike ride.
Yesterdays bike ride showed I was in zone 4 for 59 minutes and in zone 3 for 41 minutes with zones 1&2 filling out the remaining 10 minutes of the total ride time. From this there is a result that says my average percent intensity was 72. What does that mean? How do I use that information?

yirara

Honestly? It's difficult to use it if you don't know your maximum heartrate and have added it to this app. Without knowing this, this information is pretty meaningless unless you happen to be within 10% of 220-age.

AnvilHead

Heart rate zones and intensity don't mean much unless you're an athlete training in a particular protocol/for specific results. For the average, non-competitive exerciser just doing it for general health benefits/calorie burn, your HR zone/intensity isn't really very useful data.

The old "fat burning zone" BS has been debunked (as it relates to weight/fat loss).

Azdak

Heart rate information can provide some value if you are knowledgeable about that metric and know how to put it into perspective. It can help monitor that exercise intensity was in line with your plan for that workout; it can be used to monitor progress.

However there are problems with casual exercisers using HR training data. One is that,unless you know your actual HR max, the data is not accurate enough to be useful. Actual max hr can vary by 20-30 beats/min from age-predicted values.

The other problem is cardiovascular drift. This means that, during a prolonged workout, hr will “drift” higher, even with no increase in workload. Sometimes this increase can be 15-20 bpm over a 45 min workout. The HRM will record the latter minutes as being in a “higher zone” and record a higher calorie burn, even though nothing has changed except heart rate.

singletrackmtbr

Azdak wrote: »

The other problem is cardiovascular drift. This means that, during a prolonged workout, hr will “drift” higher, even with no increase in workload. Sometimes this increase can be 15-20 bpm over a 45 min workout. The HRM will record the latter minutes as being in a “higher zone” and record a higher calorie burn, even though nothing has changed except heart rate.

My understanding is this typically is due to dehydration, causing the heart rate to rise to maintain cardiac output, so it probably isn't a real factor for most gym goers. Am I thinking about this correctly?

Azdak

singletrackmtbr wrote: »

Azdak wrote: »

The other problem is cardiovascular drift. This means that, during a prolonged workout, hr will “drift” higher, even with no increase in workload. Sometimes this increase can be 15-20 bpm over a 45 min workout. The HRM will record the latter minutes as being in a “higher zone” and record a higher calorie burn, even though nothing has changed except heart rate.

My understanding is this typically is due to dehydration, causing the heart rate to rise to maintain cardiac output, so it probably isn't a real factor for most gym goers. Am I thinking about this correctly?

It was thought to be dehydration, but now that is considered a smaller factor. Currrent research suggests that it is mostly caused by decreased stroke volume, i.e. a less efficient pumping of the heart as the increased HR is sustained. That accounts for maybe 75%—the rest is dehydration and increased core temperature.

As for not being a real factor, I can only assume that, like anything else, it will vary between individuals. For me, over a low-level, 50% effort, 45 min, steady state workout, my HR will drift up at least 20 bpm from minute 5 to minute 45. With some increase of perceived effort due to modest muscle fatigue, but with no increase in breathing.

MeanderingMammal

singletrackmtbr wrote: »

Azdak wrote: »

The other problem is cardiovascular drift. This means that, during a prolonged workout, hr will “drift” higher, even with no increase in workload. Sometimes this increase can be 15-20 bpm over a 45 min workout. The HRM will record the latter minutes as being in a “higher zone” and record a higher calorie burn, even though nothing has changed except heart rate.

My understanding is this typically is due to dehydration, causing the heart rate to rise to maintain cardiac output, so it probably isn't a real factor for most gym goers. Am I thinking about this correctly?

This is an example of mine earlier this evening, 45 minutes easy cycling on my turbo trainer. You'll see constant pace and cadence up until the last five minutes when I did some 20 second spins. As commented above, a number of factors contribute, including increased body temperature.

ronocnikral

I would like to offer an alternative line of thinking to the "cardiovascular drift phenomenon." That would be it isn't a phenomenon at all, but rather a measure of one's aerobic system. The line of thinking follows when one is training with their aerobic system (below AeT), the increases in effort have a corresponding linear increase (or decrease). For example, if you increase effort by 1, HR increase by 1 (left unitless on purpose). When your anaerobic system starts to take over, the relationship is over and the individual has lost control of their HR. So, if you can go through your workout, you want the variance in pace to HR (or power to HR) ratio to remain less than 5% being ideal.

Training peaks refers to this as "aerobic decoupling," rather than cardiovascular drift. https://www.trainingpeaks.com/blog/how-to-use-aerobic-decoupling/

This metric simply compares how heart rate reacts to a steady power effort and is a fantastic reference of your fitness and an indicator for long climbs or time trialing. Your ability to maintain a steady application of power and keep “under control” will allow for a predictable duration of the application of power and energy usage.

Yes, there are many factors which impact HR. But, we should all be honest with ourselves if we are really not as fit as we think or if we have seen a 40 deg swing temp during our training session. Regardless, I'm of the school of thought to adjust my pace, not to just hammer it out.

Azdak

ronocnikral wrote: »

I would like to offer an alternative line of thinking to the "cardiovascular drift phenomenon." That would be it isn't a phenomenon at all, but rather a measure of one's aerobic system. The line of thinking follows when one is training with their aerobic system (below AeT), the increases in effort have a corresponding linear increase (or decrease). For example, if you increase effort by 1, HR increase by 1 (left unitless on purpose). When your anaerobic system starts to take over, the relationship is over and the individual has lost control of their HR. So, if you can go through your workout, you want the variance in pace to HR (or power to HR) ratio to remain less than 5% being ideal.

Training peaks refers to this as "aerobic decoupling," rather than cardiovascular drift. https://www.trainingpeaks.com/blog/how-to-use-aerobic-decoupling/

This metric simply compares how heart rate reacts to a steady power effort and is a fantastic reference of your fitness and an indicator for long climbs or time trialing. Your ability to maintain a steady application of power and keep “under control” will allow for a predictable duration of the application of power and energy usage.

Yes, there are many factors which impact HR. But, we should all be honest with ourselves if we are really not as fit as we think or if we have seen a 40 deg swing temp during our training session. Regardless, I'm of the school of thought to adjust my pace, not to just hammer it out.

Good article, but not really relevant to what we are discussing. This is not a situation where someone is riding at threshold or doing interval training. The conditions that I am discussing can be observed under low-level, steady-state aerobic exercise (e.g. 50% of VO2 max)—intensities that are well within the fitness capacity of the person doing the work. The key indicator is breathing which, if you pay attention, does not increase at all, even as HR drifts upward.

It’s not really a “phenomenon” (I looked back and I don’t think I used that word); it is a normal response as training sessions increase.

At more challenging workloads (threshold or tempo workouts), or during recovery from higher-intensity work intervals, then, yes, fitness is definitely a factor. But that’s not the topic.

ronocnikral

Azdak wrote: »

ronocnikral wrote: »

I would like to offer an alternative line of thinking to the "cardiovascular drift phenomenon." That would be it isn't a phenomenon at all, but rather a measure of one's aerobic system. The line of thinking follows when one is training with their aerobic system (below AeT), the increases in effort have a corresponding linear increase (or decrease). For example, if you increase effort by 1, HR increase by 1 (left unitless on purpose). When your anaerobic system starts to take over, the relationship is over and the individual has lost control of their HR. So, if you can go through your workout, you want the variance in pace to HR (or power to HR) ratio to remain less than 5% being ideal.

Training peaks refers to this as "aerobic decoupling," rather than cardiovascular drift. https://www.trainingpeaks.com/blog/how-to-use-aerobic-decoupling/

This metric simply compares how heart rate reacts to a steady power effort and is a fantastic reference of your fitness and an indicator for long climbs or time trialing. Your ability to maintain a steady application of power and keep “under control” will allow for a predictable duration of the application of power and energy usage.

Yes, there are many factors which impact HR. But, we should all be honest with ourselves if we are really not as fit as we think or if we have seen a 40 deg swing temp during our training session. Regardless, I'm of the school of thought to adjust my pace, not to just hammer it out.

Good article, but not really relevant to what we are discussing. This is not a situation where someone is riding at threshold or doing interval training. The conditions that I am discussing can be observed under low-level, steady-state aerobic exercise (e.g. 50% of VO2 max)—intensities that are well within the fitness capacity of the person doing the work. The key indicator is breathing which, if you pay attention, does not increase at all, even as HR drifts upward.

It’s not really a “phenomenon” (I looked back and I don’t think I used that word); it is a normal response as training sessions increase.

At more challenging workloads (threshold or tempo workouts), or during recovery from higher-intensity work intervals, then, yes, fitness is definitely a factor. But that’s not the topic.

You are correct, the article I linked to shows examples with intervals. You'll also note in the quote I left above, "This metric simply compares how heart rate reacts to a steady power effort and is a fantastic reference of your fitness...."

The "aerobic decoupling" function in training peaks works with "steady state aerobic exercise." In fact, I would argue it is a measure of one's aerobic system. Here is another article from the guys I consider to be very knowledgeable about developing very strong aerobic systems. You'll notice the suggestion of doing some sort of "steady state" activity, and even controllable and repeatable. And again, they suggest you keep the variance below 5%.

https://www.uphillathlete.com/heart-rate-drift/

Another way to do this test is on a treadmill or stair machine. First, find a pace that brings your heart rate up into what you feel is your aerobic zone. Hold that pace for an hour or so and notice if your heart rate begins to climb. If your heart rate climbs less than 5% over the course of the workout, that heart rate was within your aerobic intensity zones.

Again, we can blame dehydration, core temp, stroke efficiency of the heart or the sunrise time in mongolia. Or we can face the facts and realize our aerobic abilities aren't all we imagine them to be. You'll also refer to the training peaks article I linked to, there is a section called "the opposite is also true." Showing that it is not necessarily a "normal response" as the duration of a training session marches on. You can call a negative variance what you will, but some of us use the drift to measure if we were really in an aerobic zone or not.

sijomial

Have your zones been set following a proper max HR test? If not they could be inaccurate.

Also remember zones have very hard borders, 150bpm could be zone 3 and 151bpm could be zone 4 for example so time in zones can be skewed if you are riding near a threshold.

For a steady state ride average percent intensity could be somewhat interesting as a personal comparison piece of data from ride to ride.

For interval training or stop/go rides in traffic it could be very misleading.
I do long'ish duration intervals either side of my FTP which is really intense but the recovery periods would pull the average down to an equivalent of a very steady pace.
Or you could really attack a long hill but then coast down the other side for a middling average.

Not convinced you can actually use this piece of information for any great purpose beyond curiosity value or comparison if you ride the same route regularly.