Can you only measure your HRmax correctly when you're unfit..?

neeb

So I took 8 days off the bike completely and then did a fairly intense indoor session today. HRmax about 5-10 bpm higher than it's been for months, but I know that after 2 or 3 more regular sessions it'll be back down to it's usual level again.

It seems weird that your heart is only capable of reaching its maximum rate when you are temporarily slightly out of condition. Especially when that faster rate doesn't actually correspond to more power.

Should you regard your HRmax as the level it normally is when you are training regularly, or the level it's capable of reaching if you take a week or two off and then really push it?

Is doing the latter good or bad for you? ;-)

imposter2.0

HR max is not really a variable in the way you seem to be describing it. Just use the highest number you have seen and set your levels accordingly.

cougie

You are not unfit after a week or so off the bike.
More likely is that your usually tired so you're not as fresh to push hard enough to hit your max.

neeb

Imposter wrote:

HR max is not really a variable in the way you seem to be describing it. Just use the highest number you have seen and set your levels accordingly.

Fair enough - just seems odd that that highest number is not attainable unless I've had a significant number of days off the bike.

neeb

cougie wrote:

You are not unfit after a week or so off the bike.
More likely is that your usually tired so you're not as fresh to push hard enough to hit your max.

I don't think it's as simple as that - if I've had a a week off I might be able to push the same power (or almost), but HR (average as well as max) is higher. I wonder if it's something to do with total blood volume and how this changes over a few days of inactivity (and rapidly recovers again afterwards). Maybe when blood volume is higher the heart simply can't push it around quite as fast?

<edit - what I mean is that I can push the same power when I'm "tired" - just at a lower HR.

wongataa

neeb wrote:

Should you regard your HRmax as the level it normally is when you are training regularly, or the level it's capable of reaching if you take a week or two off and then really push it?

HR max doesn't vary. Well it may vary over long periods of time but in your situation it won't vary. If you get a higher number after a certain test you can be sure you didn't hit it on your previous tests. HR max isn't a very useful number so why do you want to know what yours is?

neeb

wongataa wrote:

HR max isn't a very useful number so why do you want to know what yours is?

Mainly because I know that it decreases with age and I'd like to stop that happening as much as is possible. I'm not sure exactly what the best way of doing that is, but monitoring would seem to be a good first step.

I'm also just interested in what is happening in the cardiovascular system to explain the inconsistent relationship between power and HR. For me at least, this inconsistency seems to relate to training load, in fact it's the most obvious thing I notice that varies with the amount of training I'm doing on a day to day or week to week timescale. HRmax is just one aspect of that, but as it does represent the maximum rate at which the heart can work, it's quite an interesting figure.

neeb

Also, it seems to me that maximum HR DOES actually vary on a day to day basis, it's just that conventionally HRmax it's not defined in a way that takes account of that. I'm almost certain that it wouldn't be physically possible for me to achieve the same HRmax on some days as I can on others.

imposter2.0

neeb wrote:

Mainly because I know that it decreases with age and I'd like to stop that happening as much as is possible.

MHR decreases 1-2bpm per year as part of the body's natural ageing process, so good luck with that. Decreased MHR does not necessarily equal decreased performance though - it's not a linear equation. Plenty of science to back that up and plenty of 50+ riders still riding at E/1/2 level to provide the anecdotal support of that.

neeb wrote:

Also, it seems to me that maximum HR DOES actually vary on a day to day basis, it's just that conventionally HRmax it's not defined in a way that takes account of that. I'm almost certain that it wouldn't be physically possible for me to achieve the same HRmax on some days as I can on others.

Your inability to hit MHR on some days and not others is not an indication that your MHR varies day-to-day. It is simply an indication that you can hit it on some days and not others.

neeb

Imposter wrote:

MHR decreases 1-2bpm per year as part of the body's natural ageing process, so good luck with that.

There's quite a lot of evidence to indicate that it decreases less in people who train regularly, I think?

imposter wrote:

Your inability to hit MHR on some days and not others is not an indication that your MHR varies day-to-day. It is simply an indication that you can hit it on some days and not others.

Surely that's just a question of definitions? There is the maximum HR you can reach on a given day, and the maximum you can reach in a given month / year. Both vary with time (the former up and down, the latter perhaps continually down), it just so happens that "HRmax" is taken to refer to the second.

fenix

Seems a silly idea to train specifically to reduce MHR - everyone is different anyway so a higher MHR doesn't mean much.

imposter2.0

neeb wrote:

Surely that's just a question of definitions? There is the maximum HR you can reach on a given day, and the maximum you can reach in a given month / year. Both vary with time (the former up and down, the latter perhaps continually down), it just so happens that "HRmax" is taken to refer to the second.

It's simpler just to stick with the established definitions, surely - rather than trying to redefine something in order to fit with your individual scenario.

Other than being useful for setting training zones (which can also be set using different measures, like LTHR), then MHR is not a particularly relevant training metric for daily use. As I said before - it is not an indicator of potential or performance, especially given that 99% of performance training will be done at levels significantly below MHR anyway..

neeb

Fenix wrote:

Seems a silly idea to train specifically to reduce MHR - everyone is different anyway so a higher MHR doesn't mean much.

I'm certainly not doing that.. :-) If anything I'd want to train to maintain it over long time periods, but obviously that wouldn't be the primary object of training.

Mine seems to have declined by about 7bpm in the last 10 years. Clearly it's related to aging, so you could hypothesise that a training regime that minimises decline over years might also be good for general maintenance of cardiovascular condition against age related degeneration. It could relate to questions such as whether short intense sessions or long endurance miles were better for minimising aging of the cardiovascular system.

neeb

Imposter wrote:

neeb wrote:

Surely that's just a question of definitions? There is the maximum HR you can reach on a given day, and the maximum you can reach in a given month / year. Both vary with time (the former up and down, the latter perhaps continually down), it just so happens that "HRmax" is taken to refer to the second.

It's simpler just to stick with the established definitions, surely - rather than trying to redefine something in order to fit with your individual scenario.

Other than being useful for setting training zones (which can also be set using different measures, like LTHR), then MHR is not a particularly relevant training metric for daily use. As I said before - it is not an indicator of potential or performance, especially given that 99% of performance training will be done at levels significantly below MHR anyway..

Yes, perhaps. As I said though, I still find the variation interesting, and I suspect there is a lot we still don't know about the mechanisms and interrelationships.

imposter2.0

neeb wrote:

It could relate to questions such as whether short intense sessions or long endurance miles were better for minimising aging of the cardiovascular system.

Would certainly be useful if the principal objective of your training was to minimise CV ageing - but I suspect it probably isn't.

neeb wrote:

Yes, perhaps. As I said though, I still find the variation interesting, and I suspect there is a lot we still don't know about the mechanisms and interrelationships.

On the contrary, I suspect it's been studied at great length.

neeb

Imposter wrote:

neeb wrote:

Would certainly be useful if the principal objective of your training was to minimise CV ageing - but I suspect it probably isn't.

It's one of several objectives! Most of these are mutually compatible. It would be surprising if minimising CV aging didn't correlate closely with maintaining performance with age. Although there are plenty people who maintain fairly good performance as they age despite their MHR falling, perhaps their MHRs would have declined much more if they had not trained or trained differently.

imposter2.0

neeb wrote:

Although there are plenty people who maintain fairly good performance as they age despite their MHR falling, perhaps their MHRs would have declined much more if they had not trained or trained differently.

That would be relevant if MHR was an indicator of performance - but it isn't.

neeb

Imposter wrote:

neeb wrote:

Although there are plenty people who maintain fairly good performance as they age despite their MHR falling, perhaps their MHRs would have declined much more if they had not trained or trained differently.

That would be relevant if MHR was an indicator of performance - but it isn't.

It's surely correlated - everyone's performance decreases at least slightly with age, and everyone's MHR decreases with age too. Obviously comparisons are only meaningful relative to one's own HR, but an inability to get your heart to pump as fast is fairly obviously going to decrease at least some aspects of performance, unless there is some other compensatory change also happening. Not trying to argue here, but it is interesting and there must be aspects of aging in this context that are not fully understood (otherwise it wouldn't be an area of active study).

fenix

What would you rather have a 1L heart pumping at 200bpm or a 2L heart pumping at 100bpm ?

craigus89

I think you're also working on the big assumption that because your max heart rate doesn't decrease over time that that is an indication that your CV system is healthy. I'm not sure that is the case.

neeb

Fenix wrote:

What would you rather have a 1L heart pumping at 200bpm or a 2L heart pumping at 100bpm ?

I don't think I have that choice.. ;-)

It's possible I suppose that as you get older, your heart beats slower but also gets larger to compensate, especially if you are trying to subject it to the same load. But if so my guess is that it would be due to the tissue becoming more sclerotic / less flexible. So I'd probably want to stick with small and fast if I had the choice..

neeb

Craigus89 wrote:

I think you're also working on the big assumption that because your max heart rate doesn't decrease over time that that is an indication that your CV system is healthy. I'm not sure that is the case.

Yes, it's an assumption that may be wrong, and of course you wouldn't assume your CV system was healthy if you were living a really unhealthy lifestyle, had a high RHR etc, but also happened to have a MHR that didn't decrease over time..

But as far as I know the trend for MHR to decrease with age is more marked in unfit people than in fit people. Also, as rather few things that are associated with aging are good for you, I think it's not unreasonable to assume that if your MHR decreases less over the years that's considerably more likely to be good than bad.

Although it's possible I suppose that the reason MHR decreases with age is to protect the heart from damage as it gets more sclerotic, and that it could be dangerous to override that (assuming it was possible to do so).

imposter2.0

You really need to let go of this 'MHR/age' thing...

neeb

Imposter wrote:

You really need to let go of this 'MHR/age' thing...

Why? It's a proven phenomenon that's clearly more and more limiting the older you get, yet it's poorly understood.

Alex_Simmons/RST

neeb wrote:

I'm also just interested in what is happening in the cardiovascular system to explain the inconsistent relationship between power and HR.

There are a multitude of factors that will influence HR response on any given day. isolating the specific impact of one factor is all but impossible. HR response to exercise is naturally variable and while correlated with power output, the correlation breaks down somewhat depending on the circumstances. It's probably better to think in terms of cardiac output (HR x stroke volume) rather than HR. like HR, SV is also variable during exercise and it also changes in response to training and de-training.

neeb wrote:

For me at least, this inconsistency seems to relate to training load, in fact it's the most obvious thing I notice that varies with the amount of training I'm doing on a day to day or week to week timescale.

Training level and fatigue are but two of dozens of factors that will influence HR response. Somewhat confusingly, fatigue can result in both an elevated and a suppressed HR response. And of course stroke volume and blood plasma volume are also affected by training (and de-training).

neeb wrote:

HRmax is just one aspect of that, but as it does represent the maximum rate at which the heart can work, it's quite an interesting figure.

Not quite, it represents the maximal rate the heart might beat but that does not imply it is performing work at a maximal rate, and by that I mean cardiac output (amount of blood being moved per unit time).

CO is a function of various things and not all of them relate to the heart alone, there are extra-cardiac factors as well. While an increase in HR generally means an increase in CO, too high a HR can also impair CO.

neeb

Thanks.

Alex_Simmons/RST wrote:

There are a multitude of factors that will influence HR response on any given day. isolating the specific impact of one factor is all but impossible. HR response to exercise is naturally variable and while correlated with power output, the correlation breaks down somewhat depending on the circumstances. It's probably better to think in terms of cardiac output (HR x stroke volume) rather than HR. like HR, SV is also variable during exercise and it also changes in response to training and de-training.

I'm fairly convinced that for me at least, when I take a few days off the bike my stroke volume decreases and my HR increases - my power output remains much the same, so I assume that my cardiac output can't be radically different.

I think I've noticed a similar thing on a much shorter timescale when I do something like run up four flights of stairs from a relaxed, un-warmed-up standing start. When I get to the top my HR will be really rapid, but if I keep monitoring it for a minute or so it usually gradually transitions to a really quite slow rate, actually slower than it was before I ran up the stairs. I think what's happening is that the sudden burst of activity takes the heart by surprise (hence the initially rapid rate), but that there is a more delayed response in the form of an increase in stroke volume. It's as if the heart is "ticking over" at a low stroke volume until exercise stretches it a bit and allows it to pump at a greater volume. But the initial sudden response is a an increase in HR, because that seems to be able to happen more quickly.

Hope that makes sense - a large element of subjectivity involved obviously..

fenix

Easy enough to do - measure HR before you run up the stairs.

Measure after your activity.

Is there a difference ?

neeb

Fenix wrote:

Easy enough to do - measure HR before you run up the stairs.

Measure after your activity.

Is there a difference ?

Yes, I've taken my pulse manually a few times - I guess if you graphed the response it would be a steep spike, followed by a slightly slower decline down to a level that is slightly lower than the starting rate.

imposter2.0

Sounds like you've just discovered 'cardiac lag'...

Alex_Simmons/RST

HR, like many physiological responses to changes in intensity of effort, has a half life response time with an order magnitude of about a minute. Which is why HR is not such great real time indicator of actual effort level. It's like driving a car while only looking in the rear view mirror.