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Replying to Using Heart Rate Variability as a measure of "biological age" (and the Palo Alto Longevity Prize)

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Posted 10 January 2017 - 04:10 PM

Yes, I have noticed, cold dramatically boosts HRV.  It would be interesting to learn more about why and what the mechanism is and if higher HRV induced this way actually has any health benefit in-and-of itself or not...

Todd Allen

Posted 09 January 2017 - 09:22 AM

Temperature seems to have a big impact on HRV.  As I posted before, a very hot bath readily drops my HRV to 1.  Previously I speculated a connection between pushing heart rate to max and an HRV of 1, but since have achieved an hrv of 1 at heart rates well below max and have managed a little hrv, as high as 10, when hitting max heart rate.


On the other end, cold dramatically escalates hrv.  Here is this morning's reading taken at 62F.  And this is after a brutally intense workout the day before yesterday that I'm not fully recovered from.


hrv 89, hr 61.96, min hr 28.00 max hr 127.66
rmssd 322.65, lnrmssd 5.78, sdnn 299.20, nn50 83, pnn50 60.145
Anyone else noticing a dramatic rise in hrv with this chilly winter?


Posted 20 October 2016 - 11:32 AM

I posted about cold exposure's impact on HRV over on the CE thread.


Posted 10 October 2016 - 10:26 PM

Leo- I am also really appreciating the value of daily HRV tracking.  Today is a perfect example, I woke up feeling "normal" but my HRV score showed a substantial drop.  This is a signal for me to be careful, and to recover, which is what I tried to do today, though as the day went on, I could tell my immune system was fighting something (which happens a lot when you have 2 young school age kids and a school teacher wife).  This is even more valuable to someone living an obsessively healthy lifestyle, because we don't get the typical symptoms when our immune systems are fighting something, the only symptom I seem to ever get is feeling tired or "off kilter" (I haven't had a fever, sore throat, cough, headache, or runny nose in years).


At any rate, I can't remember now where I saw the following link, but I searched the forum and couldn't find it.  This is an interesting TEDx talk someone recommended, and deserves to be in this thread.  

TEDxPortsmouth - Dr. Alan Watkins - Being Brilliant Every Single Day (Part 1)

He starts talking specifically about HRV around minute 13 after quite a long build up for the TED format :).  He says something to the effect of: HRV can tell you when you will die, it can tell you how much energy you have, but the real reason his clients are interested is because HRV can alter brain function. Then he actually hooks a volunteer up to a heart monitor and does a live demonstration of this.


"Your biology is controlling your brain function" In part 2 he does a live demonstration of how controlled breathing can boost HRV and "switch your brain on" making you more perceptive, insightful, etc.  "Rhythm and smoothness gives you the most powerful effect." Put your attention while you are breathing on the center of your chest and focus on the energy of your heart, this causes you to drift into a more positive state:






Through the


Every day


However this only gets you to the midpoint of where you want to be.  To take things beyond that you must learn to regulate what emotional state you are in.

Posted 05 October 2016 - 03:09 PM

Hi Karl,
I judge my hrv by a monthly rolling average and its a great aid in determining whether you're stressed or not and changing the things you can change which hopefully counteracts the stresses you cant change.
I take mine every morning standing up as ive experimented with supine readings which for me unfortunately my parasympathetic systems floods the reading.There are lots of variables that can affect readings which for me makes it more relevant and interesting.Its not as simple as watching what you eat,which is the easy part.Its all about balance.You dont see many stressed centenarians


Posted 05 October 2016 - 01:04 PM

It should also be noted that Polar Heart Rate monitors have for years had a function that uses HRV to give a resting-only test estimate of VO2max. HRV obviously correlates with cardiovascular health, which in turn also correlates with biological age, but I think most of us would agree that VO2max while generally declining with age is not by itself the best biomarker of biological age.


So I'm skeptical that HRV by itself is that useful of a bio-age marker. Though it does seem likely to be useful for dealing with the transient things mentioned above (picking up illness faster and more precisely than fever or resting HR for example, or for helping to figure out what stresses you in life or as a biofeedback marker to get better at meditation for example).


There is a lot of work exploding right now in the aging biology world on coming up with better bio-markers of biological age (or mortality prediction). DNA methylation (aka epigenetics) is a hot area for this right now (see for example the publications of Horvath and those of Hannum), though the issue is that the tests are expensive currently (and not easily available direct-to-consumer). Lots of people are trying to use machine learning ie statistics (in many recent cases the latest buzz-fad subtype of model called "deep learning" neural nets) to predict biological age. Examples include how-old.net (age from a face photo) and aging.ai (age from simple blood test values). Also notable is the recent publication of the different rate of underlying biological aging of a cohort of (at the time of publication) 38-year-olds, which I'm pretty sure was discussed on these forums somewhere, which was based on many different measurements though IIRC they didn't release a model that other people could plug their own numbers into.


I'm confident these kinds of efforts are fairly quickly going to come up with things that are better predictors of overall health/mortality than actual chronological age or just-HRV.




Posted 05 October 2016 - 12:50 PM

Sorry I'm late to this thread. A link to an episode of the podcast The Quantified Body (episode #35) was made earlier. It should be noted that this podcast has several episodes on the subject of HRV. See the list of episodes on Damien's website. Episodes specifically devoted to HRV are (so far): #1, #6, #8, #11, #20, and the previously linked #35. #20 is an interview with the longevity prize funder himself and specifically talks about the use of HRV as a biomarker of health/longevity (and is a short episode) and why it was chosen as criterion for the prize.


I'm a bit disappointed Damien didn't press Joon Yun in that episode on what seems like the obvious most important question about using HRV as a long-term general health biomarker: How is doing so appropriate when the HRV values jump around so much in response to other transient things, as aptly demonstrated by all these other episodes that are using it for other things. Eg, athletes find that drops in HRV are good signals of overtraining or temporary illness that might make them want to back off training for a bit (episode #1 of podcast). Others use HRV as a stress-level indicator and can see immediate drops just by thinking about stressful things in their lives (episode #6). There are variations depending on lying vs. sitting vs. standing, etc. These temporary confounders make it seem trickier to use HRV as a marker of long-term health / longevity / mortality predictor (whether in lab animals, as for the prize, or in us for our own health optimization).


At the very least, one wants to measure consistently (same position, time of day, etc.) and other practical tips are to try not to think too much about life or the upcoming day when doing a measurement in the morning. But even with those consistencies, to use it as a long-term health measure one has to do some kind of aggregation over many readings to get rid of transient effects. I didn't see any discussion of the right aggregating math function. Is it better to take average, or to use the highest (best) reading over a given timeframe (a month say)? That depends on which causes more fluxuation: transient drops from things like overtraining, stress, or temporary illness (colds/flu), which would argue for max, or random inconsistencies of the readings that might cause spikes that aren't real, which would argue for some type of averaging. I don't know.


More in a minutes. I'll put in a 2nd post.




Posted 25 September 2016 - 05:30 PM

Welcome Larry, sounds great.  I think our whole group is just one big collection of "outliers" haha!  My thinking is that perhaps with enough data we can sleuth out some factors that may improve HRV (and longevity) based on the practices that we follow.  I'm not sure we'll have enough data points to do that but I think it's worth a try.  In the very least, it seems to me that tracking your own HRV daily has value for general health monitoring and even early diagnosis of disease (more on that later).


Early in this thread I linked to part 1 of "hrvcourse", the other 2 parts are just as important and informative.  Here is part 2:

HRV Demographics, Part 2 – Fitness Level

One of the friendly debates I've had with Dean and others is the anaerobic vs. aerobic approach to fitness.


"Generally, a higher Heart Rate Variability is correlated with increased aerobic fitness, and vice versa. This makes perfect sense since it is well established that regular aerobic physical activity can improve cardiovascular function and health which is measured indirectly through HRV. Many studies have shown that the intensity, duration and frequency of aerobic training are directly related to HRV changes. This is why HRV analysis with respect to physical training, especially aerobic physical training, is an increasingly popular technology used by elite and recreational athletes to achieve an edge... an active life pattern can be effective in diminishing the decline of HRV associated with aging"




"The good news is that in many of these studies, the activity level required to gain the significant health benefits as measured by Heart Rate Variability is only light to moderate. In the menopausal women study, the significant HRV improvement for the active women was seen at just light to moderate activity like walking three times per week for hour long sessions.

Both of these studies suggest that regular physical activity in the older subjects tended to reverse, to a degree, the aging effects on cardiovascular health such as vagal tone decline."


What about athletes?


No surprises that "significantly greater Heart Rate Variability was seen in trained men and women at rest, likely due increased vagal tone and parasympathetic activity and reduced sympathetic activity".

But what about 

Endurance-Trained vs. Power-Trained Fitness?

"Although less studied, the available research shows HRV effects on anaerobically trained individuals in power sports to be similar to those of aerobically trained athletes (Berkoff D J et al., 2007)."


In a study comparing 145 elite track and field athletes at the 2004 Olympic Trials, Berkoff et al. found that there was no significant difference in Time Domain and Frequency Domain HRV values between the endurance athletes and power athletes for both genders. The aerobic athlete group consisted of runners training and competing in 800m or longer while the power group included sprinters and athletes competing in field events that require more anaerobic training such as weight training and sprinting. From the results, they concluded that aerobic and anaerobic training leads to similar responses in Heart Rate Variability.




"The study hypothesized that the lack of differences in HRV may be based on “autonomic benefits of anaerobic training.” It is possible that the autonomic cardiac changes that result from anaerobic training are similar to those seen with aerobic training."


I thought this warning was interesting:  

"Be Careful: It is important to point out that elevated aerobic fitness can also have a downside. Since it has such a potent effect on Heart Rate Variability, it can actually mask underlying health issues"




In general, increased aerobic and anaerobic fitness significantly increases Heart Rate Variability. This is because increasing activity level and fitness increases autonomic activity correlating with increased ability for the body to regenerate energy, repair tissue, and more capably respond to both physical and mental stress.

Fitness levels that are required for health improvements do not require high volume, repetitive endurance sport training. An active lifestyle consisting of light to moderate activity (either aerobic or anaerobic or both) has shown to be sufficient for health benefits to reverse age-related HRV decline. Improved fitness beyond an active lifestyle increases Heart Rate Variability indices but it is not clear if those increases correspond to improved health past fitness.


I would add that both CR and CE apparently boost HRV, perhaps even more so than exercise.  I'm still gathering data and watching trends, but many of my readings seem to exceed that of even elite olympians despite the fact that I work out for only minutes per day and do no endurance training at all.  This is of keen interest to me, but who knows if it's meaningful or not...



Larry Johnson

Posted 23 September 2016 - 03:47 PM

This thread looked interesting enough that I ordered a TICKR too.  I'm probably a bit of an outlier, since I'm a 65-year-old who picks through CR practices and discussions like it's a buffet, adopting things that look interesting without having ever followed a strict CR routine (too nervous about BMI dropping too low at my age).


I do cold exposure and TRF, though, exercise for a minimum of 4 hours per day (just over half of it walking, the rest a mix of resistance, flexibility, and balance exercises).  My TICKR should arrive in about a week.  If I'm not entering too late, and y'all think the data from someone of my hybrid regimen would be useful, I'm in.


Posted 22 September 2016 - 05:53 PM

Hey Thomas, yes, I think its best to gather lots of data first before trying to come to any conclusions.  And Leo, thanks for that study, it is very useful to see some normal circadian fluctuation data as it relates to HRV (and melatonin).  I am definitely a "weird" case, as I do mild cold exposure pretty much all day every day, EXCEPT when I sleep.  This is just an odd ball long term personal experiment I have chosen to do.  That said, so far my lowest readings seem to come when I first wake up, which probably corresponds best to what my HRV would be without CE.  Clearly there is pretty wide fluctuation of values throughout the day as documented in the study Leo posted.  I think the only way to do meaningful analysis might be to do 24 hour readings (like Fontana did with the CR group).  I'm not sure how practical that is with our devices, but I'll play around with it...  (I guess taking a reading every hour while awake might be a decent approximation as well).  Also not sure that an elevated HRV caused by CE implies any particular health advantage, it could be meaningless, it is interesting to me though that the link exists and reminds me of "Dean's Law" which states that everything associated with good health and longevity is in some way connected to BAT activation.


I took a whole lot of readings today while doing different paced breathing exercises (you can actually do this all within the Elite HRV app itself by the way, it just doesn't have as many options for customizing the paced breathing, basically it only lets you choose how may breaths per minute you want to do, at 0.5 breath intervals.  I feel like I need to do this a few more times before gathering "actionable" insight.

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