41 replies to this topic

[Gordo]

Leo also provided this GEM which I am sure will be of great interest and usefulness to all of us once we have those HRV monitors!  He explains all of the different flavors of measuring HRV and describes how to use HRV biofeedback to optimize your health.

 

 

“It turns out that everybody has their own unique pace, where breathing in and breathing out at that pace produces the biggest peaks and valleys, the exact right phase angle between respiration and heart rate, and when you go into that particular rhythm, it seems to have tremendously beneficial effects. Again, we often see this as a brand new idea that’s 2500 years old because this is exactly what these yogis were doing.“
– Richard Gevirtz

 

The Quantified Body

 

• Podcast

 

Episode 35 – Richard Gevirtz Heart Rate Variability Biofeedback as a Tool to Reduce Stress

 

 

What You’ll Learn

• The early days of biofeedback – key discoveries in conscious control over autonomic functions of the body (6:12).
• How the science on the benefits and mechanisms of various yogi techniques needs to improve – to produce more quality studies and reliable data (11:05).
• The degree of complexity in HRV biofeedback and the applicability of various beat-to-beat analysis in studying mechanisms of stress response (14:19).
• Optimizing breathing and heart rate rhythms has beneficial effects on the cardiovascular system (19:26).
• Why standard metrics do not apply for slow breathing, because this category is a low frequency range of approximately 4-7 breaths per minute (26:54).
• Overviewing the ups and downs of available beat-by-beat biofeedback devices (32:25).
• An average training session aimed at determining optimal breathing frequency during slow breathing. How to optimize measuring equipment and make people feel comfortable during the HRV tracking exercise (42:31).
• Performance benefits of practicing breathing exercises, with examples in sports and music (46:33).
• For optimal results, during practicing slow breathing you should be non-judgmental and self-observant at the same time (50:09).
• How the brain and heart integrate physiological feedback in the body and how this system is negatively affected by anxiety and stress (52:35).
• Positive effects on gastrointestinal health in kids with inflammatory bowel disorders, who practice slow breathing techniques (57:55).
• In most studies on depression, improvements in HRV biofeedback are accompanied with beneficial effects (1:00:01).
• Slow breathing training helps for anxiety and urge – control, by inhibiting stress response centers in the brain (1:03:52).
• Data on cortisol (the stress hormone) indicates beneficial effects of slow breathing practice in fighting stress (1:04:30).
• When practicing meditative slow breathing, it is important to measure EEG waves in low frequency ranges – in order to clearly demonstrate beneficial effects on heart performance (1:05:16).
• Gratitude and compassion mindfulness exercises are broadly related to HRV performance, but optimizing slow breathing is a practicable and improvable skill to be learned and trained (1:08:47).
• In the future, the team and Prof. Richard will continue to research outcomes of HRV studies, physiological mechanisms of slow breathing, and standardizing yoga breathing practices by beneficial effects (1:10:48).
• How to best obtain information of Prof. Richard’s research and career (1:14:27).
• People and lines of research related to Prof. Richard’s interests. Additional practical advice on integrating HRV biofeedback with your performance goals (1:14:27).

[Dean Pomerleau]

Gordo,

 

I agree 100% that that curve in no way implies a U-shaped HRV curve over one's lifetime. As you point out, those centenarians are a rare bunch, and have probably had higher than average HRV their entire lives. They should test the offspring of the centenarians to see how their HRV compares with age-matched controls.

 

--Dean

[AlPater]

Thanks Dean,

 

Or they could prospectively study centenarians directly.  The effect was not as great as dementia and age at baseline, and the sympathetic nervous system seems to be involved.  27 was a low number of subjects, unfortunately.

 

Prognostic significance of heart rate variability in centenarians.
Shimizu K, Arai Y, Hirose N, Yonemoto T, Wakida Y.
Clin Exp Hypertens. 2002 Jan-Feb;24(1-2):91-7.
PMID: 11848173
http://sci-hub.cc/10...1/ceh-100108719

Abstract

We studied the significance for further survival of heart rate variability and other variables in the very elderly. In 1992, we assessed activities of daily living, cognitive function, and nutritional status in 27 centenarians with no disease, in addition to the power of the heart rate variability in the ultralow, very low, low (LF), and high frequency (HF) bands. In 1996, we assessed survival in these centenarians; 17 had died and 10 were still living. Logistic regression analysis using backward elimination detected three factors, dementia, LF/HF, and age, that independently influenced mortality. Mortality risk increased with greater age in 1992, more severe dementia, or lower LF/HF. Sympathetic nerve activity, represented as LF/HF, may be associated with prognosis for survival in centenarians.

[Dean Pomerleau]

Al,

 

 

PMID: 11848173

 

Thanks! Great stuff. Looks like increased HRV among the oldest of the old may indeed by an indication of even more extra years ahead.

 

Sure you don't want to join us in our citizen science? As I said, the more the merrier. Your data (like Todd's) would obviously need an asterisk due to your heart abnormalities. Do you think those were congenital, or perhaps (partially) CR-induced? Remember this (anonymous) person from long back who had trouble drifting between CR and anorexia? He attributes his heart valve issues to poorly-practiced CR = eating disorder.

 

--Dean

[Gordo]

The good folks at elite HRV just posted some extremely useful and timely information on their website that should be of interest to anyone reading this thread.  In the first post of this thread I referred to HRV values by age from published research using SDNN, rMSSD, ln(rMSSD) and PNN50, but now we have values by age AND gender with additional HRV scoring methods as well as a translation of scores between the most popular apps out there! This is most likely the largest data set of its kind ever published anywhere.  Unfortunately the cohort for this large sample is most certainly not representative of the general population, but in some ways that also has value for us, as we want to see how we compare to very healthy people (who most likely aren't doing CR or CE by the way).  See:

 

Normative Elite HRV Scores by Age and Gender

 

"...Keep in mind, the Elite HRV user base may not directly represent the general population. We have a higher representation of elite and recreational athletes that typically have higher HRV scores. This may slightly skew the sample stats when compared to some medical research studies. That said, we do have a very large population sample (over a million readings) that helps increase the confidence of the data analysis. There is also a significant number of “average” health seekers and a number of people rehabilitating from serious injuries, illnesses, or diseases."

 

The average HRV score for Elite HRV users is 59.3 (on a 1-100 scale) with 75% of users’ HRV scores falling between 46.3 and 72.0.

Histogram data of HRV scores for 24,764 Elite HRV users.

Whose data are we looking at? Starting with over 72,000 users and over a million readings in our database, we first narrowed the readings down to only short-term time-domain “morning readiness” readings. Then we removed the obviously inaccurate readings (usually generated from incompatible measurement devices). We then further reduced the population sample to Elite HRV users that have taken more than one “morning readiness” reading resulting in a conservative sample population of 24,764 people. An average HRV score was generated for each person that fulfilled this criteria and those average scores were used to develop statistical HRV results.

 

Age and Gender Breakdown

The Elite HRV population sample was further broken down into age and gender groups based on user input data to allow users to compare themselves to others within their same demographic group. The Elite HRV users (based on the 35% of users that optionally input their age and gender details) are 13.9% females and 86.1% males.

As can be seen from the charts and tables below, HRV decreases with increasing age for both genders. To learn more about how gender influences HRV and why HRV decreases with age, see this post.

Chart 2 – This chart shows Elite HRV scores statistics for 8,873 males over different age ranges. The data is presented as box plots that represent the medians, 1st and 3rd quartiles, and extreme values (minimums and maximums). There are also markers for means at each age range.

 

Chart 3 – This chart shows HRV Score vs. Age for 8,873 Elite HRV male users.

 

Chart 4 – This chart shows Elite HRV scores statistics for 1,435 females over different age ranges. The data is presented as box plots that represent the medians, 1st and 3rd quartiles, and extreme values (minimums and maximums). There are also markers for means at each age range.

 

Chart 5 – This chart shows HRV Score vs. Age for 1,435 Elite HRV female users.

 

Table 1 – Data from 10,308 Elite HRV users showing ln(rMSSD) and Elite HRV Score presented by age range and gender.

 

Elite HRV Scores Compared To Other Platforms

Keep in mind, the data used to calculate these scores was gathered on Elite HRV’s platform, so it does not necessarily represent the user populations of those other platforms and does not take into account different artifact cleaning algorithms and other potential differences. There are other HRV software applications that are not listed in the below table because they either do not publish their scoring system or do not have a large user base.

Table 2 – Data gathered on Elite HRV platform shows rMSSD, ln(rMSSD), and “HRV Scores” for Elite HRV and is calculated for other HRV software applications based on published calculations. The data does not necessarily represent the user populations for the other HRV platforms.

[Gordo]

Hey Leo, good to see you here, I was hoping you'd join in!  Unfortunately I don't think there are any HRV experts in our group, and you probably have more experience with HRV tracking than anyone here...  That said, I've been doing a lot of reading lately, in part thanks to info that you provided on the CR Society Facebook group.  

 

I've been thinking a lot about cardiac coherence, and I will be posting a lot more about it after I receive my device and do some work with it as well as additional review of the scientific literature.  The basic plan will be to use one of the many paced breathing apps in conjunction with HRV measurement (or if possible, both with a single app).  Richard Gevirtz described (in the quantified body interview 'Heart Rate Variability Biofeedback as a Tool to Reduce Stress') how he finds a person's ideal breathing cadence in his practice (the ideal pace varies from person to person). I found an android app called "Paced Breathing Pro" that does everything I want for paced breathing including vibration notification and ability to vary inhale/exhale times as well as hold times at top and bottom.  I will go through a wide range of breathing styles and paces while simultaneously measuring HRV, with variations on breathing cycle duration, percentage of time inhaling vs. exhaling, and time holding at top and bottom of cycle, sitting vs. standing vs. laying down, etc. It will require a lot of careful data collection and time, but should ultimately allow me to optimize my HRV through meditation/breathing which supposedly can result in health benefits such as improved immune function and mental states although I still need to read up more on all of that and separate science from fiction.  Also note that Leo found Heart Rate Coherence Pro which may do both the breathing guide and HRV measurements in a single app, I'll have to explore that.

 

The Elite HRV FAQ has some relevant Q&A.  First, about how to do our "standard measure" - the giant data review that Elite HRV just posted about was based on what they call "Morning Rediness Readings" so I think our group should use the same standard for comparison purposes. This means taking readings first thing when you wake up, before getting out of bed, while just breathing naturally.  Of course all sorts of other readings will also be very much of interest within the group as well, I just think it will be good to have some baseline apples to apples comparisons particularly if we are trying to figure out how lifestyle factors and interventions influence HRV (and aging by extension). 

 

Q: Why is it important to measure HRV (Morning Readiness) in the morning instead of other times throughout the day?

The best way to determine your individual heart rate variability and thus nervous system activity is to take a short (1-5 min.) reading each day. Ideally you want the reading to happen at the same time, in the same way, so as to eliminate as many affecting variables as possible.

Throughout the day many factors can affect HRV. Internal processes like circadian rhythm and hormonal fluctuations cause it to slowly rise and fall over 24 hours. Also whatever you were doing before taking a reading has a very strong impact on the reading. Mental, physical and emotional experiences all affect HRV.

This is why we recommend taking the reading each morning. When you have just awoken you haven’t had the chance to experience the stresses of work, school, or the day. Your circadian rhythm and hormonal patterns should be consistent at that time as they were the previous day. We also recommend that you breath naturally for the Morning Readiness and take the reading in the same body position each time.

By calculating your baseline first thing each morning, you can eliminate a lot of variables and highlight the patterns that matter most. This allows you to cut through the “noise” and get insights about how recovered you are and how ready you are to tackle the day’s challenges.

 

Q: How do you calculate the HRV score?

Our HRV score process is broken down as follows:

• We capture the R-R intervals via the chest strap heart rate monitor.

• We apply the RMSSD calculation. Root Mean Square of Successive Differences (RMSSD) is the industry standard, time domain measurement for detecting Autonomic Nervous System activity in short-term durations (5 minutes or less).

• A natural log (ln) is applied to RMSSD. Since RMSSD behaves logarithmically, it is difficult to conceptualize the magnitude of changes as it rises and falls. Therefore, it is common practice in the application of RMSSD to apply a natural log to produce a number that behaves in a more linearly distributed fashion.

• The ln(RMSSD) is expanded to generate a useful 0 to 100 score. The ln(RMSSD) value typically ranges from 0 to 6.5. Using over 1,000,000 readings from our database, we have been able to sift out anomalous readings and create a much more accurate scale where everyone fits in a 0 to 100 range.

In regard to converting ithlete to Elite HRV scores, it looks like all you'd have to do is divide by 1.298398835516739.  Both apps apparently just multiply ln(rMSSD) by a fixed constant, but Elite made an attempt to fit everyone into a 0 to 100 scale based on their database of actual readings.

 

[Gordo]

Quick update -- I was very excited to find my new wahoo tickr waiting for me when I got home from work tonight! I could not wait to try it, I took it out, adjusted the strap, lightly moistened the electrodes, and took a sitting reading while breathing normally. First - the led indicator lights on the unit work great, that was mentioned in the reviews -- a very nice feature. Second, it quickly and easily paired with my Android phone via the Elite HRV app. The result of my first readiness reading? I have off the charts good HRV, with scores exceeding the mean from the best group (18-25 year olds) in the Elite HRV data, and exceeding the best group (10-19 year olds) in the Umetani et al., 1998 data.  My ln(rMSSD) was 4.67 corresponding to a 72 score in the Elite HRV app (4.87 or 75 score laying down later after eating).  Note: the very BEST ln(rMSSD) from the Fontana CR group (including Dean) was 3.87, with a mean for that group of 3.58 - so if my number is accurate (which remains to be seen) and comprable (to their 24 hour measurement) then I have blown them out of the water (another benchmark that can't be used in favor of severe CR).

 

My readings may come as a surprise to some (it was a surprise to me) considering I do zero endurance training and only brief HIIT workouts.  It's looking good for cold exposure especially since I had been wearing a cold vest for an hour before doing the reading... I look forward to gathering more data and doing lots of experimentation. Can't wait to find out how others from our group stack up. Hopefully my initial readings were not flukes.

 

EDIT to Add: Did a sitting reading after cold shower + ice drink + cold vest and got my highest number so far, Elite HRV score = 81, ln(rMSSD)=5.27

Definitely looking promising for cold exposure.

Edited by Gordo, 20 September 2016 - 07:56 AM.

[Thomas G]

Mine arrived today as well which is nice. It can sometimes take a long time to get things here in Alaska, so I'm glad I can join right in from the beginning.

 

I normally like to read things systematically so that I understand them as well as I possibly can, but I haven't had a chance to read up on HRV very much yet, so I only have a foggy idea of what we are doing and why it is important and how to make sense of it all.

 

I downloaded the Elite HRV app and the Wahoo TICKR synched easily. To test it out I took a "morning readiness" reading, even though it is about 8:45 p.m. here. I was sitting up and trying to breath normally but I notice that because I was being tested on something I don't think I was breathing normally. It felt a little like I was holding my breath or that my lungs were always a bit too full to be natural. I'm going to need to work on tricking myself into breathing normally.

 

If I understand the results correctly, it looks like my first initial test reading got an HRV of 59. Based on the charts above that looks about typical for someone my age (37). Nothing to get too excited about, but perhaps my HRV will gradually improve as I continue CR.

 

I haven't gone out and bought a CE vest yet, but I have been taking ice cold showers (no heat at all from start to finish) and finding I rather enjoy them, even though they are also a bit unenjoyable at first. I've also been walking my dog in lighter clothing than I otherwise would be, and riding my bike to work in the cold without heavy layers. So you could say I am dipping my toe into CE but not in a really deliberate or focused way yet. For the time being my focus is still on figuring out CR and how I want to practice it.

 

Okay, some quick dumb questions:

 

Higher HRV is better right?

For our little study we don't need to wear the monitor all the time right? Just a quick reading in the morning? Anything else particularly useful like wearing it while going for a run?

 

I will eventually do my homework on HRV, but for the time being I might need to lean on some of you who are doing a lot of research to digest it and share the main takeways. I hate mooching like that, but I'm excited to learn more and see what we discover.

[Todd Allen]

I got mine yesterday too.  I also used the EliteHRV android app, my initial sitting value was 35, but increased to 50 while doing paced breathing.  It was low 20s for most of my 20 minute hot bath at 116F, but at the end when I submerge my head twice for 20 seconds each time while holding my breath it fell to 1 and my pulse hit a peak of 170 - roughly max heart rate for my age.   I wonder if that is typical for HRV to fall to 1 at max heart rate?  While sleeping my pulse averaged 58 and I awoke in the middle of the night with an HRV of 60 but it fell back to low 30s as soon as I got up.

 

Due to the intensity of yesterday's work out I skipped this morning's workout and my cold bath, but I will use it for my next workout and cold bath.  I've also just begun practicing relaxation/meditation and I think this might provide useful feedback if a deeper state of relaxation results in higher HRV.

[Thomas G]

@Gordo, I'm curious if your initial reading was a fluke or if you've been consistently in that same range so far.

 

I've only taken four morning readiness readings so far, so it's not enough to really tell what my baseline is, but I was pleasantly surprised that this morning's Elite HRV rating was an 81. I had gotten by far the best sleep I've had this week last night, so maybe that had something to do with it. Otherwise I have two readings at 59 and one at 66.

 

I'm also having fun learning about the sympathetic and parasympathetic measurements. The first morning I was mildly sympathetic. Later that day while I was biking to work I took a corner too fast and ended up crashing. Not seriously hurt, but with some nice road rash. Since then all my readings have been parasympathetic. I might be trying to over-interpret this given that there are so many factors at play, but it would make sense if I'm doing a little bit of healing right now.

[Gordo]

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.

[Larry Johnson]

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.

[Gordo]

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"

 

 

Takeaways

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...

 

-Gordo

Edited by Gordo, 25 September 2016 - 05:35 PM.

[kpfleger]

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.

 

-Karl

[kpfleger]

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.

 

-Karl

[Gordo]

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:

 

Breathe

Rhythmically

Evenly

And

Through the

Heart

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.

Edited by Gordo, 10 October 2016 - 11:28 PM.

[Gordo]

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

Edited by Gordo, 20 October 2016 - 11:33 AM.