Track your HRV to boost adaptive reserves

Frustrated_man_at_a_desk_(cropped)Stressed out?

There’s a surprisingly simple but little-known technique for measuring your in-the-moment ability to handle physical, mental and emotional stress.  Some of us have a higher level of “adaptive reserves” than others.  And for all of us, these adaptive reserves increase or decrease throughout the day and over days or weeks.   You might have a rough, intuitive sense of when you are more resilient to stress, and when you are weak or more vulnerable. There is no shortage of advice on the Internet about “stress management”, fitness and diet.  In general, sleep, physical activity and a nutritious diet build adaptive reserves, while these reserves are easily depleted by chronic stressors like worry or overwork.

But how do you know what really works to improve your resilience and resistance to physical and psychic stressors?  How can you learn what diet, exercise, and activities actually work for YOU — not just what researchers, health professionals, bloggers or your friends claim should work?

What if I told you that there is a reasonably objective metric for your overall adaptive reserves and a simple, inexpensive, and noninvasive way to measure your adaptive reserves throughout the day.

The metric is called heart rate variability, or HRV. It can be measured in less than a minute, using an inexpensive chest strap or finger sensor, and any of several smart phone apps that can be downloaded for a few dollars. Based on a review of numerous studies and extensive personal experimentation, I’ve learned some surprising things about what tends to raise or lower HRV.  And I’ve found one few amazingly quick, effective, and to boost a low HRV and keep it up, with real impact on adaptive reserves.  (For the impatient, scroll to bottom of this post and read Recommendation #1).

Athletes and the rest of us. Endurance athletes and weightlifters have been using HRV measurements for years to improve performance, while avoiding overtraining and injury.  The technique was first piloted using sophisticated electrocardiogram equipment in exercise physiology labs.  With the advent of inexpensive heart rate monitors and smart phone software, the HRV technique is available to amateur athletes.

But the exciting thing is that heart rate variability has recently found applications well beyond optimizing athletic performance.  Low or altered HRV has been found to predict progression of diseases as diverse as cardiovascular disease, cancer, autoimmune disordersinfections, trauma, post-traumatic stress disorder, and depression.

Heart rate variability turns out to be a generalized, deep measure of health. That’s because higher HRV is a strong indicator of resilience to stress, while low HRV is a sign of reduced capacity to tolerate stress.  And at the deepest level, health is resilience, and diseases in various ways compromise resilience.

Unknown-1What is HRV anyway?  It is well known that a lower heart rate or pulse is associated with fitness.  At rest, an average adult’s heart beats between about 60 and 90 beats per minute, whereas fit athletes can have resting heart rates as low as 45 bpm.  As a general rule, a lower heart rate is a good thing, because it indicates a more powerful, efficient heart.  However, a low heart rate can also reflect genetic differences, or medicals conditions like brachyardia.

But heart rate is not the full story.  Healthy hearts don’t beat like a metronome.  The intervals between each beat vary.  If you have a resting heart rate of 60 bpm, your heart beats on average once per second. Yet if you precisely measure your heart beat, the actual beat-to-beat intervals (often called NN intervals) may be something like:

1.05 sec….0.91 sec….1.01 sec….1.07 sec…..0.93 sec….1.02 sec…1.03 sec….0.98 sec….

 The average here is 1.00 seconds, but each interval varies somewhat from the average.  That’s heart rate variability.

UnknownHRV and the autonomic nervous system.  The primary source of variability in your heart rate is the autonomic nervous system (ANS).  The pacemaker in your heart, the sinoatrial (SA) node, receives input from the two halves of your ANS — the sympathetic nervous system (SNS) and the parasympathetic nervous system (PSNS).   You may recall from your biology class that the sympathetic system arouses us for vigilance and action — so called “fight or flight” activity, whereas the parasympathetic system puts the brakes on, calming us down after action and promoting relaxation, digestion, sex and other activities best saved for times we are not faced with immediate danger or urgent priorities. The parasympathetic system also supports the prefrontal cortex in rational activities like planning and decision-making.  It strengthens willpower!

Sympathetic and parasympathetic systems “compete” with each other for control of the heart.  The sympathetic system is activated by the accelerans nerve, which releases norephinephrine (“adrenaline”) into the to the heart’s SA node, stimulating it to beat faster and more steadily.  The parasympathetic system works via the the vagus nerve and the release of acetylcholine, slowing the heart rate and introducing more variability, especially in the higher frequency (HF) ranges.

In short, a dominant sympathetic system leads to reduced heart rate variability, while a strong parasympathetic system increases HRV.

A healthy person has strong sympathetic and parasympathetic systems and a good balance or ability to shift between the two.  A weak sympathetic system leaves you slow to arouse to action and lethargic, and weak parasympathetic system can leave you hyperactive, overly reactive, and slow to calm down.

Stress and the sympathetic nervous system.  While both of these are real problems, I think its fair to say that the more significant problem in our industrial society is an overactive sympathetic system and underactive parasympathetic system.  A weak parasympathetic system leaves you unable to dial down arousal and overly reactive to physical and emotional challenge.  If the sympathetic system is dominant and not adequately checked by the parasympathetic system, your physical and emotional batteries are never “recharged”, leaving them depleted.  An overactive sympathetic nervous system that never turns down can also lead to numerous physical and psychological health problems as mentioned above.

This balance or “dance” between the two halves of the ANS is reflected not just in heart rate variability, but also in hormonal balance.   Stress hormones — most prominently cortisol, but also norephinephrine and ephiephrine — rouse us to action.  Cortisol is associated with sympathetic activation — typically highest upon waking in the morning, tapering off as the day wanes.  That’s helpful for energizing us to action.  But chronic and unrelieved stress, either from physical fatigue or an overload of mental, emotional and social stressors, result chronically elevated cortisol levels.  This leaves us anxious and burnt out, and can lead to sleep problems and depression if not corrected.

While an imbalanced ANS can be detected by running hormone tests, that’s inconvenient and expensive and there is (at least so far) no instant cortisol test that provides real time feedback.

That’s where HRV measurement comes in.  It’s cheap, convenient and fast.  You can measure your HRV in less than a minute, any time of day, at no cost beyond the initial outlay of $40 – $100 for a chest strap heart monitor and a smart phone app.

Why is “variability” good?  Another name for heart rate variability is “arrhythmia”.  But isn’t it bad to have a heart arrhythmia?  It turns out that there is “normal” arrhythmia and pathological arrhythmia, and we usually hear only about the latter.  But in general, a variable heart rate is a sign of health.  High HRV is a sign of the flexibility of the heart and the capacity of the autonomic nervous system to adapt to changes in the demands we face every day.  It’s fundamental to the idea of homeostasis — the ability of an organism to remain dynamically centered in the face of an unpredictable environment. This is something that physiologists have come to realize over the past 30 years.  James Gleick eloquently explained why variability is good in his classic book “Chaos” :

Now some physiologists speak of dynamical diseases: disorders of systems, breakdowns in coordination or control.  “Systems that normally oscillate, stop oscillating, or begin to oscillate in a new and unexpected fashion, and systems that normally do nor oscillate, begin oscillating,” was one formulation. These syndromes include breathing disorders: panting, sighing, Cheyne-Stokes respiration, and infant apnea – linked to sudden infant death syndrome

….But physiologists have also begun to see chaos as health.  It has long been understood that nonlinearity in feedback processes serves to regulate and control.  Simply put, a linear process, given a slight nudge, tends to remain slightly off track. A nonlinear process, given the same nudge, tends to return to its starting point.  (Chaos, p. 292)

Healthy variability shows up not just in the heart rate, but in a wide range of physiological features — gait, speech, and even thinking.  You can see the loss of variability in the way that victims of strokes or Parkinson’s disease walk and talk with rigidity. By contrast,  children and healthy adults have variable physiologies that make them resilient when faced with the unexpected.

access_cheststrapHow is HRV measured? There are a number of different ways that physiologists use to characterize this variability. The simplest is the standard deviation. For the example above, the standard deviation of the NN beat-to-beat interval (SDNN) is 0.054 seconds, or 5.4% of the mean.   There are many other ways to characterize HRV.  Some, like SDNN are “time-domain” methods because they look at the variability in seconds.  Others, called “frequency-domain” methods look at the percentage of intervals that fall within certain frequency ranges.  The research on HRV gets very sophisticated, but it seems that one of the most consistent metrics for parasympathetic strength is RMSSD or “root mean squared difference” between adjacent N-N intervals. Many researchers and athletes mean RMSSD when they speak of HRV.

Heart rate can be measured using a heart rate monitor that straps around your chest, or with a finger sensor, or just by measuring your pulse with your fingers.  But heart rate variability requires precise measurement and software to capture the variations and reduce them to a number.  So you’ll need a chest strap heart monitor and an app for your iPhone or Android phone from a company like Bioforce, Sweetbeat, Elite, Inner Balance or Ithlete.  I chose Ithlete based upon reviews indicating it provides consistent, dependable results, and it was also compatible with my older iPhone 4 by using an insertable receiver. (Newer phones can receive signals directly via Bluetooth).  I’ve been happy with the Ithlete.

One funky thing about Ithlete and Bioforce is that they do not report HRV using the common RMSSD measurement, but instead use lnRMSSDx20.  That just means 20 times the natural logarithm of RMSSD.  They chose this alternative metric in order to spread out the values and represent HRV using a more “natural” scale with 100 being something like perfect fitness. (Highly fit individuals could actually reach higher than 100 on this scale, but rarely).

What is a “good” HRV?  There’s no universal answer to this, but we can take some clues from a 2010 American Journal Cardiology study by Zulfigar et al. at the U. Illinois Medical Center.  They measured the HRV of 344 healthy subjects ages 10-99. Keep in mind that these HRV values were calculated using data over a full 24-hours. As excerpted by Simon Wegerif on the Ithlete Blog, here is a plot from the Zulfigar study, showing the distribution of RMSSD values by age.  It shows a lot of variation by age, but a clear trend towards lower HRV as one gets older:


Screen Shot 2014-07-19 at 7.50.21 PM

Based upon this graphical plot, we can put together a table that gives some guidance as to what is a good HRV for people of different ages.  I’ve tabulated the data using both RMSSD and the lnRMSSDx20 measure used in the popular Ithlete and BioForce apps.


Screen Shot 2014-07-19 at 8.28.54 PM

Again, keep in mind that these HRV values represent 24-hour averages.  If you are measuring your own HRV, you’ll find that it tends to be a little lower in the morning than later in the day, and it will vary based upon physical activity, diet and other factors.  While I frequently get HRV readings above 80 (I’ll be henceforth using the lnRMSSDx20 scale) which is “superior”, I often get very low HRV readings, particularly right after a vigorous workout.

Overall, my personal average HRV taken multiple times each day over a month is 68 – a fair bit better than average (62), but not “athletic” (72-79) for someone close to 60 years old. A common practice for looking at long term trends is to measure your HRV first thing in the morning, before food or activity. If I do that, my average HRV is slightly lower — about 66.  But it changes a lot depending on my behavior. Some days, my waking HRV gets into the 70-80 range, and it has dropped below 50 on one occasion.

Heart rate as a proxy for HRV?  Heart rate variability tends to increase as heart rate decreases, and vice versa. So you might be thinking: Do I really need to buy a heart rate monitor to measure HRV?  Can’t I just take my pulse as an “inverse proxy” for HRV?  The chart below shows the data I collected on myself over a months. It taught me that a lower heart rate of around 60 or less was associated with very good HRVs in the range of 70-90. Unfortunately, the correlation is very approximate. Using my own data, it is clear that if I were to just use heart rate, my estimate of HRV could be off by 20 points!  If I measure a heart rate of 80, my HRV could be as low as 53 (poor) or as high as 78 (excellent). It’s also important to point out that this relationship between heart rate and HRV varies a lot between individuals.  Some athletes with very low heart rates can have poor HRVs if they are overtrained. So if you want to do this the right way, buy the chest strap and download the app!

Screen Shot 2014-07-22 at 6.58.53 PM


By tracking my HRV like a nerdy Quantified Self enthusiast, I’ve learned a lot about how to boost HRV. And I’m very excited to learn that there are really only a few things that make a big difference.

A Short Quiz: What affects HRV?  Take a few minutes to take this quiz before reading on.  I’ll provide the answers further down, but it’s good to test your intuition first.

What follows is a numbered list of activities.  Write down the numbers 1-10 on a piece of paper.  For each number write “increase” or “decrease” based on the effect you think the action will have on HRV.

  1. Running on the treadmill for 30 minutes
  2. Lifting heavy weights for 30 minutes
  3. Eating a high carb meal (pasta, bread, ice cream)
  4. Eating a high fat, low carb, moderate protein meal (avocado and shrimp salad)
  5. Fasting for 12-20 hours
  6. Fasting for 48 hours
  7. Drinking a beer or glass of wine
  8. Drinking 3 beers or 3 glasses of wine
  9. Taking a cold shower for 2 minutes
  10. Soaking in a hot tub for 15-30 minutes

Here come the answers:

I’ll emphasize that these answers are based on a combination of my personal experience and the research literatures.  Since we are all wired a little differently, there may be variation in how you would respond.  And my limited research in this emerging field should be taken as preliminary, and not the final word.  Nevertheless, here’s what I learned:

Exercise.  (Items 1 and 2).

Unknown-4Running and weight lifting, and virtually any exercise, raises heart rate and lowers HRV in the short term.  Sometimes quite significantly.  I found that both running and indoor rock climbing significantly reduced my HRV – by as much as 40-50 points initially!  My HRV values gradually climbed back up over several hours.  The more intense the exercise, the slower the recovery.  A short walk lowered HRV only briefly.

Essentially the same effect of intensity on slower HRV recovery has been documented in an Australian study reviewed by Simon Wegerif on the Ithlete blog.

So why exercise if it reduces your resilience?  The answer is that the effect is quite temporary.  Exercise boosts your HRV higher over time, as you become more fit. This is a classic example of hormesis:  initial deterioration leading to longer term super-compensation.  The trick is to moderate the intensity and frequency of exercise so that the long term gains exceeds the transient losses.

Diet and fasting. (Items 3-6).

 I did not personally find any negative impact of the carbohydrate or fat composition of my food on my HRV.  However, I may not be the ideal subject, because my consumption of carbohydrates is fairly modest and intermittent.  A 2010 study comparing high and low carbohydrate diets found the HRV values from both diets to be similar.

Some have claimed that food sensitivities cause heart rate to increase and  HRV to decrease. Dave Asprey has worked with Sweetwater to develop an a free “Bulletproof Food Sense”  app that claims to identify your “hidden”  food sensitivities.  He also has developed a “HeartMath Inner Balance” app that trains meditation patterns designed to increase HRV.  I have not really researched science behind these ideas or tried then myself, so I can’t vouch for these products. But it may be worth looking into for those who are interested.

I have personally found that intermittent fasting significantly increased my HRV.  On days I that I fasted through the morning and afternoon, my average HRV was 78 — much higher than my average of 68 — and much of the time it was above 80!  I also found that the longer I went without eating, the higher my HRV climbed, although I have not fasted more than 20 hours at a stretch this past month.

A 2014 study in Aging Cell found that individuals who consume fewer calories have significantly higher HRV, across the age spectrum.   It also appears that regular short term fasting for less than a day tends to raise HRV, but fasting for 48 hours reduces HRV.  A 2014 study of daily fasting during Ramadan, followed 16 women and 24 men during the a month of fasting about 17 hours per day between sunrise and sunset.  The study found a statistically significant increase in HRV with high frequency gains indicative of parasympathetic strengthening.  RMSSD increased from 31.1 to 36.3 (from 68.7 to 72.2 in lnRMSSDx20 units).

However, longer term fasting may not be beneficial, at least without a period of adaptation.  A 2013 study in the European Journal of Clinical Nutrition found a small improvement in RMSSD at 24 hours.  However, they also found a significant decrease in HRV at 48 hours, indicative of “parasympathetic withdrawal with simultaneous sympathetic activation”, which the authors suggest are reflective of stress.

Alcohol.(Items 7 and 8).  

Unknown-3This one is a bit of a bummer.  Not too surprisingly, alcohol suppresses HRV.  It makes sense that alcohol impairs your stress tolerance. The good news is that a single beer or glass of wine dropped my HRV by no more than 5 or 10 points, sometimes not having any effect.  However, 2 or 3 beers or glasses or wine, or a few cocktails consumed within a few hours — while quite pleasant — really sent my HRV into a downward spiral, sometimes by as much as 35 or 40 points, to a low of 36.7 points!  Ouch!  Interestingly, the depressive effect on HRV typically took several hours to show up and continued well after I had stopped drinking and supposedly “cleared” the alcohol.

This is buttressed by the research.  A 2010 study in the American Journal of Physiology and two 2013 studies in Psychophysiology and Alcohol Clinical Experimental Research found that  moderate alcohol consumption (1 drink per day for women, 2 drinks for men) increases HRV, while heavy alcohol consumption reduces it.

This really makes a case for moderate alcohol consumption!

On the flip side, there is some evidence that caffeine increases HRV, though the effect is transient (20-40 minutes) and may be dose-dependent.

Hot and cold. (Items 8 and 9).

 Unknown-2I’ve saved the best for last.  The activity that has delivered the single biggest improvement to HRV for me has been…cold showers!  This has also been the most consistent and most immediate of all the measures I’ve tried.  With over 40 cold showers tested — both in the morning and other times of day, cold showers increased HRV by an average of 8.4 points. In many cases, particularly when HRV started low, the increase was 20 points or higher!

Conversely, heat speeds up the heart and reduces HRV.  Soaking in the hot tub dropped my HRV by an average of 9.7 points, and the longer I stayed in, the lower it dropped.

I find this particularly remarkable for several reasons:

  • I always assumed that cold showers increased my heart rate, which usually means a decrease in HRV. (See again my plot above).  In my original post on Cold Showers, I wrote: “When you start with cold water, you will experience the phenomenon of cold shock, an involuntary response characterized by a sudden rapid breathing and increased heart rate.”  But it appears that just the opposite is true — the heart slows down in the cold.  Apparently this is well-known!  I does make sense physiologically that the body conserves heat by pumping more slowly, thereby keeping internal organs warm and reducing heat loss through the skin.
  • It was also surprising to me that the hot tub lowered my HRV and sped up my heart.  Because the hot tub is so relaxing,  I assumed everything is slowing down.  I was wrong.  But it makes sense that as you warm up, the heart pumps faster in an attempt to dump heat through your skin.  That may not be particularly effective if the water is very hot, of course.
  • The HRV-raising effect of cold shower is not transient. It really does a “re-set” and bumps your HRV up for hours.  If you take a cold shower before bed, you wake up with a similar HRV in the morning.
  • Apparently the HRV-raising effect of cold exposure–which I was ignorant about before self-experimentation– is well known to physiologists.  Strengthening the parasympathetic branch of the ANS is enhanced only after some acclimatization. (See here and here for references).  So while cold showers universally boosted my HRV, it may take you several attempts to see the benefit if you are unadapted to cold water.
  • If you find it hard to take cold showers, or you like “contrast baths” that involve switching between hot springs and cold water; these findings give a good reason to end your shower or bath with cold water, rather than hot.
  • Cold showers are quite effective in reversing, almost erasing the HRV-lowering effects of exercise and alcohol.  In fact, on nights where I’ve had a few drinks and my HRV is low, I make sure to jump into the cold right before going to bed.  Perhaps this sounds awful.  But it really makes you feel great before hitting the sack!   And because it re-sets your HRV, you wake up with a higher HRV in the morning than if you went to bed without it.  That’s incredible – lowering your heartbeat all night long!  If it’s true that we all have a finite number of heartbeats in life, why not spread the heat beats out in time, particularly when you are asleep, and perhaps add a few years to your lifespan or healthspan!

I’m particularly excited because this cold shower effect on HRV provides a great explanation for another observation I made in my Cold Showers post:

“…cold showers appear to have improved my stress tolerance, by buffering emotional reactions. What I mean by this is that bad news, surprises, arguments, or events that would have previously caused a brief surge in adrenaline or an emotional flush, no longer have that effect, or at most have a very attenuated effect.”

There you have it:  Cold showers boost HRV and activate the parasympathetic nervous system, calming reactivity and strengthening our adaptive reserves!

Recommendations.  Pulling this all together, the research and my personal experience suggest that tracking your heart rate variability with a chest monitor and smart phone can help you gain a lot of insight into best to adjust your diet, exercise program, and lifestyle in order to improve your ability to handle stress.

Based upon what I’ve learned from the literature and self-experimentation, I can suggest four simple and powerful steps to boosting your HRV and becoming more resilient:

  1. Jump into a cold shower or take a cold swim for a few minutes in the morning to arm yourself against the stresses of the day.  It only takes a minute or two under the cold water to raise your HRV significantly!  Use cold showers after intense exercise or drinking alcohol to more quickly get back on track before you go to bed, so you wake up fresh each day!
  2. Exercise judiciously.  The harder you train, the more time you need to recover between sessions in order to avoid overtraining.
  3. Use intermittent fasting part of each day to power up your parasympathetic nervous system.  But be careful fasting more than a day.
  4. Use alcohol and caffeine moderately.   An alcoholic drink or two a few times a week can increase your resilience, but more than a few drinks can really set you back. Likewise, a cup or two of coffee can be helpful, but be wary of over-caffeinated energy drinks.

In all of the above, a personal heart rate monitor can help you decide whether the advice works for you, and can help you fine tune the extent and frequency of each practice that works best for you.














  1. Brenda Mitchell

    Thank you so much for sharing this.

  2. Ann

    Wow, this is powerful stuff! Thanks so much for pulling all this info together and summarizing the recommendations suggested by the research.

    When my body started showing the shift into peri-menopause (hormonal changes), one of the first signs I noticed was that my heart rate became rock-steady, instead of going up and down with my breathing as it had done all my life. At the time I didn’t know whether this was something good or bad. Now I know….

  3. john sanderson

    Great Article Todd, thanks for posting

  4. Alex

    Hi, Todd. Thank you for the great article. I am surprised you didn’t mention Kelly McGonigal’s claim that deliberately slowing your breath for few minutes a day to 5 inhalations/exhalations a minute boosts one’s HRV pretty much through the roof. I would love to hear if you have tested this yourself.

    • Todd


      Thanks for that suggestion regarding slowed breathing. I had missed that in her talk. I’ll try it. There are a number of other reported techniques for boosting HRV, such as meditation and biofeedback. In the limited space of my article I focused mainly on techniques that I personally tried and researched, but no doubt there are other effective methods.


      • Alex

        It is actually in her book – The Willpower Instinct. I tried it for a couple of weeks, but could not really test since I don’t have the sensor. Please, if you will test this, share your results! Thank you.

        • jasonmclaren

          I have a HeartMath meter and have been doing slow breathing. It definitely helps increase heart rate variability while doing it. Not sure about the long-term effects though.

      • Andy Smith

        Hey, just downloaded Ithlete and ran it up. First result was 95, not sure if this is good or bad as I’m 42 and off chart in terms of your table.

        Any advice?

        • Todd


          Most likely 95 is outstanding! Since HRV measurements can fluctuate quite a bit, check your HRV at different times of day and over several days. Also make note of your heart rate. If you are very fit, you probably have both a high HRV and a low heart rate, in the 40-60 bpm range. Under rare circumstances a very high HRV could be associated with certain health conditions resulting from excessive parasympathetic dominance and/or sympathetic weakness, but more likely it merely reflects a combination of excellent fitness (without overtraining) and favorable genetics.


  5. Vladimir

    Sorry but I don’t buy this type of testing, it’s like looking for trouble and in the end you find it and can’t get rid of it. It’s very pharmaceutical in nature. I believe stress can be observed by the deepness of the breath. Really stressed out people don’t do normal diaphragmatic breathing and have a very equal shallow type breathing and then force their lungs when they are really stressed out. Diaphragm breathing is the key for relearning to breath and dealing effectively with stress.

  6. Jay

    Interesting, but I wonder what the “perfect” HRV really is. Does it really matter to get it above a certain point? Or is more of a tool you can use it to detect if something is going wrong…

    I don’t really understand/see what the mechanism is between a cold shower, an increased HRV, and what the link to improved health is…

    Nonetheless, an interesting article and it does show a lot of promise indeed.

  7. Matias Page

    Hello, Todd. I’ve been an avid reader and practitioner of the ideas presented by you. This is yet another great article.

    I have a long question for you below. If you have the time, I’d greatly appreciate some tips or ideas. Thanks.

    I already apply most of these points, but not moderate alcohol consumption. I drink zero alcohol.

    Do you think adding that (2-3 drinks a week) is a good idea?

    I used to be an asthma sufferer all my life, from my earliest memories. I also smoked cigarettes since I was 18 until I was 32 years old.

    Since I quit smoking 4 years ago, I no longer have asthma symptoms. I also started exercising, cold showers, intermittent fasting, training in a fasted state, and tested many other protocols and habits.

    I had pain in my joints and that is also gone.

    I tried drinking red wine a few times (I live in Argentina where wine is really good and cheap). Every time I drink it. I feel very inflamed. And I end up having both acid reflux and asthma. This happened three different times in the past year.

    What other alcoholic beverages do you think are advisable, in terms of HRV optimization?

    Thank you very much for your work and your time. I really benefited with your website.


    • Todd

      Hi Matias,

      Good to hear from you again. I have to laugh a bit, because it’s not everyday I’m asked to encourage someone to take up drinking alcohol 🙂

      I think it’s possible to live a perfectly healthful, long and enjoyable life without drinking alcohol. There’s certainly no requirement for it, and it can become a vice. There is evidence that moderate alcohol consumption has hormetic benefits, but I can’t say that these are especially unique. The other forms of hormesis that you already practice (exercise, IF, cold showers) ways to strengthen your metabolism, immune system, cardiovascular system, and brain agility. Would the addition of occasional drinks provide further benefit? I really can’t say.

      The fact that drinking red wine provokes your asthma and indigestion is of some concern. It could be the alcohol, but it might also be the fact that red wine is known to be a particular trigger

      Despite the negatives, you still might be interesting in moderate drinking alcohol for a few good reasons: (1) it’s enjoyable, if you can tolerate it; (2) perhaps you can become tolerant to it. As you may know from reading my my article on Allergies and hormesis, many have used allergen immunotherapy to overcome allergy symptoms through very systematic gradual exposure, starting with extremely small amounts. Perhaps you could start by taking just one sip of a drink one day and wait to see what happens. If you can tolerate it, increase to 2 sips the next day etc. You can also use an HRV monitor to track any reaction to the small amounts of alcohol, as an objective measure. I would measure your HRV immediately before the drink, then 5, 15 and 60 minutes after. A sudden dip of more than 10 HRV points could indicate a sensitivity. Keep in mind, though, that HRV will also drop in response to larger amounts of alcohol (more than the 1-2 ounces in a standard drink like a bottle of beer or glass of wine), even without allergic sensitivities.

      I think there is at least a theoretical possibility that drinking wine, moderately and intermittently, could actually increase your stress tolerance and HRV. This might be an individual response, like exercise. A temporary HRV depression could conceivably lead to a higher HRV after a recovery period of a day or two. It’s something you could test. Again, this is pure speculation, based on the idea that moderate alcohol has been shown in numerous studies to have hormetic or protective effects on cardiovascular helath.

      You might also try different types of alcohol. Red wine contains a number of sensitizers that are not present in more pure distilled spirits. You could try adding a teaspoon of vodka to a drink to some other drink you like — fruit or vegetable juices tend to mask the flavor of vodka.

      My best suggestion might be to start with kombucha! This has become one of my favorite drinks. Kombucha is a type of fermented tea, and you can find a variety of interesting flavors including ginger, berry extracts, etc. Kombucha is typically somewhat effervescent, like champagne, and has the refreshing quality of beer or wine with a low level of alcohol (typically about 0.5%). And it has very low sugar and carbohydrate content. I find that it really satisfies my thirst and goes well by itself or with food. Kombucha might be an ideal way to test and build your tolerance for alcohol.

      But if you are happy living without alcohol, then that is just fine too.

      Good luck and I’d be interested to hear what you find.


      • Matias Page

        Hey, Todd.

        Thank you very much for your in-depth reply.

        I will test your suggestions and I plan on letting you know in the comments about the results. I had been considering kombucha for a while.

        I’m reading a lot about the gut bacteria and its relationship with inflammation and its repercussions on the immune system. Auto-immune diseases, mismatch diseases, etc. It’s a wonderful field I think. My main everyday source is the writings by Eirik Garnas, he has a website called organicfitness which I think is full of interesting material. Maybe you’d like it.


        • Todd

          Yes, I’ve seen Eirik’s site and I like his approach. I think we agree on a number of ideas, including the key role that gut microflora play in regulating our metabolism and immune system. The gut has also been called “the second brain”, with good reason, since it provides strong input to the limbic brain via hormones, neurotransmitters and even direct nerve pathways such as the vagus.

  8. Marcin

    What’s your opinion on coffee vs HRV? Despite common belief I find I’m less fit when using coffee (not necessary right before the exercise, simply using day or two before).

    • Todd


      I’m ambivalent about coffee. I do like the flavor and find it sharpens me cognitively when consumed moderately. I typically combine 80% decaf with 20% fully caffeinated and have a few small cups in the morning. But I make a point to go caffeine free one or two days a week, to counteract the potential for dependence and also just to clear out the system.

      I’ve measured my HRV after coffee and don’t see a consistent response. Usually it gives me a slight boost, but not always. I find that cold showers give a much more robust, consistent, and long lasting boost to HRV, that corresponds to my subjective increase in energy and resilience.

      You ask whether coffee could actually impair fitness or exercise performance. I haven’t seen that, and anecdotally many athletes find that judicious and moderate use of caffeine improves performance.

      The key word here is “moderate”. Excess caffeine makes us jittery and can actually impair focus. It is likely that people vary widely in their individual response and tolerance for caffeine. So experiment! If you don’t already have a heart monitor and HRV app, try it out and study your individual response to coffee in different doses and situations. Self-experimentation is the only sure way to answer your good question.

      • Marcin

        Perhaps I’m on an adaptation phase because I’ve started drinking recently. I gave up coffee and tea a year ago as I was exhausted from overdrinking (5-6 glasses daily) and it’s hard to get back to it. But on the other hand it helps me to work better (Strangely, I’m very bored and unfocued when not using!).

        I think it’s a great I idea to not to use it 1-2 days a week. I’ll abstain on weekends.

  9. Joshua

    Hi Todd,

    Great post again. This blog (which helped me fix my myopia) has some of the best health/wellness content on the ‘net. Regarding caffeine and alcohol, I have a question. Might it be the case that they might have differing results on HRV depending on your current state of sympathetic/parasympathetic balance?
    For instance, imagine you’ve just done a heavy workout and your sympathetic nervous system is seriously dominating. (I find this particularly happens after I do heavy deadlifts.) Perhaps a couple of glasses of wine several hours later might help bring the parasympathetic system more back into balance? Or conversely, perhaps you’ve had a few days were you didn’t get much exercise, slept a lot, and feel a bit sluggish. Maybe in this case some caffeine might help stimulate the sympathetic nervous system and improve HRV?

    Does this seem to make sense? Just curious as to your thoughts.

    • Todd


      That’s great that you have been able to reverse your myopia.

      Regarding HRV: I agree with your second point, namely that caffeine can be energizing when you are sluggish. However, excessive caffeine that makes you jittery is counterproductive in overstimulating the sympathetic system. So I moderate the caffeine. Typically I drink 1-2 cups of 80% decaf + 20% caffeinated blend.

      I’m not so sure about your first hypothesis, however, namely that alcohol could help boost a low HRV that results from a dominating sympathetic nervous system. I find that both heavy exercise and alcohol beyond 1-2 drinks cause my HRV to drop. The next day, HRV is back up again, but in the case of exercise, there is a super-compensating effect and it increases above baseline, whereas with alcohol I don’t usually see that. I would guess that a few glasses of wine on top of exercise might make be very relaxed, but would really depress my HRV and most likely make me sleepy.

      However, I’m quite aware that individuals may vary greatly in their responses to exercise, caffeine, alcohol and food. The beauty of HRV is that it is easy to measure, and hence to self-experiment. I’d love if you could test your hypotheses here and report back your results, Joshua.



      • Joshua

        Well, at present, I don’t have a way to directly measure HRV (no chest strap or whatnot). However, I do have some further observations that I hope may be of interest.
        Since I read this, I’ve started using cold showers (well, actually contrast showers, but often ending with cold), especially on workout days. This has had a noticeable effect. Prior to starting this, I noticed that when I was lifting heavy weights 3-4 days a week, I seemed to eventually end up in a state of near-constant, mild “hyperactivity”. That is, I would generally feel like I had lots of energy, like I wanted to move, and had a hard time sitting still for long. This had some positives — I found it easy to get many things done — but also made it a bit difficult to relax and focus on a book in the evenings, as I like to do.
        Since including cold showers in my routine, I feel noticeably more relaxed, particularly at night. Now, I can easily sit back and read for a good span of time without feeling the urge to jump up and take care of this or that.
        I postulate that what took place here is that before, my sympathetic nervous system was dominating, and keeping me a bit “on edge”. With cold exposure, the balance has been restored and my parasympathetic nervous system brought back into the picture. This is interesting and useful. I would speculate that regular cold exposure, then, might be a good way of reducing the chances of overtraining for those exercising seriously. (Perhaps any benefits of ice baths are related to this?) I’m hoping that this new routine might also protect me against upper respiratory infections. I have read anecdotal evidence (not an oxymoron, I hope) that people who have regular cold exposure tend to get sick less often. I think I had 4 colds or so last winter. (Which I attributed to living with a 5-year-old who brought them home…probably that’s at least partly the cause.) We’ll see how it goes!

  10. gbell12

    The book HeartMath Solution put forth the theory that the time-varying pattern of HRV was what mattered. When subjects felt calm and appreciative, the HRV would undulate in a near sine-wave pattern. They call this “coherent”. When subjects felt agitated, the HRV would be more erratic.

    I verified this on myself in an experiment. Plotting the HRV samples over time…

    Interesting book overall.

  11. Mel

    I’m 78 with AFib. What about taking a beta blocker to lower heart rate?

    • Todd

      Not sure that a lower heart rate from beta blockers would necessarily improve your underlying health and fitness, though it might still be medically advisable if that is what your cardiologist recommends.

  12. Michiel

    Hi Todd,
    Really interesting stuff, thanks for the profound explanation of hrv.
    Did you see the Tedx talks from Alin Watkins ? He explains hrv in a different way. One should try the improve the coherence, which I interpret as less variation.
    What do you think is the difference? Are you looking at an other way of measuring hrv? An does that lead to other conclusions?
    Looking forward to your view on this?

    • Todd

      Hi Michiel,

      Watkins’ talk was certainly interesting. But he seemed to muddle the interpretation of heart rate vs. heart rate variability. When he put his subject under pressure, he highlighted the fact that heart rate (HR) went up. But there was no direct measurement of HRV, just a vague nod to the heart rate becoming “more chaotic”. But HR and HRV don’t necessarily correlate — they can both go up, or move in opposite directions.

      Futhermore, I simply disagree with his claim that a more regular heart rate — lower HRV — is a good thing. The entire point of my article is that — in general — the opposite is true. Of course, there are exceptions in the case of certain pathologies, but in general, greater variability is an indication of improved cardiovascular fitness, a stronger parasympathetic nervous system, and increased resilience in the face of stress.

      Of course, I have to assume that as a trained neuroscientist, Alan Watkins must understand the basic meaning of HRV. But if so, it certainly did not come across in his explanation. Nor did he come close to delivering on his promise to show us “how to have a brilliant day” every day.

      Nevertheless, I was entertained by his live demonstration of how stress increases heart rate (not HRV), and I do agree on the general point that a strong, robust basic physiology is important in supporting higher level functioning — although perhaps not every day.


      • Michiel

        Thanks for your detailed reply. But not sure if you saw the second part which is even more interesting where he explains his model.
        After rethinking this all I think that he talks about three things: HR, HRV and coherence. So this comes down that one can have the same HRV and HR, but with an erratic pattern or with a coherent pattern. So coherence is what should make the difference at the base of one’s emotions and higher HRV is a measure for one’s health.

        Another source that supports this explanation (on a commercial site “…Furthermore, unlike relaxation, the coherence state does not necessarily involve a lowering of heart rate, or a change in the amount of HRV, but rather is primarily marked by a change in the heart rhythm pattern…”

        So do you agree on this? Cheers, Michiel

  13. Is a rhr constantly over hrv a bad thing?

  14. Scott

    If you’re going to attempt to judge health/fitness status by tracking arbitrary numbers with smartphones, you’re going to be wrong most of the time. Biological stress is never a purely mechanistic, physiological phenomenon.Your brain is many times more powerful and intimate than those gadgets. Ask the right questions and get correct answers psychologically.

  15. aymeric

    what about this article that you indicated :
    It seems that a lower HRV is synonym to better survival isn’t it?

    • Todd


      • aymeric

        well, I am a bit confused. A higher HRV helps you “improve your resilience and resistance to physical and psychic stressors”. But a lower HRV helps you survive. For me me both things were related. I probably didn’t get something right, english not being my first language. I love reading your articles but they are sometimes (for me) a bit complex, due to the language. Thanks a lot for the research anyway it’s fascinating.

        • Todd

          I can see where this might be confusing, but I’ll try to resolve the apparent paradox. You want to strive for lower resting HRV or parasympathetic dominance as a measure of resilience and long term health. However, in emergencies or other “calls to action” like intense exercise, your body needs to raise its heartbeat and lower the HRV temporarily. You need the sympathetic nervous system to engage and take over, as a matter of sheer survive. This is a short term rallying action, and a necessary one. However, you don’t want to be in this heightened state indefinitely or for the long term. It will wear you down. Hence you need to rest to restore balance and recover.

          So low HRV is desired for the long term, high HRV is needed occasionally for short term bursts.

          Does that help?


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