Ways to improve HRV

A lot of people are asking us lately for ways to improve HRV, so we wrote an article about it.

• For a list of all the wearables that measure it, see here
• For a list of the way that sensors measure it, see here

Heart Rate Variability is the variability in the time between each individual heartbeat. Here we will discuss actions that improve HRV.

HRV arises from the opposing signals of the Sympathetic and Parasympathetic branches of the Autonomic Nervous System (the nervous system responsible for all bodily functions). The sympathetic branch is responsible for triggering the "fight or flight" response in times of stress or intense physical activity. The parasympathetic branch, on the other hand, is the "rest and digest" side of the nervous system.

A healthy balance of the two enables a fast response to various physical and mental stimuli, and a fast return to rest when the stimuli are gone, this is represented in a high HRV. An unbalanced autonomic nervous system, where the sympathetic system dominates means that the body will stay in a stress mode for sustained periods and be unable to rest and recover, this is represented in a low HRV.

Cardiovascular Fitness

Exercises that improve cardiovascular fitness have been shown to lower resting heart rate and increase HRV in the long term.[1] Moderate to high-intensity sustained cardio exercises like running, brisk walking, cycling and swimming are good examples. The reason behind this is that by pushing your cardiovascular system to high intensity and adapting to it, your sympathetic nervous system will become less stimulated by the same physical stimuli.

Better Sleep

Less than optimal sleep has been associated with lower HRV. Both the length of sleep and the quality (a good balance of REM sleep and deep sleep) are important as it significantly reduces stress buildup as well as allow recovery from previous activities that may have lowered HRV.[2]

To achieve good quality sleep, try to be consistent so that your circadian rhythm can adapt, as well as take measures for better sleep hygiene, regulate room temperature, reduce the use of digital devices before bed and allocate sufficient time each night.

Training intensity

Physical activity in general has benefits to HRV, however, the importance of not overtraining cannot be understated. HRV drops after an intense workout, and rest is paramount to HRV recovery.[3] The body's recovery and repair mechanisms take a significant toll on the parasympathetic system, impairing sleep and other bodily functions like digestion.

HRV tracking is especially useful for users to keep track of their recovery levels and ensure they are training only when they are sufficiently recovered.

Meditation and intentional breathing

Meditation and intentional breathing exercises are often the go-to "HRV exercise". There are multiple reasons why meditation, breathing exercises, mindfulness etc help increase HRV. [4]

One of the driving mechanisms of HRV is Respiratory Sinus Arrhythmia, where the heart rate quickens during inspiration and slows down during expiration.[5] The slow deep breathing in meditation and breathing exercises will essentially force the extremes of inspiration and expiration, training the heart to speed up and slow down drastically.

Secondly, meditation and breathing exercises can reduce stress through biofeedback, by being mindful of one's stressors, one can

Hydration

Keeping hydration levels high is paramount to maintaining a good HRV.[6] Water is an important part of the majority of bodily processes, for cardiovascular circulatory function specifically, higher hydration will allow circulation at lower blood pressures and lower heart rate and therefore higher HRV.

Alcohol abstinence

Even a small amount of alcohol is shown to decrease HRV in the short term, and those with moderate drinking habits show a sustained reduction in HRV. For those who have become alcohol-dependent, even with abstinence, the recovery in HRV has not returned to the baseline.[7] The reduction in HRV is likely caused by the increased stress on the digestive system and liver to break down the alcohol compounds.

Work Stress

Gone are the days when the main source of stress are saber-tooth tigers. These days, workplace stress can also contribute to overstimulating a person's fight or flight response.[8] Sustained occupational stress has also been associated with lowering HRV, therefore to remedy this, there should be appropriate breaks at work and meaningful ways to de-stress and recover.

Nutrition and meal timing

The Mediterranean diet has been well known to be beneficial to heart health, but it has also been shown to improve HRV specifically. Specifically, Omega-3 fatty acids, polyphenols, probiotics, and B vitamins are beneficial. Conversely, consuming large amounts of saturated and trans fats, as well as high glycaemic carbohydrates have been shown to reduce HRV.[8]

Lastly, timing the meals are also important, avoid eating near bedtime as the additional stress directed to the digestive system prevents the body from fully resting and entering a high-quality sleep session. Those with intolerances or allergies who still consume those foods have also shown reduced HRV, likely due to the added stress of digestion and immune response.

Cold immersion

Immersion into cold water has shown benefits to resting heart rate RHR and HRV.[10] This is due to the Human Diving Reflex, where we have a biological instinct to hold our breath and slow down our heart rate drastically when entering cold water. This reflex causes increased parasympathetic stimulation of the cardiac pacemaker. By training this reflex, and strengthening the parasympathetic response, your body is more capable of handling stress and therefore balancing the sympathetic nervous system, increasing HRV.

Time in Nature

Spending time in nature, and including virtual representations of nature, e.g VR headset with natural surroundings projected to the wearer has also been shown to increase HRV, though to a lesser extent. This is not currently fully understood but studies suggest it is a combination of relieving stress and cardiovascular exercise, as most people tend to be walking if not outright hiking in nature.[11]

Tracking HRV

Lastly, no plan to improve HRV is complete without the ability to track it. By being able to track HRV in the short term, e.g assessing the HRV response of an intense workout, and being able to track HRV in the long term, e.g monthly HRV average to see progression, you can get a good idea of what works for you in improving HRV.

See list of wearables that track HRV

Conclusion

Many wearables measure HRV because of its usefulness as both a health and fitness metric. By tracking its progression and responses to particular stimuli, the user can learn more about themselves and what actions to take or avoid. Terra API has integrations with wearables that measure HRV, enabling health and fitness apps to track any improvements and set you on the right path.

• See this article for the various ways wearables measure and count HRV, and this link for all the articles we wrote about HRV

References

[1] Grässler B, Thielmann B, Böckelmann I, Hökelmann A. Effects of Different Training Interventions on Heart Rate Variability and Cardiovascular Health and Risk Factors in Young and Middle-Aged Adults: A Systematic Review. Front Physiol. 2021 Apr 23;12:657274. DOI: 10.3389/fphys.2021.657274. PMID: 33981251; PMCID: PMC8107721.

[2] Sajjadieh A, Shahsavari A, Safaei A, Penzel T, Schoebel C, Fietze I, Mozafarian N, Amra B, Kelishadi R. The Association of Sleep Duration and Quality with Heart Rate Variability and Blood Pressure. Tanaffos. 2020 Nov;19(2):135–143. PMID: 33262801; PMCID: PMC7680518.

[3] Mourot L, Bouhaddi M, Perrey S, Cappelle S, Henriet MT, Wolf JP, Rouillon JD, Regnard J. Decrease in heart rate variability with overtraining: assessment by the Poincaré plot analysis. Clin Physiol Funct Imaging. 2004 Jan;24(1):10–8. doi: 10.1046/j.1475–0961.2003.00523.x. PMID: 14717743.

[4] Steffen, P et al. Integrating Breathing Techniques Into Psychotherapy to Improve HRV: Which Approach Is Best? Front. Psychol., 15 February 2021 doi.org/10.3389/fpsyg.2021.624254

[5] Yasuma F, Hayano J. Respiratory sinus arrhythmia: why does the heartbeat synchronize with respiratory rhythm? Chest. 2004 Feb;125(2):683–90. DOI: 10.1378/chest.125.2.683. PMID: 14769752.

[6] Young, H.A., Cousins, A., Johnston, S. et al. Autonomic adaptations mediate the effect of hydration on brain functioning and mood: Evidence from two randomized controlled trials. Sci Rep 9, 16412 (2019). https://doi.org/10.1038/s41598-019-52775-5

[7] Karpyak, V.M., Romanowicz, M., Schmidt, J.E., Lewis, K.A. and Bostwick, J.M. (2014), Characteristics of Heart Rate Variability in Alcohol-Dependent Subjects and Nondependent Chronic Alcohol Users. Alcohol Clin Exp Res, 38: 9–26. https://doi.org/10.1111/acer.12270

[8] Järvelin-Pasanen S, Sinikallio S, Tarvainen MP. Heart rate variability and occupational stress-systematic review. Ind Health. 2018 Nov 21;56(6):500–511. DOI: 10.2486/indhealth.2017–0190. Epub 2018 Jun 16. PMID: 29910218; PMCID: PMC6258751.

[9] Young HA, Benton D. Heart-rate variability: a biomarker to study the influence of nutrition on physiological and psychological health? Behav Pharmacol. 2018 Apr;29(2 and 3-Spec Issue):140–151. DOI: 10.1097/FBP.0000000000000383. PMID: 29543648; PMCID: PMC5882295.

[10] Al Haddad H, Parouty J, Buchheit M. Effect of daily cold water immersion on heart rate variability and subjective ratings of well-being in highly trained swimmers. Int J Sports Physiol Perform. 2012 Mar;7(1):33–8. doi: 10.1123/ijspp.7.1.33. Epub 2011 Aug 30. PMID: 21941017.

[11] Scott EE, LoTemplio SB, McDonnell AS, McNay GD, Greenberg K, McKinney T, Uchino BN, Strayer DL. The autonomic nervous system in its natural environment: Immersion in nature is associated with changes in heart rate and heart rate variability. Psychophysiology. 2021 Apr;58(4):e13698. DOI: 10.1111/psyp.13698. Epub 2020 Oct 13. PMID: 33048361.