A scientific approach
to digitizing health

«If you can’t measure it, you can’t manage it»

— management guru Peter Drucker.

1. Introduction

A balanced lifestyle (i.e. equal distribution of one’s energy across all spheres of life) is a prerequisite for good health, productivity, happiness and satisfaction.

Any stress, physical or mental, should be followed by a period of recovery and vice versa. It is impossible to develop physically or intellectually without periods of both stress and recovery.

At the core of a healthy lifestyle lies basic self-care (regular medical check-ups, treatment of chronic diseases, taking medications, quitting bad habits).

According to the World Health Organization, 30% of people suffer from migraines or chronic headaches, and 25% of deaths in the 20-39 age group are alcohol related. This is why changing the way we approach our health needs to be a priority.

Diet is another key factor that contributes to a healthy lifestyle.

39% of people are overweight. Excess weight causes cardiovascular diseases, which lead to back and leg pain, as well as self-esteem issues.

Therefore, a healthy lifestyle is:

Everybody’s health is different, and depends on different factors: occupation, genetics, age, gender, bad habits, temper, etc. This means there needs to be a tool that can help us figure out our personal ideal amount of working hours and calories, the best recreational activities, and how often we should see a doctor.

This tool needs to be:

  • Sensitive to potential changes
  • Evidence-based
  • Clinically approved

 

  • Convenient for every-day use
  • Visually compelling

In fact, this tool already exists. It’s called heart rate variability analysis.

2. Heart rate variability: a basic method for assessing your stress & energy levels

Heart rate variability analysis investigates the condition of the autonomic nervous system by tracking heart rate variability (HRV), which is the variation in the beat-to-beat interval.  The fact that heart rate is variable was discovered in the 18th century: if a person’s heart rate is 60 beats per minute, the intervals between beats will not be exactly 1 second long, but will look more like this: 0.958 s., 1.12 s., 0.892 s., etc. The interval between successive heart beats is called the RR interval.

RR interval

Physiologically, the more the body is capable of changing in response to various factors, the better its adaptation abilities and survival rate are.

Heart performance directly depends on the autonomic nervous system, in particular its two branches: the sympathetic branch (which is activated during physical exercise, strain and stress) and the parasympathetic branch (which is active during recovery, sleep, rest and relaxation).

Well-coordinated functioning of all systems means that the body uses its resources evenly at an optimal rate or intensity and recovers properly. Heart rate variability analysis is one of the most effective non-invasive methods for assessing the performance of the autonomic nervous system.

Initially, the method was used in space science to assess astronaut health because it was very sensitive and precise. It was later widely used in medicine. In 1996, a team of experts from the European Society of Cardiology and the North American Society of Pacing and Electrophysiology published standards of measurements, interpretation and clinical use of the heart rate variability method. Today, it is widely used in professional sports.

However, there have already been a lot of studies that show the method is an effective way of analyzing people’s health and wellbeing in a natural environment on a day-to-day basis.

Many scientists and researchers confirm this:

Today, heart rate variability (HRV) analysis is recognized as the most informative non-invasive method of heart rate autonomic regulation qualitative assessment. HRV reflects vital regulatory mechanisms for physiological processes in the body such as autonomic balance and functional resources for regulatory mechanisms. By analysing HRV we can not only assess the functional state of the body but also track changes and, even pathological conditions with HRV decline and high death probability.

Leo A. Bokeria, Soviet and Russian cardiologist, medical science developer, inventor, educator and professor. Member of the Russian Academy of Sciences and Russian Academy of Medical Sciences, board member of the Russian Academy of Medical Sciences. Chief cardiologist of the Ministry of Health of the Russian Federation. Director of the A.N. Bakulev Scientific Center for Cardiovascular Surgery since 1994.

Whenever you want to nurture innovation, you need to have metrics… The reason HRV was chosen was… for one, we have decades worth of heart rate variability data. There is good cohort data, population level data, that suggests that declining HRV is also due to a chronologic age [and] unlike most biomarkers in health, HRV can be measured continuously, contextually.You can measure it for 24 hours.

Joon Yun, Palo Alto Longetivity Prize sponsor, President of Palo Alto Investors, LLC, certified radiology specialist., He received his B.A. from Harvard, M.D. from Duke Medical School, and clinical training at Stanford.

If you are a shift worker or someone who has short sleep chronically, this could be a reason that these groups have a higher incidence of cardiovascular disease and diabetes…” Heart-rate variability has been shown to be a good measure of cardiovascular risk.

Siobhan Banks, PhD, former Research Fellow at the Department of Psychiatry, University of Pennsylvania, USA; she is now a Senior Research Fellow at the Centre for Sleep Research, University of South Australia and a leading author of studies on sleep and health published in the SLEEP 2007 global report, National Institutes of Health.

Heart rate variability is quite simply the variation in the interbeat intervals of our heart. It is a very sensitive index of the health of our body’s stress response systems. It’s one way to measure the health and fitness of the fight or flight system.

Dr. Arpi Minassian, Clinical Professor of Psychiatry at the University of California., She is an author of a study on HRV-Post traumatic stress disorder association in military personnel.

When the body experiences stress—for example, from exercise or extreme temperatures—it can maintain a stable blood pressure and constant body temperature in part by dialing the heart rate up or down. HRV plays an important role in maintaining this balance. A familiar related problem is in driving. To get to a destination despite varying weather and traffic conditions, any driver—even a robotic one — will change factors such as acceleration, braking, steering, and wipers. If these factors suddenly became frozen and unchangeable while the car was still moving, it would be a nearly certain predictor that a crash was imminent. Similarly, loss of heart rate variability predicts some kind of malfunction or ‘crash,’often before there are any other indications

John Doyle, Professor of Control and Dynamical Systems, Electrical Engineering, and BioEngineering at the California Institute of Technology

We selected the most interesting and illustrative studies from the enormous amount of research on the convenience and precision of heart rate variability analysis as an indicator of a person’s health to show you why heart rate variability analysis can and should be used to reach the perfect state of health and balanced lifestyle.

Sources:

  • Historical description of HRV, The Ohio State University, Columbus, OH, USA, University of Oulu, Finland: George E. Billman, Heart Rate Variability – A Historical Perspective, Front Physiol. 2011; 2: 86.doi: 10.3389/fphys.2011.00086.
  • Description of heart performance and HRV, Truman State University, HeartMath University, USA ,Fred Shaffer;Rollin McCraty; Christopher L. Zerr. A healthy heart is not a metronome: an integrative review of the heart’s anatomy and heart rate variability, Front. Psychol., 30 September 2014. Truman State University. doi: 10.3389/fpsyg.2014.01040.
  • Standards of measurement, interpretation and clinical use of heart rate variability. The European Society of Cardiology and the North American Society of Pacing and Electrophysiology. Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. 1996. Heart rate variability: standards of measurement, physiological interpretation and clinical use. Circulation 93, 1043–1065. doi: 10.1161/01.CIR.93.5.1043.
  • Literature review and description of HRV spectral analysis as a reliable source of analysis of autonomic functions of the human body and the state of the cardiovascular system, McMaster University Medical School, Canada: Kamath MV, Fallen EL., Power spectral analysis of heart rate variability: a noninvasive signature of cardiac autonomic function. Crit Rev Biomed Eng. 1993;21:245-311. PubMed
  • Description of the spectral analysis of HRV as a tool to explore neural regulatory mechanisms, University of Milan, Italy: Malliani A, Lombardi F, Pagani M. Power spectral analysis of heart rate variability: a tool to explore neural regulatory mechanisms. Br Heart J. 1994;71:1-2. Heart.bmj.com
  • Using HRV as a method to prognose sympathetic disorders in diabetes patients, Clinic Bavaria Kreischa, Germany: Weck M1.; Tank J.; Baevski RM.; Mölle A.; Matthies K.; Ploewka K.Impaired activation of the baroreflex loop as early sign of sympathetic damage in diabetics with normal heart rate variability at rest. Acta Med Austriaca. 1997;24(5):175-9. PubMed
  • Description of HRV analysis in prenosological prognosis. R.M.Baevsky. Prognosis of near pathological health statuses. (Р.М.Баевский, Прогнозирование состояний на грани нормы и патологии) 1979. Moscow, Meditsina, DJVU.
  • Overall theoretical description of the HRV method, R.M. Baevsky, HRV analysis: history, philosophical points, theory and practice. Institute for Biomedical Problems of the Russian Academy of Sciences. PDF

3. Impact of lifestyles

3.1. Heart rate variability and stress

Stress is any phenomenon that changes our physical and mental state and disrupts homeostasis.

Homeostasis is the regulation of the body’s internal environment, which maintains the right conditions for the proper functioning of all systems. For example, changes in heart rate or body temperature in response to certain factors.

  • Stress can be positive (eustress) – physical exercise that makes muscles grow, for example. It can also be negative (distress), like psychological trauma
  • How quickly the body overcomes stress and gets back to its normal state is indicative of its fitness level.
  • Stress accumulates due to overstrain and lack of resources in the body to combat it. Overstrain causes chronic stress, which leads to sleep disorders and various diseases.

The basic stress response reaction is this:

stress resistance

However, the consequences and the length of each phase vary and depend on the physical and mental state of a person, their lifestyle, etc.

The autonomous nervous system is responsible for the body’s response to stress and subsequent recovery. It controls all major systems, including heart rate.

This is why regular heart rate variability measurements can detect the moment when the body is overstrained and any stressful situation can deteriorate the person’s health.

Welltory uses the Baevsky stress index, which is most widely used in sports medicine, to assess the health status of our app’s users.

Sources:

  • Description of correlation between stress and health. University of Miami, USA: Schneiderman, N.; Ironson, G.; Siegel, S. D. (2005). Stress and health: psychological, behavioral, and biological determinants. Annual Review of Clinical Psychology. 1: 607–628. doi: 10.1146/annurev.clinpsy.1.102803.144 141.
  • Meta-analysis of the correlation between stress and HRV as a marker of stress and health. The Ohio University, USA: Thayer JF1.; Ahs F.; Fredrikson M.; Sollers JJ 3rd.; Wager T.D. (2012). A meta-analysis of heart rate variability and neuroimaging studies: implications for heart rate variability as a marker of stress and health. Neurosci Biobehav Rev. 2012 Feb;36(2):747-56. doi: 10.1016/j.neubiorev.2011.11.009.
  • Description of the impact of behaviour on health, Institute of Medicine, USA: Committee on Health and Behavior (2001). Health and behavior: The interplay of biological, behavioral, and societal influences. Washington, DC: National Academy Press. PubMed
  • Various approaches to stress description, National Institute of Neurological Disorders and Stroke, USA, Goldstein, David S.; Kopin, Irwin J. (2007). Evolution of concepts of stress. Stress: The International Journal on the Biology of Stress. 10 (2): 109–120. doi: 10.1080/102538907012 88935.
  • Description of the stress and stressor phenomenon, Université de Montréal, Canada. Selye (1975). Confusion and controversy in the stress field. Journal of Human Stress. 1 (2): 37–44.doi: 10.1080/0097840X.1975.9940406.
  • Proof of high degree of correlation between stress and HRV, Information and Communication University, Inje University School of Medicine Seoul, Korea. Lizawati Salahuddin, Myeong Gi Jeong, Desok Kim, Seong-Kyeon Lim , Kim Won , Jong-Min Woo. Dependence of Heart Rate Variability on Stress Factors of Stress Response Inventory, Conference: e-Health Networking, Application and Services, 2007 9th International Conference on, doi: 10.1109/HEALTH.2007.381638.
  • The use of R.M.Baevsky’s variational pulsometry in HRV research for differential diagnostics of peptic ulcer and idiopathic duodenal ulcers Nizhny Novgorod State Medical Academy, Russia. D.А. Chizhikov; L.B. Fomin; V.I. Borisov; The Use of Heart Rate Variability Technique for Differential Diagnostics of Peptic Ulcer and Idiopathic Duodenal Ulcers. 2014 doi: 10.1769 1/stm2015.7.2.13.
  • Nizhny Novgorod State Medical Academy, Russia. D.А. Chizhikov; L.B. Fomin; V.I. Borisov; The Use of Heart Rate Variability Technique for Differential Diagnostics of Peptic Ulcer and Idiopathic Duodenal Ulcers. 2014 doi: 10.1769 1/stm2015.7.2.13 National Sports Training Centre, Russia. PDF

3.1.1. Physical stress

Heart rate variability is correlated with the amount and intensity of physical exercise, level of training, recovery rate and injury and overstrain risks.

  • Exercise increases HRV and energy recovery rate, as well as resistance to physical and psychological strain.
  • The only prerequisite for successfully tracking adaptation to stress (including exercise sessions) is taking measurements regularly.
  • A week or more of daily pulse measurements and HRV data reflects the process of adaptation to exercise better than occasional measurements.

Sources:

  • Applying HRV in the analysis of positive impacts of physical activity on human health and wellbeing, Universidade Federal de São Carlos, Sao Paolo, Universidade de São Paulo, Brasil: Melo, R., Santos, M., Silva, E., Quitério, R., Moreno, M., Reis, M., Catai, A. (2005). Effects of age and physical activity on the autonomic control of heart rate in healthy men. Braz J Med Biol Res Brazilian Journal of Medical and Biological Research, 38(9). doi: 10.1590/s0100-879×2005000900007.
  • Using HRV to assess the intensity of various cardio exercises, University of Alabama, USA, Michael R. Esco, Andrew A. Flatt, Henry N. Williford, Postexercise heart rate variability following treadmill and cycle exercise: a comparison study, 2015. doi: 10.1111/cpf.12308.
  • Confirming HRV analysis effectiveness in developing training programmes for athletes, Institute of Physical Education, P.R. China: Jin-Guo Dong, The role of heart rate variability in sports physiology. Exp Ther Med. 2016 May; 11(5): 1531–1536.doi: 10.3892/etm.2016.3104.
  • Confirming HRV analysis effectiveness in measuring the autonomic nervous system recovery rate after physical exercise, Research Institute for Olympic Sports, Jyväskylä, Finland: Kaisu Martinmäk; Heikki Rusko, Time-frequency analysis of heart rate variability during immediate recovery from low and high intensity exercise. European Journal of Applied Physiology, February 2008, Volume 102, Issue 3, pp 353–360, doi: 10.1007/s00421-007-0594-5.
  • Proof of the correlation between training load and HRV changes in judo athletes, University of Barcelona, Valencia, Spain: Morales J, Alamo JM, García-Massó X, Buscà B, López JL, Serra-Añó P, González LM. Use of heart rate variability in monitoring stress and recovery in judo athletes. J Strength Cond Res. 2014 Jul;28(7):1896-905. doi: 10.1519/JSC.000000000 0000328.
  • Determining the optimal frequency of HRV measurements to measure adaptation to physical exercise, Sport Performance Research Institute, New Zealand, Aspire Academy for Sports Excellence, Doha, Qatar: Daniel J. Plews, Paul B. Laursen, Andrew E. Kilding, Martin Buchheit. Evaluating Training Adaptation with Heart-Rate Measures: A Methodological Comparison. International Journal of Sports Physiology and Performance,Volume 8 Issue 6, November 2013. doi: 10.1123/ijspp.8.6.688.

3.1.2. Mental stress

Emotional stressors can have the same consequences as physical strain.

  • Quite often (but not always) — mental and psychological strain may lead to physical impairments and diseases.
  • These conditions are reflected in heart rate variability.

Sources:

  • Confirmation of the link between emotional burnout and HRV, The Institute of Stress Medicine, Gothenburg, Sweden: Lennartsson AK, Jonsdottir I, Sjörs A. Low heart rate variability in patients with clinical burnout.Int J Psychophysiol. 2016 Dec;110:171-178. doi: 10.1016/j.ijpsycho.2016.08.005.
  • Finding a correlation between social isolation, anger, depression symptoms and heart rate variability (a study with 300 women), Caroline Institute, Sweden: Myriam Horsten, Mats Ericson, Aleksander Perski, Sarah Wamala.Psychosocial Factors and Heart Rate Variability in Healthy Women. Psychosomatic Medicine 61:49–57 (1999) PDFPubMed.
  • Confirmation of the link between depression and HRV decline, Ruhr-University of Bochum, Germany: Agelink MW, Boz C, Ullrich H, Andrich J. Relationship between major depression and heart rate variability. Clinical consequences and implications for antidepressive treatment. Psychiatry Res. 2002 Dec 15;113(1-2):139-49. PubMed
  • Finding a correlation between fatigue and HRV frequency analysis in lorry drivers, Denmark: Niels Egelund, Spectral analysis of heart rate variability as an indicator of driver fatigue. Journal Ergonomics Volume 25, 1982 – Issue 7 Pages 663-672 Received 03 Nov 1981. Denmark. doi: 10.1080/00140138208925026.
  • Correlation of post-traumatic stress disorder consequences and HRV, University of Western Ontario, Mc Master University, Canada; Ohio State University, USA, Lawson Health Research Institute, UK: Thome J, Densmore M, Frewen PA, McKinnon MC, Théberge J,Nicholson AA, Koenig J, Thayer JF, Lanius RA. Desynchronization of autonomic response and central autonomic network connectivity in posttraumatic stress disorder. Hum Brain Mapp. 2017 Jan;38(1):27-40. doi: 10.1002/hbm.23340.
  • Correlation between HRV and panic attacks, University of Washington, USA: Friedman BH, Thayer JF. Autonomic balance revisited: panic anxiety and heart rate variability. J Psychosom Res. 1998 Jan;44(1):133-51. PubMed
  • Comparative analysis of arterial pressure and HRV as mental stress indicators, National Institute of Occupational Health, Denmark: Hjortskov N1, Rissén D, Blangsted AK, Fallentin N, Lundberg U, Søgaard K. The effect of mental stress on heart rate variability and blood pressure during computer work. Eur J Appl Physiol. 2004 Jun;92(1-2):84-9. Epub 2004 Feb 27. doi: 10.1007/s00421-004-1055-z.
  • Using the Stroop effect to confirmirm HRV sensitivity to psychological strain, University of Liverpool, UK: Delaney JP, Brodie DA. Effects of short-term psychological stress on the time and frequency domains of heart-rate variability. Percept Mot Skills. 2000 Oct;91(2):515-24. doi: 10.2466/pms.2000.91.2.515.
  • Confirmation of changes in HRV during mental stress, Catholic University of Louvain, Belgium: J. Taelman, S. Vandeput, A. Spaepen, S. Van Huffel. Influence of Mental Stress on Heart Rate and Heart Rate Variability. PDF

3.2. Heart rate variability and recovery

Recovery is a key process that should follow any type of stress.

  • Tracking HRV makes it possible to find optimal methods to recover for each person individually.
  • The more stress you experienced the longer and better your recovery needs to be.

3.2.1. Physical recovery

One of the best ways to physically recover is by sleeping. Chronic sleep deprivation and low quality of sleep will impact heart performance and in turn overall wellbeing.

Other effective ways to relieve physical stress is massage, contrast shower, floating and moderate-intensity physical activity (for example, exercises for specific parts of the body or stretching exercises). These methods were also discovered through HRV analysis.

Sources:

  • The use of HRV analysis method to analyse the impact of lack of sleep in emergency medical services workers. Neufeld EV, Carney JJ, Dolezal BA, Boland DM, Cooper CB. Exploratory Study of Heart Rate Variability and Sleep among Emergency Medical Services Shift Workers.Prehosp Emerg Care. 2016 Aug 3:1-6.UCLA, MIT, USA. doi: 10.1080/10903127.2016.1194928.
  • Confirmation of a bidirectional link between sleep and HRV. Meta-analysis, University of Milan, Italy; Federal University of São Paulo, Brazil; International Clinical Research Center, St. Anne University Hospital, Brno, Czech Republic: Eleonora Tobaldini, Lino Nobili, Silvia Strada, Karina R. Casali, Alberto Braghiroli and Nicola Montano. Heart rate variability in normal and pathological sleep. Front. Physiol., 16 October 2013 | doi: 10.3389/fphys.2013.00294.
  • Confirmation of the HRV assessment method reliability for the analysis of sleep quality and sleep disorders, University of Washington, USA: Phyllis K. Steina, Yachuan Pub. Heart rate variability, sleep and sleep disorders. Sleep Medicine Reviews. Volume 16, Issue 1, February 2012, Pages 47–66. doi: 10.1016/j.smrv.2011.02.005.
  • Using HRV to determine the minimum amount of nights without sleep that stimulates the sympathetic nervous system, University of Saõ Paolo, Brazil. Dettoni JL, Consolim-Colombo FM, Drager LF, Rubira MC, Souza SB, Irigoyen MC, Mostarda C, Borile S, Krieger EM, Moreno H Jr, Lorenzi-Filho G.Cardiovascular effects of partial sleep deprivation in healthy volunteers. J Appl Physiol (1985). 2012 Jul;113(2):232-6. doi: 10.1152/japplphysiol.01604.2011.
  • Using HRV to reveal positive effects of lymph drainage massage in a randomised study, Kangwon National University, South Korea: Sung-Joong Kim, Oh-Yun Kwon, Chung-Hwi Yi. Effects of Manual Lymph Drainage on Cardiac Autonomic Tone in Healthy Subjects, International Journal of Neuroscience Volume 119, 2009 – Issue 8, Pages 1105-1117 | Published online: 13 Aug 2009. doi: 10.1080/00207450902834884.
  • Using HRV analysis to study the impact of cold water on recovery after physical training, Brazil: Aline Castilho de Almeida, Aryane Flauzino Machado, Lara Madeiral Netto, Luiz Carlos Marques Vanderlei, Jayme Netto Jr., Carlos Marcelo Pastre. Cold water immersion in recovery of heart rate variability indices post-exercise. Physical therapy in sport, May 2014Volume 15, Issue 2, Page e3, doi: 10.1016/j.pt sp.2013.12.010.
  • Using HRV to confirm antistress effects of floating, Kawasaki University of Medical Welfare, Japan. Nishimura M, Onodera S. [Relaxative effects of supine floating on heart rate, blood pressure and cardiac autonomic nervous [correction of nerveous] system activity]. Uchu Koku Kankyo Igaku. 2000 Sep;37(3):49-56. PubMed

3.2.2. Mental recovery

One of the most popular and scientifically proven methods of using HRV analysis is HRV Biofeedback, i.e. getting feedback from the body with the help of HRV and controlling heart rate through respiratory (HRV Coherence) and meditation techniques.

Key benefit: improving emotional health and depression prevention and treatment. Moreover, just simply being outside in the country already has a positive impact on health and reduces mental stress.

Sources:

  • Confirmation of the positive impact of biofeedback sessions on the health of patients with depression, Clinic for Psychotherapy and Psychosomatic Medicine, Technical University, Germany; University for Health Sciences, Austria. Martin Siepmann, Volkan Aykac, Jana Unterdörfer, Katja Petrowski, Michael Mueck-Weymann. A Pilot Study on the Effects of Heart Rate Variability Biofeedback in Patients with Depression and in Healthy Subjects. Applied Psychophysiology and Biofeedback December 2008, Volume 33, Issue 4, pp 195–20. Doi: 10.1007/s10484-008-9064-z.
  • Using HRV to study the positive impact of meditation on the autonomic nervous system, Vivekananda Yoga Research Foundation, Bangalore, India. Hyorim An, Ravi Kulkarni, R Nagarathna, HR Nagendra, Measures of heart rate variability in women following a meditation technique, Int J Yoga. 2010 Jan-Jun; 3(1): 6–9. Bangalore, India. doi: 10.4103/0973-6131.66772.
  • The positive effect of meditation on the cardiovascular system, Oslo University Hospital, Norway. Nesvold A, Fagerland MW, Davanger S, Ellingsen Ø, Solberg EE, Holen A, Sevre K, Atar D. Increased heart rate variability during nondirective meditation. Eur J Prev Cardiol. 2012 Aug;19(4):773-80. doi: 10.1177/1741826711414625.
  • Using HRV to reveal the positive impact of walks in parks, Chiba University, Japan: Song C, Ikei H, Igarashi M, Miwa M, Takagaki M, Miyazaki Y. Physiological and psychological responses of young males during spring-time walks in urban parks. J Physiol Anthropol. 2014 May 1;33:8. doi: 10.1186/1880-6805-33-8.
  • Using HRV to determine the impact of music on people’s health, Lancaster University, UK, University of Zurich. Switzerland: Koelsch S, Jäncke L. Music and the heart. Eur Heart J. 2015 Nov 21;36(44):3043-9. doi: 10.1093/eurheartj/ehv430.

3.3. Heart rate variability and overall health

HRV is affected by natural processes such as aging, as well as by diseases and medicine intake. Regular heart rate variability analysis can help prevent diseases, find the most effective treatment and keep our physiological age in line with our biological age.

3.3.1. Age and aging

Age is one of the factors that have the greatest impact on heart rate variability.

Elderly people’s sympathetic nervous system is more active, which means that HRV declines with age and its assessment can precisely determine the level of physiological weariness.

Sources:

  • Substantiating HRV analysis as a reliable marker of biological ageing (Palo Alto Homeostatic Capacity Prize competition study). Clinic for Psychotherapy and Psychosomatic Medicine, Technical University, Germany; University for Health Sciences, Austria. Martin Siepmann, Volkan Aykac, Jana Unterdörfer, Katja Petrowski, Michael Mueck-Weymann. A Pilot Study on the Effects of Heart Rate Variability Biofeedback in Patients with Depression and in Healthy Subjects. Applied Psychophysiology and Biofeedback December 2008, Volume 33, Issue 4, pp 195–20. Doi: Palo Alto Prize.
  • Confirmation of the effectiveness of HRV analysis in assessing ageing (a study with 1742 people over 50), University of Basel, Switzerland: Felber Dietrich D, Schindler C, Schwartz J, Barthélémy JC, Tschopp JM, Roche F, von Eckardstein A, Brändli O, Leuenberger P, Gold DR, Gaspoz JM, Ackermann-Liebrich U; SAPALDIA Team. Heart rate variability in an ageing population and its association with lifestyle and cardiovascular risk factors: results of the SAPALDIA study. Europace. 2006 Jul;8(7):521-9.doi: 10.1093/europace/eul063.
  • Finding a correlation between elderly people’s cognitive skills and HRV (a study with 3853 people), Leiden University Medical Center, the Netherlands; University of Glasgow, UK: Mahinrad S, Jukema JW1, van Heemst D1, Macfarlane PW1, Clark EN1, de Craen AJ1, Sabayan B.10-Second heart rate variability and cognitive function in old age. Neurology. 2016 Mar 22;86(12):1120-7. doi: 10.1212/ WNL.0000000000002499.
  • Confirming the correlation between elderely people’s cognitive skills and HRV disorders (a study with 4763 people), Trinity College, Ireland: Frewen J, Finucane C, Savva GM, Boyle G, Coen RF, Kenny RA. Cognitive function is associated with impaired heart rate variability in ageing adults: the Irish longitudinal study on ageing wave one results. Clin Auton Res. 2013 Dec;23(6):313-23. doi: 10.1007/s10286-0 13-0214-x.
  • Using HRV to confirm the negative impact of ageing on health status and nervous system performance, Federal University of Sergipe, Brazil. Almeida-Santos MA, Barreto-Filho JA, Oliveira JL, Reis FP, da Cunha Oliveira CC, Sousa AC. Aging, heart rate variability and patterns of autonomic regulation of the heart. Arch Gerontol Geriatr. 2016 Mar-Apr;63:1-8. doi: 10.1016/j.archger.2015.11.011.

3.3.2. Diseases

HRV is effective as a tool to diagnose diseases early and predict consequences. Heart rate variability analysis is already used to estimate life expectancy in patients with cancer or diabetes, as well as patients who have had heart attacks, organ transplants, sepsis, etc.

Sources:

  • Recognising HRV analysis as an effective method in diabetic neuropathy diagnosis. Boston Medical Technologies, Inc, USA: Risk M, Bril V, Broadbridge C, Cohen A. Heart rate variability measurement in diabetic neuropathy: review of methods.Diabetes Technol Ther. 2001 Spring;3(1):63-76. doi: 10.1089/152091501750220028.
  • Confirmation of HRV effectiveness as a diagnostic method for diabetic autonomic neuropathy in children, University of Milan, Italy: Chessa M, Butera G, Lanza GA, Bossone E, Delogu A, De Rosa G, Marietti G, Rosti L, Carminati M. Role of heart rate variability in the early diagnosis of diabetic autonomic neuropathy in children. Herz. 2002 Dec;27(8):785-90. doi: 10.1007/s00059 -002-2340-4.
  • A 10-year study on HRV analysis as a method to assess heart transplant patients’ health status, Catholic University of Leuven, Belgium: Véronique A. Cornelissen, Johan Vanhaecke, André E. Aubert, Robert H. Fagard. Heart rate variability after heart transplantation: A 10-year longitudinal follow-up study. Journal of Cardiology Volume 59, Issue 2, March 2012, Pages 220–224. doi: 10.1016/j.jjcc.2011.12.002.
  • Confirmation of the link between HRV decline and mortality level rise after myocardial infarction (3489 subjects), meta-analysis, Catholic University of the Sacred Hearth, Italy: Buccelletti E, Gilardi E, Scaini E, Galiuto L, Persiani R, Biondi A, Basile F, Silveri NG. Heart rate variability and myocardial infarction: systematic literature review and metanalysis. Eur Rev Med Pharmacol Sci. 2009 Jul-Aug;13(4):299-307. PubMed
  • Confirmation of the correlation between patients’ mortality risks and changes in HRV, University of Ottawa, Canada: Saif Ahmad, Anjali Tejuja, Kimberley D Newman, Ryan Zarychanski, Andrew Seely. Clinical review: A review and analysis of heart rate variability and the diagnosis and prognosis of infection. Critical Care200913:23 doi: 10.1186/cc8132.
  • Correlation between diabetes and HRV, Sergipe University, Brazil: Almeida-Santos MA, Barreto-Filho JA, Oliveira JL, Reis FP, da Cunha Oliveira CC, Sousa AC. Aging, heart rate variability and patterns of autonomic regulation of the heart.Arch Gerontol Geriatr. 2016 Mar-Apr;63:1-8. doi: 10.1016/j.archger.2015.11.011.
  • Confirmation of HRV analysis effectiveness in health status assessment after head injuries: Saif Ahmad, Anjali Tejuja, Kimberley D Newman, Ryan Zarychanski, Andrew Seely. Clinical review: A review and analysis of heart rate variability and the diagnosis and prognosis of infection. Critical Care200913:23 doi: 10.1089/neu.2015.3989.
  • Confirmation of some HRV indeces use for life expectancy prognosis in incurable cancer patients: Korea University College of Medicine, Seoul, South Korea: Do Hoon Kim,Jeong A Kim,Youn Seon Choi,Su Hyun Kim,June Young Lee, Young Eun Kim. Heart Rate Variability and Length of Survival in Hospice Cancer Patients. J Korean Med Sci. 2010 Aug;25(8):1140-1145. English. doi: 10.3346/jkms.2010.25.8.1140.

3.3.3. Medication

Research on the impact of various medicines on HRV helps find the most effective drugs for particular diseases. It is also essential to clinical trials.

Sources:

  • Investigation into angiotensin inhibitor (captopropil) and blocker (valsartan) drugs in healthy men using HRV analysis, Turkey: Dayimi Kaya, Ali Metin Esen, İrfan Barutçu, Ataç Çelik, Celal Kilit, Ersel Onra. Comparison of the Effects of Captopril and Valsartan on Heart Rate Variability in Healthy Men. Turk Kardiyol Dern Ars. 2003; 31(6): 338-346. Archives of the Turkish Society of Cardiology
  • Investigation into the effects of antidepressants and quetiapine on HRV, College of Medicine, National Taiwan University, Taiwan: Huang WL, Liao SC, Kuo TB, Chang LR, Chen TT, Chen IM, Yang CC. The Effects of Antidepressants and Quetiapine on Heart Rate Variability. Pharmacopsychiatry. 2016 Sep;49(5):191-198.doi: 10.1055/s-0042-102964.
  • A study on the effects of levodopa on heart rate variability in patients with Parkinson’s disease, Huanhu Hospital, China: Meng L, Dunckley ED, Xu X. Effects of a single dose levodopa on heart rate variability in Parkinson’s disease. Zhonghua Yi Xue Za Zhi. 2015 Feb 17;95(7):493-5. PubMed

3.4. Heart rate variability and lifestyle

The last but not least among important heart rate variability factors is lifestyle. HRV analysis and the possibility of taking measurements without EKG equipment can precisely assess the impact of a person’s diet, habits and other aspects of their lifestyle on their health.

3.4.1. Food

Diet plays a key role in muscle tissue development, hormone status and bone structure as well as in the functioning of the whole body. Analysing your diet using HRV helps you understand what vitamins, supplements and products are best for you.

Sources:

  • A study on the effects of vitamin E and coenzyme Q10 through HRV analysis, Moradabad and Subharti Medical College, India: Singh RB, Weydahl A, Otsuka K, Watanabe Y, Yano S, Mori H, Ichimaru Y, Mitsutake G, Sato Y, Fanghong L, Zhao ZY, Kartik C, Gvozdjakova A.Can nutrition influence circadian rhythm and heart rate variability? Biomed Pharmacother. 2001;55 Suppl 1:115s-124s. PubMed
  • Using heart rate variability analysis to study the impact of diet on health, Elon University, USA: Olivia A. Murray, Proceedings of The National Conference On Undergraduate Research (NCUR) 2016 University of North Carolina Asheville Asheville, North Carolina. April 7-9, 2016. PDF
  • Confirmation of the correlation between fatty acid consumption and HRV (a study with 60 volunteers), Hjørring/Brønderslev Hospital, Denmark: Jeppe Hagstrup Christensen, Merete Stubkjœr Christensen, Jørn Dyerberg, and Erik Berg Schmidt, Heart rate variability and fatty acid content of blood cell membranes: a dose-response study with n−3 fatty acids1,2,3. 1999 American Society for Clinical Nutrition. The American Journal of Clinical Nutrition
  • The effect of fish oil on heart rate variability in survivors of myocardial infarction, Aalborg Hospital, Denmark: Jeppe Hagstrup Christensen, Peter Gustenhoff, Eva Korup, Jens Aaroe, Egon Toft, Torn Moller, Klaus Rasmussen, Jorn Dyerberg, Erik Berg Schmidt, Effect of fish oil on heart rate variability in survivors of myocardial infarction: a double blind randomised controlled trial.BMJ 1996; 312 doi: 10.1136/bmj.312.7032.677.

3.4.2. Bad habits

HRV can also be a reliable method for researching the impact of bad habits on health. Smoking, alcohol consumption and coffee abuse affect heart rate and decrease the overall HRV or some of its indices.

Sources:

  • Confirmation of the impact of alcohol consumption on heart rate using HRV, Helsinki University Central Hospital, Finland: Koskinen P, Virolainen J, Kupari M. Acute alcohol intake decreases short-term heart rate variability in healthy subjects. Clin Sci (Lond). 1994 Aug;87(2):225-30. PubMed
  • Revealing a potential link between alcohol consumption and arrhythmia using HRV, The Otto von Guericke University Magdeburg, Germany: Frank Weise, Dieter Krell, Norbert Brinkhoff, Acute alcohol ingestion reduces heart rate variability. Drug and alcohol dependence May 1986Volume 17, Issue 1, Pages 89–91. doi: 10.1016/0376-8716(86)90040-2.
  • Confirmation of adverse effects of nicotine and alcohol addiction on HRV, Turkey: Yuksel R, Yuksel RN, Sengezer T, Dane S. Autonomic Cardiac Activity in Patients with Smoking and Alcohol Addiction by Heart Rate Variability Analysis.Clin Invest Med. 2016 Dec 1;39(6):27519. PubMed
  • Using HRV to reveal the impact of coffee consumption on recovery after physical exercise, The University of Illinois, USA: Bunsawat K, White DW, Kappus RM, Baynard T. Caffeine delays autonomic recovery following acute exercise. Eur J Prev Cardiol. 2015 Nov;22(11):1473-9. doi: 10.1177/2047487314554867.

3.4.3. Weight control

Lack of control over your own weight also has a substantial impact on the state of your health, which has been repeatedly proven using HRV analysis.

Sources:

  • Confirmation of the impact of excess weight on HRV in a study with 16275 people, the University of Jyväskylä, the University of Tampere, Finland: Föhr T, Pietilä J, Helander E, Myllymäki T, Lindholm H, Rusko H, Kujala UM. Physical activity, body mass index and heart rate variability-based stress and recovery in 16 275 Finnish employees: a cross-sectional study. BMC Public Health. 2016 Aug 2;16:701. doi: 10.1186/s12889-016-3391-4.
  • Using HRV analysis to confirm the negative impact of excess weight on the heart, Sahlgrenska University Hospital, Sweden: Karason K, Mølgaard H, Wikstrand J, Sjöström L. Heart rate variability in obesity and the effect of weight loss. Am J Cardiol. 1999 Apr 15;83(8):1242-7. PubMed
  • Using HRV analysis to confirm the positive effect of weight loss on the autonomous nervous system in children, University of Tübingen, Germany, Clemson University, USA: Mazurak N1, Sauer H, Weimer K, Dammann D, Zipfel S, Horing B, Muth ER, Teufel M, Enck P, Mack I. Effect of a weight reduction program on baseline and stress-induced heart rate variability in children with obesity. Obesity (Silver Spring). 2016 Feb;24(2):439-45. doi: 10.1002/oby.21355.

4. Conclusion

At Welltory, we assess our users’ health and lifestyle factors in accordance with scientific studies on heart rate variability. We consider heart rate variability analysis to be the most effective and evidence-based non-invasive method of health assessment when the body is healthy.

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