{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,20]],"date-time":"2026-05-20T14:11:52Z","timestamp":1779286312743,"version":"3.51.4"},"reference-count":82,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2023,5,30]],"date-time":"2023-05-30T00:00:00Z","timestamp":1685404800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Fundaci\u00f3n Gonzalo R\u00edo Arronte"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>Most COVID-19 survivors report experiencing at least one persistent symptom after recovery, including sympathovagal imbalance. Relaxation techniques based on slow-paced breathing have proven to be beneficial for cardiovascular and respiratory dynamics in healthy subjects and patients with various diseases. Therefore, the present study aimed to explore the cardiorespiratory dynamics by linear and nonlinear analysis of photoplethysmographic and respiratory time series on COVID-19 survivors under a psychophysiological assessment that includes slow-paced breathing. We analyzed photoplethysmographic and respiratory signals of 49 COVID-19 survivors to assess breathing rate variability (BRV), pulse rate variability (PRV), and pulse\u2013respiration quotient (PRQ) during a psychophysiological assessment. Additionally, a comorbidity-based analysis was conducted to evaluate group changes. Our results indicate that all BRV indices significantly differed when performing slow-paced breathing. Nonlinear parameters of PRV were more appropriate for identifying changes in breathing patterns than linear indices. Furthermore, the mean and standard deviation of PRQ exhibited a significant increase while sample and fuzzy entropies decreased during diaphragmatic breathing. Thus, our findings suggest that slow-paced breathing may improve the cardiorespiratory dynamics of COVID-19 survivors in the short term by enhancing cardiorespiratory coupling via increased vagal activity.<\/jats:p>","DOI":"10.3390\/e25060874","type":"journal-article","created":{"date-parts":[[2023,5,31]],"date-time":"2023-05-31T04:40:51Z","timestamp":1685508051000},"page":"874","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Induced Relaxation Enhances the Cardiorespiratory Dynamics in COVID-19 Survivors"],"prefix":"10.3390","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-9891-2213","authenticated-orcid":false,"given":"Alejandra Margarita","family":"S\u00e1nchez-Sol\u00eds","sequence":"first","affiliation":[{"name":"School of Medicine, Universidad Aut\u00f3noma del Estado de M\u00e9xico (UAEM\u00e9x), Toluca de Lerdo 50180, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0944-8878","authenticated-orcid":false,"given":"Viridiana","family":"Pel\u00e1ez-Hern\u00e1ndez","sequence":"additional","affiliation":[{"name":"Cardiology Service, Instituto Nacional de Enfermedades Respiratorias Ismael Cos\u00edo Villegas (INER), Mexico City 14080, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Laura Mercedes","family":"Santiago-Fuentes","sequence":"additional","affiliation":[{"name":"School of Medicine, Universidad Aut\u00f3noma del Estado de M\u00e9xico (UAEM\u00e9x), Toluca de Lerdo 50180, Mexico"},{"name":"Health Sciences Department, Universidad Aut\u00f3noma Metropolitana Unidad Iztapalapa (UAM-I), Mexico City 09340, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Guadalupe Lizzbett","family":"Luna-Rodr\u00edguez","sequence":"additional","affiliation":[{"name":"Cardiology Service, Instituto Nacional de Enfermedades Respiratorias Ismael Cos\u00edo Villegas (INER), Mexico City 14080, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5361-5007","authenticated-orcid":false,"given":"Jos\u00e9 Javier","family":"Reyes-Lagos","sequence":"additional","affiliation":[{"name":"School of Medicine, Universidad Aut\u00f3noma del Estado de M\u00e9xico (UAEM\u00e9x), Toluca de Lerdo 50180, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Arturo","family":"Orea-Tejeda","sequence":"additional","affiliation":[{"name":"Cardiology Service, Instituto Nacional de Enfermedades Respiratorias Ismael Cos\u00edo Villegas (INER), Mexico City 14080, Mexico"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,5,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"754","DOI":"10.1021\/acs.molpharmaceut.0c00608","article-title":"COVID-19 Transmission, Current Treatment, and Future Therapeutic Strategies","volume":"18","author":"Salian","year":"2021","journal-title":"Mol. Pharm."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"3586","DOI":"10.1016\/j.sjbs.2022.02.006","article-title":"The Impact of COVID-19 On Comorbidities: A Review Of Recent Updates For Combating It","volume":"29","author":"Ahmed","year":"2022","journal-title":"Saudi J. Biol. Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"533","DOI":"10.1016\/S1473-3099(20)30120-1","article-title":"An Interactive Web-Based Dashboard to Track COVID-19 in Real Time","volume":"20","author":"Dong","year":"2020","journal-title":"Lancet Infect. Dis."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"e12998","DOI":"10.1111\/sji.12998","article-title":"Coronavirus Disease 2019 (COVID-19): An Overview of the Immunopathology, Serological Diagnosis and Management","volume":"93","author":"Anka","year":"2021","journal-title":"Scand. J. Immunol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"711616","DOI":"10.3389\/fpubh.2021.711616","article-title":"COVID-19: Pulmonary and Extra Pulmonary Manifestations","volume":"9","author":"Elrobaa","year":"2021","journal-title":"Front. Public Health"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"46","DOI":"10.1016\/j.ajem.2022.01.028","article-title":"Clinical Update on COVID-19 for the Emergency Clinician: Presentation and Evaluation","volume":"54","author":"Long","year":"2022","journal-title":"Am. J. Emerg. Med."},{"key":"ref_7","unstructured":"(2020). COVID-19 Rapid Guideline: Managing the Long-Term Effects of COVID-19, National Institute for Health and Care Excellence (NICE). National Institute for Health and Care Excellence: Clinical Guidelines."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"e210830","DOI":"10.1001\/jamanetworkopen.2021.0830","article-title":"Sequelae in Adults at 6 Months After COVID-19 Infection","volume":"4","author":"Logue","year":"2021","journal-title":"JAMA Netw. Open"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"157","DOI":"10.1007\/s15010-021-01669-8","article-title":"Pulmonary Function Impairment of Asymptomatic and Persistently Symptomatic Patients 4 Months after COVID-19 According to Disease Severity","volume":"50","author":"Munker","year":"2022","journal-title":"Infection"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1157","DOI":"10.1093\/eurheartj\/ehac031","article-title":"Long COVID: Post-Acute Sequelae of COVID-19 with a Cardiovascular Focus","volume":"43","author":"Raman","year":"2022","journal-title":"Eur. Heart J."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"C1","DOI":"10.1152\/ajpcell.00375.2021","article-title":"Long-Term Complications of COVID-19","volume":"322","author":"Desai","year":"2022","journal-title":"Am. J. Physiol.-Cell Physiol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1473","DOI":"10.1080\/07853890.2022.2076901","article-title":"Pathophysiology and Mechanism of Long COVID: A Comprehensive Review","volume":"54","author":"Chalon","year":"2022","journal-title":"Ann. Med."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"692","DOI":"10.1007\/s11239-021-02549-6","article-title":"Autonomic Dysfunction in SARS-CoV-2 Infection Acute and Long-Term Implications COVID-19 Editor\u2019s Page Series","volume":"52","author":"Becker","year":"2021","journal-title":"J. Thromb. Thrombolysis"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"175909142110576","DOI":"10.1177\/17590914211057635","article-title":"COVID-19-Induced Dysautonomia: A Menace of Sympathetic Storm","volume":"13","author":"Qusti","year":"2021","journal-title":"ASN Neuro"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"16144","DOI":"10.1038\/s41598-021-95565-8","article-title":"More than 50 Long-Term Effects of COVID-19: A Systematic Review and Meta-Analysis","volume":"11","author":"Perelman","year":"2021","journal-title":"Sci. Rep."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"14042","DOI":"10.1038\/s41598-021-93546-5","article-title":"Clinical Characterization of Dysautonomia in Long COVID-19 Patients","volume":"11","author":"Barizien","year":"2021","journal-title":"Sci. Rep."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"103071","DOI":"10.1016\/j.autrev.2022.103071","article-title":"The Autonomic Aspects of the Post-COVID19 Syndrome","volume":"21","author":"Dotan","year":"2022","journal-title":"Autoimmun. Rev."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"6167","DOI":"10.1007\/s10072-022-06350-y","article-title":"Autonomic and Neuropathic Complaints of Long-COVID Objectified: An Investigation from Electrophysiological Perspective","volume":"43","author":"Ser","year":"2022","journal-title":"Neurol. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Charleston-Villalobos, S., Reulecke, S., Voss, A., Azimi-Sadjadi, M.R., Gonz\u00e1lez-Camarena, R., Gait\u00e1n-Gonz\u00e1lez, M.J., Gonz\u00e1lez-Hermosillo, J.A., Hern\u00e1ndez-Pacheco, G., Schulz, S., and Aljama-Corrales, T. (2019). Time-Frequency Analysis of Cardiovascular and Cardiorespiratory Interactions During Orthostatic Stress by Extended Partial Directed Coherence. Entropy, 21.","DOI":"10.3390\/e21050468"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"834056","DOI":"10.3389\/fnetp.2022.834056","article-title":"Effects of Supplemental Oxygen on Cardiovascular and Respiratory Interactions by Extended Partial Directed Coherence in Idiopathic Pulmonary Fibrosis","volume":"2","author":"Voss","year":"2022","journal-title":"Front. Netw. Physiol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"122","DOI":"10.1016\/j.ijcard.2009.09.543","article-title":"The Relationship of Autonomic Imbalance, Heart Rate Variability and Cardiovascular Disease Risk Factors","volume":"141","author":"Thayer","year":"2010","journal-title":"Int. J. Cardiol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"371","DOI":"10.3389\/fphys.2019.00371","article-title":"The Pulse-Respiration Quotient: A Powerful but Untapped Parameter for Modern Studies About Human Physiology and Pathophysiology","volume":"10","author":"Scholkmann","year":"2019","journal-title":"Front. Physiol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"101","DOI":"10.22201\/fpsi.20074719e.2018.2.09","article-title":"Efectos Psicofisiol\u00f3gicos de La Respiraci\u00f3n Diafragm\u00e1tica y La Estimulaci\u00f3n T\u00e9rmica Sobre La Actividad Auton\u00f3mica Del Estr\u00e9s Agudo","volume":"8","year":"2018","journal-title":"Acta Investig. Psicol\u00f3gica"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1367","DOI":"10.11124\/JBISRIR-2017-003477","article-title":"Effectiveness of Diaphragmatic Breathing on Physiological and Psychological Stress in Adults: A Quantitative Systematic Review Protocol","volume":"16","author":"Hopper","year":"2018","journal-title":"JBI Database Syst. Rev. Implement. Rep."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"345","DOI":"10.1007\/s10484-022-09546-2","article-title":"Evaluation of Heart Rate Variability and Application of Heart Rate Variability Biofeedback: Toward Further Research on Slow-Paced Abdominal Breathing in Zen Meditation","volume":"47","author":"Sakakibara","year":"2022","journal-title":"Appl. Psychophysiol. Biofeedback"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"638","DOI":"10.4103\/ijmr.IJMR_559_19","article-title":"Effect of Slow Breathing on Autonomic Tone & Baroreflex Sensitivity in Yoga Practitioners","volume":"152","author":"Anasuya","year":"2020","journal-title":"Indian J. Med. Res."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"874","DOI":"10.3389\/fpsyg.2017.00874","article-title":"The Effect of Diaphragmatic Breathing on Attention, Negative Affect and Stress in Healthy Adults","volume":"8","author":"Ma","year":"2017","journal-title":"Front. Psychol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"256","DOI":"10.1017\/ipm.2020.38","article-title":"The Benefits of Meditation and Mindfulness Practices during Times of Crisis Such as COVID-19","volume":"37","author":"Behan","year":"2020","journal-title":"Ir. J. Psychol. Med."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"104576","DOI":"10.1016\/j.neubiorev.2022.104576","article-title":"Heart Rate Variability and Slow-Paced Breathing:When Coherence Meets Resonance","volume":"135","author":"Laborde","year":"2022","journal-title":"Neurosci. Biobehav. Rev."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"104711","DOI":"10.1016\/j.neubiorev.2022.104711","article-title":"Effects of Voluntary Slow Breathing on Heart Rate and Heart Rate Variability: A Systematic Review and a Meta-Analysis","volume":"138","author":"Laborde","year":"2022","journal-title":"Neurosci. Biobehav. Rev."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"e066044","DOI":"10.1136\/bmjopen-2022-066044","article-title":"HEART Rate Variability Biofeedback for Long COVID Symptoms (HEARTLOC): Protocol for a Feasibility Study","volume":"12","author":"Corrado","year":"2022","journal-title":"BMJ Open"},{"key":"ref_32","unstructured":"Pel\u00e1ez-Hern\u00e1ndez, V., Luna-Rodr\u00edguez, G.L., Orea-Tejeda, A., Mora-Gallegos, J., Keirns-Davis, C., and Gonz\u00e1lez-Islas, D. (2021). Heart Rate Variability Disturbances and Biofeedback Treatment in COVID-19 Survivors. E-J. Cardiol. Pract., 21, Available online: https:\/\/www.escardio.org\/Journals\/E-Journal-of-Cardiology-Practice\/Volume-21\/heart-rate-variability-disturbances-and-biofeedback-treatment-in-covid-19-surviv."},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Rojas, M. (2016). Handbook of Happiness Research in Latin America, Springer.","DOI":"10.1007\/978-94-017-7203-7"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"van Goor, H.M.R., van Loon, K., Breteler, M.J.M., Kalkman, C.J., and Kaasjager, K.A.H. (2022). Circadian Patterns of Heart Rate, Respiratory Rate and Skin Temperature in Hospitalized COVID-19 Patients. PLoS ONE, 17.","DOI":"10.1371\/journal.pone.0268065"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"683","DOI":"10.1111\/j.1469-7793.2000.00683.x","article-title":"An Endogenous Circadian Rhythm of Respiratory Control in Humans","volume":"526","author":"Spengler","year":"2000","journal-title":"J. Physiol."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Voss, A., Schroeder, R., Heitmann, A., Peters, A., and Perz, S. (2015). Short-Term Heart Rate Variability\u2014Influence of Gender and Age in Healthy Subjects. PLoS ONE, 10.","DOI":"10.1371\/journal.pone.0118308"},{"key":"ref_37","unstructured":"The MathWorks Inc. (2023, February 07). Signal Processing Toolbox 2022. Available online: https:\/\/www.mathworks.com\/products\/signal.html."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"45","DOI":"10.4103\/ijoy.IJOY_27_17","article-title":"Breath Rate Variability: A Novel Measure to Study the Meditation Effects","volume":"12","author":"Soni","year":"2019","journal-title":"Int. J. Yoga"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"07TR01","DOI":"10.1088\/1361-6579\/ab998c","article-title":"Pulse Rate Variability in Cardiovascular Health: A Review on Its Applications and Relationship with Heart Rate Variability","volume":"41","author":"May","year":"2020","journal-title":"Physiol. Meas."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1186\/s40101-020-00233-x","article-title":"Pulse Rate Variability: A New Biomarker, Not a Surrogate for Heart Rate Variability","volume":"39","author":"Yuda","year":"2020","journal-title":"J. Physiol. Anthropol."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"210","DOI":"10.1016\/j.cmpb.2013.07.024","article-title":"Kubios HRV\u2014Heart Rate Variability Analysis Software","volume":"113","author":"Tarvainen","year":"2014","journal-title":"Comput. Methods Programs Biomed."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"258","DOI":"10.3389\/fpubh.2017.00258","article-title":"An Overview of Heart Rate Variability Metrics and Norms","volume":"5","author":"Shaffer","year":"2017","journal-title":"Front. Public Health"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"H2039","DOI":"10.1152\/ajpheart.2000.278.6.H2039","article-title":"Physiological Time-Series Analysis Using Approximate Entropy and Sample Entropy","volume":"278","author":"Richman","year":"2000","journal-title":"Am. J. Physiol.-Heart Circ. Physiol."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"981","DOI":"10.3389\/fphys.2020.00981","article-title":"Entropy Analysis of RR-Time Series From Stress Tests","volume":"11","year":"2020","journal-title":"Front. Physiol."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"206","DOI":"10.3389\/fnhum.2017.00206","article-title":"Sample Entropy, Univariate, and Multivariate Multi-Scale Entropy in Comparison with Classical Postural Sway Parameters in Young Healthy Adults","volume":"11","author":"Hansen","year":"2017","journal-title":"Front. Hum. Neurosci."},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Kamath, M.V., Watanabe, M., and Upton, A. (2016). Heart Rate Variability (HRV) Signal Analysis: Clinical Applications, Chapman and Hall\/CRC. [1st ed.].","DOI":"10.1201\/b12756"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"266","DOI":"10.1109\/TNSRE.2007.897025","article-title":"Characterization of Surface EMG Signal Based on Fuzzy Entropy","volume":"15","author":"Chen","year":"2007","journal-title":"IEEE Trans. Neural Syst. Rehabil. Eng."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"301","DOI":"10.1016\/S0019-9958(72)90199-4","article-title":"A Definition of a Nonprobabilistic Entropy in the Setting of Fuzzy Sets Theory","volume":"20","author":"Termini","year":"1972","journal-title":"Inf. Control"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1016\/j.medengphy.2008.04.005","article-title":"Measuring Complexity Using FuzzyEn, ApEn, and SampEn","volume":"31","author":"Chen","year":"2009","journal-title":"Med. Eng. Phys."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"105718","DOI":"10.1016\/j.cmpb.2020.105718","article-title":"PyBioS: A Freeware Computer Software for Analysis of Cardiovascular Signals","volume":"197","author":"Silva","year":"2020","journal-title":"Comput. Methods Programs Biomed."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"e001070","DOI":"10.1136\/bmjresp-2021-001070","article-title":"Measurement of Breathing in Patients with Post-COVID-19 Using Structured Light Plethysmography (SLP)","volume":"8","author":"Alhuthail","year":"2021","journal-title":"BMJ Open Respir. Res."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"397","DOI":"10.3389\/fnhum.2018.00397","article-title":"Breath of Life: The Respiratory Vagal Stimulation Model of Contemplative Activity","volume":"12","author":"Gerritsen","year":"2018","journal-title":"Front. Hum. Neurosci."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"353","DOI":"10.3389\/fnhum.2018.00353","article-title":"How Breath-Control Can Change Your Life: A Systematic Review on Psychophysiological Correlates of Slow Breathing","volume":"12","author":"Zaccaro","year":"2018","journal-title":"Front. Hum. Neurosci."},{"key":"ref_54","doi-asserted-by":"crossref","unstructured":"You, M., Laborde, S., Zammit, N., Iskra, M., Borges, U., and Dosseville, F. (2021). Single Slow-Paced Breathing Session at Six Cycles per Minute: Investigation of Dose-Response Relationship on Cardiac Vagal Activity. Int. J. Environ. Res. Public. Health, 18.","DOI":"10.3390\/ijerph182312478"},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"e0639","DOI":"10.1097\/MD.0000000000010639","article-title":"Effects of Slow Breathing Rate on Heart Rate Variability and Arterial Baroreflex Sensitivity in Essential Hypertension","volume":"97","author":"Li","year":"2018","journal-title":"Medicine"},{"key":"ref_56","doi-asserted-by":"crossref","unstructured":"Shanks, J., and Ramchandra, R. (2021). Angiotensin II and the Cardiac Parasympathetic Nervous System in Hypertension. Int. J. Mol. Sci., 22.","DOI":"10.3390\/ijms222212305"},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"104451","DOI":"10.1016\/j.phrs.2019.104451","article-title":"Microglia, Autonomic Nervous System, Immunity and Hypertension: Is There a Link?","volume":"155","author":"Li","year":"2020","journal-title":"Pharmacol. Res."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"e12916","DOI":"10.1111\/anec.12916","article-title":"Altered Cardiac Autonomic Function after Recovery from COVID-19","volume":"27","author":"Afsin","year":"2022","journal-title":"Ann. Noninvasive Electrocardiol."},{"key":"ref_59","doi-asserted-by":"crossref","unstructured":"Baji\u0107, D., \u0110aji\u0107, V., and Milovanovi\u0107, B. (2021). Entropy Analysis of COVID-19 Cardiovascular Signals. Entropy, 23.","DOI":"10.3390\/e23010087"},{"key":"ref_60","first-page":"317","article-title":"Nonlinear Methods to Assess Changes in Heart Rate Variability in Type 2 Diabetic Patients","volume":"101","author":"Roy","year":"2013","journal-title":"Arq. Bras. Cardiol."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"24","DOI":"10.3389\/fphys.2020.00024","article-title":"Slow 0.1 Hz Breathing and Body Posture Induced Perturbations of RRI and Respiratory Signal Complexity and Cardiorespiratory Coupling","volume":"11","author":"Kalauzi","year":"2020","journal-title":"Front. Physiol."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"946613","DOI":"10.3389\/fphys.2022.946613","article-title":"Pulse Respiration Quotient as a Measure Sensitive to Changes in Dynamic Behavior of Cardiorespiratory Coupling Such as Body Posture and Breathing Regime","volume":"13","author":"Kalauzi","year":"2022","journal-title":"Front. Physiol."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"75949","DOI":"10.1109\/ACCESS.2019.2920911","article-title":"Effects of Different Interventions on Cardiac Regulation Using Fuzzy Entropy","volume":"7","author":"Tian","year":"2019","journal-title":"IEEE Access"},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"591","DOI":"10.3389\/fnins.2018.00591","article-title":"Cardiac Autonomic Neuropathy in Diabetes: A Predictor of Cardiometabolic Events","volume":"12","author":"Vinik","year":"2018","journal-title":"Front. Neurosci."},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"251","DOI":"10.14797\/mdcj-14-4-251","article-title":"Cardiac Autonomic Neuropathy in Diabetes Mellitus","volume":"14","author":"Agashe","year":"2018","journal-title":"Methodist DeBakey Cardiovasc. J."},{"key":"ref_66","doi-asserted-by":"crossref","unstructured":"Benichou, T., Pereira, B., Mermillod, M., Tauveron, I., Pfabigan, D., Maqdasy, S., and Dutheil, F. (2018). Heart Rate Variability in Type 2 Diabetes Mellitus: A Systematic Review and Meta\u2013Analysis. PLoS ONE, 13.","DOI":"10.1371\/journal.pone.0195166"},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"e121020186816","DOI":"10.2174\/1573399816999201012200109","article-title":"Important Role of Relaxation Techniques in Immune Functions, Glycemic Control, and Stress in Diabetic Patients with COVID-19: A Review","volume":"17","author":"Mohamed","year":"2021","journal-title":"Curr. Diabetes Rev."},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"24","DOI":"10.1590\/s1806-37562017000000086","article-title":"Complexity of Autonomic Nervous System Function in Individuals with COPD","volume":"44","author":"Vanzella","year":"2018","journal-title":"J. Bras. Pneumol."},{"key":"ref_69","doi-asserted-by":"crossref","unstructured":"Hamasaki, H. (2020). Effects of Diaphragmatic Breathing on Health: A Narrative Review. Medicines, 7.","DOI":"10.3390\/medicines7100065"},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"772","DOI":"10.5603\/CJ.a2019.0002","article-title":"Slow Breathing Improves Cardiovascular Reactivity to Mental Stress and Health-Related Quality of Life in Heart Failure Patients with Reduced Ejection Fraction","volume":"27","author":"Lachowska","year":"2020","journal-title":"Cardiol. J."},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"48","DOI":"10.1007\/s00392-018-1310-7","article-title":"Long-Term Effects of Device-Guided Slow Breathing in Stable Heart Failure Patients with Reduced Ejection Fraction","volume":"108","author":"Lachowska","year":"2019","journal-title":"Clin. Res. Cardiol."},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"573325","DOI":"10.3389\/fphys.2020.573325","article-title":"Slow-Paced Breathing and Autonomic Function in People Post-Stroke","volume":"11","author":"Larson","year":"2020","journal-title":"Front. Physiol."},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"927058","DOI":"10.3389\/frvir.2022.927058","article-title":"Prevalence of Post-Traumatic Stress Disorder, Emotional Impairments, and Fear in COVID-19 Surviving Patients","volume":"3","year":"2022","journal-title":"Front. Virtual Real."},{"key":"ref_74","doi-asserted-by":"crossref","first-page":"2387","DOI":"10.1007\/s11136-022-03081-7","article-title":"Short-Term Impact of COVID-19 on Quality of Life, Perceived Stress, and Serious Psychological Distress in an Adult Population in the Midwest United States","volume":"31","author":"Egede","year":"2022","journal-title":"Qual. Life Res."},{"key":"ref_75","doi-asserted-by":"crossref","first-page":"601","DOI":"10.1038\/s41591-021-01283-z","article-title":"Post-Acute COVID-19 Syndrome","volume":"27","author":"Nalbandian","year":"2021","journal-title":"Nat. Med."},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"1095249","DOI":"10.3389\/fmed.2022.1095249","article-title":"Cardiovascular and Autonomic Dysfunction in Long-COVID Syndrome and the Potential Role of Non-Invasive Therapeutic Strategies on Cardiovascular Outcomes","volume":"9","author":"Allendes","year":"2023","journal-title":"Front. Med."},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"102750","DOI":"10.1016\/j.ctim.2021.102750","article-title":"Heart Rate Variability Biofeedback in Chronic Disease Management: A Systematic Review","volume":"60","author":"Chouchou","year":"2021","journal-title":"Complement. Ther. Med."},{"key":"ref_78","doi-asserted-by":"crossref","first-page":"756","DOI":"10.3389\/fpsyg.2014.00756","article-title":"Heart Rate Variability Biofeedback: How and Why Does It Work?","volume":"5","author":"Lehrer","year":"2014","journal-title":"Front. Psychol."},{"key":"ref_79","doi-asserted-by":"crossref","first-page":"110","DOI":"10.5298\/1081-5937-41.3.01","article-title":"The Promise of Heart Rate Variability Biofeedback: Evidence-Based Applications","volume":"41","author":"Gevirtz","year":"2013","journal-title":"Biofeedback"},{"key":"ref_80","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1016\/j.psyneuen.2019.01.016","article-title":"Impact of Mental Stress, the Circadian System and Their Interaction on Human Cardiovascular Function","volume":"103","author":"Scheer","year":"2019","journal-title":"Psychoneuroendocrinology"},{"key":"ref_81","doi-asserted-by":"crossref","first-page":"1040","DOI":"10.3389\/fpsyg.2014.01040","article-title":"A Healthy Heart Is Not a Metronome: An Integrative Review of the Heart\u2019s Anatomy and Heart Rate Variability","volume":"5","author":"Shaffer","year":"2014","journal-title":"Front. Psychol."},{"key":"ref_82","doi-asserted-by":"crossref","first-page":"2578","DOI":"10.1017\/S0033291717001003","article-title":"The Effect of Heart Rate Variability Biofeedback Training on Stress and Anxiety: A Meta-Analysis","volume":"47","author":"Goessl","year":"2017","journal-title":"Psychol. Med."}],"container-title":["Entropy"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1099-4300\/25\/6\/874\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T19:45:02Z","timestamp":1760125502000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1099-4300\/25\/6\/874"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,5,30]]},"references-count":82,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2023,6]]}},"alternative-id":["e25060874"],"URL":"https:\/\/doi.org\/10.3390\/e25060874","relation":{},"ISSN":["1099-4300"],"issn-type":[{"value":"1099-4300","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,5,30]]}}}