A predictive model of the psychophysiological state of students with an analysis of anxiety and cardiorespiratory coordination: A pilot study
DOI:
https://doi.org/10.33910/2687-0223-2025-7-3-216-226Keywords:
students, clinoorthostatic test, cardiorespiratory coordination, anxiety, psychophysiological stateAbstract
High school students and first-year university students are highly susceptible to psycho-emotional stress. Compared to the general population, their anxiety levels are significantly elevated, especially during the pre-exam period. Prolonged stress can lead to dysregulation of cardiac and respiratory rhythms and an increased risk of developing cardiovascular and other diseases. This underscores the importance of developing programs to prevent morbidity and maintain the health of school and university students. One promising approach is the creation of predictive models for assessing the psychophysiological state of individuals.
This study aims to evaluate the possibility of creating a predictive model of physiological and psychometric indicators of students at the end of a semester based on psychophysiological data obtained at the beginning of the semester.
A longitudinal study was conducted involving 150 students aged 19–20 years. A modified clinoorthostatic test with ECG and respiratory rate recording was performed twice: in September and December. Before the clinoorthostatic test, participants completed the Spielberger–Khanin situational and personal anxiety test. Principal components analysis was performed for each student based on the time series of R-peak frequency of the ECG and respiratory movements in two states (lying and standing). The PLS regression method was used to analyze the relationships between the data matrices.
A model was created to predict the psychophysiological state of undergraduates at the end of a semester based on cardio-respiratory and anxiety measures at the beginning of the semester. The values of the indicators predicted by the PLS regression prior to the exams in December showed a significant correlation with the measured values, demonstrating the possibility of predicting assessment results before the exams based on the screening data collected in September.
References
ЛИТЕРАТУРА
Баевский, Р. М. (1976) Кибернетический анализ процессов управления сердечным ритмом. В кн.: А. М. Чернуха (ред.). Актуальные проблемы физиологии и патологии кровообращения: сборник научных работ, посвященный памяти академика В. В. Парина. М.: Медицина, с. 161–175.
Баевский, Р. М. (1979) Прогнозирование состояний на грани нормы и патологии. М.: Медицина, 298 с.
Баевский, Р. М., Иванов, Г. Г., Гаврилушкин, А. П. и др. (2002) Анализ вариабельности сердечного ритма при использовании различных электрокардиографических систем (часть 1). Вестник аритмологии, № 24, с. 65–86.
Гаврилова, Е. А. (2018) Вариабельность ритма сердца и спорт. СПб.: Институт спорта и здоровья, 186 с.
Гриневич, А. А., Танканаг, А. В., Чемерис, Н. К. (2013) Исследование зависимости амплитудно-частотных спектров сердечного ритма человека от контролируемой частоты дыхания. Математическая биология и биоинформатика, т. 8, № 2, с. 537–552. https://doi.org/10.17537/2013.8.537
Даниченко, М. Ю., Мельник, О. В., Михеев, А. А. и др. (2013) Оценка синхронизированности деятельности сердечно-сосудистой и дыхательной систем организма. Биотехносфера, № 1 (25), с. 2–6.
Ковалева, А. В., Панова, Е. Н., Горбачева, А. К. (2013) Анализ вариабельности ритма сердца и возможности его применения в психологии и психофизиологии. Современная зарубежная психология, т. 2, № 1, с. 35–50.
Кривощеков, С. Г., Николаева, Е. И., Вергунов, Е. Г., Приходько, А. Ю. (2022) Многомерный анализ показателей тормозного и автономного контроля при ортостазе и в эмоциональных ситуациях. Физиология человека, т. 48, № 1, с. 26–37. https://doi.org/10.31857/S0131164621060059
Кривощеков, С. Г., Урюмцев, Д. Ю., Гультяева, В. В., Зинченко, М. И. (2021) Кардио-респираторная координация при острой гипоксии у легкоатлетов-бегунов. Физиология человека, т. 47, № 4, с. 80–90. https://doi.org/10.31857/S0131164621030085
Кубекова, А. С., Абдуллаев, С. С., Сергеева, М. А. (2021) Уровень депрессивности и отношение к депрессии в студенческой среде. Мир науки. Педагогика и психология, т. 9, № 6, статья 15.
Проскурякова, Л. А., Лобыкина, Е. Н. (2017) Структура и оценка эффективности мероприятий системы сохранения здоровья студентов. Гигиена и санитария, т. 96, № 1, с. 79–84. https://doi.org/10.47470/0016-9900-2017-96-1-79-84
Рахимова, Г. К. (2023) Анализ данных заболеваемости студентов в процессе обучения и влияние на успеваемость. Вестник науки и образования, № 4 (135), с. 104–108.
Спицин, А. П., Резцов, О. В., Княжев, И. С. (2025) Корреляции между показателями тревожности и вариабельности сердечного ритма у студентов при интенсивной когнитивной деятельности. Национальный вестник медицинских ассоциаций, т. 2, № 1 (2), с. 31–35.
Ткаченко, А. А., Саитгареева, И. Ф., Кувшин, Е. С. и др. (2020) Исследования уровня тревожности в период экзаменационной сессии. Международный студенческий научный вестник, № 1, статья 18.
Федотова, Г. Г., Пожарова, Г. В., Гераськина, М. А. (2015) Оценка функционального состояния организма студентов на основе анализа вариабельности сердечного ритма. Современные проблемы науки и образования, № 5, статья 697.
Ханин, Ю. Л. (1976) Краткое руководство к шкале реактивной и личностной тревожности Ч. Д. Спилбергера. Л.: ЛНИИТЕК, 18 с.
Шлык, Н. И. (2022) Вариабельность сердечного ритма и методы ее определения у спортсменов в тренировочном процессе. Ижевск: Изд-во Удмуртского государственного университета, 80 с.
Ahmed, I., Hazell, C. M., Edwards, B. et al. (2023) A systematic review and meta-analysis of studies exploring prevalence of non-specific anxiety in undergraduate university students. BMC Psychiatry, vol. 23, no. 1, article 240. https://doi.org/10.1186/s12888-023-04645-8
Balagué, N., González, J., Javierre, C. et al. (2016) Cardiorespiratory coordination after training and detraining. A principal component analysis approach. Frontiers in Physiology, vol. 7, article 35. https://doi.org/10.3389/fphys.2016.00035
Balagué, N., Hristovski, R., Almarcha, M. et al. (2020) Network physiology of exercise: Vision and perspectives. Frontiers in Physiology, vol. 11, article 611550. https://doi.org/10.3389/fphys.2020.611550
Bandara, K. M. E. L. N., Wijesiriwardana, R. (2021) Heart rate variability and breathing rate variability analysis during four limbs exercise. In: 3rd International conference on electrical, control and instrumentation engineering (ICECIE). Kuala Lumpur: [s. n.], pp. 1–5. https://doi.org/10.1109/ICECIE52348.2021.9664687
Chalmers, J. A., Quintana, D. S., Abbott, M. J.-A., Kemp, A. H. (2014) Anxiety disorders are associated with reduced heart rate variability: A meta-analysis. Frontiers in Psychiatry, vol. 5, article 80. https://doi.org/10.3389/fpsyt.2014.00080
Coşkun Şimşek, D., Günay, U. (2023) The effects of stress on adolescents’ school engagement. Journal of Child and Adolescent Psychiatric Nursing, vol. 36, no. 1, pp. 35–43. https://doi.org/10.1111/jcap.12397
Da Silva, C. D., Catai, A. M., de Abreu, R. M. et al. (2023) Cardiorespiratory coupling as an early marker of cardiac autonomic dysfunction in type 2 diabetes mellitus patients. Respiratory Physiology & Neurobiology, vol. 311, article 104042. https://doi.org/10.1016/j.resp.2023.104042
De Abreu, R. M., Cairo, B., Rehder-Santos, P. et al. (2024) Cardiorespiratory coupling is associated with exercise capacity in athletes: A cross-sectional study. Respiratory Physiology & Neurobiology, no. 320, pp. 104198. https://doi.org/10.1016/j.resp.2023.104198
De Abreu, R. M., Porta, A., Rehder-Santos, P. et al. (2022) Cardiorespiratory coupling strength in athletes and non-athletes. Respiratory Physiology & Neurobiology, vol. 305, article 103943. https://doi.org/10.1016/j.resp.2022.103943
Ernst, H., Scherpf, M., Pannasch, S. et al. (2023) Assessment of the human response to acute mental stress — An overview and a multimodal study. PLoS One, vol. 18, no. 11, article e0294069. https://doi.org/10.1371/journal.pone.0294069
Feng, G., Xu, X., Lei, J. (2023) Tracking perceived stress, anxiety, and depression in daily life: A double-downward spiral process. Frontiers in Psychology, vol. 14, article 1114332. https://doi.org/10.3389/fpsyg.2023.1114332
Gronwald, T., Schaffarczyk, M., Hoos, O. (2024) Orthostatic testing for heart rate and heart rate variability monitoring in exercise science and practice. European Journal of applied Physiology, vol. 124, no. 12, pp. 3495–3510. https://doi.org/10.1007/s00421-024-05601-4
Gultyaeva, V. V., Uryumtsev, D. Y., Zinchenko, M. I. et al. (2021) Cardiorespiratory coordination in hypercapnic test before and after high-altitude expedition. Frontiers in Physiology, vol. 12, article 673570. https://doi.org/10.3389/fphys.2021.673570
Igasaki, T., Nagasawa, K., Murayama, N., Hu, Z. (2015) Drowsiness estimation under driving environment by heart rate variability and/or breathing rate variability with logistic regression analysis. In: 8th International conference on biomedical engineering and informatics (BMEI 2015). Shenyang: Institute of Electrical and Electronic Engineers Publ., pp. 189–193. https://doi.org/10.1109/BMEI.2015.7401498
Levine, G. N. (2022) Psychological stress and heart disease: Fact or folklore? The American Journal of Medicine, vol. 135, no. 6, pp. 688–696. https://doi.org/10.1016/j.amjmed.2022.01.053
Li, W., Zhao, Z., Chen, D. et al. (2022) Prevalence and associated factors of depression and anxiety symptoms among college students: A systematic review and meta-analysis. Journal of Child Psychology and Psychiatry, vol. 63, no. 11, pp. 1222–1230. https://doi.org/10.1111/jcpp.13606
Nikolaeva, E. I., Belousova, L. V. (2018) Personality as moderator of aging effects on inhibition functions and brain activity. International Journal of Psychophysiology, vol. 131, no. S, p. S96.
Soni, R., Muniyandi, M. (2019) Breath rate variability: A novel measure to study the meditation effects. International Journal of Yoga, vol. 12, no. 1, pp. 45–54. https://doi.org/10.4103/ijoy.IJOY_27_17
Stromájer, G. P., Csima, M., Iváncsik, R. et al. (2023) Stress and anxiety among high school adolescents: Correlations between physiological and psychological indicators in a longitudinal follow-up study. Children, vol. 10, no. 9, article 1548. https://doi.org/10.3390/children10091548
Tort, A. B. L., Laplagne, D. A., Draguhn, A., Gonzalez, J. (2025) Global coordination of brain activity by the breathing cycle. Nature Reviews. Neuroscience, vol. 26, no. 6, pp. 333–353. https://doi.org/10.1038/s41583-025-00920-7
Van den Bosch, O. F. C., Alvarez-Jimenez, R., de Grooth, H.-J. et al. (2021) Breathing variability — implications for anaesthesiology and intensive care. Critical Care, vol. 25, no. 1, article 280. https://doi.org/10.1186/s13054-021-03716-0
Van Diest, I., Thayer, J. F., Vandeputte, B. et al. (2006) Anxiety and respiratory variability. Physiology and Behavior, vol. 89, no. 2, pp. 189–195. https://doi.org/10.1016/j.physbeh.2006.05.041
REFERENCES
Ahmed, I., Hazell, C. M., Edwards, B. et al. (2023) A systematic review and meta-analysis of studies exploring prevalence of non-specific anxiety in undergraduate university students. BMC Psychiatry, vol. 23, no. 1, article 240. https://doi.org/10.1186/s12888-023-04645-8 (In English)
Baevsky, R. M. (1976) Kiberneticheskij analiz protsessov upravleniya serdechnym ritmom [Cybernetic analysis of heart rate control processes]. In: A. M. Chernukha (ed.). Aktual’nye problemy fiziologii i patologii krovoobrashcheniya: sbornik nauchnykh rabot, posvyashchennyj pamyati akademika V. V. Parina [Actual problems of physiology and pathology of blood circulation: Collection of scientific papers dedicated to the memory of Academician V. V. Parin]. Moscow: Meditsina Publ., pp. 161–175. (In Russian)
Baevsky, R. M. (1979) Prognozirovanie sostoyanij na grani normy i patologii [Predicting conditions on the verge of normality and pathology]. Moscow: Meditsina Publ., 298 p. (In Russian)
Baevsky, R. M., Ivanov, G. G., Gavrilushkin, A. P. et al. (2002) Analiz variabel’nosti serdechnogo ritma pri ispol’zovanii razlichnykh elektrokardiograficheskikh sistem (chast’ 1) [Analysis of heart rate variability using various electrocardiographic systems (part 1)]. Zhurnal aritmologii — Journal of Arrhythmology, no. 24, pp. 65–86. (In Russian)
Balagué, N., González, J., Javierre, C. et al. (2016) Cardiorespiratory coordination after training and detraining. A principal component analysis approach. Frontiers in Physiology, vol. 7, article 35. https://doi.org/10.3389/fphys.2016.00035 (In English)
Balagué, N., Hristovski, R., Almarcha, M. et al. (2020) Network physiology of exercise: Vision and perspectives. Frontiers in Physiology, vol. 11, article 611550. https://doi.org/10.3389/fphys.2020.611550 (In English)
Bandara, K. M. E. L. N., Wijesiriwardana, R. (2021) Heart rate variability and breathing rate variability analysis during four limbs exercise. In: 3rd International conference on electrical, control and instrumentation engineering (ICECIE). Kuala Lumpur: [s. n.], pp. 1–5. https://doi.org/10.1109/ICECIE52348.2021.9664687 (In English)
Chalmers, J. A., Quintana, D. S., Abbott, M. J.-A., Kemp, A. H. (2014) Anxiety disorders are associated with reduced heart rate variability: A meta-analysis. Frontiers in Psychiatry, vol. 5, article 80. https://doi.org/10.3389/fpsyt.2014.00080 (In English)
Coşkun Şimşek, D., Günay, U. (2023) The effects of stress on adolescents’ school engagement. Journal of Child and Adolescent Psychiatric Nursing, vol. 36, no. 1, pp. 35–43. https://doi.org/10.1111/jcap.12397 (In English)
Da Silva, C. D., Catai, A. M., de Abreu, R. M. et al. (2023) Cardiorespiratory coupling as an early marker of cardiac autonomic dysfunction in type 2 diabetes mellitus patients. Respiratory Physiology & Neurobiology, vol. 311, article 104042. https://doi.org/10.1016/j.resp.2023.104042 (In English)
Danichenko, M. Y., Melnik, O. V., Mikheev, A. A. et al. (2013) Otsenka sinkhronizirovannosti deyatel’nosti serdechno-sosudistoj i dykhatel’noj system organizma [Estimation of synchronization in functioning of the cardiovascular and respiratory systems of the body]. Biotekhnosfera, no. 1 (25), pp. 2–6. (In Russian)
De Abreu, R. M., Cairo, B., Rehder-Santos, P. et al. (2024) Cardiorespiratory coupling is associated with exercise capacity in athletes: A cross-sectional study. Respiratory Physiology & Neurobiology, no. 320, pp. 104198. https://doi.org/10.1016/j.resp.2023.104198 (In English)
De Abreu, R. M., Porta, A., Rehder-Santos, P. et al. (2022) Cardiorespiratory coupling strength in athletes and non-athletes. Respiratory Physiology & Neurobiology, vol. 305, article 103943. https://doi.org/10.1016/j.resp.2022.103943 (In English)
Ernst, H., Scherpf, M., Pannasch, S. et al. (2023) Assessment of the human response to acute mental stress — An overview and a multimodal study. PLoS One, vol. 18, no. 11, article e0294069. https://doi.org/10.1371/journal.pone.0294069 (In English)
Fedotova, G. G., Pozharova, G. V., Geraskina, M. A. (2015) Otsenka funktsional’nogo sostoyaniya organizma studentov na osnove analiza variabel’nosti serdechnogo ritma [Evaluation of the functional state of the organism students based heart rate variability analysis]. Sovremennye problemy nauki i obrazovaniya — Modern Problems of Science and Education, no. 5, article 697. (In Russian)
Feng, G., Xu, X., Lei, J. (2023) Tracking perceived stress, anxiety, and depression in daily life: A double-downward spiral process. Frontiers in Psychology, vol. 14, article 1114332. https://doi.org/10.3389/fpsyg.2023.1114332 (In English)
Gavrilova, E. A. (2018) Variabel’nost’ ritma serdtsa i sport [Heart rate variability and sports]. Saint Petersburg: Institute of Sports and Health Publ., 186 p. (In Russian)
Grinevich, A. A., Tankanag, A. V., Chemeris, N. K. (2013) Issledovanie zavisimosti amplitudno-chastotnykh spektrov serdechnogo ritma cheloveka ot kontroliruemoj chastoty dykhaniya [The study of the dependence of the human heart rate from the frequency of controlled breathing]. Matematicheskaya biologiya i bioinformatika — Mathematical Biology and Bioinformatics, vol. 8, no. 2, pp. 537–552. https://doi.org/10.17537/2013.8.537 (In Russian)
Gronwald, T., Schaffarczyk, M., Hoos, O. (2024) Orthostatic testing for heart rate and heart rate variability monitoring in exercise science and practice. European Journal of applied Physiology, vol. 124, no. 12, pp. 3495–3510. https://doi.org/10.1007/s00421-024-05601-4 (In English)
Gultyaeva, V. V., Uryumtsev, D. Y., Zinchenko, M. I. et al. (2021) Cardiorespiratory coordination in hypercapnic test before and after high-altitude expedition. Frontiers in Physiology, vol. 12, article 673570. https://doi.org/10.3389/fphys.2021.673570 (In English)
Igasaki, T., Nagasawa, K., Murayama, N., Hu, Z. (2015) Drowsiness estimation under driving environment by heart rate variability and/or breathing rate variability with logistic regression analysis. In: 8th International conference on biomedical engineering and informatics (BMEI 2015). Shenyang: Institute of Electrical and Electronic Engineers Publ., pp. 189–193. https://doi.org/10.1109/BMEI.2015.7401498 (In English)
Khanin, Yu. L. (1976) Kratkoe rukovodstvo k shkale reaktivnoj i lichnostnoj trevozhnosti Ch. D. Spilbergera [A brief guide to C. D. Spielberger’s scale of reactive and personal anxiety]. Leningrad: LSRIPC Publ., 18 p. (In Russian)
Kovaleva, A. V., Panova, E. N., Gorbatchova, A. K. (2013) Analiz variabel’nosti ritma serdtsa i vozmozhnosti ego primeneniya v psikhologii i psikhofiziologii [Analysis of heart rate variability and possibility of its utilization in psychology and psycho-physiology]. Sovremennaya zarubezhnaya psikhologiya — Journal of Modern Foreign Psychology, vol. 2, no. 1, pp. 35–50. (In Russian)
Krivoshchekov, S. G., Nikolaeva, E. I., Vergunov, E. G., Prihodko, A. Yu. (2022) Mnogomernyj analiz pokazatelej tormoznogo i avtonomnogo kontrolya pri ortostaze i v emotsional’nykh situatsiyakh [Multivariate analysis of indicators of inhibitory and autonomic control in orthostasis and emotional situations]. Fiziologiya cheloveka — Human Physiology, vol. 48, no. 1, pp. 20–29. https://doi.org/10.1134/S0362119721060050 (In Russian)
Krivoshchekov, S. G., Uryumtsev, D. Yu., Gultyaeva, V. V., Zinchenko, M. I. (2021) Kardio-respiratornaya koordinatsiya pri ostroj gipoksii u legkoatletov-begunov [Cardiorespiratory coordination in acute hypoxia in runners]. Fiziologiya cheloveka — Human Physiology, vol. 47, no. 4, pp. 429–437. https://doi.org/10.1134/S0362119721030087 (In Russian)
Kubekova, A. S., Abdullaev, S. S., Sergeeva, M. A. (2021) Uroven’ depressivnosti i otnoshenie k depressii v studencheskoj srede [Depression level and attitudes towards depression in the student environment]. Mir nauki. Pedagogika i psikhologiya — World of Science. Pedagogy and Psychology, vol. 9, no. 6, article 15. (In Russian)
Levine, G. N. (2022) Psychological stress and heart disease: Fact or folklore? The American Journal of Medicine, vol. 135, no. 6, pp. 688–696. https://doi.org/10.1016/j.amjmed.2022.01.053 (In English)
Li, W., Zhao, Z., Chen, D. et al. (2022) Prevalence and associated factors of depression and anxiety symptoms among college students: A systematic review and meta-analysis. Journal of Child Psychology and Psychiatry, vol. 63, no. 11, pp. 1222–1230. https://doi.org/10.1111/jcpp.13606 (In English)
Nikolaeva, E. I., Belousova, L. V. (2018) Personality as moderator of aging effects on inhibition functions and brain activity. International Journal of Psychophysiology, vol. 131, no. S, p. S96. (In English)
Proskuryakova, L. A., Lobykina, E. N. (2017) Struktura i otsenka effektivnosti meropriyatij sistemy sokhraneniya zdorov’ya studentov [Structure and evaluation of the effectiveness of measures of the system of preservation of students’ health]. Gigiena i sanitariya — Hygiene and Sanitation, vol. 96, no. 1, pp. 79–84. https://doi.org/10.47470/0016-9900-2017-96-1-79-84 (In Russian)
Rakhimova, G. K. (2023) Analiz dannykh zabolevaemosti studentov v protsesse obucheniya i vliyanie na uspevaemost’ [Analysis of data on the morbidity of students in the learning process and the impact on academic performance]. Vestnik nauki i obrazovaniya — Bulletin of Science and Education, no. 4 (135), pp. 104–108. (In Russian)
Shlyk, N. I. (2022) Variabel’nost’ serdechnogo ritma i metody ee opredeleniya u sportsmenov v trenirovochnom protsesse [Heart rate variability and methods of its determination in athletes in the training process]. Izhevsk: Udmurt State University Publ., 80 p. (In Russian)
Soni, R., Muniyandi, M. (2019) Breath rate variability: A novel measure to study the meditation effects. International Journal of Yoga, vol. 12, no. 1, pp. 45–54. https://doi.org/10.4103/ijoy.IJOY_27_17 (In English)
Spitsin, A. P., Reztsov, O. V., Knyazhev, I. S. (2025) Korrelyatsii mezhdu pokazatelyami trevozhnosti i variabel’nosti serdechnogo ritma u studentov pri intensivnoj kognitivnoj deyatel’nosti [Correlations between indicators of anxiety and heart rate variability in students with intensive cognitive activity]. Natsional’nyj vestnik meditsinskikh assotsiatsij — National Bulletin of Medical Associations, vol. 2, no. 1 (2), pp. 31–35. (In Russian)
Stromájer, G. P., Csima, M., Iváncsik, R. et al. (2023) Stress and anxiety among high school adolescents: Correlations between physiological and psychological indicators in a longitudinal follow-up study. Children, vol. 10, no. 9, article 1548. https://doi.org/10.3390/children10091548 (In English)
Tkachenko, A. A., Saitgareeva, I. F., Kuvshin, E. S. (2020) Issledovaniya urovnya trevozhnosti v period examenatsionnoj sessii [Studies of the level of anxiety during the examination session]. Mezhdunarodnyj studencheskij nauchnyj vestnik — European Student Scientific Journal, no. 1, article 18. (In Russian)
Tort, A. B. L., Laplagne, D. A., Draguhn, A., Gonzalez, J. (2025) Global coordination of brain activity by the breathing cycle. Nature Reviews. Neuroscience, vol. 26, no. 6, pp. 333–353. https://doi.org/10.1038/s41583-025-00920-7 (In English)
Van den Bosch, O. F. C., Alvarez-Jimenez, R., de Grooth, H.-J. et al. (2021) Breathing variability — implications for anaesthesiology and intensive care. Critical Care, vol. 25, no. 1, article 280. https://doi.org/10.1186/s13054-021-03716-0 (In English)
Van Diest, I., Thayer, J. F., Vandeputte, B. et al. (2006) Anxiety and respiratory variability. Physiology and Behavior, vol. 89, no. 2, pp. 189–195. https://doi.org/10.1016/j.physbeh.2006.05.041 (In English)
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