Introduction. According to the WHO the concept of individual resilience, which is the basis of healthy aging, refers to the totality of all physical and mental abilities of a person. Despite the high interest in this issue, today there is no single idea about the physical aspect of age-related resilience, as well as about its variability in different age periods. The effectiveness of the functional systems of the body, among which one of the most important is the cardiovsular system, is largely determined by the predictive of their regulation. The neuroendocrine system plays a leading role in regulating of functional systems in the human body, the reactivity of which can be assessed by comparing the parameters of the resilience of rhythms different parts of the cardiovascular system, in particular, heart rate and pulse rhythms. The purpose research in improving the diagnosis of the physical aspect of age-related resilience according to the features of the regulatory circulatory systems in middle-aged and elderly patients. Material and methods. Two groups of patients undergoing respiratory rehabilitation were examined, middle-aged (45-59 years old) and elderly (60-74 years old) according to the WHO classification. The study of the physical condition was carried out according to the traditional method. Additionally, a spiroarteriocardiorhythmography (SACR) study was performed at rest and when performing a test with physical activity. Results. The advantages of assessing the regulatory circulatory systems in terms of the randomness of the variability of circulatory parameters compared with the traditional approach are shown. Conclusion. The article demonstrates the advantages of using approximate entropy in comparison with the traditional approach. The differences between the time series of the RR, systole-systole and diastole-diastole intervals were revealed when performing the test with stepwise increasing physical activity in the groups of middle-aged and elderly patients. It also describes the distinctive features of the behavior of the approximate entropy indicator in middle-aged patients compared with elderly patients in the recovery period after a physical exercise test.