Dr.Med., Professor A.M. Durov¹
Dr.Med., Professor N.Y. Prokop'ev¹
Associate Professor, PhD L.N. Shatilovich¹
PhD V.I. Nazmutdinova^1
1Tyumen State University, Tyumen

Keywords: chronobiology, biological age, adaptive capabilities, definition.

Introduction. Determination of functional and adaptive capabilities that are the basis of human biological age rating is one of the currently important issues of modern science strongly requiring a solution [2]. The issue is also relevant when studying people engaged in physical culture and sports [11]. It is known that performance in sports largely depends on the functionality level of the athlete’s body.   

The issue of determining biological age is narrowed down by some researchers to calculating it based on the pattern known for this population between a certain physiological indicator and chronological age using the individual value of this indicator [3]. Obvious irregularity and asynchronicity of the process of aging creates a situation when a notion of the adaptive capabilities of an individual based on just one dynamic indicator is often erroneous. Only a set of physiological parameters characterizing various systems of the body makes it possible to accurately approach the issue of evaluating its functionality [8, 12].

Objective of the research was to justify the use of the chronobiological approach in rating functionality, adaptive capabilities and human biological age.

Methods and structure of the study. A number of physiological parameters (Table 1) were studied 5 times per day – at 7 am, 11 am, 3 pm, 7 pm and 11 pm – in healthy subjects of 5 age groups: young, mature 1, mature 2, elderly and old age.

Results and discussion. To date, there is a significant number of tests to determine human biological age. Here are just the main ones [2]: morphological, physiological, biochemical and psychological.

However, these tests have one common flaw: they do not take into account dynamic variability of all functions of the living and therefore are not informative and integral enough. That is why we suggest a chronobiological approach to determine the functionality of an individual and his biological age, since this approach opens up new possibilities in this regard. A lot of attention of many researchers to biological rhythms is currently due to the fact that the latter are one of the most important mechanisms of a human body in terms of adaptation to the environment and are considered an integral criterion of the functional state of the body and its well-being [1, 5].

Many researchers believe that biorhythms structure is one of the most important criteria for human physiological adaptation capabilities, a sensitive indicator of the functional state of the body [1, 4]. Studying fatigue in athletes showed that a violation of the daily body temperature variation is the earliest symptom of overtraining [1]. For all the complexity and controversy of aging mechanisms, almost all researchers are of the opinion that a decrease in adaptive capabilities of the body comes with age compared with older age. It was found in our earlier studies that in terms of a number of carbohydrate metabolism indicators the circadian rhythm amplitude in rats is maximal at a mature age and reduces significantly in the later stages of ontogenesis [4, 5, 6].

The basis of the method for rating human biological age is the fact that there are certain values of various biorhythm parameters for each age period, the parameters being daily average, amplitude (deviation from the daily average) and chronodesm (fluctuation range). Circadian rhythm amplitude is of the greatest interest among all the parameters when assessing biological age. The bigger the amplitude values, the higher the level of human functional and adaptive capabilities and, therefore, the younger one’s biological age. Our data show that amplitudes of the studied physiological parameters are maximal during young and mature I age periods. They slightly decline during the mature II age period and reach their minimum during old age [9, 10]. Charts were made based on the obtained data that can be used to determine biological age of a person [10].

Of all the studied indicators (43) for biological age rating we selected only 17 that relate to the 5 systems and are the most informative for this purpose. They are presented in Table 1. Circadian rhythm amplitude (1) is used most often in determining biological age, while daily average (8) and chronodesm (7) are used less. 

Table 1. Indicators suggested for human biological age rating

How is biological age rated? First, biorhythm parameters of 17 physiological indicators (daily average, amplitude and chronodesm) are determined using the chronobiological approach (5 times per day: at 7 am, 11 am, 3 pm, 7 pm and 11 pm). Second, biological age is determined for each of the 17 indicators using the charts (there can be less indicators, but the accuracy of age ranking will decrease accordingly). This biological age is expressed by a number from 1 to 9, each number corresponds to a particular age period (1 – 17-21 years old, 2 – 22-35 years, 3 – 36-40, 4 – 41-45, 5 – 46-60, 6 – 61-69, 7 – 70-74, 8 – 75-79, 9 – 80-90). Third, the biological age is calculated by system (there are 5 of them in total) and is expressed by a number from 1 to 9. Fourth, biological age of a particular person is determined (mean value of the 5 systems is calculated and biological age of the examined person is determined).  

It was found in a chronobiological study of workers in Kharasavey settlement that had an average length of time worked in the Arctic Circle of 6.5 years that out of 34 people biological and real age matched in 17; biological age exceeded real one in 16 people, and only 1 subject’s biological age was less than that in his passport. Deviations of the physiological functions dynamics beyond age norms are seen as risk criteria for health conditions development [7]. The method of human biological age ranking we developed is quite informative and easy to perform.  

Conclusions:

• Circadian organization of physiological parameters of the hemic system, the cardiovascular system, external respiration, gas composition and acid-base status changes naturally alongside postnatal ontogenesis. It is expressed the most during young and mature 1 age periods, which is manifested primarily in the maximal rhythms amplitudes. During these age periods maximal amplitudes correspond to the maximal adaptive capabilities and maximal reliability of the functional systems of the body. 
• Circadian rhythms decay is observed during late ontogenesis stages (elderly and old age periods), which manifests itself in decreased amplitudes of circadian rhythms. 
• Chronobiological approach is informative in assessing the functional state and adaptive capabilities of the body, meets all the requirements for tests used to rank human biological age and can be successfully used to determine it. 
• Chronobiological approach can be used to assess functional and adaptive capabilities of athletes at various stages of the training process. An athlete should be at the peak of his capabilities by the most important competitions, and this peak should correspond to the maximum amplitude values of the most important physiological parameters.  

References

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12. Nazmutdinova V.I., Durov A.M., Shatilovich L.N. Dinamika veso-rostovykh pokazateley studentov g. Tyumeni s raznym urovnem dvigatel'noy aktivnosti [Dynamics of body mass indices of Tyumen students with different levels of physical activity]. Meditsinskaya nauka i obrazovanie Urala, 2015, no. 4, pp. 90-93.

Corresponding author: amdurov@mail.ru

Abstract

The authors offer a chronobiological rating approach that increases several times the value of the standard physiological criteria applied for the biological age ratings. The approach gives the means to identify daily average, amplitude, acrophase, chronodesm and daily adaptive capability rate. Structure of biorhythms may be applied as a sensitive indicator of the body's functional status and one of the most important criteria of the human physical adaptation rate. A daily rhythm amplitude is considered the pivotal value to rate the body's adaptive capability and biological age. Amplitude- and phase-related characteristics of the rhythms make it possible to rate the athlete’s functionality and in future they will become a part of the basic methods to identify the optimal athletic form and its timeframes.