The goal is to create a unified ontogenetic method for determining biological age.
The choice of physical performance is determined by several factors:
1. the indicator has a strict direction in ontogeny (increases during maturation, decreases during maturity and aging);
2. the sign reflects the adaptive capabilities of the human body as a whole;
3. the technique has a strict order of execution and interpretation.
Characteristics of the groups of subjects
People were selected for the survey by random sampling.
The state of health of the subjects was judged by anamnestic data, the results of a preliminary medical examination and analysis of case histories. Excluded from the sample were those who had a history of myocardial infarction, stroke, and other states of decompensation of physiological systems.
We used the following age classification: children of primary school age (7-12 years old), middle school age (13-14 years old), senior school age (15-17 years old), young people (18-19 years old), mature (20- 59 years), elderly (60-74 years) and senile (75-89 years) age.
A total of 589 people were examined.
Physical performance was measured by steppergometry with increasing load until reaching the submaximal possible heart rate or the appearance of generally accepted contraindications.
The study began after a 20-minute adaptation of the subject in a sitting position, after which the studied parameters were recorded. The initial load was 100 kGm/min, the work at each stage lasted 4 minutes, the rest between loads lasted 3 minutes, the increase in load at each subsequent stage was 100 kGm/min. Before the load, at each minute of load and recovery, an electrocardiogram and blood pressure were recorded.
To determine the biological age, indicators were used – submaximal physical performance (FR1), submaximal physical performance per kg of body weight (FR2); heart rate (HR), systolic (BP) and diastolic pressure (BPd) at the height of the load.
Table 1 provides a matrix for chronological age and physical performance indicators during puberty.
In female children and adolescents, positive significant correlations were found between age and physical performance in kGm / min (high degree), with heart rate at the height of the load (moderate degree) and systolic blood pressure at the height of the load (high degree). No correlations with age were found for physical performance in kGm/min/kg and diastolic blood pressure at the height of the load.
Table 1. Correlation of chronological age with indicators of physical
working capacity (7-17 years)
In boys and young men, positive significant correlations were registered between age and physical performance in kGm / min (high degree), heart rate at the height of the load (moderate degree), systolic blood pressure at the height of the load (noticeable degree) and diastolic blood pressure at the height of the load (moderate degree). There was no correlation with age for physical performance in kGm/min/kg.
The difference in correlations concerns only diastolic blood pressure at the height of the load. It is significant for females and absent in male subjects. Signs of correlations for all indicators had no gender differences.
Based on the method of multiple linear regression, the following formulas are proposed for determining the biological age by physical performance in conditional years during the development period (7-17 years):
1) BV (women) u003d 0.4360 + 0.0186FR1 – 0.5379FR2 + 0.0404HR + 0.0265BPs – 0.018ADd
Multiple correlation coefficient – 0.86; reliability according to the Dieter criterion – P<0.001;
2) BV (men) = -2.8866 + 0.0130FR1 – 0.4273FR2 + 0.0696HR + 0.0144BPs + +0.0078BPd
Multiple correlation coefficient – 0.88; reliability according to the Fisher criterion – P<0.001.
Table 2 provides a matrix for chronological age and physical performance indicators during maturity and aging.
Table 2. Correlation of chronological age with indicators of physical
working capacity (18-89 years)
In women, negative significant correlations were found between age and physical performance in kGm / min and kGm / min / kg, heart rate at the height of the load (high degree), positive significant correlations of age and systolic blood pressure at the height of the load (appreciable degree), diastolic blood pressure at the height of the load (moderate degree).
In men, negative significant correlations were registered between age and physical performance in kGm/min and kGm/min/kg, heart rate at the height of the load (high degree). They did not show correlations with age for systolic and diastolic blood pressure at the height of the load.
To determine the biological age in conventional years during periods of maturity and aging (18-89 years), the following formulas have been created:
1. BV (women) u003d 112.66 – 0.04FR1 – 2.30FR2 – 0.24HR + 0.12BPs – 0.09ADd
Multiple correlation coefficient – 0.93; reliability according to the Fisher criterion – P<0.001;
2. BV (men) = 97.85 – 0.05FR1 – 0.33FR2 – 0.05HR + 0.13BPs – 0.21BPd
Multiple correlation coefficient – 0.97; significance according to the Fisher criterion – P<0.001.
The age biomarkers we have chosen meet all the requirements for indicators of biological age:
1. physical performance significantly correlates with chronological age, which proves its direction, regularity and continuity of changes throughout ontogenesis;
2. changes in working capacity are sufficient in intensity in the process of ontogenesis;
3. this feature is easily measurable quantitatively;
4. it is working capacity that is the leading tool for assessing changes in a person’s adaptive capabilities;
5. health data is stable and reproducible;
6. physical performance reflects the objective characteristics of the functional state of a person;
7. Physical performance measurements are safe for people of all ages.
In the above formulas, the values of the calculated coefficients are determined by their correlation with chronological age, cross-correlation (and, in connection with this, the share of their independent informational contribution), and, finally, their absolute value.
All equations have high and significant coefficients of multiple correlation with chronological age, which indicates sufficient information about maturation, maturity and aging, which we included in the models of biological age.
The mathematical model of multiple regression opens up the possibility of determining the average biological age of compared population groups that differ in sex, lifestyle, geographic location, the presence of risk factors, applied geriatric treatments, etc. With this approach, the systematic error in calculating the biological age, which manifests itself in the distortion of its indicators at the edges of the regression (in the younger age group it is somewhat overestimated, in the older age group it is underestimated compared to the chronological age), is not significant, since it is equally represented in assessment of compared groups or subpopulations.
In cases where it is necessary to determine the exact biological age of an individual, the phenomenon of “narrowing” must be taken into account. Based on this, a direct comparison of the calculated biological age and the chronological age of one person is incorrect. The calculated biological age should be compared with the value of the proper biological age, which characterizes the population standard of the rate of age-related changes. After examining a person, it is necessary to compare his biological age with the average biological age of all persons in this age group.
In order to compare the rates of age-related changes in women and men, as well as to establish the proper biological age in certain age groups, its average values were calculated for all age groups (Table 3).
Table 3. Chronological and biological age (7-89 years)
Note: * – P<0.05-0.001 significance of differences in biological age between women and men of the same age group.
The average chronological age of the subjects in all groups did not have significant differences, which made it possible to analyze the biological age in different sex groups with a high degree of reliability.
In children of 7 years old, boys were significantly older than girls (1.36 conditional years), at 8-11 years old, the rate of maturation for both remained the same, at 12 and 13 years old, girls became older than boys (12 – by 1.28; 13 – by 1.31 conditional years), at the age of 14-17 the rate of maturation leveled off again. Women aged 18-19 are significantly older than men of this age (by 3.87 conditional years). The opposite trend was noted for the period of maturity – in all groups, men had a significantly greater biological age compared to women (20-29 – by 13.10; 30-39 – by 8.54; 40-49 – by 5.28; 50- 59 – for 6.41 conditional years). With aging (60-74, 75-89) no differences were found in the rate of age-related changes.
To compare the leading trend in the rate of age-related changes, we used the ratio of the squares of the multiple correlation coefficients, since one year of chronological age corresponds to R2 of biological age. With this approach, the ratio R2 of men: R2 of women shows how many times the rate of age-related changes is greater or less than the rate of women.
As evidenced by the data obtained, the ratio in the ripening period was 1.04; in the period of maturity and aging 1.09. The rate of age-related changes is higher in men than in women in all periods of ontogeny.
In accordance with both methods (biological age and the square of multiple regression coefficients), a single pattern was established: women have a slower rate of age-related changes during periods of maturation, maturity and aging compared to men. This pattern is most clearly manifested at the stage of maturity – 20-59.
Thus, the longer life expectancy of women corresponds to a lower rate of change over time. This proves that the influence of factors related to the physiology of sex is the leading one in terms of its contribution to the aging process.
The sensitivity of the ontogenetic method to gender differences in age-related changes suggests that the developed method for determining biological age by physical performance, which reflects the adaptive capabilities of the body, is a tool for an objective assessment of the rate of development, maturity and aging of a person and allows one to judge the effectiveness of various factors in changing the rate of ontogenesis.