1. Introduction

In recent years, the development of women’s sports has become one of the priority directions of state policy in our country. The popularization of sports among girls not only promotes a healthy lifestyle but also contributes to the formation of an active, morally mature, and strong-willed generation in society. Under the conditions of the Republic of Karakalpakstan, however, this process requires more complex physiological adaptations. This is due to the fact that the region’s climatic characteristics, environmental background, and social factors have a direct impact on the morphofunctional development of female athletes [1]. Therefore, studying the level of adaptation of female athletes’ bodies to physical loads, as well as their morphological indicators and functional capacities, represents a relevant and important scientific direction.

Regular repetition of physical exercises and systematic, long-term training strengthen motor skills and contribute to improving the functional state of trained systems. In order to adequately select physical exercises, it is necessary to have information about the level of physical development of the body and its functional state [2].

In practice, to date, numerous functional tests and trials are used to assess the physical indicators of athletes, allowing evaluation of the body’s reserve capacities and the adaptive characteristics of various physiological systems to physical loads. However, it should also be emphasized that athletes must select physical loads that are appropriate to the individual characteristics of their bodies.

In this regard, the World Health Organization (WHO) has developed a number of requirements for the selection and implementation of physical loads, including:

- the load should be quantitatively measurable and involve at least two-thirds of the muscle mass, ensuring maximal activation of physiological systems;

- complex, highly coordinated (coordination-demanding) movements should be limited;

- the selected load should be characterized by simplicity and general accessibility;

- the possibility of recording physiological parameters during testing should be ensured [2,3].

Therefore, in our study, simple and non-strenuous functional tests and trials were applied.

The study of cardiovascular system function occupies a central role in assessing the functional state of students engaged in physical education and sports. This is because, during dynamic observations both at rest and in response to physical load, not only the cardiovascular system but also the adaptive state of the entire organism is evaluated. In addition, during late adolescence, growth processes are completed and the main physiological parameters characterizing the level of students’ physical health become stabilized. Studying the functional characteristics of the cardiovascular and respiratory systems is essential for determining the quality of the body’s adaptation to physical loads [4].

A number of studies related to athletes have been conducted in Karakalpakstan. In particular, hormonal changes, blood cell counts, and specific features of the somatotype have been investigated in male football players [5]. More recently, total body dimensions have been investigated in boys and girls aged 8-16 years engaged in basketball, and accelerated growth rates were observed at the ages of 15-16 years [6]. In addition, changes in muscle strength and physical endurance, as well as their relationships with hematological parameters, have been identified in adolescents who do not regularly participate in sports [7]. Studies have also been reported on handgrip strength and cardiorespiratory system function in girls who do not engage in regular sports activities [8,9]. Recent scientific studies have shown that identifying the morphological and functional indicators of athletes and analyzing them according to age and type of sport is of great importance for improving the effectiveness of sports training [1].

However, under the conditions of the Republic of Karakalpakstan, the morphofunctional characteristics of female athletes and their responses to physical loads across different types of sports have not been sufficiently studied.

The aim of the Study is to investigate the indicators of physical development, the state of the cardiorespiratory system, and its responses to physical loads in female athletes under the conditions of the Republic of Karakalpakstan, with consideration of different types of sports.

2. Materials and Methods

2.1. Participants and Study Area

In the spring season of 2025, morphofunctional examinations were conducted among 149 voluntary female student athletes aged 19-20 years who study at the Faculties of Physical Culture of Karakalpak State University, Nukus State Pedagogical Institute, and the Nukus branch of the Uzbekistan State University of Physical Education and Sport, and who permanently reside in the Republic of Karakalpakstan. Among the participants, 31 athletes regularly practice athletics, 53 are engaged in freestyle wrestling, 33 in basketball, and 32 in volleyball.

Information on the age of the participating female athletes and the duration of their engagement in specific sports is presented in Table 1.

Table 1. Contingent of the study participants

The Republic of Karakalpakstan is considered one of the most environmentally challenging regions of Uzbekistan. The drying of the Aral Sea has had a serious negative impact on the ecological, medico-biological, and social conditions of the region. Salt and dust storms rising from the Aralkum desert, high levels of air pollution, and contamination of soil, water, and food products with heavy metals, pesticides, and dioxins directly affect the health of the population [10-12]. As a result, respiratory diseases, cardiovascular disorders, reduced growth and development indicators, weakened immunity, gastrointestinal problems, and anemia are widespread among the population of the region [13-15].

Figure 1. Location of the Republic of Karakalpakstan in Uzbekistan [16]

At the same time, preventive, ecological, and medical programs aimed at improving public health are being implemented in Karakalpakstan. With the participation of international organizations, measures are being taken to stabilize the ecological situation, enhance healthcare services, and improve the quality of life of the population [17,18].

2.2. Measurement of Anthropometric Parameters

Measurements were conducted in two stages. They were carried out during the spring-summer period, in the morning shift, in a room with comfortable temperature, sufficient lighting, and isolation. At the first stage, anthropometric measurements of all participants were performed using standard accepted methods [19,20]:

Body length was measured with a medical stadiometer SECA 217 (Germany) with an accuracy of up to 5 mm.

Body weight was measured using an electronic medical scale SECA 803 (Germany) with an accuracy ranging from 50 g to 150 g, depending on the weight.

Chest, upper-arm, and calf circumferences were measured using a non-stretchable metric tape (accuracy 0.01 cm) and an electronic tape measure (“Measure King”, VAHIGCY, China).

Bone size level indicators, including elbow and knee joint widths, were measured with a movable caliper (“Argentum” LLC, Russia) with an accuracy of 1 mm.

The following skinfolds were measured: subscapular skinfold, suprailiac skinfold, triceps skinfold, calf skinfold. The skinfolds were measured using Slim Guide Caliper, China, applying equal pressure (10 g per mm²) with an accuracy of 0.5 mm.

Handgrip strength was determined using a hand dynamometer (MEGEON – 34090, Russia, 2017) designed to measure grip strength with an accuracy of 0.5 kg.

2.3. Measurement of Physiological Parameters and Conducting Functional Tests

In the second stage of the study, a series of tests and examinations were conducted to assess the cardiorespiratory system functions of the athletes.

Assessment of Respiratory System Functions:

Lung Vital Capacity (LVC) – measured using an electronic vital capacity tester, FCS-10000, Grows Instrument (China, 2018) [20].

Dynamic Spirometry allows the evaluation of respiratory system condition by monitoring changes in LVC during physical load [21]. After measuring LVC at rest, the volunteer performs a standard physical load (20 sit-ups in 30 seconds). LVC is then measured again. Dynamic spirometry is calculated as the difference between LVC at rest and after the physical load. The results are interpreted as follows: if LVC does not change – “satisfactory”; if LVC decreases by more than 200 ml – “unsatisfactory”; if LVC increases by more than 200 ml – “good” [21].

Shtange Test – a physiological test designed to assess the condition of the respiratory and cardiovascular systems by measuring the duration of breath-holding after a deep inhalation. It reflects the body’s resistance to oxygen deficiency (hypoxia) and its adaptive capabilities [22]. As a reference, untrained individuals can hold their breath for 40-55 seconds after a deep inhalation, while trained individuals can hold it for 60-90 seconds or longer.

Genchi Test – this diagnostic test is also aimed at evaluating the respiratory and cardiovascular system functions. It determines the body’s adaptive response to hypoxia (oxygen deficiency) by measuring the duration of breath-holding after a full exhalation [22]. As a reference, untrained individuals can hold their breath for 25-30 seconds after exhalation, whereas trained individuals can hold it for 40-60 seconds or longer.

Assessment of Cardiovascular System Functions:

Systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) in the participants were measured on the shoulder using the Korotkov method with an OMRON 711 electronic tonometer (HEM-8712-CM2) (China, 2017).

Robinson Index describes the systolic function of the heart. Additionally, this index reflects the myocardial oxygen demand and, together with the adaptive potential, serves as an indicator of cardiovascular system condition and the body’s adaptation mechanisms. The Robinson Index is calculated using the following formula:

Here, HR – heart rate (beats/min); SBP – systolic blood pressure (mmHg).

The higher these indicators during physical exertion, the greater the functional capacity of the heart muscles. The index is used to evaluate the level of metabolic and energy processes occurring in the body. The results of the index are interpreted as follows: ≤69 conditional units – excellent; 70-84 – good; 85-94 – average; 95-110 – poor; ≥111 – very poor [23].

Ruffier Functional Test is used to assess the cardiovascular system’s adaptation to physical exertion and also serves as a simple and indirect method for determining physical fitness. It is based on quantitatively evaluating the HR response and recovery speed after performing 30 sit-ups in 45 seconds [22,24].

The Ruffier index is calculated using the formula:

Here, P1 – HR measured over 15 seconds at rest; P2 – HR measured over the first 15 seconds after performing 30 sit-ups; P3 – HR measured during the last 15 seconds of the first minute of the recovery period; 200 – triple sum of the average HR in adults; 10 – used to simplify comparison.

The resulting index is then evaluated according to the following scale: 15 – unsatisfactory result, poor heart function, possibly severe heart failure; 10-15 – poor result, weak heart function, or moderate heart failure; 6-9 – satisfactory result, average performance, no insufficiency; 3-5 (normal) – good result, good performance; 0-3 (normal) – excellent result, very good heart function [22,24].

Functional Changes Index (Adaptation Potential). The functional changes index reflects the adaptive capacity of the circulatory system (CS). The functional state of the CS was evaluated using the following formula:

Here: HR – heart rate at rest (beats/min), SBP – systolic arterial pressure (mmHg), DBP – diastolic arterial pressure (mmHg), A – age (years), BW – body weight (kg), BL – body length (cm).

Evaluation of adaptation potential values: 0-2.6 – CS is functioning satisfactorily; 2.6-3.1 – functional stress is present; 3.1-3.5 – functional state is unsatisfactory; 3.5 and above – dysfunction is present in the CS [25].

2.4. Statistical Analysis

Statistical hypotheses regarding differences in main trends across the four groups were tested on quantitative variables using the Kruskal-Wallis test. When statistically significant differences were identified, post-hoc comparisons were conducted using the Mann-Whitney test with Bonferroni correction to eliminate inflation of Type I error. Results were considered statistically significant at p < 0.05.

All results were obtained using functions in Microsoft Excel (Microsoft Office 2010) and with statistical software Past (version 2.17, Norway, Oslo, 2012) and Origin Pro v.8.5 SR1 (EULA, Northampton, MA 01060-4401, USA).

The age of the athletes and the duration of engagement in a specific sport are presented as mean (M) ± standard deviation (m). All other data are presented as mean values (µ) with lower (LL) and upper (UL) bounds of the 95% confidence interval (µ; LL; UL 95% CI) for anthropometric and physiometric parameters.

3. Results

The anthropometric characteristics of female athletes engaged in various sports and their intragroup comparisons can be seen in Table 2. According to the comparison results, statistically significant intergroup differences were found in body weight, knee joint width, chest circumference, upper-arm circumference, and calf circumference (p < 0.05). Specifically, female athletes practicing wrestling and volleyball had significantly higher body weight compared to those engaged in athletics (p < 0.001). Female wrestlers also exhibited significantly greater knee joint width compared to athletes in track and field (p < 0.05). Furthermore, chest circumference in wrestlers was statistically higher than in track-and-field and basketball athletes (p < 0.05). Upper-arm and calf circumferences were significantly lower in track-and-field athletes compared to wrestlers and volleyball players (p < 0.01). In addition, upper-arm circumference was higher in wrestlers than in basketball players (p < 0.01).

Table 2. Anthropometric indicators and their comparison in the studied groups

For all other parameters, including body height, elbow joint width, skinfolds in various anatomical regions, and handgrip strength, no statistically significant differences were observed among the studied groups (p > 0.05).

The physiological parameters and functional test results in the studied groups are presented in Table 3. According to these results, no statistically significant intergroup differences were identified in any of the physiological parameters or functional test outcomes among the female athletes (p > 0.05).

Table 3. Comparison of the results of physiological parameters and functional tests in the studied groups

Most of the results obtained from the Shtange and Genchi tests were found to be below the normative values. Among all types of female athletes, the proportion of those meeting the normative standards was on average 20% for the Shtange test and 15% for the Genchi test.

When evaluating the results of dynamic spirometry, female athletes practicing athletics showed superiority in the “good” category with 42%, compared to other athletes (basketball players – 30.3%, volleyball players – 25%, and wrestlers – 22.6%). In the “satisfactory” category, volleyball players dominated with 65.6%, followed by wrestlers – 54.8%, basketball players – 45.5%, and track-and-field athletes – 32.2%. Additionally, 25.8% of the track-and-field athletes fell into the “unsatisfactory” category. The subsequent proportions were as follows: basketball players – 24.2%, wrestlers – 22.6%, and volleyball players – 9.4%.

The results based on the Robinson index can be seen in Figure 2. According to it, 21.2% of basketball players fell into the “excellent” category, 32.1% of wrestlers into the “good” category, 21.8% of volleyball players into the “average” category, 41.9% of track-and-field athletes into the “poor” category, and 21.2% of basketball players into the “very poor” category.

Figure 2. Robinson index results (%) among female athletes practicing different sports

The results of the Ruffier test are presented in Figure 3. Among the participants, 15.6% of volleyball players fell into the “excellent” category, 18.9% of wrestlers into the “good” category, 38.9% of track and field athletes into the “satisfactory” category, 41.9% of track and field athletes into the “poor” category, and 12.1% of basketball players into the “unsatisfactory” category.

Figure 3. Assessment of the physical working capacity of female athletes using the Ruffier test (%)

According to the Functional Changes Index, the best results were observed in the female athletes practicing athletics, with 96.8% showing satisfactory adaptation (Figure 4). Among the tested basketball players, 18.2% exhibited signs of stress in the CS.

Figure 4. Functional Changes Index results (%) in the studied groups

4. Discussion

The results of the conducted study demonstrated that the physical development indicators of female athletes engaged in different sports are formed depending on their sport specialization. Intergroup comparisons of anthropometric parameters confirmed statistically significant differences in certain morphological characteristics. In particular, the body weight of athletes practicing wrestling and volleyball was significantly higher than that of those engaged in track and field, which can be explained by the relatively greater muscle mass in wrestlers and volleyball players, as well as the predominance of strength and power components [26]. In track and field, the relatively lower body weight is associated with training loads focused on speed and endurance [27].

The greater knee joint width observed in female athletes practicing wrestling compared to track and field athletes can be explained by the higher loads placed on the musculoskeletal system in this sport and the adaptive morphological remodeling of the joints [28]. Similarly, the larger chest circumference in wrestlers compared to track and field and basketball athletes indicates better-developed respiratory muscles and thoracic volume [29].

Higher values of upper-arm and calf circumferences in wrestlers and volleyball players are associated with pronounced muscle hypertrophy. Additionally, the observation that wrestlers have a greater upper-arm circumference than basketball players reflects the functional adaptation linked to the active involvement of the upper-arm region in wrestling. At the same time, no statistically significant differences were found among the studied groups in indicators such as skinfolds and handgrip strength. This can be attributed to the fact that all female athletes belonged to the same age group, were not part of a sedentary population, and had similar overall levels of physical fitness.

No statistically significant differences (p > 0.05) were found in the average values of physiological parameters and functional tests among female athletes regularly engaged in different sports. This indicates that, in the studied age group, general adaptive mechanisms are already well-formed and that sports activity exerts a positive effect on the functional state of the organism.

However, analysis of the Shtange and Genchi tests revealed that most of the athletes had insufficient hypoxia tolerance of the respiratory system. The low proportion of athletes meeting the normative standards (20% and 15%, respectively) points to the need for further development of the functional capabilities of the cardiorespiratory system. This is especially relevant for youth living in environmentally challenging conditions. It should also be noted that tissue hypoxia can result not only from environmental oxygen deficiency or respiratory system dysfunction but also from cardiovascular diseases. Literature reports indicate that in pathological conditions, including anemia, breath-holding time is reduced [22]. Furthermore, studies have demonstrated a decrease in vital lung capacity among students living in areas with high atmospheric pollution [30].

Subjects who demonstrated high results in hypoxic tests also showed better adaptation to physical loads. Research indicates that 4-8 months of regular aerobic training leads to a decrease in HR and blood pressure, reflecting an improvement in the functional readiness of women aged 25-30 for physical activity [31].

Differences in dynamic spirometry results across sports can be explained by the nature of the training. The high proportion of “good” results (42%) among female athletes practicing track and field is associated with the predominance of aerobic loads in this sport and the well-developed respiratory muscles. In contrast, volleyball players showed predominance in the “satisfactory” category, while wrestlers and basketball players more frequently fell into the “unsatisfactory” category, reflecting the predominance of short-term, high-intensity loads in these sports.

Results from the Robinson index and Ruffier test demonstrated partial differences in cardiovascular system functionality depending on the type of sport. The presence of “excellent” results among basketball players indicates well-balanced development of speed and endurance qualities. In contrast, the high proportion of “poor” and “very poor” categories among track and field athletes may reflect the one-sided nature of the training load or insufficient recovery measures during the training process.

Studies conducted among students revealed relatively low Ruffier index values, highlighting the necessity of regular use of general endurance development tools and methods in physical education sessions [32]. Other research identified that both female and male students had satisfactory to poor physical health, characterized by low heart performance and poor physical work capacity [33]. E.N. Mokasheva et al. reported “poor” (99.85±4.99) and “very poor” (111.15±5.55) Robinson index categories among students, which they interpreted as indicative of extremely poor myocardial oxygen supply regulation [34]. In additional studies, first-year female students showed 10% “poor” and 30% “very poor” categories according to the Robinson index, while second-year female students had 30% “poor” and 10% “very poor” categories [23].

The high level of satisfactory adaptation (96.8%) observed in track and field female athletes according to the Functional Changes Index confirms the overall good adaptive capacity of their cardiovascular system. Previous studies have also shown that athletes engaged in track and field exhibit a high functional state of the cardiovascular system [35]. The detection of stress in the CS in some basketball players indicates the need to individualize training loads.

Other studies among university students of both sexes have shown a decrease in adaptive potential before and after physical exertion (p < 0.01) [36]. This indicates a sharp reduction in functional capacities of the CS and reflects strain on adaptive mechanisms. According to several authors [37, 38], even in the absence of disease symptoms, a decrease in adaptive capacity signals low health status and increases the risk of disease development. In addition, the unfavorable ecological conditions of the studied region may negatively affect the cardiovascular performance of female athletes. Research has demonstrated a correlation between the nature of technogenic loads and a reduction in adaptive potential in adolescents [30]. Moreover, residents in areas with anthropogenic pollution have shown increases in minute blood volume and systolic volume [39]. Under urban technogenic pollution, a decline in cardiovascular functional state and adaptive capacity has also been observed among male adolescents [4].

Overall, the analysis and interpretation of the results indicate that female athletes exhibit a relatively low functional state of the cardiorespiratory system. When organizing physical training for these athletes, it is necessary not only to include strength and speed-strength exercises but also to ensure the inclusion of aerobic exercises. Measures should also be taken to optimize the physical training of female student athletes.

5. Conclusions

The results suggest that in female athletes engaged in different types of sports, anthropometric characteristics and the functional state of the cardiorespiratory system may be influenced by the type of sport and the ecological conditions of their living environment. This underscores the importance of considering sport type, training load intensity, and individual functional capacities when planning training programs. Such information can be of practical significance for sports coaches in athlete selection, training planning, and monitoring the health of female athletes.

Conflicts of Interest

The authors declare no conflict of interest.

Author contributions

K.U. Rozumbetov: Writing – original draft, Supervision and Project Administration, Conceptualization, Visualization, Methodology, Investigation, Resources, Formal analysis. G.D. Shirliyeva: Writing – review & editing, Investigation, Resources, Data curation. A.T. Esimbetov: Writing – review & editing, Validation, Data curation.

Funding

The author(s) reported no funding associated with the work featured in this article.

ACKNOWLEDGEMENTS

We thank the participants for their participation in this study.