**1. Introduction**

It is generally believed that level of physical activity (PA) largely reflects state of health, as reflected in the saying "healthy body, healthy mind". Numerous studies have proven that, among other things, lack of physical activity contributes to the occurrence and development of many diseases [1–4]. Therefore, much attention is paid to promoting physical activity and pro-health lifestyles in society for everyone, from children to older people. Deficiencies in physical activity caused by civilization should be reduced by conscious participation in physical activities.

In the uniformed services, a high level of physical fitness is very desirable in the aspects of professional preparation and efficient fulfilling of service tasks (e.g., a soldier on the battlefield, a policeman during an intervention or a firefighter during a rescue operation) [5,6]. The way to achieve the desired level of physical fitness for a soldier (an officer of a particular formation) is participation in various forms of physical activity during

**Citation:** Tomczak, A.; Anyzewska, ˙ A.; Bertrandt, J.; Lepionka, T.; Kruszewski, A.; Ga ´zdzi ´nska, A. Assessment of the Level of Physical Activity and Body Mass Index of Soldiers of the Polish Air Force. *IJERPH* **2022**, *19*, 8392. https://doi.org/10.3390/ ijerph19148392

Academic Editor: José António Ribeiro Maia

Received: 9 June 2022 Accepted: 7 July 2022 Published: 9 July 2022

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**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

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work and leisure time. This should be reflected in a high level of physical activity. Soldiers, as part of their professional work, should participate in obligatory physical education classes, diversified by the number of hours depending on military specialty [7].

The group of soldiers in the Air Force includes soldiers of various specialties, most of which specialties are also in both the Navy and the Land Forces. These specialties are, for example, administration or logistics. Even such specialties as ground service of aviation equipment (engineering and aviation service) occurs in other branches of armed forces. In the Air Force there are particular specialties typical of military air services, like that of a supersonic airplane pilot. There is the main division of the flight crew and ground staff. The main differences are the environment of performing official tasks (air, land) and the way of logging in to perform them [8]. These differences also apply to physical preparation, in terms of the volume of classes and means of physical education (i.e., physical exercises).

In the literature, we can find many papers on the physical fitness of soldiers [9–11]. So far, not much work has been published regarding the assessment of the physical activity level of Polish soldiers, and those from other countries. In Poland, comparative research has been conducted among soldiers of military administration, special units, soldiers of the Land Forces Training Center, soldiers of the Land Forces and among soldiers of the special unit of the Military Police, and there have been assessments of physical activity level carried out among candidates seeking to become professional soldiers [12–16]. In general, a high level of physical activity was revealed for soldiers. However, a small percentage of soldiers also revealed a low level of it, which is not a good predictor of efficient performance of service duties. Mierzejewski conducted research on the level of physical activity among soldiers of land troops qualified for the Officer's Study. He stated that 79.0% of the respondents presented a high level of physical activity and 21.0% a moderate level [14]. In turn, Tomczak et al. conducted research using the International Physical Activity Questionnaire (IPAQ) tool among Polish soldiers of the Military Police. Based on the research, they found that 84.6% of the respondents were characterized by a high level of physical activity, 7.7% were moderate, and 7.7% were low [15]. Comparative research on the physical activity among soldiers of the National Reserve Force was carried out by Szettler-Degler [17]. She concluded that the level of metabolic equivalent (MET) was similar between men and women. Łyzwi ´ ˙ nski, on the basis of his own study, found that 80.0% of the surveyed Polish soldiers of the land forces perceived there to be a relationship between physical fitness and better performance of official tasks. More than half of the respondents revealed that they undertook physical activity outside of business hours and that they assessed their physical fitness as very good [13]. In many works, attention is paid to the need to raise awareness of the necessity to undertake physical activity and to motivate people to undertake physical activity [15,18,19].

The main aim of the research presented here was to assess the level of physical activity and the body mass index (BMI) of soldiers of the Polish Air Force. The specific objectives were to identify differences in the levels of physical activity and BMI between flight crew and ground staff and age groups (up to 30 years of age, 31–40 years of age and a group over 40). We hypothesized that the flight crew would reveal a higher level of physical activity than ground staff and that a higher level of physical activity would be presented by younger soldiers. Our hypothesis regarding flight crew versus ground staff was justified by the fact that flight crew participate in more compulsory physical education and recreation classes than other soldiers.

#### **2. Materials and Methods**

#### *2.1. Study Design and Participations*

A total of 543 professional soldiers (men) doing military service in military units of the Polish Air Force underwent the examination. The subjects were selected randomly. The soldiers performed professional military service in 35 military units of the Air Force. The research sample accounted for about 3% of the population of soldiers of the Air Force. The average age of examined soldiers amounted to 34.8 ± 9.0 (19–59) years old. Due to

the failure to meet the criteria of credibility, 66 questionnaires did not qualify for further studies. The percentage of questionnaires that qualified for the analysis was 87.8%.

The results of the research were presented in two basic groups, i.e., flight crew 37.49 ± 7.54 (21–59) years old and ground staff 32.70 ± 9.57 (19–59) years old. The flight crew included military pilots, on-board technicians, and on-board navigators, whereas the ground staff included ground service of the aircraft, engineers, technicians, and staff soldiers. The justification for such division was the environment of performing main official tasks (flight crew—in the air; ground staff—on the ground). Subsequently, the research material was divided into the following age groups: up to 30 years old, 31–40 years old and a group over 40 years old. The age of the respondents was determined based on date of birth.

The research was carried out in 2017–2018 as part of the National Health Program research project. The permission of the Bioethics Committee of the Military Institute of Hygiene and Epidemiology in Warsaw (Poland) was obtained for conducting the research (No 01/2016). All procedures were performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. All participants provided informed consent.

#### *2.2. Physical Activity Assessment*

In order to carry out the research, the long version of IPAQ was used. In the introduction to the questionnaire a vigorous physical activity and moderate physical activity were defined in a way accessible for everybody. Vigorous physical activity is understood as heavy physical exercise that forces strong, increased breathing, and, therefore, accelerated heart rate. Moderate physical activity is understood as an average effort with slightly increased breathing and a little accelerated heart action [20,21]. The first part of the questionnaire dealt with physical efforts related to professional work (Part 1: Job-related PA). Three types of efforts were distinguished, i.e., vigorous, moderate and walking. The second part dealt with physical efforts related to relocating (walking, cycling; Part 2: Transportation (relocation) physical activity). In the third part, subjects were asked about the time they spent on taking physical activity related to housework, general housekeeping and for family care (Part 3: Housework, house maintenance, and caring for family). The fourth part of the questionnaire was connected with recreation, sport and physical activity in leisure time (Part 4: Recreation, sport, and leisure-time physical activity). The fifth part contained questions related to time spent sitting, divided into weekend and week days (Part 5: Time spent sitting).

Based on the number of days, time spent on given physical activity and MET rate determined for a given physical activity, a total energy expenditure for each type of physical exercise was calculated. 1 MET corresponds to the average energy expenditure during rest (in a sitting position). It is equivalent to the consumption of oxygen in a sitting position of a person weighing 70 kg, which is 3.5 mL O2/min/kg [22].

#### *2.3. Somatic Measurements*

The measurement of basic morphological features was based on the analysis of the following values of somatic measurements, which were measured according to the Martin technique, body height, and body mass [23]. Body height was measured with an anthropometer (Holtain, UK) to the nearest 1 mm, in a standing upright position, without shoes. Body mass was measured using a Charder MS 4202L electronic weight floor scale (measurement accuracy < 50 g). Each measurement was performed under the same test conditions (in the morning, about 30 min before the first meal). The respondent was wearing sports clothes and barefoot. The same measuring equipment was used during all stages of the research, the accuracy of which was checked periodically. Measurements were made by people who graduated in physical education.

Based on these data, the BMI was calculated (BMI = body mass/height<sup>2</sup> [kg/m2]). The scale of BMI classification reported by the World Health Organization (WHO) was accepted [24].

#### *2.4. Statistical Analysis*

Descriptive statistics were means (±standard deviations), medians, quartiles 1 and 3, as well as interquartile range. Normality checks were done with the Shapiro–Wilk test. To compare groups, we used the Mann–Whitney test, as well as the Kruskall-Wallis test. The Chi-square test, to relate nominal data, and the Spearman correlation, and its 95% CI, were also used. Effect sizes were calculated (partial eta square, and Cramer's V). These analyses were done in Statistica v.13.3 (Statsoft, Kraków, Poland), and the significance level was set at 5%. Further sample size estimation was done with the G\*Power v. 3.1. software (Heinrich-Heine-Universität, Düsseldorf, Germany).
