Subject
The study included 29 cadets in two male groups studying at the Air Force Military Academy in Dęblin. Group A (study; n = 17) was represented by cadets with an average age of 19.94 ± 1.3 years studying to become an aircraft pilot. Group B (control; n = 12) consisted of cadets with an average age of 19.83 ± 1.27 years studying ground navigation. In both groups fitness and physiological tests were performed twice: before the training process—study I; after the training process—study II. The following somatic parameters were examined: body mass, body height and BMI. In group A in study I: body mass was 76.32 ± 9.37 [kg], body height was 178.63 ± 6.74 [cm] and BMI 23.94 ± 2.83 [kg m−2], while study II showed a body mass of 76.7 ± 9.84 [kg] and a BMI of 23.97 ± 2.64 [kg m−2]. In group B, the somatic parameters examined in study I, were as follows: body mass 79.65 ± 12.10 [kg], body height 181.66 ± 7.93 [cm] and BMI 24.04 ± 2.45 [kg m−2], while in study II: body mass 81.1 ± 11.06 [kg], and BMI 24.5 ± 2.24 [kg m−2]. Body height was unchanged in both studies, in both groups. In group A and B between study I and II in body mass and BMI there was no significant difference. Using Student's t-test there was a difference between groups A and B for body mass (p = 0.41), and BMI (p = 0.92) in study I and in study II respectively (p = 0.27) and (p = 0.57).
Ethical issue
The investigators obtained the approval of the Bioethics Committee, at the Medical University of Poznan, issued on May 15, 2019, with the number 610/19.
Physiological study
Heart rate (HR) and body components were measured twice in both groups in study I and II. Analysis of the dynamics of HR changes was recorded before and after ASET using POLAR—TEAM 2 system. POLAR—TEAM 2 system was also used during the training unit to monitor the training intensity. Cadets during study I and study II was wearing directly on center the chest a strap with wireless transmitter. Each strap with the transmitter was connected to the POLAR TEAM 2 system from which the HR values were read. Based on that measures was given the intensity range of the training process, HR before execiution ASET and HR after execiution ASET.
Analysis of body components
Measurement was performed with an AKERN type BIA 101SE body composition analyzer according to the guidelines for body components issued by the European Society of Parenteral and Enteral Nutrition (ESPEN). During the analysis of body components, the subject was in a supine position with his limbs at a 30-degree deviation from the body axis. Electrodes were adhered to the skin on the hand and on the foot. On the hand, they were stuck on the medial surface between the wrist joint and the third metacarpophalangeal joint, 4 cm from the metacarpophalangeal joint. On the foot, on the medial top part of the foot, between the ankle and shin joint and the third metatarsophalangeal joint, at a distance of 7 cm from the metatarsophalangeal joint. Before sticking the electrodes, the skin was washed with gauze and disinfectant [16].
Fitness tests
An analytical fitness test was conducted to assess the level of general fitness. This test consisted of 40 m, 100 m and 1000 m run and pull-ups. It was conducted before and after the training process. Time measurement during the running trials was performed with an accuracy of 0.01 s. The pull-ups on the bar were performed with an overhand grip from an overhanging position, keeping the elbow joints straight. The subject had to pull up to such a height that his chin was above the bar in order to be considered a correctly performed repetition. The Aviation Synthetic Efficiency Test (ASET) was used to assess the cadets' level of directed physical fitness.
Aviation Synthetic Efficiency Test (ASET)
This is a test consisting of 16 stations and is performed in a timed manner. All stations included in the test are located at a distance of 60 m. The test includes such fitness elements as speed, strength, endurance, flexibility, and jumping ability (e.g. roll over, rolling, jumping, and numerous changes in body position in relation to the ground) (Fig. 1). It is a complex test in terms of difficulty of execution, with high intensity and short work volume. This test diagnoses the subjects in terms of ability to adapt motor activities to changing conditions and situations (orientation), quick reaction, balance and motor adaptation to the pilot's work environment [5, 6]. The exercise stations are set in the right order in such a way that they provide a stimulus of influence for those muscle parts that are involved in the anti-overload maneuver. The following scale is used to evaluate the result (time) obtained during the test.
Assessment criteria
Time and assessment standards for men when performing ASET:
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43 s—very good grade;
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45 s—good grade;
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47 s—satisfactory grade.
Study group training program
The study group was implementing a directed training program as a didactic element of the "pilot" course at the Air Force Military Academy in Dęblin. The training program included 35 training hours and was conducted over a period of 60 days. Training unit included 2 training hours and was 90 min long. In every week were two training sessions. The purpose of the directed training of pilots is to improve the level of physical fitness by mastering physical exercises affecting the muscle groups involved in the execution of the muscle-tensioning maneuver (increasing the tolerance of acceleration +Gz) and improving spatial orientation, agility and motor coordination [8]. Each training session included a 20-min general warm-up. The main part of trainings included speed-strength, strength-endurance, speed-agility exercises. The program included an obstacle courses running, jump exercises, forward and backward flips, balance exercises with the use of devices, exercises with an external load. The final part of trainings included stretching exercises for all parts of the body. In the main part of each trainings cadets had 3 series of exercises. In each series was 8–9 exercises and 3 min of rest between each series. Time of each exercise was 15–20 s of maximum intensity. After every exercise cadets had 25–35 s of rest. During rest cadets did only breathing exercises. Duration of exercise and rest was regulated by the teacher. The stage of directed physical preparation of pilots for flying in high-maneuverability aircraft is preceded by training on Special Aviation Gymnastics Instruments (SAGI) [17]. Based on the heart rate index, the trainings aimed at shaping the directed physical fitness of the pilot were conducted in the zone of aerobic-anaerobic metabolism with the predominance of anaerobic metabolism. The average intensity level of a given training unit measured HR was maintained in the range of 140–170 bpm. The training units were conducted using the repetition, interval, circuit, station and stream methods.
Training program for the control group
The control group followed a standard physical education program designed for Polish Army cadets. The program included a set of general development exercises, team games and elements of hand-to-hand combat. Training unit included 2 training hours and lasted 90 min. The training program included 35 training hours and was conducted over a period of 60 days. Based on the heart rate index the trainings were conducted in the zone of aerobic metabolism. The average intensity level of a given training unit as measured by HR was kept in the range of 130–140 bpm. The training units were conducted using repetition, station and traditional methods.
All subjects were provided with the same living and eating conditions. The cadets received a standard diet according to the principles of mass nutrition. Daily rations consisted of an average of 4500 kcal, including 150 g of fat (30%), 112.5 g of protein (10%), and 675 g of carbohydrates (60%).The cadets in both groups drank water before and after training, about 1 l in total. They performed the exercises in the ambient temperature of 18 °C.
Statistical analysis
Descriptive statistics were used in the study by calculating for study I and II arithmetic mean (M), standard deviation (SD); for the study group (group A) and the control group (group B). The results of study I and II were subjected to normality distribution analysis using Shapiro–Wilk Test. The homogeneity of variance was measured with Levene's test. Comparisons of the parameters between groups A versus B and study I and study II was carried out by two-factor analysis of variance Anova with repeated measures. Was used for measured the difference in scores between group A and group B in study I and study II used analysis of variance the Tukey's test (HSD) post hoc pairwise. The effect size between fitness tests and body components at study I and study II was assessed using Hedges’ag test for dependent samples. The effect size between groups was assessed using Hedges’ag test for independent samples. Pearson’s (r)-correlation between body components and physical fitness tests was calculated. The obtained calculation values were considered statistically significant with p < 0.05. Statistical analysis was performed using the Statistica 13.3 program.
