I.Kh. Vakhitov, professor, Dr.Biol.
S.N. Pavlov, associate professor, Ph.D.
E.G. Kabysh, candidate
A.V. Petrov, candidate
Institute of physical culture and rehabilitation medicine of Kazan (Volga) federal university, Kazan

Key words: heart rate, blood stroke volume, skydivers, athletes of various qualifications.

Introduction. Recently extreme sports have become most popular among youth. Herewith, skydiving is the most popular one in Russia and the Republic of Tatarstan among senior schoolchildren, students and adults. Skydiving sport makes specific demands to the ones practicing it. Skydivers are usually not subject to intensive muscular loads like in other cyclic and acyclic sports. However, essential changes take place in skydiver’s body while getting ready for a jump (starting from parachute packing to boarding), jumping (when human body suffers from overload at free fall) and landing. Moreover, certain psychological properties are necessary in skydiving. Skydiving has its own specifics, differing from "land" sports [2] mainly by the effect of stress factors (atmospheric pressure drop, accelerations, overloads, naupathia etc.) on a skydiver's body while jumping. Long-term occupations of this sport are assumed to provoke significant changes in functioning of some organs and systems [1]. Herewith, the specifics of changes in heart pumping indices of the growing organism in case of regular skydiving occupations are still understudied.

The purpose of the present work was to study heart rate indices and blood stroke volume in young people regularly practicing skydiving. Experiments were carried out on the Kurkachi airfield (the Republic of Tatarstan) not far from Kazan. Athletes ranging from beginners to world-class athletes were subject to examination. The beginners were young men inexperienced in skydiving, undergoing annual field trainings in a landing club within military patriotic activities and organized by the Ministry for youth, sports and tourism of the Republic of Tatarstan and the Republican sports and patriotic center "Patriot" in collaboration with ROSTO (DOSAAF) of the Republic of Tatarstan.

Rated athletes, masters of sport and world-class athletes took part in Russian skydiving championships.

Another group examined was made of 40-45-aged ex-masters of sports in skydiving and skydiving veterans, those leading active way of life, without bad habits and any skydiving experience for approximately 10-15 years after finishing their sports career.

Skydivers’ heart rate and stroke volume were recorded in the morning in the day of jumps, right after waking up, then right before boarding and after landing. Rheograms in all three examinations were recorded while lying. Heart rate and stroke volume were defined by means of tetrapolar chest rheography [3].

Research results and discussion. Proceeding from our researches, the divergence of heart rate indices in the morning of the day of jumps and before boarding was insignificant in the inexperienced teenaged skydivers aged 16-17. So heart rate of teenaged beginning skydivers changes slightly before boarding compared with original data. However, heart rate indices were much higher after a jump, i.e. after landing. The spread in heart rate indices before boarding and right after landing was 81,7 bpm (Р<0,05).

The disparity in heart rate indices of mass rated skydivers (aged 20-22) at rest and before boarding was 10,1 bpm (Р<0.05), which was higher than the indices of teenaged beginning skydivers. The difference between heart rate indices before boarding and after landing comprised 69,6 bpm (Р<0.05), which is 12,1 bpm less than the indices of beginning athletes. Therefore, mass rated skydivers’ heart rate reaction decreases significantly compared to the teenagers aged 16-17.

The spread of heart rate indices of masters of sports in skydiving at rest and before boarding was 14,3 bpm (Р<0.05), and it was 69,9 bpm more than the basic data right after landing. Thus, the disparity in heart rate indices of mass rated athletes and masters of sports before boarding and right after landing was almost the same, in the range of 69-70 bpm.

Heart rate indices of world-class athletes (under 35 years old) differed insignificantly at rest and before boarding. Right after landing their heart rate was on the level of 97, 4±1,7 bpm. The disparity of their heart rate indices before boarding and right after landing was much lower than in the groups examined earlier and comprised only 14,7 bpm (Р<0.05).

We also examined heart's pumping indices in ex-masters of sports in skydiving. Skydiving veterans’ heart rate in the morning in the day of jumps was 101,7±1,9 bpm and decreased significantly before boarding to 91,5±1,4 bpm (Р<0.05). However, right after landing their heart rate was significantly high - 187,4±1,3 bpm. As for ex-masters of sports, the disparity of heart rate indices before boarding and right after landing comprised 95,9 bpm (Р<0.05), which was significantly higher than in the previous groups.

Thereby, based on the above, the disparity in heart rate indices before boarding and after landing was assumed to decrease significantly with skydivers’ professional development. Thus heart rate was proved to decrease unequally. Thus only world-class athletes have the least disparity in heart rate indices, by it remained on the high level in mass rated athletes and masters of sports and comprised approximately 69-70 bpm (Р<0.05). The highest disparity in heart rate indices before boarding and after landing was shown by ex-masters of sports - 95,9 bpm, whereas in the teenaged inexperienced skydivers it was only 81,7 bpm, which is 14,2 bpm less than the disparity of ex-masters. These must be psychological adaptation and athletes' fitness level that influence the decrease in the disparity in the indices before and after a jump.

Herewith, we analyzed changes of skydivers’ stroke volume on different stages of skydiving training and after landing. As proved by our researches, the stroke volume of teenaged beginning skydivers aged 16-17 in the day of jumps comprised 37,7±1,9 ml in the morning after waking up (table 2) and 40,5±1,4 ml - before boarding. The disparity in the stroke volume indices in the morning and before boarding was insignificant. Therefore, we didn't observe any considerable change in beginning skydivers’ stroke volume before boarding compared to the morning indices after waking up in the day of jumps. The values of stroke volume after a jump, i.e. right after landing, were only 28,4±1,4 ml. The disparity in the stroke volume indices before boarding and right after landing was 12,1 ml (Р<0.05), testifying to the lack of significant changes in the stroke volume indices of beginning inexperienced skydivers before boarding in the plane. Nevertheless, the stroke volume indices of these skydivers decreased significantly right after landing.

The stroke volume values of mass rated skydivers (aged 20-22) remained approximately on the level of 51-55 ml before boarding and after a jump, i.e. after landing.

The stroke volume of masters of sports in skydiving was 67,4±1,4 ml in the morning right after waking up in the day of jumps, followed by its increase by 7,3 ml before boarding up to 74,7±1,3 ml (Р<0,05). While registering stroke volume of masters of sports in skydiving right after landing, we have not revealed any notable difference between blood systolic discharge and stroke volume indices before boarding, which comprised 72,5±1,2 ml. Therefore, some increase of stroke volume of masters of sports in skydiving occurs only before boarding.

The morning stroke volume indices of world-class athletes (aged under 35) right after waking up in the day of jumps were 62,7±1,4 ml, followed by the increase by 18,7 ml up to 81,4±1,3 (Р<0,05) right before boarding and rising up to 98,7± 1,7 ml right after landing. The disparity between the world-class athletes’ stroke volume indices before boarding and right after landing was equal to 17,3 ml (Р<0,05), proving the significant increase in the values of high-qualified skydivers before boarding and right after landing compared to the basic data.

Heart pumping indices of ex-masters of sports in skydiving were also subjected to examination. The stroke volume of skydiving veterans was 54,3±1,3 ml in the morning, in the day of jumps, 48,9±1,4 ml before boarding, differing insignificantly from the morning values at rest. However, it dropped significantly right after landing compared to the values before boarding and comprised 35,4±1,7 (Р<0,05). The disparity in these two indices was 13,5 ml (Р<0.05).

Proceeding from the above, the stroke volume reaction is assumed to increase with the rise of skydivers' fitness level. However, it was the first time we revealed the negative reaction of the stroke volume of beginning skydivers and ex-masters of sports after a jump. The rising stroke volume reaction of masters of sports and world-class athletes before boarding and after landing must be due to performance of more difficult jumps: various free fall and complex acrobatic exercises, requiring attention focusing, concentration and synchronism and provoking the risk caused by growing complexity of the jump. The negative reaction of stroke volume allocated in beginning skydivers and ex-masters of sports after a jump is assumed to be stipulated by high heart rate indices. In case of its high values the diastolic heart failure must decrease, resulting in the reduced ventricular blood pumping effect stipulating the decrease of skydivers’ stroke volume.

Table 1. Heart rate indices of skydivers

* - Significant compared to previous values (Р≤0,05)

Table 2. Stroke volume indices of skydivers

* - Significant compared to previous values (Р≤0,05)

Bibliography

1. Vakhitov, I.Kh. Specific changes in heart rate of athletes regularly practicing skydiving. // Proceedings of the All-Russian theoretical conference with the international participation “Actual researches in the field of the science of physical culture”. Kazan, 2010. (In Russian)

2. Gavrilina, A.V. The effect of emotional tension on accuracy of teaching timing in an extreme situation // Proceedings of the theoretical students’ conference of Dubna university, 2006, P. 27-30. (In Russian)

3. Kubicek, W.G, Kamegis, J.W, Patterson, RP, Witsoe, D.A, Mattson, R.H. Development and evaluation of an impedance cardiac output system. Aerospace Med 1966,37:1208-12

Author’s contacts: tggpy-mbofk@mail.ru