Specifics of kinetic structure of small ball throwing by 7-8-aged pupils in view of their sex

Фотографии: 

S.A. Barantsev, professor, Dr.Hab. Institute of age physiology of RAE, Moscow
V.V. Prosyankin, Ph.D. Aktyubinsk state pedagogical institute, Aktobe, Kazakhstan
 
Key words: kinetic structure of motion, apparatus departure angle, resultant velocity, kinetic energy of motion.
 

Relevance. Throwing action is one of the key motor actions children study at school. They are rated as the basic types of movement and are included in the school curriculum of physical education starting from the first form. Throwings are of the great applied value and used in everyday life and work and in training of military men of the Russian Army. Throwings are used in various action games, relay races, render the all-round influence on a schoolchild's body and facilitate harmonious development.

Some research works are devoted to the problem of formation of the kinetic structure of the small ball throwing strategy of 8-10- (V.V. Prosyankin, 2009), 10-12-year-old pupils (V.P. Chicherin, 1996) in view of their age and gender features, but similar studies for younger schoolchildren are lacking and of interest regarding the investigation of the age features of formation of the kinetic structure of the commutative movement.

The purpose of the study was to consider the gender features of the kinetic structure of the small-ball throwing strategy of the 7-8-year-old pupils.

Materials and methods. The methods applied in the study were as follows:

1. Biomechanical methods: kymocyclography (in 83 characteristics). The method of high-speed video recording and subsequent biomechanical analysis was applied to study angular, speed motion characteristics of movement; vertical and horizontal displacement of a projectile, right-hand wrist and shoulder joints of the right hand, left and right hip joints; horizontal displacement of the total body center of mass from the start of the final effort to the projectile departure, height and angle of ball departure, duration of the throwing movement, work force indices of the studied movement, ballistic wave and other kinematic characteristics of the small-ball throwing action and result of throwing (83 characteristics in total). The biomechanical analysis also involved the studies of the kinematic characteristics of the final effort, its three control points: start of the final effort, “drawn bow” position and projectile departure (N.G. Ozolin et al., 1989). According to the metrological assessment, the applied measuring system was proved to satisfy the necessary requirements for studies of every type of movements (S.A. Barantsev et al., 1993).

2. Mathematical and statistical methods: analysis of variance.

There were measured mean values (M) and standard deviations (σ). The normalcy of distribution of research results was estimated by asymmetry (Аs) and excess coefficients (Ех) by n≥30 and by chi-square criterion by n≤29. The reliability of the difference scores was estimated by Student’s t-test and by means of the Mann-Whitney-Wilcoxon test criterion when lacking normal distribution.

Kymocyclography was carried out in the end of the academic year in the gymnasium №710 RAE Moscow. All the subjects were from the basic medical group for physical exercises in respect to their fitness. The studies involved 22 boys and 30 girls at the age of 7-8 years old (2nd formers).

The first-formers were taught the strategy of throwing actions for small balls in accordance with the methodology by I.N. Stolyak (1989). Hereby the method of pulling an arm with a ball was “straight-backwards”. The second-formers learned the method “from behind over the shoulder”, which is more complex compared to the first-formers (S.A. Barantsev, V.V. Prosyankin, A.A. Kalyuzhny, 2002).

Results and discussion. When starting the final effort to the projectile departure the throwing arm with a ball is closer to the horizontal position among boys rather than girls (р<0,01). The body lean backward is more significant in boys (р<0,01), so the boys’ throwing arm is pulled backwards stronger. The resultant velocity of hips and shoulder of the throwing arm and the projectile is much higher among girls.

Boys lean back (р<0,01) and pull their throwing arm backwards (р<0,01) stronger in the “drawn bow” position and bend both legs in the knee stronger (р<0,01). In other words, boys have the more expressed so called “drawn bow” position. However, no significant differences were marked in the resultant velocity of the knee and hip joints of the rear leg and the shoulder and joints of the throwing arm. Girls have higher resultant velocity of the projectile (р<0,01). The horizontal motion path of the shoulder joint from the start of pulling to the “drawn bow” position is larger among boys (р<0,05).

In the projectile departure position the boys’ body bent forward and the forefoot bent in the knee are stronger (р<0,01 and р<0,05 - respectively). The height of the projectile departure lacks significant difference. The ball departure angle is significantly stronger among boys and close to optimal. Boys have higher resultant velocity of the elbow joint (р<0,01) and their take-off speed of the projectile tends to larger values (р>0,05). The ball throwing result is significantly better among boys (р<0,01).

The vertical movement of the shoulder joint of the throwing arm and the duration of the horizontal displacement of a projectile to the position of pulling to the projectile departure was proved stronger among boys (р<0,01). The absolute and relative values of the body external work, the peak values of the kinetic structure of the total body center of mass from the position of pulling to the projectile departure are higher among boys (р<0,01). Girls have a better throwing performance index (р<0,01).

The ballistic wave indicators, such as minimal resultant velocity of the knee, hip, shoulder, wrist joints and the projectile were practically the same among boys and girls. The maximal resultant velocity of the knee, shoulder and elbow joints and the projectile was significantly higher among boys as well as the time from minimal to maximal velocity for the knee, hip, shoulder and wrist joints. Thus, some of the boys’ ballistic wave indicators are better, but the structure of their ballistic wave is underdeveloped and does not result in the significantly higher speed of the projectile departure.

The kinetic structure of the throwing motion was proved to be better formed in 7-8-year-old boys rather than girls.

Conclusions

  1. 7-8-year-old boys have a larger horizontal movement of the projectile from the start of pulling to the “drawn bow” position compared to girls by stronger pulling of the throwing arm backwards (р<0,01). The girls’ resultant velocity of hips and shoulder of the throwing arm and a projectile is significantly higher when starting the departure.
  2. Boys have the more notable so called “drawn bow” position. In the projectile departure position their resultant velocity of the elbow joint (р<0,01) and the angle of ball departure (р<0,01) are larger and close to optimal.
  3. Some of the boys’ ballistic wave indicators (maximal resultant velocity of knee, shoulder and elbow joints - р<0,01 etc.), absolute and relative values of external work, peak values of kinetic energy of the total body center of mass from the position of pulling to the projectile departure are better than among girls (р<0,01).

References

1. Barantsev, S.A. A set of technical means for studying of human locomotions and its metrological assessment / S.A. Barantsev, N.A. Yakunin //Collected inter-university researches "New teaching methods and means" / Ed. by N.N. Evtikhiev. – Moscow, 1993. – P. 98–101. (In Russian)

2. Barantsev, S.A. Algorithmization in teaching the key locomotions of young pupils: study guide for teachers of physical culture of comprehensive secondary schools and students of the faculty of physical culture / S.A. Barantsev, V.V. Prosyankin, A.A. Kalyuzhny. – Aktobe: publ. department of Aktyubinskiy state un-ty named after K. Zhubanov. 2002. – 47 P. (In Russian)

3. Zdanevich, A.A. Formation of the motor skill in throwings among IV-V-formers combined with development of coordination: abstract of Ph.D. thesis / A.A. Zdanevich. – Moscow, 1987. – 24 P. (In Russian)

4. Athletics: textbook for institutes of physical culture. /Ed. by N.G. Ozolin, V.I. Voronkina, Yu.G. Primakova. – 4th ed., rev. and cor. – Moscow: Fizkultura i sport. 1989. – 671 P. (In Russian)

5. Prosynkin, V.V. Technique of teaching complicated coordfination acyclic locomotions of pupils aged 8-10 based on the features of the kinematic motor structure (case study of small ball throwing): Ph.D. thesis / V.V. Prosyankin. – Moscow, 2009. – 191 P. (In Russian)

6. Stolyak, I.N. Formation of basic motor skills in 6-year-old pupils at the lessons of physical culture (case study of running, jumps, throws): Ph.D. thesis / I.N. Stolyak. – Moscow, 1989. – 178 P. (In Russian)

7. Chicherin, V.P. Technology of enhancement of small ball throwing technique by V-VI-formers based on the features of the kinematic structure of the studied motion: abstract of Ph.D. thesis / V.P. Chicherin. – Moscow, 1996. – 28 P. (In Russian)

Author’s contacts: barancev_sergei@mail.ru