Quantitative sex differentiation of morphological characteristics in children aged 11 to 14 years.

Sex is one of major factors of individual variability. In kinesiology, we explore and record changes brought on by growth and development, so we will use a sample of 1020 subjects, at the age of powerful changes caused by sexual maturation, to investigate differences in morphological characteristics of children and to determine the significance of differences based on sex. The aim of this transversal research was to determine the sex differentiation of morphological characteristics in 5th and 8th grade students of elementary school as well as structural differences between the sexes. Differential sex differences in the structure of morphological parameters surely exist, and in their basis lies in a different temporal, or periodical onset of development phases, while multivariate analysis of variance for each age removes any doubt about these differences being more than obvious. Differences in the structure of discriminant function in children aged 11 are conditioned primarily by diverse structuring of transverse dimensions, in a way that boys are distinctly superior in knee diameter, and girls in bicristal diameter. As early as the age of 11, it can clearly be recognized that pre-puberty had already progressed in girls, which is then followed by puberty. At the age of 12 girls are already experiencing a puberty spurt, which is manifested in further development of bicristal diameter and longitudinal dimensionality of the skeleton, particularly of lower extremities. Thirteen year old boys are on the verge of a puberty spurt, which is manifested through the development of longitudinal dimensionality, and to a lesser extent, of transverse dimensionality of the skeleton. Secondary discriminant distinctiveness can be observed continuously across all variables assessing the dimension of deposition of fat reserves, and also, absolute values of measures of subcutaneous fat tissue are more prominent in female students. It is indicative that subcutaneous fat deposits are still secondary determinants in distinguishing groups of children according to sex, in a way that this dimension is continuously expressed more perceptibly in girls.

Quantitative sex differentations of motor abilities in children aged 11-14.

Sex differentiations of motor development in certain time periods of growing in boys and girls are changes provoked by maturity. The aim of this research was to establish sex differentiations in motor abilities on the transversal sample of 1020 subjects, pupils from the fifth to the eighth grade of the elementary school. Sex differentiations are significantly more expressed in puberty than in pre-puberty age, which approves that the development trend of certain motor abilities is different compared to the sex. We established a statistically significant difference between boys and girls in performing applied motor tests in all four age categories. In both younger and older age groups it is evident girls are more superior to boys in flexibility manifested in the bigger range of movement in a certain joint or a set of joints, i.e. in joint movability, as well as in the easiness and gracefulness of movements. In children of younger ages, motor efficiency of boys in relation to girls is manifested in the greater power of the trunk, greater explosive power of jump and sprint type and in coordination. The boys of older age have increased the difference in explosive power, particularly of throw type with better agility, equilibrium and greater static strength of arm and shoulder belt. There has evidently been a greater development of the muscle mass in the male sex compared to the female sex. On the basis of research results it has been concluded that the motor development follows faster, i.e. sooner in girls compared to boys and that puberty peak happens at the age of twelve for girls (6th grade) and at the age of thirteen for boys (7th grade).

Sex differences in motor characteristics of elementary school children included/not included in swimming training.

The aim of the study was to assess the development of motor abilities in elementary school fifth- to eighth-graders (age 11-14 years) according to sex, age and physical activity. Study sample included 312 subjects divided according to age and sex into four groups: male subjects aged 11-12 (n = 93) and 13-14 years (n = 84); and female subjects aged 11-12 (n = 65) and 13-14 years (n = 70). Then, differences in basic motor abilities between children included (experimental group) and those not included (control group) in swimming training were analyzed. In male fifth- and sixth-graders, experimental group was superior to control group in the variables of trunk repetitive strength, sprint, flexibility and coordination, while in male seventh- and eighth-graders experimental group showed better performance than control group in agility, aerobic endurance and explosive throw and jump strength. In female fifth- and sixth-graders, experimental group proved superior to control group in the variables of explosive strength, coordination, trunk strength and aerobic endurance, whereas in female seventh- and eighth-graders experimental group had better performance in coordination, endurance, explosive strength, speed and flexibility. Discriminative analysis of motor variables between male and female subjects revealed male subjects to be superior in explosive strength, throw strength in particular, coordination and aerobic endurance, whereas female subjects showed better performance in the variables of flexibility and movement frequency, leg movement in particular. Study results showed the formation of appropriate motor system determining achievement of top results in swimming to be influenced by swimming training from age 11 to 14. In male children, motor system was found to integrate coordination/agility, aerobic endurance and explosive strength, whereas in female children it integrated coordination in terms of cortical movement regulation, aerobic endurance, explosive strength and psychomotor speed.