Abstract
Youth participation in sports shows upward tendency. There is a strong interaction between nutrition, growth / development and success achievement in sport. Some physical aspects of the physiology of children aged 7-12 years, are not sufficiently clear. Needs assessment of children for macro/micronutrients hinders physiological variability of growth during puberty. However, we can point out the general needs of this population: 1) rehydratation in order to maintain optimal function of the cardiovascular system, based on the principles that apply to adults, 2) meeting the needs for energy and macronutrients. Daily energy needs, aged 9-13 are 1400-3000 kcal, depending on gender, stages of puberty and physical requirements. The recommended protein intake is 1,5-2,2 g / kg of BM. The intake of carbohydrates should be above 50% of daily energy needs. Intake of essential fatty acids should be in accordance with the recommendations. 3) Optimal input of micronutrients provide satisfaction of energy needs and implementation of balanced diet. The most common mineral deficits, with young athletes are related to iron and calcium. Supplementation with vitamin-mineral beneficiary substances showed no effects on growth and physical achievement.

 Abstract
In ten-week period, junior basketball players divided into two groups, experimental and control, were subjected to various training programs. Experimental group members, in addition to regular technical and tactical basketball training, had additional complex training twice a week, while the subjects in the control group only had a technical-tactical basketball training. The aim of this study was to test the impact of complex training on explosive leg strength in the performance of different jump variants of junior basketball players. Countermovement jump and Squat jump were tested as well as the following variables: maximum jump height (h), maximum force (Fmax) and the time needed for the achievement of the maximum force (tmax) in concentric contraction when performing jumps and explosive strength Index (IES = Fmax / tmax). Comparing the results obtained on the basis of the initial and final measurements, it has been proved that the tested variables have changed under the infl uence of experimental factors. In both tested jumps the maximum jump height (p=.00) and maximum force (p=.00) were significantly improved, whereas IES improved only in the Countermovement jump
(p=.00). the time of the maximum force realization remained unchanged during the ten-week treatment. The research has proven that the complex training has influenced the improvement of explosive leg strength in junior basketball players.

 Abstract
Reasons for withdrawing from sports are issues that experts in many countries address with special attention. In Bosnia and Herzegovina (hereinafter: BiH), these issues have not been previously researched. Therefore, this was a good ground for the author to assess what the most common reasons for withdrawing from sports for the BiH athletes were. 160 former athletes took part in the adapted survey for determining reasons for withdrawing from sports. The factor analysis produced eight factors (reasons for withdrawal). Besides determining the main reasons for withdrawing from sports for the entire sample, the T test was used to also examine the differences between male and female athletes (N=79 females, N=81 males), differences between athletes involved in individual and team sports (N=77 individual, N=83 team), as well as differences between athletes at the national and international level of competing (N=101 national, N=59 international) regarding favoring certain reasons for withdrawing. It has been determined that the BiH athletes fi nd the following reasons for withdrawal most important: "interest in other activities", "dissatisfaction with the coach/club" and "money problems." When the results are compared with the results of athletes coming from other countries, we can notice some specifi cs in the BiH athletes regarding reasons for withdrawal, where the main factors seem to be "dissatisfaction with the coach/club" and "money problems".

 Abstract
The research was carried out in order to determine the influence of morphological characteristics, motor and functional abilities (predictor sets) on the athletics program content of physical education (criterion set) of the elementary school students. A sample of 105 respondents was taken from the population of the seventh and eighth grade male students of elementary schools in Nis. 14 measuring instruments for the assessment of morphological characteristics were used, nine for the assessment of motor abilities, three for evaluation of functional abilities and four athletics program content of physical education variables. The results of canonical correlation analysis showed that all three predictor sets (morphological characteristics, motor and functional abilities) have statistically significant impact on the criterion set (athletics program content of physical education) with the students of elementary schools. Within the relations between the system of morphological characteristics and criterion two canonical factors that significantly explain the level of connection (CR = .75 and .69). Between the system of motor abilities and the criterion, three canonical factors that significantly explain the level of connection (CR = .91, .78 and .45) were obtained. The system of functional capabilities is significantly associated with the system of criterion variables at the level of .01 together with one canonical factor (CR .65). These results are also confirmed by the use of regressive analysis, so that all sets of predictor variables significantly influenced each of the individual criterion variable.

 Abstract
There is a notion that sport participation is positively related to students' academic achievement. The results of numerous studies abroad support this relationship, however, little research has been done at home on that matter. The present study is an attempt to examine existence of relationship between sport participation and academic achievement of secondary school students. Participating students (N=359), have filled in a questionnaire concerning students' involvement in sports and academic achievement. Student's t-test was utilized to test the difference between the means for sport participating students and sport non-participating students. Pearson's linear correlation was used to examine level of correlations for all variables. The relationship between investigated domains was additionally explored by2 test for contingency tables. Results of Student's t-test for independent samples have shown that differences between sport participating and sport non-participating students do exist, in favour of fi rst mentioned group, but the results of Pearson' linear correlations indicate that there is no relationship between the variables that define sport participation and academic achievement does for sport participating subsample (N=82). Аttained results of 2 test for contingency tables of variables of academic achievement and sport participation, indicate that these two domains were not in statistically significant relationship. These findings indicate that sport participation did not affect academic achievement, but better academic achievement of sport participating students is caused by some other factor.

 Abstract
The object of this paper is ski school and it's role in socialization process of preschool children. Socialization is the process of social learning through which an individual obtains the socially relevant behavioral patterns and is formed as a personality with all of the specific features. Socialization and development of personality being provided through social agents (factors) in the society that has the characteristics of a group. The following could be the socialization agents: family, school, peers, mass communication media and other institutions and persons with which and whom the individual has the contact with, for instance the coach, instructor and other. Ski school, in which the children actually meet with those values, requests and norms which exist and rule the society, might be one of the socialization factors. An important role in that process could be taken by: playing, peer group and the ski instructor. Playing is the most appropriate method for adopting the techniques and also for socialization, where there is an interaction between developing the certain functions and social relations. It contributes to development of some dispositions that could be transformed into abilities just by themselvesbalance, coordination, agility, quickness and other. Playing stimulates and develops emotions. Motives inspired by the emotions can be the prompters and directors of children's activities. A peer group can represent an important agent in the socialization process of an individual; it helps developing sociality, adopting the new social attitudes, regular mental and physical development, avoiding the eccentric behavior and encourages personal independence. Ski instructors, their personalities and their actions toward children could be of extreme relevance for the formation of personality as those people represent the role models for children, to look up to and identify with. Ski school with its own characteristics important for socialization (play as work method, group learning method, ski instructor as educator) is an important factor in socialization process of preschool children. School programs, durations of lessons and working with pre-school children should be adapted to specific requirements, needs and abilities, in accordance with their development.