Adequate nutrition is critically important for the achievement of the adolescent athlete's optimal performance. The purpose of the present study was to evaluate the adequacy of macro-and micro-nutrients in the adolescent Greek female volleyball players' diet. The subjects of the study consisted of 16 players who were members of the Junior National Team (NP) and 49 players who participated in the Junior National Championship (CP). Dietary intake was assessed using a 3-day food record. Protein intake (16.0 ± 4.9% of total energy intake) was satisfactory, whereas fat consumption (37.5 ± 11.1%) was above recommended values and at the expense of carbohydrate intake (45.9 ± 12.5%). There were no significant differences between NP and CP concerning the intake of macronutrients, except for the fat intake (when this is expressed in grams per day and grams per kilogram of body weight and the saturated fat intake, which were both higher in NP compared to CP players (p < .05). The mean energy intake was 2013 ± 971 and 1529 ± 675 kcal for NP and CP, respectively (p < .05). NP, in particular, consumed fat and especially saturated fat in order to meet their energy needs. As for micronutrients, the volleyball players fell short of meeting the RDA values for calcium, iron, folic acid, magnesium, zinc, and vitamins A, B 1 , B 2 , and B 6 . There was no difference between NP and CP in micronutrient intake. In conclusion, subjects in the current study lacked proper nutrition in terms of quantity and quality.Key Words: nutrition, elite athletes, energy, team sports Adolescent athletes have increased energy needs because of physical activity and physical development. This is especially true for elite adolescent athletes, who exercise strenuously in order to maximize their performance. These athletes should consume high density food for both nutrients and kilocalories (32). Proper nutrition is essential for optimizing athletic performance (9). A general recommendation for all athletes is to consume 60-70% of total energy intake from carbohydrates (CHO), 12-15% from proteins, and 25-30% from fats (20).Generally, young athletes may be inclined to stress fracture (7). Proper nutrition can play a valuable role in avoiding such injuries, as inappropriate nutrition may

Plyometric training in children, including different types of jumps, has become common practice during the last few years in different sports, although there is limited information about the adaptability of children with respect to different loads and the differences in performance between various jump types. The purpose of this study was to examine the effect of gender and training background on the optimal drop jump height of 9- to 11-year-old children. Sixty prepubertal (untrained and track and field athletes, boys and girls, equally distributed in each group [n = 15]), performed the following in random order: 3 squat jumps, 3 countermovement jumps (CMJs) and 3 drop jumps from heights of 10, 20, 30, 40, and 50 cm. The trial with the best performance in jump height of each test was used for further analysis. The jump type significantly affected the jump height. The jump height during the CMJ was the highest among all other jump types, resulting in advanced performance for both trained and untrained prepubertal boys and girls. However, increasing the dropping height did not change the jumping height or contact time during the drop jump. This possibly indicates an inability of prepubertal children to use their stored elastic energy to increase jumping height during drop jumps, irrespective of their gender or training status. This indicates that children, independent of gender and training status, have no performance gain during drop jumps from heights up to 50 cm, and therefore, it is recommended that only low drop jump heights be included in plyometric training to limit the probability of sustaining injuries.

The relative age effect (RAE) on human performance has been well studied in many sports, especially in soccer; however, little information has been available about the prevalence of RAE in volleyball, and its role on anthropometric and physiological characteristics. The aim of the present study was to examine (a) the prevalence of RAE in selected (i.e., to be considered for the national team) and non-selected youth female volleyball players, and (b) the relationship of birth quarter (BQ) with anthropometric and physiological characteristics. Selected (n = 72, age 13.3 ± 0.7 years, weight 62.0 ± 7.2 kg, height 1.72 ± 0.06 m) and non-selected female volleyball players (n = 53, age 13.9 ± 1.1 years, weight 56.4 ± 7.3 kg, height 1.66 ± 0.06 m) performed a series of anthropometric and physiological tests. Twenty-six selected participants were born in the first quarter of the year, 19 in the second, 14 in the third, and 13 in the forth. The corresponding frequency by BQ in non-selected participants was 12, 12, 17, and 12. No association was observed between the number of participants and their frequency by BQ neither in the selected (χ2 = 2.79, p = 0.425) nor in the non-selected group (χ2 = 0.64, p = 0.886). Anthropometric and physiological characteristics did not vary by BQ (p > 0.05). The absence of RAE in female volleyball players and the similarities of anthropometric and physiological characteristics among BQ might be due to technical-tactical character of this sport. These findings would be of great practical value for coaches and fitness trainers working with young volleyball players.

The aim of the present trial was to investigate the effect of two stretching programs, a dynamic and a static one, on the sprint ability of recreational volleyball players. The sample consisted of 27 male recreational volleyball players (age 21.6 ± 2.1 years, mean ± standard deviation, body mass 80.3 ± 8.9 kg, height 1.82 ± 0.06 m, body mass index 24.3 ± 2.5 kg.m−2, volleyball experience 7.7 ± 2.9 years). Participants were randomly divided into three groups: (a) the first performing dynamic stretching exercises three times per week, (b) the second following a static stretching protocol on the same frequency, and (c) the third being the control group, abstaining from any stretching protocol. The duration of the stretching exercise intervention period was 6 weeks, with all groups performing baseline and final field sprinting tests at 4.5 and 9 m. The post-test sprint times were faster in both the 4.5 (p = 0.027, η2 = 0.188) and 9 m tests (p < 0.001, η2 = 0.605) compared to the pre-test values. A large time × group interaction was shown in both the 4.5 (p = 0.007, η2 = 0.341) and 9 m tests (p = 0.004, η2 = 0.363) with the static and dynamic stretching groups being faster in the post-test than in the pre-test, whereas no change was found in the control group. The percentage change in the 4.5 m sprint time correlated with volleyball experience (r = −0.38, p = 0.050), i.e., the longer the volleyball experience, the larger the improvement in the 4.5 m sprint. Thus, it is concluded that both stretching techniques have a positive effect on the velocity of recreational male volleyball players, when performed at a frequency of three times per week for 6 weeks under the same conditions as defined in the study protocol.

The purpose of this study was to analyse selected serve characteristics in top-level male volleyball, with a special focus on detecting adaptations of the serve skill among seasons. The indicators examined were type, position, direction and quality of serve. The sample consisted of 5482 serves from three final phases of different top-level tournaments (Olympic Games 2012, N = 1942, World League 2017, N = 1883, World Championship 2018, N = 1657). The interrelationships between variables were analyzed using chi-squared tests, log-linear modelling and multiple correspondence analysis. The results showed that the interaction of all serve indicators are statistically important, but the combination of the variables’ categories that were more responsible for association alternated across the seasons under study. A 3-way association term was revealed for season 2012 (type/position/direction) and 2018 (type/position/quality), while for season 2017 multiple 2-way interactions were found (type/position, type/direction, position/quality, direction/quality). The direction of the serve to the horizontal axis of the court was correlated to the quality of serve and consequently with the advantage of the serving team, while a more tactical perspective for serve skill is formed over periods in top level male volleyball.