Evangelos Bekris

Combined visual and dribbling performance in young soccer players of different expertise

ABSTRACT We aimed to evaluate dribbling performance in terms of technique and visual skills assessment of both young experienced (EX, n = 24) and novice (NO, n = 24) soccer players. Both groups performed two dribbling tests with four levels of difficulty in visual signals (A1–A4 and B1–B4; B – half distance of A; 1 – no visual signal; 4 – signal with the shorter flashing time). All players performed slower when visual signals were added to the testing process (~2.5 s; p < 0.01). EX completed all tests faster than NO (~3 s, p < 0.01). The average number of visual mistakes was significantly lower for EX than NO in all tests (p < 0.01). These results demonstrated the importance of evaluating dribbling along with visual stimuli in young soccer EX and NO players.

Playing Position: Anthropometric and Fitness Demands in Youth Soccer

Abstract The aim of this study was to examine the anthropometric and fitness characteristics of soccer players with different positional role. Although, players’ skills are not equally distributed in each position, at elite soccer they have to perform each skill at a sufficient level. However, coaches expertise those from an early age in specific positions without giving them an holistic individualized training. In the study participated 312 Greek players aged 6 to 17 (M= 11.89; SD= 2.33) of 5 age groups (group U7-U8; group U9-U10; group U11-U12; group U13-U14; group U15-U16; group U17). Anthropometric (height, weight, body mass index and body fat) and fitness characteristics (flexibility, vertical jump, running speed, agility and VO2max) of participants were measured. The study showed that goalkeepers and central defenders tend to perform worse than players of the other positional groups in most of their fitness characteristics for almost all the age groups. Furthermore, many tendencies were observed in anthropometric and fitness characteristics between players with different positional roles. This study provides suggestions to coaches regarding their practice of positioning players according to their anthropometric and fitness characteristics for a short term success.

The dribbling agility test as a potential tool for evaluating the dribbling skill in young soccer players

ABSTRACT The present study examined the construct validity and reliability of a new dribbling agility test (DAT) that incorporates reactive agility and multiple change of direction. To check its’ validity, (a) DAT was performed by four groups (under 10, under 12, under 14 and under 16 yrs) of young soccer players (n = 125 in each group) and (b) a regression analysis was conducted to define the best DAT predictors. The reliability of DAT was assessed with repeated measurements. This test can differentiate the dribbling skill between groups (p < 0.01). Furthermore, 68% of the observed variance in DAT was explained by zigzag dribbling test, Illinois agility test, reaction time and running speed. The test-retest reliability was high in all groups (ICC = 0.77 – 0.90, p < 0.01). It was concluded that DAT can be a potential tool to evaluate the dribbling performance in young soccer players.

The Relationship of Kicking Ball Velocity with Anthropometric and Physiological Factors in Soccer

Abstract The purpose of the current study was to examine the relationship of kicking ball velocity with anthropometric and physiological parameters in soccer. Specifically, the researchers examined how the anthropometric variables such as body weight, body fat, body mass index, and body height, as well as the physiological variables such as running speed, lower body explosive strength, lower limb endurance, balance, and agility are related to ball velocity. Fifty eight U-12 male soccer players, sixty one U-14, forty three U-16, and thirty five adult male soccer players participated in this study. The results showed that ball velocity is related to both anthropometric and physiological factors differently according to the age of the players. It was also confirmed that ball velocity is an indicator of playing level. The key finding from this research was that ball velocity is related to the explosive strength parameters. Thus this relationship is an indicator that coaches and trainers have to take into account so as maximize the kicking potential of their players.

From Preparation to Competitive Period in Soccer: Hematological Changes

Abstract Hematological parameters affect the aerobic capacity which is considered as basic for technical and tactical development of soccer players. However, the hematological parameters such as hemoglobin (HBG), hematocrit (HCT), red blood cells (RBC), iron status and ferritin concentration, change throughout a season. Therefore, the current longitudinal study aimed to examine the changes of hematological parameters in professional soccer players throughout a 6-month period. The researchers examined 25 soccer players (25.7 ± 2.1) at the beginning of the preparation period, at the middle, and at the end of the preparation period, as well as at the competitive period. The results indicated that in the first part of the preparation period there was an increasing trend for all the hematological parameters. This trend developed significant increases at the end of the preparation period, which corresponds at the beginning of the competitive period. In summary, the current findings showed that the players improve and maintain their hematological values throughout the season because of aerobic training during preparation period.