Under-17 Research Articles

Intensidade de jogos de futebol de uma competição real e entre jogadores de diferentes posições táticas. DOI: 10.5007/1980-0037.2011v13n5p341

Most investigations on soccer match intensity have evaluated friendly, simulated or a small number of games on a recreational basis or including a small number of players. There are no studies investigating real competitive situations including a considerable number of athletes and games or differences among player positions using heart rate as an intensity parameter. The aim of this study was to determine Brazilian soccer game intensity (GI) during official competitive matches and to compare GI among different player positions. Heart rate (HR) was measured in 26 under-17 (U-17) and 18 under-20 (U-20) soccer players (age 16.38 ± 0.5 and 18.24 ± 0.66 years, respectively) during 14 and 15 official games, respectively. Individual maximal heart rate (HRmax) and anaerobic threshold (AT) HR were evaluated in field tests. GI defined as %HRmax was monitored considering five intensity zones ranging from 1 = < 70% HRmax to 5 = 95-100% HRmax. Mean GI and AT intensity were 84.4 ± 5.1 and 86.3 ± 4.0% HRmax for the U-17 category and 84.1 ± 4.1 and 87.0 ± 5.1% HRmax for the U-20 category, respectively. Wingbacks (WB) spent more time in zone 5 than forwards (FW) (p<0.05). Midfielders (MF) spent more time in zone 3 than all other players and in zone 4 than defenders and FW (p<0.05). Mean GI and AT intensity were similar. WB performed more maximum effort than FW. MF did not participate as much in maximum effort as did WB and FW.

Epidemiological Study of Injuries in Men's International Under-20 Rugby Union Tournaments

To determine the incidence, nature, and causes of match injuries sustained during Under-20 (U-20) international rugby. Prospective cohort study; definitions and procedures were compliant with the international consensus statement for epidemiological studies in rugby. 2008 and 2010 IRB U-20 Junior World Championships and Junior World Rugby Trophies. Nine hundred forty-one players representing 35 international teams. Injuries reported as functions of playing position and nature and cause of injury. Incidence, location, type, severity, and causes of match injuries. Incidence of injury was 57.2 per 1000 player-match-hours (forwards, 55.3; backs, 59.4) with a mean severity of 22.4 days (forwards, 27.7; backs, 16.9) and a median severity of 6 days (forwards, 8; backs, 6). Lower limb ligament (25.3%) and muscle (21.3%) pathologies were the main injuries. Most injuries were acute (90.4%) and sustained during tackles (45.1%) and collisions (17.7%). The study showed that the overall risk of injury for players in international U-20 rugby is significantly lower than that reported at the full international level of play; the nature and causes of injury at U-20 are similar to those at the full international level of play.

An analysis of the performance of Black African junior provincial cricket batsmen

Objectives. This study investigated the difference in performance of white (W), coloured/Indian (C/I) and black African (BA) cricket batsmen at a junior provincial level in South Africa over a period of 7 years. Methods. Data of all players participating in the South African interprovincial under-15 (U15) and under-19 (U19) tournaments between the years 2004 and 2010 were analysed. The number of participants, batting averages and number of batsmen in the top 20 run scorers in the tournament were compared between groups. Results. 52% of players were white and 48% were black (27% BA and 21% C/I). BA batting averages (runs/dismissal) were significantly ( p <0.05) lower than W batting averages for every year from 2004 to 2010 for both the U15 and U19s. W batsmen only had significantly better batting averages than C/I for the U/15s in 2010 and for the U19s in 2009 and 2010. W batsmen dominated the top 20 run scorers in the tournament in each year for both U15s and U19s while there were few BA batsmen represented in the top 20. Conclusion. The performances of BA batsmen at junior provincial level are well below those of W batsmen and appear to follow the same trend as the senior provincial batsmen.

Age And Experience Differences In Work Intensity During Soccer Matches

PURPOSE: The purpose of this project was to compare the distribution of movement intensity for a men's under-20 (U-20) and a boy's under-12 (U-12) team.FIGUREMETHODS: Step rate data were recorded on 5 players from each team during competitive matches using StepWatch Activity Monitors. Step rates were categorized into 7 levels of intensity: Walk, Slow Jog, Fast Jog, Run, Fast Run, Sprint, and Max as a percentage of the total samples. Each level was compared between the two teams using ANOVAs. First Referees' step rates were also recorded. RESULTS: For U-12 players the step rate data showed much more time spent in recovery at low levels of intensity (Walk, Slow Jog, Fast Jog), less time spent in Run, Fast Run, and Sprint intensities, but more time at Max intensity compared to the U-20 team. The First Referees' distributions mimicked the players they were officiating. CONCLUSIONS: Data confirm that younger players are apt to run more often at maximum intensity, with more frequent low-level recovery periods. The U-20 players were able to compress their step rates to maintain a moderate to high level of activity more often but spent less time at either the slowest or fastest rates. U-20 players rarely hit top speed unless a critical play was forming that might result in a scoring opportunity in either goal. So, these more experienced players were also more likely to avoid frequent rest periods necessary after bouts of maximum speed. This is likely due to reduced fitness and ball control skills by U-12 players, and not an inability to read the development of a critical play. Coaches may want to encourage younger teams to focus more on ball control skills as it would allow these younger players to better modulate work intensity to manageable levels during soccer matches.

The relative age effect in youth soccer across Europe

The potential asymmetries in the birth-date distributions of youth soccer players across ten European countries (2175 age citations) were considered. First, we examined the birth-dates of players representing national youth teams in international competitions. Second, the birth-dates of players representing professional club teams in international youth tournaments were analysed. Kolmogorov-Smirnov tests were used to assess differences between observed and expected birth-date distributions. Regression analyses were employed to examine the relationship between month of birth and number of players in the different samples. The results showed an over-representation of players born in the first quarter of the selection year (from January to March) for all the national youth selections at the under-15 (U-15), U-16, U-17 and U-18 age categories, as well as for the UEFA U-16 tournaments and Meridian Cup. Players with a greater relative age are more likely to be identified as “talented” because of the likely physical advantages they have over their “younger” peers. Some options for reducing the relative age effect are offered.

Specific muscular development in under-18 soccer players.

A comparison of the under-18 (U-18) and under-16 (U-16) squads of the Canadian national soccer team with a representative sample of Canadians (Canada Fitness Survey, 1983) showed a tendency for the development or selection of the older players in teams of stature (U-18, 175.8 cm; U-16, 171.1 cm; CFS, 170.9 cm) and lean body mass (U-18, 63.4; U-16, 57.9; CFS, 54.2 kg). The larger lean mass of the older players could not be explained simply by size. The U-18s also showed greater isokinetic leg extension force (particularly for rapid movements) and explosive strength (vertical jump) relative to the younger players, although the knee extension force was less than in some classes of athlete. Part of the gain in mass seems due to local training of the hip and leg muscles and part to a more general muscular development. Contrary to some reports, the hip flexibility of the Canadian players (sit and reach test) was greater than for a national sample; this may be important in avoiding soft tissue injuries to the legs. However, aerobic power (58.3 +/- 5.3 ml kg-1 min-1) and body fat (8.0 +/- 1.1%) were unremarkable.