Elementary School Group Research Articles

Injury Prevalence among Young Elite Baseball Players.

This study aimed to describe the injury profiles of young Korean baseball players according to position and age as the proportion and distribution of injuries based on playing position and age remains unclear. A total of 271 elite youth baseball players aged 8 to 16 years were divided into two groups: elementary school (ES) (n = 135) and middle school (MS) (n = 136). The participants' basic, baseball practice, and injury information were collected. Injuries in the MS group were not limited to the elbow and shoulder, and injury prevalence varied by age group and baseball position. The most injured body region in the ES group was the elbow joint, regardless of the position. In contrast, the most injured body region in the MS group was the lower back, except for infielders whose elbows were the most injured. Additionally, the MS group was more likely to experience injuries to the lower back (OR = 4.27, 95% CI = 2.47-7.40), shoulder (OR = 1.93, 95% CI = 1.08-3.43; p = 0.024), and knee (OR = 2.15, 95% CI = 1.17-3.94; p = 0.012). Our findings indicate that excessive practice and a lack of rest during MS (growth spurt period) can significantly increase the risk of lower back problems in young baseball players.

Cross-sectional comparison of the probabilistic structure in the distribution of pitching location among baseball pitchers of different ages

ABSTRACT The present study was a cross-sectional comparison of probabilistic structure in the distribution of pitching location among baseball pitchers of various age groups (25 elementary school (ES), 20 junior high school (JH), 15 high school (HS), and 18 college students (CL)). In the results, despite the general age-dependent variations in pitching precision, the difference was reflected not only in error ‘size’ but also in the ‘shape’ of error as it was shown by fitting 95% confidence ellipse to the two dimensional distribution of pitch location. While the precision measure as a reflection of trial-by-trial variability of release timing (major axis length of the ellipse) was constant, minor axis length of the ellipse as a reflection of variability in the pitching form of each participant demonstrated significant differences among the groups. In the ES group particularly, the trial-by-trial variability in the trajectory angle of the throwing arm was significantly correlated with the minor axis length; this correlation was far greater than those in older groups. The present study is the first to demonstrate the detailed structure of the variability of pitching location of baseball dependent on age.

The Selected Nature of a Particular School Population

For years evidence as to the selected nature of the successive grades in school has been accumulating. So much evidence has been collected that today many of the phenomena of the school are explained in terms of this selection. The following analysis of a particular school population, however, seems to indicate that there are trends in this selective process that have not been noted in other studies and trends that are contrary to those found elsewhere. As to whether or not similar conditions would be found in other schools, the writer does not care to predict. Certainly there is need for investigation, need for the analysis of the data now available, and need for securing new data for analysis. General conditions and conclusions are not necessarily applicable to particular situations, as is well illustrated by the facts here presented. The population under consideration consisted of 551 white pupils attending the high schools of Lincoln Parish, Louisiana, and 467 white pupils in the fifth, sixth, and seventh grades of this parish.' The following schools were included in the study: three small consolidated rural schools teaching all grades through the high school, one school in a town of approximately i,ooo population housing the elementary school and the high school in separate buildings, and the only high school and two elementary schools in a town of approximately 5,000 population. These schools enrolled the entire highschool population of the parish and approximately two-thirds of the elementary-school population, the remaining one-third being in small oneand two-room schools. The high-school group included all the high-school pupils who were present on the particular days the schools were visited. The elementary-school group included all