Analysis of the pitching arm of the professional baseball pitcher.
Explore the source record for details and available documents.
SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
1. The optimal ocular position after vitreoretinal surgery with intravitreous gas tamponade is with the axis of the eye pointed downward. 2. Careless prone fixation may cause accidents of eyeball depression. 3. To help patients keep the proper prone facial and ocular positions, a modified catcher's mask was developed for use as a facial support.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
PURPOSE: The ability of a baseball infielder to respond to a batted ball may provide the best defense for avoiding injury. This study investigated the response times of young athletes performing a simulated baseball-fielding task to estimate the maximum velocity with which a baseball can leave the bat and allow a player, standing 13.7 m away, to safely respond to the approaching ball. METHODS: Fifty boys and 50 girls between the ages of 8 and 16 yr participated. Baseballs were projected at the subjects who were standing in a standardized position behind a safety net. Two components of response time, reaction time and movement time, were determined using a motion capture system. The influences of baseball velocity (26.8 and 33.5 m.s(-1) and level of attention (full attention and attention splitting) on response time for a simulated baseball-fielding task were characterized. Based on the response times for each age group, the maximum exit-velocity from a baseball-bat interaction that would allow a young baseball player sufficient time to safely respond to an approaching baseball was calculated. RESULTS: The results showed that subjects had sufficient time to respond to exit-velocities from 26.8 m.s-1 (8- to 9-yr-old group) to 33.5 m.s-1 (16-yr-old group). However, the accuracy of the response was negatively affected by baseball velocity. CONCLUSIONS: If the exit-velocities seen during actual competition exceed the calculated maximum exit-velocities for these age groups, then our preliminary data suggest that modifications to the game of baseball that would reduce the actual exit-velocities and serve as an effective means to reduce the potential for serious or catastrophic injury are warranted.
OBJECTIVE: Sudden cardiac death that results from chest wall blows (commotio cordis) the second leading cause of death in young athletes. Most events are caused by blows from projectiles, such as baseballs or lacrosse balls, with a substantial proportion occurring despite the use of a chest protector. In the present experiment, we tested the effectiveness of commercially available chest protectors in preventing ventricular fibrillation (VF) that results from chest wall strikes with baseballs and lacrosse balls. METHODS: Twelve different baseball or lacrosse chest protectors were evaluated in juvenile swines that were subjected to 40-mph baseball or lacrosse ball blows to the precordium during the vulnerable period of repolarization for VF and were compared with control impacts without chest protectors. Seven baseball chest protectors were hit by regulation baseballs, and 5 lacrosse chest protectors were tested by blows with standard lacrosse balls. Each animal received 2 chest blows for each protector and 2 control impacts without a chest protector, with the sequence of impacts assigned randomly. RESULTS: VF was elicited by 12 (32%) of 37 strikes in control animals without baseball chest protectors. None of the baseball chest wall protectors tested were shown to decrease significantly the occurrence of VF when compared with controls. VF was elicited by 11 (46%) of 24 strikes in control animals without lacrosse chest protectors. None of the lacrosse chest wall protectors tested decreased significantly the occurrence of VF when compared with controls. CONCLUSION: In our experimental animal model of commotio cordis, commercially available baseball and lacrosse chest wall protectors were ineffective in protecting against VF that was triggered by chest blows and, by inference, sudden cardiac death. Improvements in materials and design of chest wall barriers are necessary to reduce the occurrence of these tragic events and make the athletic field safer for youths.
It is not known how the brain decides to act on moving objects. We demonstrated previously that neurons in the macaque supplementary eye field (SEF) reflect the rule of ocular baseball, a go/nogo task in which eye movements signal the rule-guided interpretation of the trajectory of a target. In ocular baseball, subjects must decide whether to pursue a moving spot target with an eye movement after discriminating whether the target will cross a distal, visible line segment. Here we identify cortical regions active during the ocular baseball task using event-related human functional magnetic resonance imaging (fMRI) and concurrent eye-movement monitoring. Task-related activity was observed in the SEF, the frontal eye field (FEF), the superior parietal lobule (SPL), and the right ventrolateral prefrontal cortex (VLPFC). The SPL and right VLPFC showed heightened activity only during ocular baseball, despite identical stimuli and oculomotor demands in the control task, implicating these areas in the decision process. Furthermore, the right VLPFC but not the SPL showed the greatest activation during the nogo decision trials. This suggests both a functional dissociation between these areas and a role for the right VLPFC in rule-guided inhibition of behavior. In the SEF and FEF, activity was similar for ocular baseball and a control eye-movement task. We propose that, although the SEF reflects the ocular baseball rule, both areas in humans are functionally closer to motor processing than the SPL and the right VLPFC. By recording population activity with fMRI during the ocular baseball task, we have revealed the cortical substrate of an oculomotor decision process.
Psychologists and baseball players were among those Americans who formed professional associations in the last quarter of the nineteenth century. Psychologists used laboratory tasks to quantify mental and behavioral processes while sportswriters and baseball organizers measured individual and team performance. The most popular baseball player of the 1920s, George Herman "Babe" Ruth, possessed superior batting skills that were evident in the statistical indices of baseball performance. In 1921, he was brought to the psychological laboratory at Columbia University to perform standard laboratory tasks in an effort to discover the basis for his success in hitting home runs and to suggest the potential of tests for identifying future baseball stars. Baseball's addiction to quantitative indices of performance was thus brought together with a new science devoted to quantitative assessment and a desire to make such assessments useful. The attempt to analyze the basis of Ruth's batting skills is part of the history of applied psychology, sport psychology, and popular interest in the science of psychology.
BACKGROUND: The syndrome of sudden death due to low-energy trauma to the chest wall (commotio cordis) has been described in young sports participants, but the mechanism is unknown. METHODS: We developed a swine model of commotio cordis in which a low-energy impact to the chest wall was produced by a wooden object the size and weight of a regulation baseball. This projectile was thrust at a velocity of 30 miles per hour and was timed to the cardiac cycle. RESULTS: We first studied 18 young pigs, 6 subjected to multiple chest impacts and 12 to single impacts. Of the 10 impacts occurring within the window from 30 to 15 msec before the peak of the T wave on the electrocardiogram, 9 produced ventricular fibrillation. Ventricular fibrillation was not produced by impacts at any other time during the cardiac cycle. Of the 10 impacts sustained during the QRS complex, 4 resulted in transient complete heart block. We also studied whether the use of safety baseballs, which are softer than standard ones, would reduce the risk of arrhythmia. A total of 48 additional animals sustained up to three impacts during the T-wave window of vulnerability to ventricular fibrillation with a regulation baseball and safety baseballs of three degrees of hardness. We found that the likelihood of ventricular fibrillation was proportional to the hardness of the ball, with the softest balls associated with the lowest risk (two instances of ventricular fibrillation after 26 impacts, as compared with eight instances after 23 impacts with regulation baseballs). CONCLUSIONS: This experimental model of commotio cordis closely resembles the clinical profile of this catastrophic event. Whether ventricular fibrillation occurred depended on the precise timing of the impact. Safety baseballs, as compared with regulation balls, may reduce the risk of commotio cordis.
OBJECTIVE: To determine the baseline injury rate for children ages 7 to 13 participating in community organized baseball, softball, soccer, and football. METHODS: In this observational cohort study, 1659 children were observed during 2 seasons of sports participation in an urban area. Data were collected by coaches using an injury survey tool designed for the study. A reportable injury was defined as one requiring on-field evaluation by coaching staff, or causing a player to stop participation for any period of time, or requiring first aid during an event. Logistic regression analyses were done within and across sports for injury rates, game versus practice injury frequencies, and gender differences where appropriate. RESULTS: The injury rates, calculated per 100 athlete exposures during total events (games plus practices), were: baseball, 1.7; softball, 1.0; soccer, 2.1; and football, 1.5. The injury rates for baseball and football were not significantly different. Across sports, contusions were the most frequent type of injury. Contact with equipment was the most frequent method of injury, except in football where contact with another player was the most frequent method. In baseball, 3% of all injuries reported were considered serious (fracture, dislocation, concussion); in soccer, 1% were considered serious; and in football, 14% were considered serious. The frequency of injury per team per season (FITS), an estimation of injury risk, was 3 for baseball and soccer, 2 for softball, and 14 for football for total events. For all sports, there were more game than practice injuries; this difference was significant except for softball. There were no significant gender differences in soccer for injury rates during total events. CONCLUSIONS: Given the classification of football as a collision sport, the high number of exposures per player, the FITS score, and the percentage of injuries considered serious, youth football should be a priority for injury studies. Health professionals should establish uniform medical coverage policies for football even at this age level. RECOMMENDATIONS FOR MODIFICATIONS: Injury surveillance for youth sports is gaining momentum as an important step toward formulating injury prevention methods. However, establishing patterns of injuries, taking preventive measures, and evaluating equipment and coaching modifications may take years. In addition to the objective findings of this study, our direct observations of community sports through 2 seasons showed areas where immediate modifications could reduce injury risk. The first recommendation is that youth sports leagues provide and require first aid training for coaches. Training could be done by sports medicine professionals and include recognition and immediate response to head, neck, and spine injuries, as well as heat-related illnesses. The second recommendation is that youth sports leagues have clear, enforceable return to play guidelines for concussions, neck and back injuries, fractures, and dislocations. The third recommendation is that baseball and softball leagues consider the injury prevention potential of face guards on batting helmets.