Peripheral vision and simple catching: the screen paradigm revisited

The importance of effector visual feedback has previously been indicated using an opaque screen to prevent sight of the catching hand for the final 150-200 ms of a flight path of 850 ms in total. Attention was drawn to the finding that the ability to position the arm correctly in the line of flight of the ball deteriorated as a consequence of the number of trials without visual feedback. However, the use of only 20 test trials allows a possibility that the proprioceptive system may be able to re-establish predominant control under conditions of prolonged visual decrement. In order to verify this notion, the number of experimental trials was quadrupled for 24 subjects of mixed sex in a replication of the initial paradigm. The results provided preliminary support for the view that the positioning of the catching arm is more seriously affected by visual occlusion than the timing of the grasp phase. However, increments in accuracy of limb orientation were evidenced in all screen conditions, as the number of trials increased. The grasp component of one-handed catching appeared to remain unaffected by the increase in experimental trials. The relative influence of skill level on catching errors was next addressed by comparing the performance of the six best and worst catchers in the group. The results did not support previous research which found a relation between skill level and error type. The number of position, but not grasp, errors decreased as a function of task practice for both subgroups. Future investigations should, perhaps, focus on the developmental nature of movement control in one-handed catching to obtain a clearer picture of this relation.     

Influence of pelvis rotation styles on baseball pitching mechanics

Efficient, sequential timing is essential for upper level pitching. Interestingly, pitchers vary considerably in timing related elements of pitching style including pelvis rotation, arm cocking, stride leg behaviour, and pitch delivery time. The purpose of this study was to determine whether relationships exist among these elements by examining the overall style of pitchers exhibiting different pelvis rotation patterns. Pitching styles were defined by pelvis orientation at the instant of stride foot contact. Pitchers demonstrating a pelvis orientation greater than 30 degrees were designated as 'early rotators', while pitchers demonstrating a pelvis orientation less than 30 degrees were designated as 'late rotators'. Kinematic and temporal differences were associated with the two styles. During the arm cocking phase, early rotators showed significantly greater shoulder external rotation at the instant of stride foot contact, earlier occurrence of maximum pelvis rotation angular velocity, and shorter time taken to complete the phase. However, by the instant of maximum shoulder external rotation, early and late rotators appeared remarkably similar as no significant difference occurred in pelvis and arm orientations. Therefore, it appears that early and late rotators used different methods to achieve similar results, including throwing velocity. Significant differences in throwing arm kinetics were also found for 10 of the 11 measures in the study. As the pelvis assumed a more open position at stride foot contact, maximum kinetic values were found to both decrease in magnitude and occur at an earlier time within the pitch.     

Factors determining the spin axis of a pitched fastball in baseball

In this study, we wished to investigate the factors that determine the direction of the spin axis of a pitched baseball. Nineteen male baseball pitchers were recruited to pitch fastballs. The pitching motion was recorded with a three-dimensional motion analysis system (1000?Hz), and the orientations of the hand segment in a global coordinate system were calculated using Euler rotation angles. Reflective markers were attached to the ball, and the direction of the spin axis was calculated on the basis of their positional changes. The spin axis directions were significantly correlated with the orientations of the hand just before ball release. The ball is released from the fingertip and rotates on a plane that is formed by the palm and fingers; the spin axis of the ball is parallel to this plane. The lift force of the pitched baseball is largest when the angular and translational velocity vectors are mutually perpendicular. Furthermore, to increase the lift forces for the fastballs, the palm must face home plate.     

Whole-body vibration effects on the muscle activity of upper and lower body muscles during the baseball swing in recreational baseball hitters

The purpose of this study was to evaluate the effects of whole-body vibration (WBV) on the muscle recruitment of selected upper and lower body muscles during the baseball swing. Participants were recreationally trained males (n = 16, 22 +/- 2 years, 181.4 +/- 7.4 cm, 84.7 +/- 9.0 kg), with previous baseball experience. Subjects participated in three randomized sessions on separate days, consisting of three sets of five swings offa hitting tee. Exercises (upper and lower body dynamic and static movements) with or without WBVexposure were performed between swing sets. During each swing, the gastrocnemius, biceps femoris, gluteus maximus, pectoralis major, latissimus dorsi, and triceps brachii were evaluated for electromyographic (EMG) activity. EMG values were normalized to EMG measured during maximal voluntary isometric contraction. Statistical analysis revealed no significant differences in EMG activity across the three treatments. In addition, the results displayed a specific muscle recruitment order during the swing, starting with the lower body followed by the upper body muscles. This study was the first to report the recruitment order during the baseball swing. Although acute exposure to WBV did not significantly alter the muscle recruitment, these results may prove useful for practitioners looking to enhance baseball swing performance.     

棒球运动项目一般特征分析与研究

棒球运动是智慧与竞技的运动,是时间与距离的运动,具有很强的欣赏性和刺激性。棒球运动项目的一般特征包括:竞赛特征、技术特征、战术特征、文化特征、价值特征。通过对棒球运动项目一般特征的重新认识、概括与分析,旨在为更好地认识棒球的专项特征以及更好地开展和认识棒球运动提供理论参考依据。     

Path analysis examining self-efficacy and decision-making performance on a simulated baseball task

The purpose of this study was to examine the relationship between decision-making self-efficacy and decision-making performance in sport. Undergraduate students (N = 78) performzed 10 trials of a decision-making task in baseball. Self-efficacy was measured before performing each trial. Decision-making performance was assessed by decision speed and decision accuracy. Path analyses examined the relationships between self-efficacy, residualized past performance, and current performance. The results indicated that self-efficacy was a significant and consistent predictor of decision speed (eight of nine trials), but not decision accuracy (four of nine trials). It was also found that experience does not have a meaningful effect on the relationship between self-efficacy and decision-making performance in sport.     

The effect of pitch type on ground reaction forces in the baseball swing

Coaches have identified the batter's weight shift as a critical component for promoting proper timing and balance in a baseball swing. Analysing the weight shift through maximum horizontal (Fx) and vertical (Fz) ground reaction forces (GRFs) of professional batters (N = 29; height = 185 +/- 6 cm; mass = 92 +/- 9 kg), the purpose of this study was to compare GRFs among swings against fastballs and changeups. General linear models were used to compare three conditions of interest: successful results against fastballs, successful results against changeups, and unsuccessful results against changeups. Batters had a similar loading mechanism and initial weight transfer from back foot to front foot regardless of pitch type, but peak front foot GRFx and GRFz occurred with significantly different magnitudes and at significantly different times, depending on the pitch type and hit result. Peak front foot GRFs were greater for successful swings against fastballs compared to both successful and unsuccessful swings against changeups. Peak front foot GRFs of unsuccessful swings against changeups occurred, on average, 15-20 ms earlier than successful swings against changeups and 30-35 ms earlier than successful swings against fastballs, quantifying how a changeup can disrupt the coordination of a hitter's weight shift.     

Effects of focus of attention on baseball batting performance in players of differing skill levels

This study addressed the question, what should baseball players focus their attention on while batting? Less-skilled and highly skilled (college) baseball players participated in four dual-task conditions in a baseball batting simulation: two that directed attention to skill execution (skill/internal [movement of the hands] and skill/external [movement of the bat]) and two that directed attention to the environment (environmental/irrelevant [auditory tones] and environmental/external [the ball leaving the bat]). Batting performance for highly skilled players was best in the environmental/external condition and worst in the skill/internal condition. Performance of less-skilled batters was significantly better in the two skill conditions than in either of the two environmental conditions. We conclude that the optimal focus of attention for highly skilled batters is one that does not disrupt proceduralized knowledge and permits attention to the perceptual effect of the action, whereas the optimal focus of attention for less-skilled batters is one that allows attention to the step-by-step execution of the swing.     

Comparison of kinematics in skilled and unskilled arms of the same recreational baseball players

We examined mechanisms of coordination that enable skilled recreational baseball players to make fast overarm throws with their skilled arm and which are absent or rudimentary in their unskilled arm. Arm segment angular kinematics in three dimensions at 1000 Hz were recorded with the search-coil technique from the arms of eight individuals who on one occasion threw with their skilled right arm and on another with their unskilled left arm. Compared with their unskilled arm, the skilled arm had: a larger angular deceleration of the upper arm in space in the forward horizontal direction; a larger shoulder internal rotation velocity at ball release (unskilled arms had a negative velocity); a period of elbow extension deceleration before ball release; and an increase in wrist velocity with an increase in ball speed. It is suggested that some of these differences in arm kinematics occur because of differences between the skilled and unskilled arms in their ability to control interaction torques (the passive torque at one joint due to motion at adjacent joints). It is proposed that one reason unskilled individuals cannot throw fast is that, unlike their skilled counterparts, they have not developed the coordination mechanisms to effectively exploit interaction torques.     

Manipulating visual informational constraints during practice enhances the acquisition of catching skill in children.

Previous motor learning studies examining the effects of practicing to catch one-handed under varying informational constraints on subsequent skill acquisition are equivocal, perhaps due to the use of relatively inexperienced adult participants. Ecological theory predicts that directing the learner's search for information in the perceptual-motor workspace can enhance skill acquisition. This study manipulated visual informational constraints on novice children (ages 9-10 years) learning to catch one-handed. A crossover transfer design was implemented in which one group acted as controls while two other groups practiced either without visual restrictions before transferring to full vision, or vice versa. The data indicated that learners forced to seek additional information sources under restricted viewing conditions demonstrated a greater positive, accumulative residual effect on acquiring a catching skill. The findings contradict current work on the specificity of practice hypothesis and suggest that varying visual informational constraints to encourage exploratory practice may represent a significant pedagogical approach to motor learning in sport.     

Quiet eye training aids the long-term learning of throwing and catching in children: Preliminary evidence for a predictive control strategy

Abstract

Quiet eye training (QET) may be a more effective method for teaching children to catch than traditional training (TT) methods, but it is unclear if the benefits accrued persist in the long term. Thirty children were randomly allocated into a QET or TT group and, while wearing a mobile eye tracker, underwent baseline testing, training and two retention tests over a period of eight weeks, using a validated throw and catch task. During training, movement-related information was provided to both groups, while the QET group received additional instruction to increase the duration of their targeting fixation (QE1) on the wall prior to the throw, and pursuit tracking (QE2) period on the ball prior to catching. In both immediate (R1) and delayed (R2, six weeks later) retention tests, the QET group had a significantly longer QE1 duration and an earlier and longer QE2 duration, compared to the TT group, who revealed no improvements. A performance advantage was also found for the QET compared to the TT group at both R1 and R2, revealing the relatively robust nature of the visuomotor alterations. Regression analyses suggested that only the duration of QE1 predicted variance in catch success post-training, pointing to the importance of a pre-programming visuomotor strategy for successful throw and catch performance.     

A night at Delmonico's: The Spalding baseball tour and the imagination of Empire

This article casts the Spalding world baseball tour of 1888–1889 in a context of the campaign to construct a national identity during the late 19th century. In doing so, it intends to show how baseball magnate Albert Spalding and fellow sporting missionaries used cultural perspectives promoted on the tour to assert baseball's national purpose and, through the sport, stake America's claim in the Anglo-Saxon imperium of the times. Spalding initiated the mission with a remarkable tourist venture that spanned the globe, from Chicago across the Pacific and through Europe before returning from overseas. In New York, at a famous reception at Delmonico's restaurant, the tourists and commentators imbued the sport with the rhetoric of nationalism so critical to constructing empire ten years later. The banquet serves as the window in which to look on parts of the tour, particularly the contrasting results of the visits to Australia and Britain.     

广州亚运会中国棒球队与亚洲强队攻防技术能力的比较研究

采用文献资料、观察统计、对比分析,对我国棒球队与亚洲棒球强队在第16届广州亚运会比赛中的攻防技术能力进行对比分析。研究表明:1)中国棒球队整体技术水平与亚洲强队相比还存在着一定的差距;2)中国棒球队整体防守能力要好于进攻能力;3)中国棒球队在投手这一重要环节上实力比较薄弱。     

The experience of watching baseball games in Korea: an analysis of user-generated content on social media using Leximancer

The current study explores international tourists’ experiences of watching professional baseball games in Korea. Total 152 reviews posted by tourists on TripAdvisor were analyzed through Leximancer, a computer program used in the qualitative content analysis. The software identified three dominant themes of tourist experiences: the distinctive atmosphere of Korean professional baseball games, the diverse services in the stadium, and fanatical cheering behavior for the team. Moreover, it revealed that international tourists were generally positive toward the culturally distinctive style of Korean professional baseball games. This study suggests that the professional sports of a travel destination can be a form of providing international tourists with pleasurable experiences and a way to learn about the distinctive Korean baseball culture.     

职业体育市场的资产专用性

机会主义行为和有限理性的不可避免使专用性投资最终决定了契约的内容和形式.由于职业体育的生产者和消费者都具有很高的专用性投资,加上契约的天然不完善,这就促使市场交易主体必须建立各种不同形式的组织形态和制度安排以保护其各自的专用性投资,这也成为职业体育顺利发展的根本.     

北京奥运会中国棒球队与对手攻防能力的比较研究

采用文献资料、逻辑分析和比较研究等方法,对第29届奥运会中国棒球队全部比赛场次的技术数据进行统计研究,分析了中国棒球队的整体攻防技术能力存在的不足,以为中国队今后训练、比赛提供参考.     

先天因素、后天因素与幼儿体质相关性研究

运用文献资料法、问卷调查法、数理统计法、访谈法等,对幼儿体质与先天因素、后天因素进行相关性分析,深入探索先天因素、后天因素与幼儿体质变化的关系,旨在为提高幼儿体质水平,以及更好地开展幼儿体质研究具有一定的现实和理论意义。     

Influence of a horizontal approach on the mechanical output during drop jumps

This study investigated the influence of a horizontal approach to mechanical output during drop jumps. Participants performed drop jumps from heights of 15, 30, 45, and 60 cm with zero, one, two, and three approach steps. The peak summed power during the push-off phase changed quadratically across heights (6.2 +/- 0.3, 6.7 +/- 0.4, 6.4 +/- 0.4, and 6.0 +/- 0.4 kW, respectively) driven by the ankle joint response. Summed peak power was 10% greater with an approach attributed to the knee joint response. Downward phase dorsiflexion (31%), knee flexion (35%), and peak vertical force (32%) increased with drop heights. Vertical approach force (22%) increased, while knee flexion (11%) and downward duration (17%) decreased. An approach may improve drop jump training for explosive tasks.