Softballs

There is currently much debate about the safety of the sport of softball. Batted‐ball speed and average pitcher reaction time are factors often used to determine safe performance. Batted‐ball speed is shown to be the most important factor to consider when determining safe play. Average pitcher reaction time is explained and directly correlated to batted‐ball speed. Eleven aluminum multi‐wall, three aluminum single‐wall and two composite softball bats were tested with mid‐compression polyurethane softballs averaging 1721 ±62 N/6.4 mm to represent the relative bat‐ball performance for the sport of slow‐pitch softball. Nine men and six women were chosen for this study out of a test group of over three hundred slowpitch softball players. On average, aluminum bat performance results were within the recommended safety limits established by the national softball associations. However, when composite bats were used, their performance results exceeded the recommended safety limits which can pose a significant safety risk. Using aluminum softball bats, batted‐ball speeds ranged from 80 to 145 km.h^‐1. Using composite softball bats, batted‐ball speeds ranged from 146 to 161 km.h^‐1. The scientific relevance of this study is to provide performance information that can lead to injury prevention in the sport of softball.     

Assessment of softball bat safety performance using mid-compression polyurethane softballs

There is currently much debate about the safety of the sport of softball. Batted-ball speed and average pitcher reaction time are factors often used to determine safe performance. Batted-ball speed is shown to be the most important factor to consider when determining safe play. Average pitcher reaction time is explained and directly correlated to batted-ball speed. Eleven aluminum multi-wall, three aluminum single-wall and two composite softball bats were tested with mid-compression polyurethane softballs averaging 1721+/-62 N/6.4 mm to represent the relative bat-ball performance for the sport of slowpitch softball. Nine men and six women were chosen for this study out of a test group of over three hundred slowpitch softball players. On average, aluminum bat performance results were within the recommended safety limits established by the national softball associations. However, when composite bats were used, their performance results exceeded the recommended safety limits which can pose a significant safety risk. Using aluminum softball bats, batted-ball speeds ranged from 80 to 145km x h(-1) Using composite softball bats, batted-ball speeds ranged from 146 to 161 km x h(-1). The scientific relevance of this study is to provide performance information that can lead to injury prevention in the sport of softball.     

The influence of moment of inertia on baseball/softball bat swing speed

The speed at which a player can swing a bat is central to the games of baseball and softball, determining, to a large extent, the hit speed of the ball. Experimental and analytical studies of bat swing speed were conducted with particular emphasis on the influence of bat moment of inertia on swing speed. Two distinct sets of experiments measured the swing speed of colege baseball and fast-pitch softball players using weighted rods and modified bats. The swing targets included flexible targets, balls on a tee and machine pitched balls. Internal mass alterations provided a range of inertial properties. The average measured speeds, from 22 to 31 m s⁻¹, are consistent with previous studies. Bat speed approximately correlates with the moment of inertia of the bat about a vertical axis of rotation through the batter's body, the speed generally decreasing as this moment of inertia increases. The analytical model assumes pure rotation of the batter/bat system about a vertical axis through the batter's body. Aerodynamic drag of the batter's arms and the bat is included in the model. The independent variable is bat moment of inertia about the rotation axis. There is reasonable agreement between the model and the measured speeds. Detailed differences between the two suggest the importance of additional degrees of freedom in determining swing speed.     

2008年全国女子垒球锦标赛技术统计与分析

运用统计法对获得2008年全国女子垒球锦标赛前8名队伍的投手、防守和击球技术进行对比研究,结果表明：近几年我国女子垒球击球技术水平及防守能力逐步提高,各省市队伍水平差距明显缩小;投手投球能力虽有较大提高,但有特点的尖子投手不多。     

Describing the plastic deformation of aluminium softball bats

Hollow aluminium bats were introduced over 30 years ago to provide improved durability over wooden bats. Since their introduction, however, interest in hollow bats has focused almost exclusively around their hitting performance. The aim of this study was to take advantage of the progress that has been made in predicting bat performance using finite elements and apply it to describe bat durability. Accordingly, the plastic deformation from a ball impact of a single-wall aluminum bat was numerically modelled. The bat deformation from the finite-element analysis was then compared with experiment using a high-speed bat test machine. The ball was modelled as an isotropic, homogeneous, viscoelastic sphere. The viscoelastic parameters of the ball model were found from instrumented, high-speed, rigid-wall ball impacts. The rigid-wall ball impacts were modelled numerically and showed good agreement with the experimentally obtained response. The strain response of the combined bat-ball model was verified with a strain-gauged bat at intermediate ball impact speeds in the elastic range. The strain response of the bat-ball model exhibited positive correlation with the experimental measurements. High-speed bat-ball impacts were performed experimentally and simulated numerically at increasing impact speeds which induced correspondingly increased dent sizes in the bat. The plastic deformation from the numerical model found good agreement with experiment provided the aluminium work hardening and strain rate effects were appropriately described. The inclusion of strain rate effects was shown to have a significant effect on the bat deformations produced in the finite-element simulations. They also helped explain the existence of high bat stresses found in many performance models.     

十运会与九运会垒球决赛技术统计比较

通过对参加十运会女子垒球决赛的11支运动队的技术进行统计,并与九运会前8名运动队的技术统计进行比较,结果发现:我国女子垒球运动员的击球技术总体水平有明显提高;各队的防守水平较九运会有所下降;受规则修改的影响,投手水平呈下降趋势,优秀投手在比赛中的作用被削弱。建议继续加强击球、防守能力的训练,提高运动员对赛场环境、比赛气氛的适应能力;创新投手训练方法,尽快培养优秀投手。     

太极柔力球的发源、发展及现状

太极柔力球运动是一改传统硬性击球方式,以弧形引化过程触及球体并顺势将球抛出为主要技术特征、有鲜明民族特色的新兴体育运动项目.现就太极柔力球的发源、发展及运动特点进行研究,并对发展过程中面临的困难提出了相应对策,为今后更好发展该项目提供参考.     

Field and laboratory measurements of softball player swing speed and bat performance

The swing speed of the bat is one of the most important factors affecting the hit-ball speed. Most field studies tend to focus on measuring ball speed, which is easier to measure and quantify than bat speed. For this reason, relatively little data exist describing bat motion in field conditions. The following describes a relatively large swing speed field study involving bats of the same model with nearly constant weight and varying inertia. The study was conducted using right-handed batters on a regulation outdoor field with a live pitcher. Swing speed was measured by tracking markers on the bat with two high-speed video cameras so that the bat markers could be traced in three-dimensional space. The ball motion was tracked using the same high-speed video cameras and a three-dimensional Doppler radar system. Bat swing speed was observed to be proportional to the batter skill level and the normalised swing speed increased with decreasing bat inertia. The bat centre of rotation during impact was close to the knob of the bat. The bats were tested under controlled laboratory conditions using a standardised performance test. The field and laboratory results showed good agreement including the hit-ball speed and the subtle effect of bat inertia on the maximum performance location. The vibrational response of the bats was considered using modal analysis. The maximum performance location was correlated with the node of the first vibrational mode.     

康复性体能训练在女子垒球项目中的应用

康复性体能训练是体能训练领域较新的研究和实践方向,同时发展也较为迅速,它为运动员的损伤预防和伤病恢复提供了很好的解决方向和方法。运用体能测试和FMS功能测试等方法对江苏女子垒球队的身体功能情况进行系统的阶段性的评估,并制定针对性的康复体能训练计划。经过4个阶段20周的康复性体能训练后,15名主力队员的体能水平得到了较大程度的提高,并且有伤运动员伤病得到了很好的恢复,这为江苏女子垒球队在12届全国运动会上取得良好的比赛成绩打下了坚实的基础。     

Ground reaction forces, kinematics, and muscle activations during the windmill softball pitch

The aims of the present study were to examine quantitatively ground reaction forces, kinematics, and muscle activations during the windmill softball pitch, and to determine relationships between knee valgus and muscle activations, ball velocity and muscle activation as well as ball velocity and ground reaction forces. It was hypothesized that there would be an inverse relationship between degree of knee valgus and muscle activation, a direct relationship between ground reaction forces and ball velocity, and non-stride leg muscle activations and ball velocity. Ten female windmill softball pitchers (age 17.6 ± 3.47 years, stature 1.67 ± 0.07 m, weight 67.4 ± 12.2 kg) participated. Dependent variables were ball velocity, surface electromyographic (sEMG), kinematic, and kinetic data while the participant was the independent variable. Stride foot contact reported peak vertical forces of 179% body weight. There were positive relationships between ball velocity and ground reaction force (r = 0.758, n = 10, P = 0.029) as well as ball velocity and non-stride leg gluteus maximus (r = 0.851, n = 10, P = 0.007) and medius (r = 0.760, n = 10, P = 0.029) muscle activity, while there was no notable relationship between knee valgus and muscle activation. As the windmill softball pitcher increased ball velocity, her vertical ground reaction forces also increased. Proper conditioning of the lumbopelvic-hip complex, including the gluteals, is essential for injury prevention. From the data presented, it is evident that bilateral strength and conditioning of the gluteal muscle group is salient in the windmill softball pitch as an attempt to decrease incidence of injury.     

第11届世界女子垒球锦标赛四强实力分析

以参加2006年8月27日~9月5日在北京举行的第11届世界女子垒球锦标赛前4名队伍为研究对象,对其在本次比赛中的各项技、战术指标进行统计分析。研究认为,在强强对阵中,美国队有着超强的进攻能力和有效的防守能力,总体实力处在“超级霸主”地位,日本与澳大利亚队进攻实力相当,防守水平日本队强于澳大利亚队,中国队的进攻和防守实力明显比前3名队伍逊色;中国队投手的总体实力不比前3名队伍逊色,但缺少明星投手。     

Relationship between decision-making self-efficacy,task self-efficacy,and the performance of a sport skill

Abstract

The purpose of this study was to examine the relationships between decision-making self-efficacy and task self-efficacy and subsequent decision-making and task performance. Sixty undergraduate students (30 males, 30 females) participated in this study, which involved infield defensive plays in softball. The physical task required participants to throw a ball at a target. The decision-making task required participants to watch video scenes depicting different infield defensive situations and decide where to throw the ball in each situation. Both tasks used manipulated failure. Self-efficacy was assessed before performance. Strength of decision-making and task self-efficacy predicted physical performance, but not decision-making performance.     

Ground reaction forces,kinematics, and muscle activations during the windmill softball pitch

Abstract

The aims of the present study were to examine quantitatively ground reaction forces, kinematics, and muscle activations during the windmill softball pitch, and to determine relationships between knee valgus and muscle activations, ball velocity and muscle activation as well as ball velocity and ground reaction forces. It was hypothesized that there would be an inverse relationship between degree of knee valgus and muscle activation, a direct relationship between ground reaction forces and ball velocity, and non-stride leg muscle activations and ball velocity. Ten female windmill softball pitchers (age 17.6 ± 3.47 years, stature 1.67 ± 0.07 m, weight 67.4 ± 12.2 kg) participated. Dependent variables were ball velocity, surface electromyographic (sEMG), kinematic, and kinetic data while the participant was the independent variable. Stride foot contact reported peak vertical forces of 179% body weight. There were positive relationships between ball velocity and ground reaction force (r = 0.758, n = 10, P = 0.029) as well as ball velocity and non-stride leg gluteus maximus (r = 0.851, n = 10, P = 0.007) and medius (r = 0.760, n = 10, P = 0.029) muscle activity, while there was no notable relationship between knee valgus and muscle activation. As the windmill softball pitcher increased ball velocity, her vertical ground reaction forces also increased. Proper conditioning of the lumbopelvic–hip complex, including the gluteals, is essential for injury prevention. From the data presented, it is evident that bilateral strength and conditioning of the gluteal muscle group is salient in the windmill softball pitch as an attempt to decrease incidence of injury.     

棒、垒球运动员流畅心理状态的主要特征研究

结合我国运动员运动竞赛的亲身体验，重新翻译和检验《流畅状态量表》。通过对200名棒垒球运动员的调查，结果发现，棒垒球运动员流畅心理状态最主要的四个特征是：挑战一技能平衡、行动一意识融合、高度控制感和自我意识的丧失；运动员流畅心理状态主要特征与比赛成绩高度相关；棒垒球运动员流畅心理状态的结构特点为：流畅心理较低型占总人数的3396，优秀型和良好型共占总人数的6796；棒垒球运动员流畅心理状态具有一定的稳定性，流畅心理状态主要特征中心坐标95％置信区间值可作为运动员流畅心理水平的评价标准。     

我国高校垒球运动的现状与发展

阐述了近年来高校垒球运动的发展现状，并根据高等教育特点进行分析，探索推广普及垒球运动的有效途径．使垒球运动人口得到提高。     

Response Time Comparisons among Four Base Running Starting Techniques in Slow Pitch Softball

Abstract

The purpose of this study was to compare response times among four starting techniques—cross-over step, jab-step, standing sprinter's start, and the momentum start—to determine the fastest start for optimum speed in base running in slow pitch softball. The subjects were 30 adult male amateur softball players. Response time was recorded to the nearest 1/100 second using a Dekan Automatic Performance Analyzer arranged with two starting lights and a stop gate. A one way repeated measures ANOVA indicated that the momentum start was significantly (p < .01) faster than the other starts compared while there were no significant differences among the other starts. Reliability coefficients ranging from .90 to .95, obtained using the intraclass correlation coefficient for multiple trial data, signified no trends among trials and high reliability of the testing procedures and equipment. The results suggested that the momentum start was the fastest starting technique for optimum speed for running bases in slow pitch softball.     

在全民健身运动中开展太极柔力球运动的研究

为推进太极运动在全民健身运动中的开展,文章采用文献资料法、逻辑分析法,以推进太极柔力球在全民健身运动中开展为研究对象,对太极柔力球运动在全民健身运动中的优势、作用及其开展对策进行了深入研究。研究认为：太极柔力球运动形式多样,趣味性强,适合不同年龄、体质、阶层的人进行锻炼,是一项融快乐于体育锻炼之中的一项新兴体育运动项目,它具有健身、娱乐、观赏、教育等作用;同时提出加强太极柔力球运动在学校的推广与传播,加强太极柔力球的师资培训,加强对太极柔力球运动重视,以活动促竞赛等措施来促进太极柔力球运动在全民健身活动中开展。     

关于中国垒球运动发展状况的思考

采用文献法和历史调查法,通过对垒球发展史以及垒球在中国的开展情况进行调查研究,发现目前中国垒球运动的发展必须采取两条腿走路的方式:一是加强专业队伍建设;二是在高校中推广,改变垒球在中国不普及,选材面很狭窄的现状.     

The effects of baseball bat mass properties on swing mechanics,ground reaction forces,and swing timing

Swing trajectory and ground reaction forces (GRF) of 30 collegiate baseball batters hitting a pitched ball were compared between a standard bat, a bat with extra weight about its barrel, and a bat with extra weight in its handle. It was hypothesised that when compared to a standard bat, only a handle-weighted bat would produce equivalent bat kinematics. It was also hypothesised that hitters would not produce equivalent GRFs for each weighted bat, but would maintain equivalent timing when compared to a standard bat. Data were collected utilising a 500 Hz motion capture system and 1,000 Hz force plate system. Data between bats were considered equivalent when the 95% confidence interval of the difference was contained entirely within ±5% of the standard bat mean value. The handle-weighted bat had equivalent kinematics, whereas the barrel-weighted bat did not. Both weighted bats had equivalent peak GRF variables. Neither weighted bat maintained equivalence in the timing of bat kinematics and some peak GRFs. The ability to maintain swing kinematics with a handle-weighted bat may have implications for swing training and warm-up. However, altered timings of kinematics and kinetics require further research to understand the implications on returning to a conventionally weighted bat.     

垒球投手间隙训练法浅谈

在垒球教学训练中,对投手采取间隙训练法进行训练,能有效地适应垒球比赛的特点,适应实战的需要,对投手投球训练效果将产生更积极的作用。