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71.
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. 相似文献
72.
Jason Wicke David W. Keeley Gretchen D. Oliver 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):315-323
Coaches teach proper mechanics at a young age in an effort to increase pitching efficiency (i.e., proper pitching mechanics). Unfortunately, the mechanics taught to beginning pitchers are based on the findings from adult pitchers and may result in techniques that are detrimental to younger pitchers. The purpose of this study was to compare kinematics published for pitchers across various ages in an effort to determine whether the pitching techniques vary across developmental periods. A meta-analysis of papers published describing pitching kinematics for youth and adult pitchers was conducted. Maximal rotational velocity of the trunk and maximum external rotation of the shoulder were observed during the arm cocking phase. Peak magnitudes for abduction, horizontal adduction, and shoulder internal rotation were observed during the deceleration phase of the movement. In addition, by comparing previously published data across youth and adult pitchers, valuable insight into the differences in mechanics was gained. The results demonstrated that there are some distinct differences between youth and adult pitching mechanics. This finding may allow increased focus to be applied to those parameters observed to differ across age, increasing the knowledge base available for coaches to properly instruct youth pitchers. 相似文献
73.
Gretchen Jennings Jim Cullen Janeen Bryant Kayleigh Bryant‐Greenwell Stacey Mann Charlette Hove Nayeli Zepeda 《Curator: The Museum Journal》2019,62(4):505-526
The Empathetic Museum is a group of colleagues who advocate institutional empathy as a transforming force for museums. Our initiative emerged in the second decade of the 21st century amidst a confluence of seismic events in the US that forced the museum field to examine its relationship to social issues. The Empathetic Museum arose as a critique of museums’ indifference and reluctance to engage with issues deeply affecting their communities, especially those of color. We propose a lack of institutional empathy as a subtle yet powerful cause of this indifference. The article traces the development of the Empathetic Museum initiative; the evolution of its philosophy of institutional empathy; the creation of the Maturity Model as a key tool for empathetic practice; and its use and impact in the field. As a work in progress, the Empathetic Museum initiative has evolved and expanded through constant observation of, reflection on, and engagement with the important issues of our time. 相似文献
74.
75.
Carlos Balsalobre-Fernández Gretchen Geiser John Krzyszkowski Kristof Kipp 《Journal of sports sciences》2020,38(6):710-716
ABSTRACTThe purpose of this study was to investigate the validity of a smartphone app to measure biomechanical barbell parameters during the snatch. Ten collegiate NCAA division I athletes performed two repetitions each at 40, 50, 60, 70, and 80% of their 1-repetition maximum snatch. Barbell motions were simultaneously recorded with a motion capture system and the smartphone app. The motion capture system recorded the 3-D position of a reflective marker attached to the end of the barbell while the smartphone app was used to record sagittal plane video and track the shape of the weight plate from which the barbell center was derived. Peak forward (PFD) and backward (PBD) displacements and peak vertical displacement (PVD) and velocity (PVV) were calculated from both sets of data. Significant, strong to very strong Pearson’s product-moment correlation coefficients between both systems were noted for all parameters (r = 0.729–0.902, all p < 0.001). Small significant biases between systems were observed for PVD (ES = 0.284, p < 0.001) and PFD (ES=0.340, p < 0.01), while trivial to small, non-significant biases were observed for PBD (ES = 0.143) and PVV (ES = –0.100). Collectively, the results suggest that the app can provide biomechanical data of barbell motions similar to a 3-D motion capture system. 相似文献
76.
Gretchen Whitney 《Publishing Research Quarterly》1990,6(3):44-75
The Unesco Statistical Yearbook includes in its annual volumes tables reporting the number of books published by countries
in subject classes according to the UDC classification system. These statistics are examined to assess global trends in subjects
areas such as pure, social, medical, and applied sciences, and literature. Data from Asia, Latin America, Africa, and North
America are found to be highly inconclusive due to nonreporting patterns. Data from Europe and the USSR are more comprehensive.
According to these data, social science titles form the largest percentages of the world's production, followed by applied
sciences and literature. Overall, literature and medical science titles appear to be increasing in production faster than
other subject areas.
Gretchen Whitney is an assistant professor at the Graduate Library School of the University of Arizona and author ofLanguage Distribution in Databases. She teache in the fields of information science and information policy. 相似文献
77.
Scores on state standards‐based assessments are readily available and may be an appropriate alternative to traditional placement tests for assigning or accepting students into particular courses. Many community colleges do not require test scores for admissions purposes but do require some kind of placement scores for first‐year English and math courses. In this study, we examine the efficacy of using the reading and math portions of the Kansas State Assessment (KSA) for predicting the success of high school students taking College Algebra and College English I at a Kansas community college. Results showed that in this sample KSA scores predicted as well or better than more traditional placement tests and with no extra cost to the institution. 相似文献
78.
79.
Covering violence is an expected part of the daily job for many journalists in the United States; however, are college and university programs fully preparing students for what they may experience? This study surveyed accredited journalism schools in the United States. Of the 41 respondent schools, only one offered a course specifically aimed at teaching journalists how to protect themselves from psychological trauma and how best to interact with victims of trauma. Results show that although schools believe the topic of trauma is important and worth teaching to future journalists, the approach to the topic is mostly reactive and inconsistent. Implications for the future of journalism education are discussed. 相似文献
80.
Gretchen Oltman 《Clearing house (Menasha, Wis.)》2017,90(5-6):172-176
Survival for public school teachers goes beyond curriculum design, discipline and other skills. School law is critical for teachers to face the areas of challenge that are currently present. There are two types of common legal mistakes made by teachers: a) failing to take disciplinary action when they should, and b) unintentionally violating students rights. Social media, religion, the rights of transgender students and the possibility of teachers right to carry a weapon are all within the realm of rapidly changing public school law. Teachers should stay well-informed, so they are ready to protect students and their own constitutional freedoms. 相似文献