The effects of limb dominance and a short term,high intensity exercise protocol on both landings of the vertical drop jump: implications for the vertical drop jump as a screening tool     

Enda F. Whyte  Patrick Kennelly  Oliver Milton  Chris Richter  Siobhán O’Connor  Kieran A. Moran 《Sports biomechanics / International Society of Biomechanics in Sports》2018,17(4):541-553

The effectiveness of vertical drop jumps (VDJs) to screen for non-contact ACL injuries is unclear. This may be contributed to by discrete point analysis, which does not evaluate patterns of movement. Also, limited research exists on the second landing of VDJs, potential lower limb performance asymmetries and the effect of fatigue. Statistical parametric mapping investigated the main effects of landing, limb dominance and a high intensity, intermittent exercise protocol (HIIP) on VDJ biomechanics. Twenty-two male athletes (21.9 ± 1.1 years, 180.5 ± 5.5 cm, 79.4 ± 7.8 kg) performed VDJs pre- and post-HIIP. Repeated measures ANOVA identified pattern differences during the eccentric phases of the first and second landings bilaterally. The first landing displayed greater (internal) knee flexor (η² = 0.165), external rotator (η² = 0.113) and valgus (η² = 0.126) moments and greater hip (η² = 0.062) and knee (η² = 0.080) flexion. The dominant limb generated greater knee flexor (η² = 0.062), external rotator (η² = 0.110) and valgus (η² = 0.065) moments. The HIIP only had one effect, increased thoracic flexion relative to the pelvis (η² = 0.088). Finally, the dominant limb demonstrated greater knee extensor moments during the second landing (η² = 0.100). ACL injury risk factors were present in both landings of VDJs with the dominant limb at potentially greater injury risk. Therefore, VDJ screenings should analyse both landings bilaterally.  相似文献   

Reliability and validity of field-based measures of leg stiffness and reactive strength index in youths     

Rhodri S. Lloyd  Jon L. Oliver  Michael G. Hughes  Craig A. Williams 《Journal of sports sciences》2013,31(14):1565-1573

Abstract

The aim of the study was to assess the reliability of a mobile contact mat in measuring a range of stretch–shortening cycle parameters in young adolescents. Additionally, vertical leg stiffness using contact mat data was validated against a criterion method using force–time data. The reliability study involved 18 youths completing a habituation and three separate test sessions, while 20 youths completed a single test session for the validity study. Participants completed three trials of a squat jump, countermovement jump, and maximal hopping test and a single trial of repeated sub-maximal hopping at 2.0 Hz and 2.5 Hz. All tests were performed on the contact mat. Reliability statistics included repeated-measures analysis of variance, intraclass correlation coefficient, and coefficient of variation (CV), while the correlation coefficient (r) and typical error of estimate (TEE) were reported for the validity study. Squat jump height was the most reliable measure (CV = 8.64%), while leg stiffness during sub-maximal hopping, and reactive strength index produced moderate reliability (CV = 10.17–13.93% and 13.98% respectively). Measures of leg stiffness obtained from contact mat data during sub-maximal hopping were in agreement with the criterion measure (r = 0.92–0.95; TEE = 6.5–7.5%), but not during maximal hopping (r = 0.59; TEE = 41.9%). The contact mat was deemed a valid tool for measuring stretch–shortening cycle ability in sub-maximal but not maximal hopping. Although reliability of performance was generally moderate, the tests offer a replicable assessment method for use with paediatric populations.  相似文献   

Effects of playing surface on physiological responses and performance variables in a controlled football simulation     

Michael G. Hughes  Laurence Birdsey  Rob Meyers  Daniel Newcombe  Jon Lee Oliver  Paul M. Smith 《Journal of sports sciences》2013,31(8):878-886

Abstract

In spite of the increased acceptance of artificial turf in football, few studies have investigated if matches are altered by the type of surface used and no research has compared physiological responses to football activity on artificial and natural surfaces. In the present study, participants performed a football match simulation on high-quality artificial and natural surfaces. Neither mean heart rate (171 ± 9 beats · min^?1 vs. 171 ± 9 beats · min^?1; P > 0.05) nor blood lactate (4.8 ± 1.6 mM vs. 5.3 ± 1.8 mM; P > 0.05) differed between the artificial and natural surface, respectively. Measures of sprint, jumping and agility performance declined through the match simulation but surface type did not affect the decrease in performance. For example, the fatigue index of repeated sprints did not differ (P > 0.05) between the artificial, (6.9 ± 2.1%) and natural surface (7.4 ± 2.4%). The ability to turn after sprinting was affected by surface type but this difference was dependent on the type of turn. Although there were small differences in the ability to perform certain movements between artificial and natural surfaces, the results suggest that fatigue and physiological responses to football activity do not differ markedly between surface-type using the high-quality pitches of the present study.  相似文献   

Resource constraints as triggers of radical innovation: Longitudinal evidence from the manufacturing sector     

Marcus Matthias Keupp  Oliver Gassmann 《Research Policy》2013

Despite the significant role of radical innovation as a driver of firm growth and performance, the consequences of resource constraints for radical innovation outcomes remain unknown. Our paper addresses this gap. We combine arguments from entrepreneurship theory and the theory of recombinative innovation to construct an overarching theoretical framework that argues why resource constraints can promote, rather than impede, radical innovation. We then build hypotheses on two specific resource constraints, knowledge and financial, and test these by a lagged-variable random-effects Tobit model with longitudinal data from an exceptionally large and detailed innovation survey. Controlling for absorptive capacity, firm age, and firm growth, we find full support for the hypothesis that knowledge constraints spur radical innovation and partial support for the hypothesis that financial constraints spur radical innovation. We discuss the theoretical significance of these findings and point to managerial implications and paths for future research.  相似文献   

“Biting one’s lip” and “distancing”: exploring pre-service teachers’ strategies in dysfunctional professional relationships     

Emmanuel O’Grady  Liam Guilfoyle  Oliver McGarr 《Asia-Pacific Journal of Teacher Education》2018,46(4):369-383

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Pathways from parental stimulation of children’s curiosity to high school science course accomplishments and science career interest and skill     

Adele Eskeles Gottfried  Kathleen Suzanne Johnson Preston  Allen W. Gottfried  Pamella H. Oliver  Danielle E. Delany  Sirena M. Ibrahim 《International Journal of Science Education》2016,38(12):1972-1995

Curiosity is fundamental to scientific inquiry and pursuance. Parents are important in encouraging children’s involvement in science. This longitudinal study examined pathways from parental stimulation of children’s curiosity per se to their science acquisition (SA). A latent variable of SA was indicated by the inter-related variables of high school science course accomplishments, career interest, and skill. A conceptual model investigated parental stimulation of children’s curiosity as related to SA via science intrinsic motivation and science achievement. The Fullerton Longitudinal Study provided data spanning school entry through high school (N?=?118). Parental stimulation of curiosity at age 8 years comprised exposing children to new experiences, promoting curiosity, encouraging asking questions, and taking children to a museum. Intrinsic motivation was measured at ages 9, 10, and 13 years, and achievement at ages 9, 10, and 11 years. Structural equation modelling was used for analyses. Controlling for socio-economic status, parental stimulation of curiosity bore positive and significant relations to science intrinsic motivation and achievement, which in turn related to SA. Gender neither related to stimulation of curiosity nor contributed to the model. Findings highlight the importance of parental stimulation of children’s curiosity in facilitating trajectories into science, and relevance to science education is discussed.  相似文献   

Becoming a Supervisor: Doctoral Student Perceptions of the Training Experience     

Kaye W. Nelson  Marvarene Oliver  Fred Capps 《Counselor Education & Supervision》2006,46(1):17-31

Thirteen doctoral students, 7 Caucasians and 6 Hispanics, participated over 3 semesters of practicum/internship in a qualitative research project exploring the experience of becoming supervisors. A follow‐up study with 5 different doctoral students confirmed and refined findings 1½ years later. The research team of 2 female faculty members and 1 male research assistant (the authors) identified 6 themes emerging from individual and group interviews with supervisors‐in‐training regarding the process of becoming a supervisor: (a) learning, (b) supervisee growth, (c) individual uniqueness, (d) reflection, (e) connections, and (f) putting it all together.  相似文献   

Graphonomics,automaticity and handwriting assessment     

Oliver Tucha  Lara Tucha  Klaus W. Lange 《Literacy》2008,42(3):145-155

A recent review of handwriting research in Literacy concluded that current curricula of handwriting education focus too much on writing style and neatness and neglect the aspect of handwriting automaticity. This conclusion is supported by evidence in the field of graphonomic research, where a range of experiments have been used to investigate this issue from a movement perspective. The present article offers a brief introduction to a graphonomic approach to handwriting analysis and the findings of graphonomic research about handwriting automaticity. These findings indicate that attentional control to any characteristic of the writing process (e.g. direction, lexical status, movement, style) results in an impairment of handwriting automaticity. These findings support and add a new dimension to previous conclusions.  相似文献   

Does parental homework involvement mediate the relationship between family background and educational outcomes?     

Hanna Dumont  Ulrich Trautwein  Oliver Lüdtke  Marko Neumann  Alois Niggli  Inge Schnyder 《Contemporary educational psychology》2012

This research examines whether parental homework involvement mediates the relationship between family background and educational outcomes such as academic achievement and academic self-concept. Data from two studies in which grade 8 students (N = 1274 and N = 1911) described their parents’ involvement in the homework process were reanalyzed via structural equation modeling. Perceived parental homework interference and perceived homework-related conflict were negatively related to students’ academic development, whereas perceived parental support and perceived parental competence to help with homework were positively related to academic outcomes. Although there were small associations between some aspects of parental homework involvement and family background variables, parental homework involvement did not mediate the relationship between family background and educational outcomes. Findings highlight the need for differentiated conceptualizations of parental homework involvement as well as detailed analyses of the processes underlying the association between family background and educational outcomes.  相似文献   

LONG-TERM OUTCOMES OF EARLY CHILDHOOD SCIENCE EDUCATION: INSIGHTS FROM A CROSS-NATIONAL COMPARATIVE CASE STUDY ON CONCEPTUAL UNDERSTANDING OF SCIENCE     

Ying Tao  Mary Oliver  Grady Venville 《International Journal of Science and Mathematics Education》2012,10(6):1269-1302

The purpose of this research was to explore the long-term outcomes of either participating or not participating in early childhood science education on grade 6 students?? conceptual understanding of science. The research is situated in a conceptual framework that evokes Piagetian developmental levels as both potential curriculum constraints and potential models of efficacy. The research design was a multiple case study of grade 6 children from 3 schools in China (n?=?140) who started formal science education in the third grade and grade 6 children from 3 matched schools in Australia (n?=?105) who started learning science in kindergarten. The students?? understanding was assessed by a science quiz and an in-depth interview. The data showed that participating children from the high socioeconomic schools in China and Australia had similar understandings of science. Divergence between the medium and low socioeconomic schools, however, indicated that the grounding in early childhood science education in Australia may have placed these children at an advantage. Alternative explanations for the divergence, including the nature of classroom instruction in the two countries, are discussed.  相似文献