Strength training: Isometric training at a range of joint angles versus dynamic training     

Jonathan P Folland  Kate Hawker  Ben Leach  Tom Little  David A Jones 《Journal of sports sciences》2013,31(8):817-824

Strength training with isometric contractions produces large but highly angle-specific adaptations. To contrast the contractile mode of isometric versus dynamic training, but diminish the strong angle specificity effect, we compared the strength gains produced by isometric training at four joint angles with conventional dynamic training. Thirty-three recreationally active healthy males aged 18?–?30 years completed 9 weeks of strength training of the quadriceps muscle group three times per week. An intra-individual design was adopted: one leg performed purely isometric training at each of four joint angles (isometrically trained leg); the other leg performed conventional dynamic training, lifting and lowering (dynamically trained leg). Both legs trained at similar relative loads for the same duration. The quadriceps strength of each leg was measured isometrically (at four angles) and isokinetically (at three velocities) pre and post training. After 9 weeks of training, the increase in isokinetic strength was similar in both legs (pooled data from three velocities: dynamically trained leg, 10.7%; isometrically trained leg, 10.5%). Isometric strength increases were significantly greater for the isometrically trained leg (pooled data from four angles: dynamically trained leg, 13.1%; isometrically trained leg, 18.0%). This may have been due to the greater absolute torque involved with isometric training or a residual angle specificity effect despite the isometric training being divided over four angles.  相似文献   

Physical demands of elite basketball during an official U18 international tournament     

Jairo Vázquez-Guerrero  Ben Jones  Bruno Fernández-Valdés  Gerard Moras  Xavi Reche  Jaime Sampaio 《Journal of sports sciences》2013,31(22):2530-2537

ABSTRACT

The aims of this study were (a) to compare players’ physical demands between different playing positions in elite U18 basketball games and (b) to identify different clusters of performance. Data were collected from 94 male subjects (age: 17.4 ± 0.7 years), competing in a Euroleague Basketball Tournament. Guards covered a greater relative distance than centres and forwards (small to moderate effect). Forwards and guards had more peak accelerations, high accelerations and high decelerations than centres (moderate to large effects). A cluster analysis allowed to classify all cases into three different groups (Lower, Medium and Higher activity demands), containing 37.4%, 52.8% and 9.8% of the cases, respectively. The high accelerations, high decelerations, peak accelerations and total distance covered were the variables that most contributed to classify the players into the new groups. The percentage of cases distributed in the clusters according to playing position, game type (worst vs worst, mixed opposition, best vs best) and team were different. Centres have lower physical demands specially related with the number of accelerations and decelerations at high intensity and the peak acceleration when compared with guards. Each team has a different activity profile, that does not seem to influence the tournament outcome.  相似文献   

Tackle and ruck technique proficiency within academy and senior club rugby union     

Steve den Hollander  Michael Lambert  Ben Jones  Sharief Hendricks 《Journal of sports sciences》2013,31(22):2578-2587

ABSTRACT

This study examined the validity of a tool that assesses tackle and ruck technique in training and established reference data for tackle, ball-carry and ruck technique at different levels of play in rugby union. One hundred and thirty-one amateur rugby union players; 37 senior, 51 first-grade academy and 43 second-grade academy players, participated in a two-on-two contact drill. The drill was filmed and the players’ tackle, ball-carry and ruck technique were assessed using standardized technical criteria. Senior level players scored significantly higher in all three assessments; tackle technique senior vs academy 1^st (p < 0.01, effect size (ES) = 0.7, moderate), senior vs academy 2^nd (p < 0.01, ES = 0.7, moderate); ball-carry technique senior vs academy 1^st (p < 0.01, ES = 0.6, moderate), senior vs academy 2^nd (p < 0.01, ES = 0.8, moderate); ruck technique senior vs academy 1^st (p < 0.01, ES = 0.7, moderate), senior vs academy 2^nd (p < 0.01, ES = 0.4, small). These findings emphasize the importance of developing contact technique to allow players to progress to higher levels, and provide validity to an assessment tool which can facilitate this process.  相似文献   

Association Between Accelerometer-Assessed Physical Activity and Objectively Measured Hearing Sensitivity Among U.S. Adults With Diabetes     

Paul D. Loprinzi  Ben Gilham  Bradley J. Cardinal 《Research quarterly for exercise and sport》2013,84(3):390-397

Purpose: The purpose of this study was to examine the association between objectively measured physical activity and hearing sensitivity among a nationally representative sample of U.S. adults with diabetes. Method: Data from the 2003–2006 National Health and Nutrition Examination Survey were used. One hundred eighty-four U.S. adults with diabetes wore an ActiGraph 7164 accelerometer and had their hearing function objectively assessed. A negative binomial logistic regression was used to examine the association between moderate-to-vigorous physical activity (MVPA) and hearing sensitivity. Results were adjusted for age, gender, race/ethnicity, education, body mass index, comorbidity index, marital status, cotinine, homocysteine, high-density lipoprotein cholesterol, glycohemoglobin (HbA_1c), C-reactive protein, microalbuminuria, noise exposure, and vision impairment. Results: Compared to those with hearing within normal limits, results showed that participants with mild hearing loss and moderate or greater hearing loss, respectively, engaged in 93% fewer minutes of MVPA (incident rate ratio = 0.07; 95% CI [0.01, 0.60]) and 94% fewer minutes of MVPA (incident rate ratio = 0.06; 95% CI [0.01, 0.54]). Conclusion: Adults with diabetes who have greater hearing impairment are less physically active. Future research is needed to determine the direction of causality.  相似文献   

An investigation on the unwillingness of nodes to participate in mobile delay tolerant network routing     

Jingwei Miao  Omar Hasan  Sonia Ben Mokhtar  Lionel Brunie  Kangbin Yim 《International Journal of Information Management》2013

Message routing in mobile delay tolerant networks inherently relies on the cooperation between nodes. In most existing routing protocols, the participation of nodes in the routing process is taken as granted. However, in reality, nodes can be unwilling to participate. We first show in this paper the impact of the unwillingness of nodes to participate in existing routing protocols through a set of experiments. Results show that in the presence of even a small proportion of nodes that do not forward messages, performance is heavily degraded. We then analyze two major reasons of the unwillingness of nodes to participate, i.e., their rational behavior (also called selfishness) and their wariness of disclosing private mobility information.  相似文献   

Preference and resistance to change in concurrent variable-interval schedules     

Matthew C. Bell  Ben A. Williams 《Learning & behavior》2002,30(1):34-42

Pigeons were trained on a multiple schedule in which separate concurrent schedules were presented in the two components of the schedule. During one component, concurrent variable-interval 40-sec variableinterval 80-sec schedules operated. In the second component, concurrent variable-interval 40-sec variableinterval 20-sec schedules operated. After stable baseline performance was obtained in both components, extinction probe choice tests were presented to assess preference between the variable-interval 40-sec schedules from the two components. The variable-interval 40-sec schedule paired with the variableinterval 80-sec schedule was preferred over the variable-interval 40-sec schedule paired with the variableinterval 20-sec schedule. The subjects were also exposed to several resistance-to-change manipulations: (1) prefeeding prior to the experimental session, (2) a free-food schedule added to timeout periods separating components, and (3) extinction. The results indicated that preference and resistance to change do not necessarily covary.  相似文献   

Peer assessment of oral presentations: effects of student gender,university affiliation and participation in the development of assessment criteria     

A. Mark Langan  C. Philip Wheater  Emma M. Shaw  Ben J. Haines  W. Rod Cullen  Jennefer C. Boyle 《Assessment & Evaluation in Higher Education》2005,30(1):21-34

Peer assessment provides a useful mechanism to develop many positive qualities in students studying in higher education (HE). Potential influences on peer‐awarded marks include student qualities such as gender, HE background (e.g. university affiliation) and participation in the development of the assessment criteria. Many studies that have investigated peer assessment have placed great emphasis on marks from a single tutor, or very few tutors, from a single university. This study examined grades awarded by 11 tutors (affiliated with four universities) to oral presentations delivered on a residential field course by second‐year undergraduate students from two universities studying environmental or biological disciplines. Student assessors awarded marks of fairly high precision (correlating strongly with tutor grades) but averaged 5% higher than their tutors (i.e. of only moderate accuracy). Marginally higher marks (circa 1.6%) were awarded by student assessors to speakers studying at the same university. Gender influences were detected as males tended to grade other male speakers very slightly more highly than female speakers. Marks from females were unaffected by speaker gender. Students who participated in the development of the assessment criteria did not achieve higher grades for their presentations. However, when these ‘participants’ were assessing, they awarded lower marks than their peers (i.e. closer to, but not as low as, those awarded by tutors). Lower marks were also awarded during the middle of sessions, possibly resulting from factors associated with motivation and attention of speakers and markers. Overall, the potential biases in marking by naive assessors examined in this study may influence the validity of marks generated by peer assessment schemes, but the experience of this type of assessment had positive effects on those involved.  相似文献   

高职产学研合作教育模式的探索与实践   总被引：1，自引：0，他引：1  

李本初  孔新舟 《孝感职业技术学院学报》2005,8(4):5-9

文章介绍了湖北职业技术学院产学研合作教育的几种模式，着重剖析了“围绕专业办产业，办好产业促专业”的专业实体化产学研合作教育模式。  相似文献   

Affordances of teacher professional learning in secondary schools     

Wilfried Admiraal  Joke Kruiter  Ditte Lockhorst  Wouter Schenke  Henk Sligte  Ben Smit 《Studies in Continuing Education》2016,38(3):281-298

It is commonly understood that teachers in secondary school should develop throughout their career in order to stay as an essential factor in student learning. Schools can offer opportunities to link teachers’ professional learning to their school practice with a positive impact on teachers’ motivation to learn and the effectiveness of their learning. In this field study, teachers, school leaders, policy-makers, educational consultants and educational scholars were asked for their perceptions of conditions for teacher learning in school and of interventions in school to enhance teacher professional learning. These conditions and interventions were understood as affordances in schools that enable and support teacher professional learning. The main affordance in school these stakeholders mentioned was an open, but critical way in which teachers share their practices, collaborate and reflect upon their teaching practice. Collaborative practices seem to stimulate many interventions of teacher professional learning in school. Two implications of this finding are discussed. First, we suggest that the maximum teaching time should be reduced, team teaching should be more implemented or classes should be scheduled in such a way that teachers can meet. Second, distributed leadership approaches match with our findings about the role of school leaders in teacher professional learning.  相似文献   

Comparing Examination Standards: is a purely statistical approach adequate?     

Ben E. Jones 《Assessment in Education: Principles, Policy & Practice》1997,4(2):249-264

There has recently been a renewed interest in three types of comparability of standards in the United Kingdom [1] public examination system: between years, between subjects and between the six examination boards. Whilst comparisons of raw grade distributions are now generally acknowledged to be invalid indicators of relative standards, comparisons are regularly made for this purpose between adjusted grade distributions. Such adjustments are typically the result of statistically controlling for some of the relevant variables. The dangers of such an approach are that only easily quantifiable variables are used in the adjustment and that any residual differences between distributions will automatically be attributed to difference in standard. Using candidate‐level data from four 1994 Advanced level (A level) [2] mathematics examinations (designed for 18‐year‐old students), and paying particular attention to the Schools’ Mathematics Project (SMP) 16‐19 [3] syllabus, the paper reports on two such analyses. It then discusses some reasons why attributing differences in the adjusted grade distribution to differences in standard could be invalid. Whilst the study focuses on four A level mathematics syllabuses, the same principles apply irrespective of the context in which statistical comparisons of examination results are made. The methodologies, their shortcomings and the pleas for caution are not, therefore, specific to this study, this type of comparison or this examination system.  相似文献