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In this study we investigated if the occurrence of the sticking region was a result of diminishing potentiation (coinciding delayed muscle activation) or the result of a mechanically poor region in which the muscles can produce less force. A regular one-repetition maximum (1RM) free-weight bench press was compared with isometric bench presses performed at 12 different positions. A lower force at the sticking region compared to the other regions in the isometric bench presses would confirm the mechanically-poor-position hypothesis. Twelve resistance-trained males (age 21.7 ± 1.3 years, mass 78 ± 5.8 kg, height 1.81 ± 0.05 m) were tested in 1RM and in isometric contractions in bench press in 12 different positions, indicated by the vertical distance between barbell and sternum, covering the whole range of motion during the concentric phase. Barbell kinematics and muscle activity were registered. In both types of executions a region of lower force output was observed, which supports the mechanically-poor-position hypothesis. Electromyographic activity of four muscles showed the same pattern in the isometric and 1RM attempts. It was concluded that diminishing effect potentiation could not explain the existence of the sticking region. 相似文献
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Atle H. Saeterbakken Roland van den Tillaar Marius S. Fimland 《Journal of sports sciences》2013,31(5):533-538
Abstract The purpose of this study was to compare one-repetition maximum (1-RM) and muscle activity in three chest-press exercises with different stability requirements (Smith machine, barbell, and dumbbells). Twelve healthy, resistance-trained males (age 22.7 ± 1.7 years, body mass 78.6 ± 7.6 kg, stature 1.80 ± 0.06 m) were tested for 1-RM of the three chest-press exercises in counterbalanced order with 3–5 days of rest between the exercises. One-repetition maximum and electromyographic activity of the pectoralis major, deltoid anterior, biceps, and triceps brachii were recorded in the exercises. The dumbbell load was 14% less than that for the Smith machine (P ≤ 0.001, effect size [ES] = 1.05) and 17% less than that for the barbell (P ≤ 0.001, ES = 1.11). The barbell load was ～3% higher than that for the Smith machine (P = 0.016, ES = 0.18). Electrical activity in the pectoralis major and anterior deltoid did not differ during the lifts. Electrical activity in the biceps brachii increased with stability requirements (i.e. Smith machine <barbell <dumbbells; P ≤ 0.005; ES = 0.57, 1.46, and 2.00, respectively), while triceps brachii activity was reduced using dumbbells versus barbell (P = 0.007, ES = 0.73) and dumbbells versus Smith machine (P = 0.003, ES = 0.62). In conclusion, high stability requirements in the chest press (dumbbells) result in similar (pectoralis major and anterior deltoid), lower (triceps brachii) or higher (biceps brachii) muscle activity. These findings have implications for athletic training and rehabilitation. 相似文献
3.
Atle Selberg 《Resonance》1996,1(12):81-91
This article is based on the tape of an extemporaneous talk to a general audience at the Tata Institute of Fundamental Research,
Bombay, India, given after the conclusion of the Centenary Conference held there (January 1988).
Reproduced fromAtle Selberg, Collected Papers. Vol 1”, pages 695–701, Springer Verlag, 1989. 相似文献
4.
AbstractThe aim of the study was to examine the sticking region and concomitant neuromuscular activation of the prime movers during six-repetition maximum (RM) bench pressing. We hypothesised that both peak velocities would decrease and that the electromyography (EMG) of the prime movers (deltoid, major pectoralis and triceps) would increase during the pre-sticking and sticking region during the six repetitions due to fatigue. Thirteen resistance-trained males (age 22.8 ± 2.2 years, stature 1.82 ± 0.06 m, body mass 83.4 ± 7.6 kg) performed 6-RM bench presses. Barbell kinematics and EMG activity of pectoralis major, deltoid anterior, and triceps brachii during the pre-, sticking and post-sticking region of each repetition in a 6-RM bench press were analysed. For both the sticking as the post-sticking region, the time increased significantly from the first to the sixth repetition. Vertical barbell height at the start of sticking region was lower, while the height at the end of the sticking region and post-sticking region did not change during the six repetitions. It was concluded that in 6-RM bench pressing performance, the sticking region is a poor mechanical force region due to the unchanged barbell height at the end of the sticking region. Furthermore, when fatigue occurs, the pectoralis and the deltoid muscles are responsible for surpassing the sticking region as indicated by their increased activity during the pre- and sticking region during the six-repetitions bench press. 相似文献
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6.
Atle Skaftun Mari-Ann Igland Dag Husebø Sture Nome Arne Olav Nygard 《Learning, Media and Technology》2018,43(1):42-55
This socio-culturally informed qualitative study examines digitalised classrooms in Norwegian secondary schools, with a focus on the relationship between information and communication technology (ICT) and dialogic aspects of literacy practices. In the article, we foreground two cases: one on the use of digital mind maps and one on a writing process with online response. These cases display productive results of the tensions between old practices and new technology in that they open up spaces for dialogic interaction. This experience calls for a deeper historical contextualisation, and in the article we refer to different time scales: First, the restricted time scale of practices observed in the local school contexts over an academic year; second, the somewhat wider perspective of 20–30 years of educational research addressing technological innovation; and third, the extensive time scale of cultural history, with an analogy to the slow move from orality to literacy in ancient Greece. On this basis we suggest the term ‘transitional practices’ as an appropriate reference to all of these three time scales. Against this background, the glimpses of dialogue observed are seen as promising precursors of future development, but also as vulnerable plant shoots that may very well shrivel and die if they are not supported. 相似文献
7.
Oddny Judith Solheim Atle Skaftun 《Assessment in Education: Principles, Policy & Practice》2009,16(2):149-164
During the last three decades the constructed response format has gradually gained entry in large‐scale assessments of reading‐comprehension. In their 1991 Reading Literacy Study The International Association for the Evaluation of Educational Achievement (IEA) included constructed response items on an exploratory basis. Ten years later, in Progress in International Reading Literacy Study (PIRLS) 2001, the constructed response format is ascribed special significance as bearer of central insights to the definition of reading literacy. This article focuses on the significance of the scoring guides and the relation between these guides on the one hand, and the text and the items on the other hand. A discussion of this relation as it is to be found in PIRLS 2001 is performed, showing both examples of success and more problematic aspects in the operationalisation of the intentions expressed in the theoretical framework for the test. Handling the problem of semantic openness is essential in representing depth of understanding and represents a field of possibilities for further research and development. 相似文献
8.
The purpose of this study was to compare one-repetition maximum (1-RM) and muscle activity in three chest-press exercises with different stability requirements (Smith machine, barbell, and dumbbells). Twelve healthy, resistance-trained males (age 22.7 ± 1.7 years, body mass 78.6 ± 7.6 kg, stature 1.80 ± 0.06 m) were tested for 1-RM of the three chest-press exercises in counterbalanced order with 3-5 days of rest between the exercises. One-repetition maximum and electromyographic activity of the pectoralis major, deltoid anterior, biceps, and triceps brachii were recorded in the exercises. The dumbbell load was 14% less than that for the Smith machine (P ≤ 0.001, effect size [ES] = 1.05) and 17% less than that for the barbell (P ≤ 0.001, ES = 1.11). The barbell load was ～3% higher than that for the Smith machine (P = 0.016, ES = 0.18). Electrical activity in the pectoralis major and anterior deltoid did not differ during the lifts. Electrical activity in the biceps brachii increased with stability requirements (i.e. Smith machine 相似文献
9.
Kari Dyregrov Mathilde Endsjø Thormod Idsøe Atle Dyregrov 《Emotional and Behavioural Difficulties》2013,18(3):289-301
Little is known about how teachers and head teachers (school personnel) attend to children experiencing grief. Our aim was to investigate what the school personnel perceive to be optimal help from the school in such situations. We conducted seven focus group interviews and one single interview among 17 teachers and 5 head teachers from primary and secondary schools. Although the school personnel obviously have high levels of empathy and commitment towards grieving students, they expressed limited knowledge about how child bereavement affects school performance, concentration, and learning, and how this restricted their own efforts to arrange for grieving children during the school day. They also signalled tensions created by the need to mediate too many tasks in the teacher’s role, school staff’s lack of grief knowledge, and guilt for not doing more for bereaved children at school. Despite the existence of solid theoretical and research base in the field of grief in children, opportunities for provision of evidence-validated intervention by teachers and other school personnel in response to grief, and prompt referral of bereaved children suffering more complex grief reactions, appear to be severely compromised. The school personnel pointed out the necessities for action plans and written routines, resources and clarifications of roles, and some basic help principles, key help measures, and improvements to improve the support for bereaved schoolchildren. 相似文献
10.
Ola P. Hole Finn O. Winther Henrik R. Cederkvist Sigurd Nitter‐Hauge 《Health information and libraries journal》2013,30(2):149-154
Purpose: Bibliometric analysis of publications was used to investigate the research output relating to the development of drugs in Norway and to evaluate the impact of Norwegian involvement in this research. Material and methods: One hundred and nine articles published between 2002 and 2008 were analysed. Bibliometric methods used were as follows: information on peer review, impact factor (IF), the Science Citation Index (SCI) and the representation of Norwegians in the list of authors. Results: All publications were in journals with peer review or in publications with corresponding evaluation. Industrial support, international research cooperation and drug development in phases I, II and III seem to promote publication in journals with high IF and a high SCI. In 63% of the international project articles, the Norwegian contributors were not represented in the list of authors. Conclusion: In addition to a scientific standard secured by referees, three probably independent factors – industrial support, international cooperation and early phases of the research (phases I, II and III) – seem to promote publications in journals with high IF and a high SCI. A more active Norwegian contribution to the research should be encouraged. 相似文献