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1.
Abstract Our aim was to present a mathematical model of rowing and sculling that allowed for a comparison of oar blade designs. The relative movement between the oar blades and water during the drive phase of the stroke was modelled, and the lift and drag forces generated by this complex interaction were determined. The model was driven by the oar shaft angular velocity about the oarlock in the horizontal plane, and was shown to be valid against measured on-water mean steady-state shell velocity for both a heavyweight men's eight and a lightweight men's single scull. Measured lift and drag force coefficients previously presented by the authors were used as inputs to the model, whichs allowed for the influence of oar blade design on rowing performance to be determined. The commonly used Big Blade, which is curved, and it's flat equivalent were compared, and blade curvature was shown to generate a 1.14% improvement in mean boat velocity, or a 17.1-m lead over 1500 m. With races being won and lost by much smaller margins than this, blade curvature would appear to play a significant role in propulsion. 相似文献
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Participation trends in 100 m (161 km) ultramarathon running competitions in North America were examined from race results from 1977 through 2008. A total of 32, 352 finishes accounted for by 9815 unique individuals were identified. The annual number of races and number of finishes increased exponentially over the study period. This growth in number of finishes occurred through a combination of (1) an increase in participation among runners ≥40 years of age from less than 40% of the finishes prior to the mid-1980s to 65–70% of the finishes since 1996, (2) a growth (p < 0.0001) in participation among women from virtually none in the late 1970s to nearly 20% since 2004, and (3) an increase in the average annual number of races completed by each individual to 1.3. While there has been considerable growth in participation, the 161 km ultramarathon continues to attract a relatively small number of participants compared with running races of shorter distances. 相似文献
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Roland Messmer 《Sportwissenschaft》2018,48(4):508-515
The school subject Physical Education (PE) deals explicitly with the body and movement. Therefore, it is essential to define the content of PE based on these two aspects. Historically, school is mainly oriented towards the mind, which has recently been named competency. For that reason, the mind-body problem is omnipresent in PE. Additionally, the recent shift to developing competencies in PE is intensifying the dualism of mind and body by opposing knowledge and knowing-how. In a first step, this categorical difference between mind and body will be explained in the course of a philosophical discussion and illustrated with appropriate examples. As will be shown, the mind-body contrast should be considered as a continuum instead of a dualism. Therefore—in a second step—Green’s teaching continuum will give an answer to the question if the subject matter of PE is a combination of cognitive and motor activity or not. In a third step, Dewey’s concept of experience will be outlined, based on which the practice of doing sport is explained and developed. A fourth step will be to develop a complementary curricular model that attempts to connect the two poles “mind” and “body” by linking performance with content standards (forms of sport), based on the current discourse on competencies and standards. In this manner, the presentation of a curricular model for PE overcomes the Cartesian contrast between mind and body. Additionally, it gives an answer to the current discussion about competencies and standards in PE that emanates from other disciplines and should be self-confidently discussed in our own discipline. 相似文献
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The purpose of this study was to compare home advantage at the top two levels of the domestic leagues of a wide selection of countries worldwide. Limited previous work has been inconclusive with home advantage at level 2 appearing at least as high as at level 1. Home advantage was quantified for the most recent seven seasons of the top two levels for 47 countries worldwide and included 168,341 matches. A paired t?test was used to assess the difference between levels for each country. Home advantage was significantly more likely to be higher at level 2 than at level 1. The difference was especially apparent in Bosnia–Herzegovina, Serbia and Iran (all p?<?0.001). Kazakhstan was the only country with a significantly higher advantage at level 1. Possible factors that might be contributing to this finding include players and referees at level 1 being better trained to avoid being influenced by crowd support. Level 2 players may be more intimidated by performing away from home, less well equipped to cope with unfamiliar surroundings and routines, and will also have travelled in less comfort. 相似文献
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F. J. Amaro-Gahete A. De-la-O L. Jurado-Fasoli A. Espuch-Oliver T. de Haro A. Gutierrez 《Journal of sports sciences》2013,31(19):2175-2183
ABSTRACTThis study aimed to investigate the effects of different training modalities on the soluble Klotho (S-Klotho) plasma levels in sedentary middle-aged adults. A total of 74 middle-aged adults (53.4 ± 5.0 years old; 52.7% women) were enrolled in the FIT-AGEING study. We conducted a 12-week randomised controlled trial. The participants were randomly assigned to 4 different groups: (i) a control group (no exercise), (ii) a physical activity recommendation from the World Health Organization group (PAR), (iii) a high intensity interval training group (HIIT), and (iv) a high intensity interval training group adding whole-body electromyostimulation training group (HIIT-EMS). S-Klotho plasma levels, anthropometric measurements, and body composition variables were measured before and after the intervention programme. All exercise training modalities induced an increase in the S-Klotho plasma levels (all P ≤ 0.019) without statistical differences between them (all P ≥ 0.696). We found a positive association between changes in lean mass index and changes in the S-Klotho plasma levels, whereas a negative association was reported between changes in fat mass outcomes and changes in the S-Klotho plasma levels after our intervention study. In conclusion, our results suggest that the link between exercise training and the increase in S-Klotho plasma levels could be mediated by a decrease of fat mass and an increase of lean mass. 相似文献
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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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Ka Man Leung Pak-Kwong Chung Lynda B. Ransdell Yong Gao 《Measurement in physical education and exercise science》2016,20(2):112-120
We examined psychometric properties of a Modified Physical Activity Questionnaire for Children (MPAQ-C). Thirty-two parents (Study 1), 40 students (6–9 years) and one of each student’s parents (Study 2), and 625 parents (Study 3) completed the MPAQ-C. The MPAQ-C (six items) measured children’s physical activity (PA) after school, and during evenings and weekends for 7 days. Test–retest reliability (Study 1) and convergent validity (Study 2) were measured. Factor validity of the MPAQ-C (Study 3) was examined using confirmatory factor analysis. A single-factor model of the MPAQ-C fit the data well (χ2 (9) = 42.78, p < .001; comparative fit index[CFI] = .977; non-normed fit index [NNFI] = .962; root mean square error of approximation [RMSEA] = .079 [90% confidence interval {CI} = .057 to .11]), with good test–retest reliability, composite reliability (.80) and convergent validity. The factor loadings of MPAQ-C were invariant across fathers/mothers (Δχ2 (6) = 3.44, p > .05). The MPAQ-C is a suitable parent proxy for measuring young Chinese children’s PA. 相似文献
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Health literacy represents an increasingly important subject in health sciences. This article initially illustrates a domain-specific model of physical activity-related health competence. Movement competence, control competence, and PA-specific self-regulation competence are described as sub-competencies. 相似文献
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Joel T. Cramer Travis W. Beck Terry J. Housh Laurie L. Massey Sarah M. Marek Suzanne Danglemeier 《Journal of sports sciences》2013,31(6):687-698
Abstract The aims of this study were to examine the acute effects of static stretching on peak torque, work, the joint angle at peak torque, acceleration time, isokinetic range of motion, mechanomyographic amplitude, and electromyographic amplitude of the rectus femoris during maximal concentric isokinetic leg extensions at 1.04 and 5.23 rad · s?1 in men and women. Ten women (mean ± s: age 23.0 ± 2.9 years, stature 1.61 ± 0.12 m, mass 63.3 ± 9.9 kg) and eight men (age 21.4 ± 3.0 years, stature 1.83 ± 0.11 m, mass 83.1 ± 15.2 kg) performed maximal voluntary concentric isokinetic leg extensions at 1.04 and 5.23 rad · s?1. Following the initial isokinetic tests, the dominant leg extensors were stretched using four static stretching exercises. After the stretching, the isokinetic tests were repeated. Peak torque, acceleration time, and electromyographic amplitude decreased (P≤ 0.05) from pre- to post-stretching at 1.04 and 5.23 rad · s?1; there were no changes (P > 0.05) in work, joint angle at peak torque, isokinetic range of motion, or mechanomyographic amplitude. These findings indicate no stretching-related changes in the area under the angle – torque curve (work), but a significant decrease in peak torque, which suggests that static stretching may cause a “flattening” of the angle – torque curve that reduces peak strength but allows for greater force production at other joint angles. These findings, in conjunction with the increased limb acceleration rates (decreased acceleration time) observed in the present study, provide tentative support for the hypothesis that static stretching alters the angle – torque relationship and/or sarcomere shortening velocity. 相似文献
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Christian Saal Jochen Zinner Harald Fiedler Ralf Lanwehr Jürgen Krug 《Sportwissenschaft》2018,48(3):334-340
The aim of this study was to investigate the reliability and validity of a soccer short passing test using the Footbonaut training system. Forty-eight young skilled soccer players and 31 lesser-skilled soccer players completed a test and a retest, each involving four sessions a day of a Footbonaut short passing test (FSPT). We found significant differences in mean execution times for skilled (mean [M]?=?2487, standard deviation [SD] ?=?155) and lesser-skilled players (M?=?2682, SD?=?176) but no significant difference in accuracy (M?=?74.13, SD?=?7.65; M?=?72.19, SD?=?8.13) between groups. The results from linear mixed-effects models show that there were no significant effects of repeated measurements on execution time. In contrast, we found an estimated increase of 0.86% in accuracy per session for both groups. In conclusion, the FSPT offers a reliable and valid method to differentiate young soccer players at different competitive levels, using execution time. 相似文献
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Malcolm MacLean 《国际体育史杂志》2013,30(1):23-34
This paper addresses issues raised in Paul Ward's essay ‘Last man picked’, focusing on methodological and discipline-refining questions to call for a more open dialogue between sports historians and others in the discipline. The argument includes a call on the wider discipline to both recognise the need for and participation in sub-discipline specific debates. 相似文献
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Neil Wigglesworth 《国际体育史杂志》2013,30(2):145-157
Open-boat sailing boomed in Sydney, Australia, during the 1890s, as a number of new sailing clubs emerged in the city's working waterfront suburbs. Open boats have since been remembered as ‘typically Australian’, radically opposed to the forms and ceremonies of the yachting establishment, and even as sharing the characteristics of the bushman, an archetype of Australian national identity. This article traces the rise of open-boat sailing as a working-class spectator sport and the associated image of an ‘open boat legend’. It argues that open-boat sailing remained a Sydney legend in the 1890s. However, links to working traditions and place have made it possible for popular histories of sailing and yachting to present the open boats and sailors of the period with identifiably Australian characteristics. 相似文献
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Cardiovascular disease is the leading cause of human death worldwide. Autophagy is an evolutionarily conserved degradation pathway,which is a highly conserved cellular degradation process in which lysosomes decompose their own organelles and recycle the resulting macromolecules.Autophagy is critical in maintaining cardiovascular homeostasis and function, and excessive or insufficient autophagy or autophagic flux can lead to cardiovascular disease. Enormous evidence indicates that exercise training plays a beneficial role in the prevention and treatment of cardiovascular diseases. The regulation of autophagy during exercise is a bidirectional process. For cardiovascular disease caused by either insufficient or excessive autophagy, exercise training restores normal autophagy function and delays the progression of cardiovascular disease.An in-depth exploration and discussion of exercise-mediated regulation of autophagy in the cardiovascular system can broaden our view about the prevention of various autophagy-related diseases through exercise training. In this article, we review autophagy and its related signaling pathways,as well as autophagy-dependent beneficial effects of exercise in cardiovascular system. 相似文献
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Anderson' s works pose a great challenge to critics due to his revolt against the literary tradition and the difficulty of the classification of his works. His language is tainted with obscurity and va... 相似文献
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Pascal Charitas 《国际体育史杂志》2015,32(7):909-922
After World War II, the principle of a colonized countries' self-determination was at stake in the international relationships emerging from the context of a Cold War and the decolonizations of Empires. Non-Governmental Organizations such as the International Olympic Committee (IOC) become not only analyzers of the effects of competition between the different colonial powers, but also enlighteners of the imperial strategies which would turn the power struggles into partnership and cooperation. The fear of a political harnessing from the Occidental countries resulted in two reactions: the progressive integration of English-speaking African National Olympic Committees (NOCs) based on a Great Britain-controlled International Federations (1950–1972) and, eventually and as a direct consequence, the creation of French-speaking African NOCs (1956–1968) through the International Olympic Aid Commission (1961). From 1944 to 1963, conditions for possibility seemed to be gathered for the realization of a process of internationalization of African sport through the integration of new English- and French-speaking African countries into the IOC. 相似文献
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Alexander A. Mikheev 《中国体育科技》2009,45(1)
The article presents the most important results of metabolic (hormonal) study of dosed vibration training (DVT).The author presents vibrating training as an alternative to anabolic steroids on the basis of a comparison of the effectiveness of two types of stimulants - forbidden (doping) and non-medicinal non-invasive, relating to permitted physical means.The study shows that the level of androgens (testosterone),corticosteroids (cortisol), thyroid hormones (thyroxine,triiodothyronine),hormones of adenohypophysis (prolactin) increased under the effect of dosed vibration training.At the same time the level of hormones have no changes under traditional strength training with the use of a synthetic anabolic steroid (retabolil).For the duration of a limited period of time (1 microcycles) dosed vibrotraining causes a more powerful secretion of testosterone than the traditional strength training with the use of anabolic steroids. In this case,the overall time spent on the performance of the DVT training program comprises not more than 15% of the time spent on the traditional training exercises. 相似文献
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This paper investigates the potential of international youth football tournaments for youth development in the Global South. The tournaments under study were East Africa Cup in Tanzania, and Norway Cup in Norway. Through qualitative interviews with tournament participants, we addressed the following research question: What are the participant’s views of the potentials of Norway Cup and East Africa Cup in dealing with development issues facing youth in the Global South? Our findings demonstrate that all interviewees consider the tournaments potentially beneficial for youth development in the Global South. In the analysis, we identified four different categories, mostly representing positive outcomes of tournament participation. We argue that a functionalist neo-liberal notion of sport is visible in the data material. Thus, our findings correspond with Sport for Development and Peace (SDP) research showing how reproductions of the SDP functionalist discourse ‘continue to be leveraged through sport and sealed into the success story of SDP’. 相似文献
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Wendell Arthur Lopes Neiva Leite Larissa Rosa da Silva Diego Trevisan Brunelli Arthur Fernandes Gáspari Rosana Bento Radominski 《Journal of sports sciences》2016,34(20):1902-1912
The objective of the present study was to investigate the effects of combined training without caloric restriction on inflammatory markers in overweight girls. Thirty-three girls (13–17 years) were assigned into overweight training (n = 17) or overweight control (n = 16) groups. Additionally, a normal-weight group (n = 15) was used as control for the baseline values. The combined training programme consisted of six resistance exercises (three sets of 6–10 repetitions at 60–70% 1 RM) followed by 30 min of aerobic exercise (walking/running) at 50–80% VO2peak, performed in the same 60 min session, 3 days/weeks, for 12 weeks. Body composition, dietary intake, aerobic fitness (VO2peak), muscular strength (1 RM), glycaemia, insulinemia, lipid profile and inflammatory markers (C-reactive protein, interleukin-6, tumour necrosis factor-alpha, interleukin-10, leptin, resistin and adiponectin) were measured before and after intervention. There was a significant decrease in body fat (P < 0.01) and increase in fat-free mass (P < 0.01), VO2peak (P < 0.01), 1 RM for leg press (P < 0.01) and bench press (P < 0.01) in the overweight training group. Concomitantly, this group presented significant decreases in serum concentrations of C-reactive protein (P < 0.05) and leptin (P < 0.05), as well as in insulin resistance (P < 0.05) after the experimental period. In conclusion, 12 weeks of combined training without caloric restriction reduced inflammatory markers associated with obesity in overweight girls. 相似文献