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Senda Sammoud Alan Michael Nevill Yassine Negra Raja Bouguezzi Chaabene Helmi Younés Hachana 《Journal of sports sciences》2019,37(10):1162-1167
The purpose of this study was to estimate the optimal body size, limb-segment length, girth or breadth ratios for 100-m backstroke mean speed performance in young swimmers. Sixty-three young swimmers (boys [n = 30; age: 13.98 ± 0.58 years]; girls [n = 33; age: 13.02 ± 1.20 years]) participated in this study. To identify the optimal body size and body composition components associated with 100-m backstroke speed performance, we adopted a multiplicative allometric log-linear regression model, which was refined using backward elimination. The multiplicative allometric model exploring the association between 100-m backstroke mean speed performance and the different somatic measurements estimated that biological age, sitting height, leg length for the lower-limbs, and two girths (forearm and arm relaxed girth) are the key predictors. Stature and body mass did not contribute to the model, suggesting that the advantage of longer levers was limb-specific rather than a general whole-body advantage. In fact, it is only by adopting multiplicative allometric models that the abovementioned ratios could have been derived. These findings highlighted the importance of considering somatic characteristics of young backstroke swimmers and can help swimming coaches to classify their swimmers and enable them to suggest what might be the swimmers’ most appropriate stroke (talent identification). 相似文献
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Alan M. Nevill Yassine Negra Tony D. Myers Senda Sammoud Helmi Chaabene 《Journal of sports sciences》2020,38(7):787-794
ABSTRACTThis study identified key somatic and demographic characteristics that benefit all swimmers and, at the same time, identified further characteristics that benefit only specific swimming strokes. Three hundred sixty-three competitive-level swimmers (male [n = 202]; female [n = 161]) participated in the study. We adopted a multiplicative, allometric regression model to identify the key characteristics associated with 100 m swimming speeds (controlling for age). The model was refined using backward elimination. Characteristics that benefited some but not all strokes were identified by introducing stroke-by-predictor variable interactions. The regression analysis revealed 7 “common” characteristics that benefited all swimmers suggesting that all swimmers benefit from having less body fat, broad shoulders and hips, a greater arm span (but shorter lower arms) and greater forearm girths with smaller relaxed arm girths. The 4 stroke-specific characteristics reveal that backstroke swimmers benefit from longer backs, a finding that can be likened to boats with longer hulls also travel faster through the water. Other stroke-by-predictor variable interactions (taken together) identified that butterfly swimmers are characterized by greater muscularity in the lower legs. These results highlight the importance of considering somatic and demographic characteristics of young swimmers for talent identification purposes (i.e., to ensure that swimmers realize their most appropriate strokes). 相似文献
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Montassar Tabben Jeremy Coquart Helmi Chaabène Nihel Ghoul Claire Tourny 《Journal of sports sciences》2015,33(8):841-849
The aim of this study was to define the time-motion (i.e., fighting, preparatory and breaking activity), technical (i.e., attack, timed-attack, counterattack, blocking and grasps) and tactical (i.e., upper limb, lower-limb, combination and throwing) profiles of the senior top-level karate competition played under the most recent rules of the International Karate Federation in relation to gender, match outcome and weight categories. Time-motion, tactical actions and technical executions were investigated of senior karatekas (n = 60) during the Karate World Championship. The referee’s decisions caused an overall activity-to-break ratio of ~1:1.5 with a significant difference (P = 0.025) between karateka’s weight categories (light = 1:1.5; middle = 1:2 and heavy = 1:1). High-intensity actions (i.e., attack and defensive actions performed quickly and powerfully) were higher in male compared to female athletes. Top-level karatekas used upper limb techniques more than lower limb ones, with both applied in the head more than in the body. For the high-intensity-actions to pause ratio and the percentage of combined techniques, light weight category was significantly higher than middle weight category. These findings suggest that training programs may need to be specific to the requirements of the gender and weight categories. 相似文献
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The Internet provides a venue for several purposes. One purpose is to disseminate information. Compared to other infrastructures, the Internet is one of the more cost-effective ways of improving a country's educational system. Online education is growing in popularity as it provides accessibility and encourages collaborative communication among student peers. The main purpose of this paper was to analyze the impetus of online education through the perception of adult learners at Curtin Business School. The majority of the respondents valued the direct interaction of traditional classes and easy access to information on subjects being offered on online courses. A combination of both traditional and online methods proved to be the most comprehensive solution as students were able to increase their interpersonal skills and computer literacy. Based upon the conducted survey, the three main driving forces to the development of online education were identified as information technology, education brokers (universities), and market demands. The main implications of technology to universities were identified in its changing roles and organizational structure and being able to form partnerships with other business counterparts. Simultaneously, this trend would produce a new generation of knowledge workers with new expectations on career advancement and learning opportunities. As such, it becomes imperative that universities and information communication technology-based organizations form a symbiotic relationship to meet the expectations of the new e-generation. 相似文献
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Denguezli M Ben Chiekh I Ben Saad H Zaouali-Ajina M Tabka Z Abdelkrim Z 《Journal of sports sciences》2008,26(12):1351-1359
The aim of this study was to determine whether endurance training in athletes induces airway inflammation and pulmonary function disorders. Respiratory pattern and function were analysed in ten healthy endurance runners at rest, during sub-maximal exercise, and during the recovery. Inflammatory cells and metabolites (histamine, interleukin-8, and leukotriene E(4)) were measured in sputum at rest and after exercise. The experiments were conducted on three different occasions (basic endurance training, pre-competitive and competitive periods). In spite of the absence of post-exercise spirometric changes and respiratory symptoms, airway cells counts and inflammatory markers changed significantly. At the beginning of the experiment, athletes' induced sputum showed an abundance of macrophages compared with neutrophils. We found a high percentage of neutrophils during the pre-competitive and competitive periods of the sport season (41% and 37%), a significant increase in macrophage counts during the pre-competitive period (51%), and a significant rise in total cells, interleukin-8, leukotriene E(4), and histamine during the competitive period. In conclusion, one year's training increased markers of inflammation in the airways of endurance runners without symptoms or changes in pulmonary function, suggesting that airway inflammation is of insufficient magnitude to markedly impact lung function in healthy athletes. 相似文献
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ABSTRACT
The purpose of this systematic review with meta-analysis was to examine the effects of strength training (ST) on selected components of physical fitness (e.g., lower/upper limb maximal strength, muscular endurance, jump performance, cardiorespiratory endurance) and sport-specific performance in rowers. Only studies with an active control group were included if they examined the effects of ST on at least one proxy of physical fitness and/or sport-specific performance in rowers. Weighted and averaged standardized mean differences (SMD) were calculated using random-effects models. Subgroup analyses were computed to identify effects of ST type or expertise level on sport-specific performance. Our analyses revealed significant small effects of ST on lower limb maximal strength (SMD = 0.42, p = 0.05) and on sport-specific performance (SMD = 0.32, p = 0.05). Non-significant effects were found for upper limb maximal strength, upper/lower limb muscular endurance, jump performance, and cardiorespiratory endurance. Subgroup analyses for ST type and expertise level showed non-significant differences between the respective subgroups of rowers (p ≥ 0.32). Our systematic review with meta-analysis indicated that ST is an effective means for improving lower limb maximal strength and sport-specific performance in rowers. However, ST-induced effects are neither modulated by ST type nor rowers’ expertise level. 相似文献
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Yassine Negra Helmi Chaabene Thomas Stggl Mehrz Hammami Mohamed Souhaiel Chelly Youns Hachana 《运动与健康科学(英文)》2020,9(6):620-627
PurposeThis study aimed to assess the effectiveness and time course for improvements in explosive actions through resistance training (RT) vs. plyometric training (PT) in prepubertal soccer players.MethodsThirty-four male subjects were assigned to: a control group (n = 11); an RT group (5 regular soccer training sessions per week, n = 12); a PT group (3 soccer training sessions and 2 RT sessions per week, n = 11). The outcome measures included tests for the assessment of muscle strength (e.g., 1 repetition maximum half-squat test), jump ability (e.g., countermovement jump, squat jump, standing long jump, and multiple 5 bounds test), linear speed (e.g., 20 m sprint test), and change of direction (e.g., Illinois change of direction test).ResultsThe RTG showed an improvement in the half-squat (Δ = 13.2%; d = 1.3, p < 0.001) and countermovement jump (Δ = 9.4%; d = 2.4, p < 0.001) at Week 4, whereas improvements in the 20-m sprint (Δ = 4.2%; d = 1.1, p < 0.01); change of direction (CoD) (Δ = 3.8%; d = 2.1, p < 0.01); multiple 5 bounds (Δ = 5.1%; d = 1.5, p < 0.05); standing long jump (Δ = 7.2%; d = 1.2, p < 0.01); squat jump (Δ = 19.6%; d = 1.5, p < 0.01); were evident at Week 8. The PTG showed improvements in CoD (Δ = 2.1%; d = 1.3, p < 0.05); standing long jump (Δ = 9.3%; d = 1.1, p < 0.01); countermovement jump (Δ = 16.1%; d = 1.2, p < 0.01); and squat jump (Δ = 16.7%; d = 1.4, p < 0.01); at Week 8 whereas improvements in the 20-m sprint (Δ = 4.1%; d = 1.3, p < 0.01); and multiple 5 bounds (Δ = 7.4%; d = 2.4, p < 0.001); were evident only after Week. The RT and PT groups showed improvements in all sprint, CoD, and jump tests (p < 0.05) and in half-squat performance, for which improvement was only shown within the RTG (p < 0.001).ConclusionRT and PT conducted in combination with regular soccer training are safe and feasible interventions for prepubertal soccer players. In addition, these interventions were shown to be effective training tools to improve explosive actions with different time courses of improvements, which manifested earlier in the RTG than in the PTG. These outcomes may help coaches and fitness trainers set out clear and concise goals of training according to the specific time course of improvement difference between RT and PT on proxies of athletic performance of prepubertal soccer players. 相似文献
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Myriam Denguezli Imen Ben Chiekh Helmi Ben Saad Monia Zaouali-Ajina Zouhaier Tabka Abdelkrim Zbidi 《Journal of sports sciences》2013,31(12):1351-1359
Abstract The aim of this study was to determine whether endurance training in athletes induces airway inflammation and pulmonary function disorders. Respiratory pattern and function were analysed in ten healthy endurance runners at rest, during sub-maximal exercise, and during the recovery. Inflammatory cells and metabolites (histamine, interleukin-8, and leukotriene E4) were measured in sputum at rest and after exercise. The experiments were conducted on three different occasions (basic endurance training, pre-competitive and competitive periods). In spite of the absence of post-exercise spirometric changes and respiratory symptoms, airway cells counts and inflammatory markers changed significantly. At the beginning of the experiment, athletes' induced sputum showed an abundance of macrophages compared with neutrophils. We found a high percentage of neutrophils during the pre-competitive and competitive periods of the sport season (41% and 37%), a significant increase in macrophage counts during the pre-competitive period (51%), and a significant rise in total cells, interleukin-8, leukotriene E4, and histamine during the competitive period. In conclusion, one year's training increased markers of inflammation in the airways of endurance runners without symptoms or changes in pulmonary function, suggesting that airway inflammation is of insufficient magnitude to markedly impact lung function in healthy athletes. 相似文献
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