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141.
Daniel D. Bingham Silvia Costa Stacy A. Clemes Ash C. Routen Helen J. Moore Sally E. Barber 《Journal of sports sciences》2016,34(20):2005-2010
This study presents a worked example of a stepped process to reliably estimate the habitual physical activity and sedentary time of a sample of young children. A total of 299 children (2.9 ± 0.6 years) were recruited. Outcome variables were daily minutes of total physical activity, sedentary time, moderate to vigorous physical activity and proportional values of each variable. In total, 282 (94%) provided 3 h of accelerometer data on ≥1 day and were included in a 6-step process: Step-1: determine minimum wear-time; Step-2: process 7-day-data; Step-3: determine the inclusion of a weekend day; Step-4: examine day-to-day variability; Step-5: calculate single day intraclass correlation (ICC) (2,1); Step-6: calculate number of days required to reach reliability. Following the process the results were, Step-1: 6 h was estimated as minimum wear-time of a standard day. Step-2: 98 (32%) children had ≥6 h wear on 7 days. Step-3: no differences were found between weekdays and weekend days (P ≥ 0.05). Step-4: no differences were found between day-to-day variability (P ≥ 0.05). Step-5: single day ICC’s (2,1) ranged from 0.48 (total physical activity and sedentary time) to 0.53 (proportion of moderate to vigorous physical activity). Step-6: to reach reliability (ICC = 0.7), 3 days were required for all outcomes. In conclusion following a 7 day wear protocol, ≥6 h on any 3 days was found to have acceptable reliability. The stepped-process offers researchers a method to derive sample-specific wear-time criterion. 相似文献
142.
Hikabwa D. Chipande 《国际体育史杂志》2016,33(15):1847-1865
AbstractThis paper explores multiple and complex relationships between football (soccer), politics, and the economy in postcolonial Zambia. Based on archival and oral sources collected in Zambia, the paper argues that President Frederick Chiluba’s government failed to support football development when it came into power in 1991 because it was elected on a platform of liberalizing the collapsing national economy. Chiluba privatized state-owned companies that were sponsoring the game resulting in the plummeting of the local standards and migration of talented footballers abroad in search of better livelihoods. Furthermore, the paper argues that while the exodus of talented footballers led to the deterioration of the standards of the local league, their transnational experience boosted the performance of the Zambia national football team. This led to the emergence of one of the best national teams the country has ever had. Unfortunately, this particular team perished in the Gabon air disaster in 1993 following the government’s disinvestment in the game. However, a few months after the disaster, the country managed to rebuild a national football team, which emerged as runners up to Nigeria in the 1994 African Cup of Nations final as a result of a large pool of local and foreign-based football players. 相似文献
143.
144.
Cultural Studies of Science Education - Over the last few decades, there has been an international focus on productive talk in science classrooms, requiring teachers to use more dialogic practices... 相似文献
145.
Aaron J. Beach René E. D. Ferdinands Peter J. Sinclair 《Sports biomechanics / International Society of Biomechanics in Sports》2016,15(3):295-313
Spin bowling is generally coached using a standard technical framework, but this practice has not been based upon a comparative biomechanical analysis of leg-spin and off-spin bowling. This study analysed the three-dimensional (3D) kinematics of 23 off-spin and 20 leg-spin bowlers using a Cortex motion analysis system to identify how aspects of the respective techniques differed. A multivariate ANOVA found that certain data tended to validate some of the stated differences in the coaching literature. Off-spin bowlers had a significantly shorter stride length (p = 0.006) and spin rate (p = 0.001), but a greater release height than leg-spinners (p = 0.007). In addition, a number of other kinematic differences were identified that were not previously documented in coaching literature. These included a larger rear knee flexion (p = 0.007), faster approach speed (p < 0.001), and flexing elbow action during the arm acceleration compared with an extension action used by most of the off-spin bowlers. Off-spin and leg-spin bowlers also deviated from the standard coaching model for the shoulder alignment, front knee angle at release, and forearm mechanics. This study suggests that off-spin and leg-spin are distinct bowling techniques, supporting the development of two different coaching models in spin bowling. 相似文献
146.
Konstantinos D. Tambalis Demosthenes B. Panagiotakos Glykeria Psarra Stelios Daskalakis Stavros A. Kavouras Nickos Geladas 《European Journal of Sport Science》2016,16(6):736-746
The aim of the this study was to establish age- and gender-specific physical fitness normative values and to compare percentiles and Z scores values in a large, nationwide sample of Greek children aged 6–18 years. From March 2014 to May 2014, a total of 424,328 boys and girls aged 6–18 years who attended school in Greece were enrolled. The studied sample was representative, in terms of age–sex distribution and geographical region. Physical fitness tests (i.e. 20?m shuttle run test (SRT), standing long jump, sit and reach, sit-ups, and 10?×?5?m SRT) were performed and used to calculate normative values, using the percentiles of the empirical distributions and the lambda, mu, and sigma statistical method. Normative values were presented as tabulated percentiles for five health-related fitness tests based on a large data set comprising 424,328 test performances. Boys typically scored higher than girls on cardiovascular endurance, muscular strength, muscular endurance, and speed/agility, but lower on flexibility (all p values <0.001). Older boys and girls had better performances than younger ones (p?0.001). Physical fitness tests' performances tended to peak at around the age of 15 years in both sexes. The presented population-based data are the most up-to-date sex- and age-values for the health-related fitness of children and adolescents in Greece and can be used as standard values for fitness screening and surveillance systems and for comparisons among the same health-related fitness scores of children from other countries similar to Greece. Schools need to make efforts to improve the fitness level of the schoolchildren through the physical education curriculum to prevent cardiovascular risk. 相似文献
147.
Walid Briki Keith D. Markman Guillaume Coudevylle Stéphane Sinnapah Olivier Hue 《European Journal of Sport Science》2016,16(3):350-357
The present study examined the influence of momentum sequence (positive vs. negative) and environmental climate (hot–wet vs. neutral) on supporters’ (i.e. virtual observers’) reported levels of perceived psychological momentum (PM) during a simulated cycling competition. Participants supported one of two competing cyclists involved in a race that was displayed on a screen in a lecture hall. The race scenario was manipulated so that the supported cyclist appeared to undergo either a positive or negative momentum sequence. In addition, participants were either exposed to a hot–wet environmental climate or to a neutral environmental climate while observing the race scenario. According to the results, reported levels of PM were higher in the positive momentum sequence condition than in the negative momentum sequence condition, consistent with the notion that supporters’ PM is influenced by a positivity bias, and reported levels of PM were also found to be higher in the hot–wet climate condition than in the neutral climate condition, consistent with the notion that environmental climate is a contextual factor that influences PM through the operation of a causal augmenting mechanism. 相似文献
148.
D P Sen Gupta 《Resonance》2007,12(3):54-69
Alternating Current (AC) is used all over the world today. In India we use AC at 50 Hz (cycles per second) and in USA and
Canada at 60 Hz. During the latter part of the 19th century, even during the early part of the 20th century, Direct Current
or DC was widely used. Had we continued with DC, electricity would not have been as widely available as it is today and its
use would have been cumbersome, costly and severely restricted. We owe it mainly to the Serbian genius Nikola Tesla that electricity
has reached almost every nook and corner of most continents. 相似文献
149.
150.
1IntroductionRecent advances in wireless communication,digitallibrary,distributed multi media,massive storage,andmobile computing technologies are sti mulating the de-velopment of mobile multi media digital library systems(M2DLS)that allow mobile clients to access multi me-dia material anywhere and anyti me over a cellular ra-dio network[1,2].In M2DLS,multi media objects,ingeneral,can be composed of multiple media streamssuch as audio and video,whose retrieval must proceedso as to not only … 相似文献