首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   11篇
  免费   0篇
科学研究   4篇
体育   7篇
  2019年   1篇
  2018年   1篇
  2017年   2篇
  2015年   1篇
  2013年   4篇
  2010年   1篇
  2006年   1篇
排序方式: 共有11条查询结果,搜索用时 31 毫秒
1.
Although the effects of short versus long inter-set rest intervals in resistance training on measures of muscle hypertrophy have been investigated in several studies, the findings are equivocal and the practical implications remain unclear. In an attempt to provide clarity on the topic, we performed a systematic literature search of PubMed/MEDLINE, Scopus, Web of Science, Cochrane Library, and Physiotherapy Evidence Database (PEDro) electronic databases. Six studies were found to have met the inclusion criteria: (a) an experimental trial published in an English-language peer-reviewed journal; (b) the study compared the use of short (≤60?s) to long (>60?s) inter-set rest intervals in a traditional dynamic resistance exercise using both concentric and eccentric muscle actions, with the only difference in resistance training among groups being the inter-set rest interval duration; (c) at least one method of measuring changes in muscle mass was used in the study; (d) the study lasted for a minimum of four weeks, employed a training frequency of ≥2 resistance training days per week, and (e) used human participants without known chronic disease or injury. Current evidence indicates that both short and long inter-set rest intervals may be useful when training for achieving gains in muscle hypertrophy. Novel findings involving trained participants using measures sensitive to detect changes in muscle hypertrophy suggest a possible advantage for the use of long rest intervals to elicit hypertrophic effects. However, due to the paucity of studies with similar designs, further research is needed to provide a clear differentiation between these two approaches.  相似文献   
2.
We evaluated (1) the test-retest reliability of the Wingate test conducted on a rowing ergometer, and (2) the sensitivity of this test in determining the differences in performance attained by 12- to 18-year-old rowers. Altogether, 297 male rowers aged 12.0-18.9 years (mean?±?s: 14.8?±?1.7) completed a maximal 30-s test on a rowing ergometer, and 80 rowers representing all age groups were retested after 5-7 days. No change was evident in participants' performance in terms of mean power output (P?=?0.726; Cohen's d?=?0.04), maximal power output (P?=?0.567; Cohen's d?=?0.06), and minimum power output (P?=?0.318; Cohen's d?=?0.11) in the second test. The intra-class correlation coefficients were high (≥0.973) and coefficients of variation were low (≤7.3%). A series of analyses of variance were used to compare the performances among 12- to 18-year-old rowers, and age-related increases in performance were evident (P?相似文献   
3.
Abstract

We evaluated (1) the test–retest reliability of the Wingate test conducted on a rowing ergometer, and (2) the sensitivity of this test in determining the differences in performance attained by 12- to 18-year-old rowers. Altogether, 297 male rowers aged 12.0–18.9 years (mean ± s: 14.8 ± 1.7) completed a maximal 30-s test on a rowing ergometer, and 80 rowers representing all age groups were retested after 5–7 days. No change was evident in participants' performance in terms of mean power output (P = 0.726; Cohen's d = 0.04), maximal power output (P = 0.567; Cohen's d = 0.06), and minimum power output (P = 0.318; Cohen's d = 0.11) in the second test. The intra-class correlation coefficients were high (≥0.973) and coefficients of variation were low (≤7.3%). A series of analyses of variance were used to compare the performances among 12- to 18-year-old rowers, and age-related increases in performance were evident (P < 0.001; Cohen's d = 1.91–1.96). The age-related increases in performance were similar, although reduced, when the effects of body mass were partitioned out when using analysis of covariance (P < 0.001; Cohen's d = 0.82–0.85). The results suggest that: (1) the described test is reliable and can be used for maximal-intensity exercise assessment in youth rowing, and (2) it discriminates performance among 12- to-18-year-old rowers.  相似文献   
4.
Simultaneous two-dimensional comparisons of time series data—vertically (static difference) and horizontally (Sicherl-time-distance)—for numerous ITU and Eurostat datasets show that estimates of the magnitude of digital divide can differ substantially between conventional static measures and Sicherl-time-distance, a dynamic measure of disparity. Comparing digital divide indicators with other indicators of social inequality (life expectancy, infant mortality), the analysis shows that high ICT growth rate improved well-being in developing countries and reduced some world inequalities. This methodology enables researchers, policy makers, and business managers how to draw new insights from existing data, including monitoring the attainment of targets.  相似文献   
5.
The goal of this randomized, double-blind, cross-over study was to assess the acute effects of caffeine ingestion on muscular strength and power, muscular endurance, rate of perceived exertion (RPE), and pain perception (PP) in resistance-trained men. Seventeen volunteers (mean?±?SD: age?=?26?±?6 years, stature?=?182?±?9?cm, body mass?=?84?±?9?kg, resistance training experience?=?7?±?3 years) consumed placebo or 6?mg?kg?1 of anhydrous caffeine 1?h before testing. Muscular power was assessed with seated medicine ball throw and vertical jump exercises, muscular strength with one-repetition maximum (1RM) barbell back squat and bench press exercises, and muscular endurance with repetitions of back squat and bench press exercises (load corresponding to 60% of 1RM) to momentary muscular failure. RPE and PP were assessed immediately after the completion of the back squat and bench press exercises. Compared to placebo, caffeine intake enhanced 1RM back squat performance (+2.8%; effect size [ES]?=?0.19; p?=?.016), which was accompanied by a reduced RPE (+7%; ES?=?0.53; p?=?.037), and seated medicine ball throw performance (+4.3%, ES?=?0.32; p?=?.009). Improvements in 1RM bench press were not noted although there were significant (p?=?.029) decreases in PP related to this exercise when participants ingested caffeine. The results point to an acute benefit of caffeine intake in enhancing lower-body strength, likely due to a decrease in RPE; upper-, but not lower-body power; and no effects on muscular endurance, in resistance-trained men. Individuals competing in events in which strength and power are important performance-related factors may consider taking 6?mg?kg?1 of caffeine pre-training/competition for performance enhancement.  相似文献   
6.

The term “digital divide” has been used for almost a decade and typically relates to sociodemographic differences in the use of information and communication technology. However, the corresponding measurement is still relatively imprecise. Very often it is simply reduced to comparisons of Internet penetration rates. This article extends the measurements above the usual bivariate comparisons. Within this context, three essential approaches are presented and critically evaluated. First, loglinear modeling is used to address the interactions among the factors affecting the digital divide. Second, compound measures (i.e., the Digital Divide Index) that integrate a number of variables into a single indicator are discussed. Third, time-distance methodology is applied to analyze changes in the digital divide. The article argues that these approaches often yield entirely different conclusions compared to simple bivariate analysis. The examples are presented as a general warning against an oversimplified methodological approach to digital divide studies.  相似文献   
7.
Abstract

In this study, we evaluated the extent to which 2000-m rowing ergometer performance times predicted final rankings at the World Rowing Championships in a sample of 638 rowers of both sexes and body-mass classifications (i.e. open-category and lightweight rowers). Rowing ergometer performance times were examined using a questionnaire, and in 17 of 23 events they were positively correlated (P ≤ 0.049) with the final rankings at the Championships. The highest correlations were for the ergometer performance times achieved by rowers in lightweight men's single sculls (r = 0.78; P = 0.005), women's single sculls (r = 0.75; P = 0.002), men's single sculls (r = 0.72; P = 0.004), and lightweight men's double sculls (r = 0.72; P < 0.001). We used linear regression to establish regression equations to predict final rankings based on 2000-m rowing ergometer performance times for each event in which there was a correlation greater than r = 0.50. Although correlations in 12 events met this criterion, the large standard errors of the estimate hindered ranking predictions in all of the studied events. Regression equations could be used to determine the most probable 2000-m ergometer performance time for a rower to achieve specific rankings at the World Rowing Championships.  相似文献   
8.
9.
This case study reports the results of a 12-year (2005–2016) follow-up study of two Olympic champion rowers. The rowers were prospective athletes at the junior level when the study began, and we monitored their relevant physiological and performance data annually. Our findings indicated that their V?O2max gradually increased up to about 22 years of age and leveled off at a value of approximately 7 l·min?1 with minimal fluctuations thereafter. However, the variables that directly influence the V?O2max changed. There was an age-related decline in maximal heart rate of about 0.5 beats·year?1, while oxygen pulse, which serves as an indirect measure of stroke volume, correspondingly increased by about 1 ml O2·beat?1 per year, allowing the athletes to maintain exceptional V?O2max values. Maximal minute power of the studied rowers, derived each year from their ramp-wise tests, closely resembled the mean power output sustained during the 2000-m all-out tests on a rowing ergometer. A 12-year improvement of 28% and 33% occurred for the mean power output sustained over 2000 and 6000-m on a rowing ergometer, respectively. The findings contribute to the body of knowledge on athletes representing the true elites of their respective sports.  相似文献   
10.
Methodological Challenges of Digital Divide Measurements   总被引:1,自引:0,他引:1  
The term “digital divide” has been used for almost a decade and typically relates to sociodemographic differences in the use of information and communication technology. However, the corresponding measurement is still relatively imprecise. Very often it is simply reduced to comparisons of Internet penetration rates. This article extends the measurements above the usual bivariate comparisons. Within this context, three essential approaches are presented and critically evaluated. First, loglinear modeling is used to address the interactions among the factors affecting the digital divide. Second, compound measures (i.e., the Digital Divide Index) that integrate a number of variables into a single indicator are discussed. Third, time-distance methodology is applied to analyze changes in the digital divide. The article argues that these approaches often yield entirely different conclusions compared to simple bivariate analysis. The examples are presented as a general warning against an oversimplified methodological approach to digital divide studies.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号