The match demands of international rugby sevens

The purpose of this study was to quantify the global match demands of international rugby sevens and to compare the match demands of forwards and backs, and between tournament rounds. To assess the match demands, global positioning system (GPS) and video analysis were collected from 27 international rugby sevens players from the same team across an entire International Rugby Board Sevens World Series season. Differences in running demands and match activities between forwards and backs were mostly trivial and small (ES = 0.05–0.84) while differences in running demands and match activities between Pool and Cup rounds were trivial (ES = 0.001–0.12). Cup round matches showed an increase in long-duration ball-in-play sequences (proportion ratio 0.46). These findings suggest international rugby sevens forwards and backs experience similar match demands while overall match demands remain consistent across tournament rounds.     

High-intensity efforts in elite soccer matches and associated movement patterns,technical skills and tactical actions. Information for position-specific training drills

ABSTRACT

This study aimed to translate movement patterns, technical skills and tactical actions associated with high-intensity efforts into metrics that could potentially be used to construct position-specific conditioning drills. A total of 20 individual English Premier League players’ high-intensity running profiles were observed multiple times (n = 100) using a computerised tracking system. Data were analysed using a novel high-intensity movement programme across five positions (centre back [CB], full-back [FB], central midfielder [CM], wide midfielder [WM] and centre forward [CF]). High-intensity efforts in contact with the ball and the average speed of efforts were greater in WMs than CBs, CMs and CFs (effect sizes [ES]: 0.9–2.1, P < 0.05). WMs produced more repeated efforts than CBs and CMs (ES: 0.6–1.3, P < 0.05). In possession, WMs executed more tricks post effort than CBs and CMs (ES: 1.2–1.3, P < 0.01). FBs and WMs performed more crosses post effort than other positions (ES: 1.1–2.0, P < 0.01). Out of possession, CFs completed more efforts closing down the opposition (ES: 1.4–5.0, P < 0.01) but less tracking opposition runners than other positions (ES: 1.5–1.8, P < 0.01). CFs performed more arc runs before efforts compared to CBs, FBs and WMs (ES: 0.9–1.4, P < 0.05), however, CBs completed more 0–90° turns compared to FBs, CMs and WMs (ES: 0.9–1.1, P < 0.01). The data demonstrate unique high-intensity trends in and out of possession that could assist practitioners when devising position-specific drills.     

Phases of match-play in professional Australian Football: Distribution of physical and technical performance

ABSTRACT

The current study aimed to describe the distribution of physical and technical performance during the different phases of play in professional Australian Football. The phases of play (offence, defence, contested play, umpire stoppages, set shots and goal resets) were manually coded from video footage for a single team competing in 18 matches in the Australian Football League. Measures of physical performance including total distance (m), average speed (m · min^?1), low-speed running (LSR, <14.4 km h^?1), high-speed running (HSR, >14.4 km h^?1), accelerations (2.78 m · s^?2) and decelerations (?2.78 m · s^?2) were derived from each phase of play via global positioning system (GPS) devices. Technical skill data including tackles, handballs and kicks were obtained from a commercial statistics provider and derived from each phase of play. Linear mixed-effects models and effect sizes were used to assess and reflect the differences in physical and technical performance between the six phases of play. Activity and recovery cycles, defined as periods where the ball was in or out of play were also described using mean and 95% confidence intervals. The analysis showed that several similarities existed between offence and defence for physical performance metrics. Contested play involved the highest total distance, LSR, accelerations, decelerations and tackles compared to all other phases. Offence and defence involved the highest average speed and HSR running distances. Handballs and kicks were highest during offence, while tackles were highest during contested play, followed by defence. Activity and recovery cycles involved mean durations of ~110 and ~39 s and average speeds of ~160 and ~84 m · min^?1, respectively. The integration of video, GPS and technical skill data can be used to investigate specific phases of Australian Football match-play and subsequently guide match analysis and training design.     

Comment on ‘Performance analysis in football: A critical review and implications for future research’

Abstract

MacKenzie and Cushion (2013) recently reviewed performance analysis research in association football (soccer). Their critical review focused on several themes related to methodological approaches such as sample size, match context and operational definitions and the implications of research findings to professional practice. In this response letter, we comment on additional pragmatic concerns regarding these key themes as well as some of the difficulties commonly faced when conducting performance analysis research.     

Influence of playing standard on the physical demands of professional rugby league

Abstract

In this paper we report on two studies that investigated the physical demands of professional rugby league match-play. Instudy one, National Rugby League (NRL) and National Youth Competition (NYC) players underwent global positioning system (GPS) analysis during competitive matches. No differences (P > 0.05) were observed between playing standards for minutes played, total distance covered, or the distances covered at low and high speeds. However, NRL players engaged in significantly more repeated high-intensity effort bouts than NYC players (13.1 ± 0.8 bouts vs. 9.7 ± 1.1 bouts). Reductions in physical performance occurred from the first to second half for both NRL and NYC players. In study two, we investigated, in the same players, the physical demands of professional rugby league match-play when players were competing in trial and regular fixture matches. The locomotor demands of trial matches were lower than fixture matches, with players covering less distance per minute of match-play, including less distance at low and high speeds. Players were also less likely to engage in repeated high-intensity effort bouts in trial matches than fixtures. These findings demonstrate that neither NYC matches nor NRL trial matches adequately reflect the intense physical demands of NRL fixture matches.     

Changes in locomotive rates during senior elite rugby league matches

Abstract

The aim of this study was to quantify the changes in locomotive rates across the duration of senior elite rugby league matches. A semi-automated image recognition system (ProZone 3, ProZone®, Leeds, England) was used to track the movements of 59 players from six teams during three competitive matches. The players were classified into one of four positional groups: props (n = 9), back row (n = 9), pivots (n = 14) or outside backs (n = 27). Players' movements were classified as low, high or very high intensity running and reported as locomotive rates (distance covered per minute played) for successive quarters of each match. Analysis of variance revealed that only the outside backs showed a significantly lower overall locomotive rate during the final quarter compared to the first (P < 0.05). However, locomotive rates for high and very high intensity running during the final quarter were significantly lower (P < 0.05) than the first quarter among outside backs, pivots and props despite no change in the rate of involvements in contact. On the basis of these findings, it is suggested that high and very high intensity running locomotive rates may be more affective methods of detecting fatigue during competitive matches than overall locomotive rate.     

Validity and reliability of a 6-a-side small-sided game as an indicator of match-related physical performance in elite youth Brazilian soccer players

ABSTRACT

The aims of this study were: (i) to compare the external and internal load during a 6-a-side small-sided game (6v6-SSG) according to age-group; (ii) to relate these parameters between the 6v6-SSG and official matches; and (iii) to test the reliability of the 6v6-SSG. A total of 51 Brazilian youth soccer players participated in this study (U11 [n = 16]; U13 [n = 10]; U15 [n = 9]; U17 [n = 8]; U20 [n = 8]). Three experiments were conducted. Experiment A: fifty-one U11 to U20 players were submitted to 6v6-SSGs (n = 10 games; two for each age-group). Experiment B: thirty-two players were randomized to also play official matches (n = 6 matches). Experiment C: thirty-five youth players played the 6v6-SSG twice for test and retest reliability analysis. External load was obtained using Global Positioning Systems and the internal load parameter was calculated through mean heart rate. Statistical approaches showed progressive increases in all parameters according to categories (U11< U13< U15< U17< U20; p < 0.05; ES = 0.42?23.68). Even controlling for chronological age, all parameters showed likely to almost certain correlations between 6v6-SSG and official matches (r = 0.25?0.92). Collectively, the proposed protocol indicates good reliability (CV% = 2.0?12.6; TE% = 2.3?2.7%; ICC = 0.78?0.90). This research suggests that the 6v6-SSG is an alternative tool to indicate match-related physical performance in youth soccer players.     

An integrated analysis of match-related fatigue in professional rugby league

This study examined the changes in external outputs, including metabolic power variables, and internal response whilst considering contextual factors on physical performance variables during rugby league match play. Physical performance (total distance, high-speed running and high-power distances, average metabolic power), heart-rate (percentage heart-rate peak and training impulse), collisions (attacking and defensive) and contextual (time in attack, time in defence, time out of play) data were collected from 18 rugby league players during 38 games throughout two National Rugby League seasons. Physical variables were highest in the first 10-min period of each half (P < 0.001). Heart-rate indices peaked in the second 10-min period and were lower during second half periods (P < 0.001). Few differences existed in collisions and contextual factors across 10-min periods. Physical variables were highest during the first 5-min period compared to the final (P < 0.001). There was no difference in heart-rate response, attacking collisions or contextual factors between these periods. Following the peak 5-min period in the match, there were reductions in physical, heart-rate, defensive collisions and contextual factors (P < 0.001). The data show temporal changes in physical performance, heart-rate response and collisions during rugby league match play, although these are affected by contextual factors.     

Network-based centrality measures and physical demands in football regarding player position: Is there a connection? A preliminary study

ABSTRACT

This study’s main objective is to analyse the relationship between network-based centrality measures and physical demands in elite football players. Thirty-six matches from La Liga, the Spanish league, were analysed in the 2017/18 season. The analysis of networks formed by team players passing the ball included: degree-prestige (DP), degree-centrality (DC), betweenness-centrality (BC), page-rank (PRP) and closeness-centrality (IRCC). A video-based system was used for analysing total distance (TDpos) and distance run >21Km/h (TD21pos) when the team was in possession of the ball. A magnitude-based inference and correlation analysis were applied. There were different styles of play, team-A was characterized by greater ball circulation (e.g. higher values of DP, DC, BC and IRCC) while team-B used a more direct game (lower values in centrality-metrics except with PRP). Furthermore, TDpos was higher in team-A than in team-B, but those differences disappeared for TD21pos between teams with the exception of the forwards. Finally, the correlation among centrality measures and physical performance were higher in team-B. Coaches could identify the key opponents and players who are linked to them, allowing to adjust performance strategies. Furthermore, interaction patterns between teammates can be used to identify preferential paths of cooperation and to take decisions regarding these relations in order to optimize team performance.     

The Development and Validation of a Racquetball Skills Test Battery for Young Adult Beginners

This study was designed to develop a racquetball skills test battery for young adult beginners. Based on a review of literature and the content validity phase, 5 racquetball skills components with 8 test items were formulated: service placement (left and right), power drive (forehand and backhand), power shot placement (forehand and backhand), ceiling shot, and wall rally. Participants (N = 131) were 87 male and 44 female college students who were provided two 90-min sessions of practice and preparation 1 week before the testing. The test was conducted on 2 official size racquetball courts. Each test item had 20 trials (3 trials for wall rally), and each was administered twice within 1 week. A single round-robin tournament was conducted for male and female participants, respectively. Participants were simultaneously evaluated on their overall skill levels by a trained evaluator using a subjective 5-point rating scale. Data on subjective rating and tournament standing were used as criterion variables for examining the test validity. Intercorrelations revealed that all test items had validity coefficients equal to or greater than .50, except for 2 items, service placement to the left and the right, which were dropped from further analysis. Multiple regression analyses revealed that the remaining 6 skills test items were predictive of the 2 criterion variables, with the multiple correlations equal to .67 and .68 for males and .61 and .75 for females. Using factorial repeated measures analysis of variance, generalizability reliability was computed. The G coefficients for the items ranged from .61 to .84. The D studies revealed that testing over a minimum of 2 days would be the best test protocol for most racquetball skills test items. To achieve sufficient reliability (i.e., G coefficient >>.70), the minimum number of trials administered each day was suggested for each item.     

对武术概念的再探析

文章通过对众多武术教材中关于“武术”概念的综合分析、研究,结合有关武术产生、发展过程的理论文献,对武术概念进行了一些分析研究,以使武术的概念更科学、全面、准确。     

Utility of the BMI50 and BMI85 in the Assessment of Short- and Long-Term Change in BMI among Children: A Descriptive Analysis

Interpreting change in Body mass index (BMI) among youth by comparison to growth charts can be difficult because of maturation-related changes. The aim of this paper was to evaluate the utility of several alternative methods for assessing change in BMI among children. Participants included 1,615 children measured for stature and body mass in first grade and then again the following year. A total of 1,101 students were also assessed in eighth grade. Change was examined using BMI percentiles (BMI%), BMI z-scores, “Percent Over BMI” (BMI50), and the Healthy Fitness Zone continuum, also referred to as BMI85. Youth at lower BMI levels at baseline showed a positive mean change in BMI%/z-score, whereas those at higher levels at baseline showed a negative mean change in BMI%/z-score. These patterns were not seen with BMI50 or BMI85. Assessing change in weight by using BMI% may result in bias so researchers are encouraged to use BMI85 as a more appropriate approach.     

大学生健康危险行为调查

自制健康危险行为问卷，对422名二年级大学生进行了有关健康危险行为的调查。结果：危害大学生健康的行为在大学生中较为普遍，一些健康危险行为存在性别差异。男生吸烟率为40．9％；男生喝啤酒率为92．6％，女生为71．0％；有32．2％的男生和12．9％的女生经常体育锻炼；有29．5％男生和6．5％女生发生过意外伤害，有的40．9％男生和38．7％女生有过骑摩托车或坐摩托车不带头盔的情况发生，有32．9％的男生和16．1％女生有过通宵娱乐或学习。     

武术套路学习过程的心理分析

武术作为中华民族的文化遗产,具有悠久的历史,是中华民族智慧的结晶。武术是劳动人民根据自己的社会实践活动创造出来的,并造福于人民。武术已走向世界,受到世界各国人民的喜爱。本文从心理学角度分析武术套路教学中学生掌握套路动作的规律,以更好完成教学任务。     

我国竞技健美运动裁判员的现状分析

健美运动是一项惠及个人和国家的很好的运动项目,经过30多年在我国的恢复和发展,已有了广泛的群众基础,为了促进健美竞技水平的进一步提高,通过对我国竞技健美裁判员的现状分析,增进了对我国健美运动的全面了解,以期促使我国竞技健美裁判员水平的提高,促进竞技健美裁判员队伍更好地发展壮大,进一步普及健美运动,整体提高我国健美运动水平。     

冬奥会竞技实力的格局分析--以GLM分析为例

采用文献资料法、数理统计法、逻辑分析法,以前人涉足较少的冬奥会15个冬季项目为主要研究方向,对第18~23届冬奥会各个国家所获奖牌的数量、项目和奖牌积分进行分析,梳理强国排名,并对影响原因进行探究。研究表明:源生地、地形地势气候、国家政策、体育引导方式以及竞技迎战技巧对国家的冰雪综合实力均有影响。建议:加强立法为冰雪运动普及推广奠定坚实的基础;积极构建"金字塔"式的人才输送体系;建立实施新生运动力量的"新苗运动"计划;落实确立技术发展以先进高端的科研为主导,推进创建世界共赢的竞技发展基地等。旨在对我国冰雪事业的发展和备战2022北京冬奥提供思路。     

现代排球运动发展趋势浅析

现代排球运动竞争激烈 ,技、战术变化多样 ,形成了排球运动新的格局和发展趋势。对排球运动发展趋势的研究 ,是适应科技发展及排球运动自身的需要 ,对提高现代排球的技、战术水平有着深远的意义。根据最新的世界排球动态 ,结合深入的调查研究 ,对现代排球运动的发展趋势作以分析概述。     

关于散打对抗意识定量评定方法的研究

本研究探索出一种能客观地评定运动员对抗意识的方法 ,对改变教练员在训练中单凭经验、直观感觉和传统的训练方法与控制对抗意识训练过程有促进作用。     

城市休闲体育发展的SWOT分析与策略研究

为了推进休闲体育的发展,使全民健身计划得以全面实施。文章从休闲及休闲体育的内涵出发,进一步阐述休闲体育的发展现状及存在问题,最后提出相应的优化措施。