Match-related fatigue reduces physical and technical performance during elite rugby league match-play: a case study

Purpose:To describe the physical and technical demands of rugby league 9s (RL9s) match play for positional groups.Methods:Global positioning system data were collected during 4 games from 16 players from a team competing in the Auckland RL9s tournament. Players were classified into positional groups (pivots, outside backs, and forwards). Absolute and relative physical-performance data were classified as total high-speed running (HSR; >14.4 km/h), very-high-speed running (VHSR; >19.0 km/h), and sprint (>23.0 km/h) distances. Technical-performance data were obtained from a commercial statistics provider. Activity cycles were coded by an experienced video analyst.Results:Forwards (1088 m, 264 m) most likely completed less overall and high-speed distances than pivots (1529 m, 371 m) and outside backs (1328 m, 312 m). The number of sprint efforts likely varied between positions, although differences in accelerations were unclear. There were no clear differences in relative total (115.6−121.3 m/min) and HSR (27.8−29.8 m/min) intensities, but forwards likely performed less VHSR (7.7 m/min) and sprint distance (1.3 m/min) per minute than other positions (10.2−11.8 m/min, 3.7−4.8 m/min). The average activity and recovery cycle lengths were ~50 and ~27 s, respectively. The average longest activity cycle was ~133 s, while the average minimum recovery time was ~5 s. Technical involvements including tackles missed, runs, tackles received, total collisions, errors, off-loads, line breaks, and involvements differed between positions.Conclusions:Positional differences exist for both physical and technical measures, and preparation for RL9s play should incorporate these differences.

Download Full-text

Influence of Contextual Factors, Technical Performance, and Movement Demands on the Subjective Task Load Associated With Professional Rugby League Match-Play

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2019-0998 ◽

2020 ◽

pp. 1-9

Author(s):

Thomas Mullen ◽

Craig Twist ◽

Matthew Daniels ◽

Nicholas Dobbin ◽

Jamie Highton

Keyword(s):

Contextual Factors ◽

Rugby League ◽

Match Play ◽

Final Model ◽

Task Load ◽

Technical Performance ◽

Mental Demand ◽

Technical Errors ◽

Perception Of Effort ◽

Data Points

Purpose: To identify the association between several contextual match factors, technical performance, and external movement demands on the subjective task load of elite rugby league players. Methods: Individual subjective task load, quantified using the National Aeronautics and Space Administration Task Load Index (NASA-TLX), was collected from 29 professional rugby league players from one club competing in the European Super League throughout the 2017 season. The sample consisted of 26 matches (441 individual data points). Linear mixed modeling revealed that various combinations of contextual factors, technical performance, and movement demands were associated with subjective task load. Results: Greater number of tackles (effect size correlation ± 90% confidence intervals; η2 = .18 ± .11), errors (η2 = .15 ± .08), decelerations (η2 = .12 ± .08), increased sprint distance (η2 = .13 ± .08), losing matches (η2 = .36 ± .08), and increased perception of effort (η2 = .27 ± .08) led to most likely–very likely increases in subjective total task load. The independent variables included in the final model for subjective mental demand (match outcome, time played, and number of accelerations) were unclear, excluding a likely small correlation with technical errors (η2 = .10 ± .08). Conclusions: These data provide a greater understanding of the subjective task load and their association with several contextual factors, technical performance, and external movement demands during rugby league competition. Practitioners could use this detailed quantification of internal loads to inform recovery sessions and current training practices.

Download Full-text

Influence of Physical Characteristics and Match Outcome on Technical Errors During Rugby League Match Play

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2018-0354 ◽

2019 ◽

Vol 14 (8) ◽

pp. 1043-1049

Author(s):

Rich D. Johnston

Keyword(s):

Bayes Factor ◽

Rugby League ◽

Physical Characteristics ◽

Lower Body ◽

Match Play ◽

Technical Performance ◽

Technical Errors ◽

Body Strength ◽

Lower Body Strength ◽

The Relationship

Purpose: To explore the relationship between technical errors during rugby league games, match success, and physical characteristics. Methods: A total of 27 semiprofessional rugby league players participated in this study (24.8 [2.5] y, 183.5 [5.3] cm, 97.1 [11.6] kg). Aerobic fitness, strength, and power were assessed prior to the start of the competitive season before technical performance was tracked during 22 competitive fixtures. Attacking errors were determined as any error that occurred in possession of the ball that resulted in a handover to the opposition. Defensive errors included line breaks, penalties, and missed or ineffective tackles. Match outcome, the zone on the field in which each error occurred, and the number of errors in an error chain (≤60 s between errors) were assessed. Results: During a loss, there were more defensive errors in the 0- to 40-m zone than when a match was won (effect size = 0.99 [0.04–1.94]). Error chains were a predictor of conceding a try (P = .0001, r2 = .22), with the odds ratio increasing to 2.33 when there were 7 errors per chain. High lower-body strength was associated with fewer defensive errors for backs (Bayes factor = 3.67) and forwards (Bayes factor = 19.31); relative bench press was also important for backs (Bayes factor = 3.21). Conclusions: Fewer defensive errors occur in the 0- to 40-m zone during winning matches; lower-body strength is strongly associated with fewer defensive errors in rugby league players.

Download Full-text

Does Caffeine Consumption Influence Postcompetition Sleep in Professional Rugby League Athletes? A Case Study

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2020-0841 ◽

2021 ◽

pp. 1-4

Author(s):

Johnpaul Caia ◽

Shona L. Halson ◽

Patrick M. Holmberg ◽

Vincent G. Kelly

Keyword(s):

Sleep Duration ◽

Pearson Correlation ◽

Rugby League ◽

Caffeine Intake ◽

Caffeine Consumption ◽

Caffeine Concentration ◽

Previous Night ◽

Activity Monitors ◽

The Relationship

Purpose: To examine the sleep of rugby league athletes the night before and following an evening match and to investigate the association between caffeine intake and sleep on the night of competition. Methods: On the night prior to, night of, and night after a professional rugby league match, 15 athletes had their sleep monitored using wrist activity monitors. Additionally, saliva samples were collected 60 minutes before and 30 minutes after the competition to assess salivary caffeine concentration. Differences in sleep across the 3 nights were examined using linear mixed models, and changes were assessed using effect size (ES). Pearson correlation (r) assessed the relationship between salivary caffeine levels and sleep indices. Results: On the night of competition, athletes went to bed later than the night before (P = .00002, ES = 1.84) and night after (P = .0003, ES = 1.49) competition. Consequently, their sleep duration was reduced on the night of competition compared with the previous night (P < .0000003, ES = 2.36) and night after competition (P = .001, ES = 1.53). Postcompetition salivary caffeine concentration was substantially elevated in athletes when compared with precompetition measures (P < .00000001, ES = 4.44), and moderate, nonsignificant correlations were observed between changes in salivary caffeine concentration and delayed bedtime (r = .48, P = .07), increased sleep latency (r = .45, P = .09), decreased sleep duration (r = −.30, P = .28), and reduced sleep efficiency (r = −.34, P = .22). Conclusions: These results demonstrate that evening competition results in sleep disturbance in rugby league athletes, and caffeine supplementation prior to and during competition leads to substantial increases in postcompetition salivary caffeine concentration.

Download Full-text

STUDY ON THE INFLUENCE OF WELDER’S FATIGUE ON THE QUALITY OF WELD LINES

Journal of Engineering Studies and Research ◽

10.29081/jesr.v26i3.212 ◽

2020 ◽

Vol 26 (3) ◽

pp. 107-111

Author(s):

DIANA LUNGU ◽

ALEXANDRU ACSINTE ◽

CAROL SCHNAKOVSZKY ◽

EUGEN HERGHELEGIU ◽

CRINA RADU

Keyword(s):

Weld Line ◽

Visual Quality ◽

Technical Performance ◽

Medium Level

In this paper a case study is presented, based on certain exercises applied to different welders, to evaluate the influence of welder’s fatigue on the quality of welding. The performed test was aimed at evaluating the technical performance (the welding act) of subjects, as well as the accuracy of weld lines. Five modules of exercises were applied. The exercises of each module were various, they were of medium level, so that they were neither overburdened, nor unsolicited, because both situations could lead to accidents due to fatigue. A weld line was performed after each exercises’ module. The visual quality of welding was appreciated according to the EN ISO 17637:2011 standard.

Download Full-text

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

Journal of Sports Sciences ◽

10.1080/02640414.2020.1754726 ◽

2020 ◽

Vol 38 (14) ◽

pp. 1682-1689 ◽

Cited By ~ 1

Author(s):

Michael J. Rennie ◽

Stephen J. Kelly ◽

Stephen Bush ◽

Robert W. Spurrs ◽

Damien J. Austin ◽

...

Keyword(s):

Match Play ◽

Technical Performance ◽

Australian Football

Download Full-text

Evidence of Concussion Signs in National Rugby League Match Play: a Video Review and Validation Study

Sports Medicine - Open ◽

10.1186/s40798-017-0097-9 ◽

2017 ◽

Vol 3 (1) ◽

Cited By ~ 27

Author(s):

Andrew J. Gardner ◽

David R. Howell ◽

Christopher R. Levi ◽

Grant L. Iverson

Keyword(s):

Validation Study ◽

Rugby League ◽

Match Play ◽

Video Review

Download Full-text

Optimized Design of Modular Multilevel DC De-Icer for High Voltage Transmission Lines

Electronics ◽

10.3390/electronics7090204 ◽

2018 ◽

Vol 7 (9) ◽

pp. 204 ◽

Cited By ~ 4

Author(s):

Jiazheng Lu ◽

Qingjun Huang ◽

Xinguo Mao ◽

Yanjun Tan ◽

Siguo Zhu ◽

...

Keyword(s):

Transmission Lines ◽

Engineering Application ◽

Optimized Design ◽

Multilevel Converter ◽

Power Outage ◽

Total Cost ◽

Technical Performance ◽

Promising Solution

Ice covering on overhead transmission lines would cause damage to transmission system and long-term power outage. Among various de-icing devices, a modular multilevel converter based direct-current (DC)de-icer (MMC-DDI) is recognized as a promising solution due to its excellent technical performance. Its principle feasibility has been well studied, but only a small amount of literature discusses its economy or hardware optimization. To fill this gap, this paper presents a quantitative analysis and calculation on the converter characteristics of MMC-DDI. It reveals that, for a given DC de-icing requirement, the converter rating varies greatly with its alternating-current (AC) -side voltage, and it sometimes far exceeds the melting power. To reduce converter rating and improve its economy, an optimized configuration is proposed in which a proper transformer should be configured on the input AC-side of converter under certain conditions. This configuration is verified in an MMC-DDI for a 500 kV transmission line as a case study. The result shows, in the case of outputting the same de-icing characteristics, the optimized converter is reduced from 151 MVA to 68 MVA, and the total cost of the MMC-DDI system is reduced by 48%. This conclusion is conducive to the design optimization of multilevel DC de-icer and then to its engineering application.

Download Full-text

Influence of Contextual Variables on Physical and Technical Performance in Male Amateur Basketball: A Case Study

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17041193 ◽

2020 ◽

Vol 17 (4) ◽

pp. 1193 ◽

Cited By ~ 4

Author(s):

Antonio Fernández-Leo ◽

Carlos D. Gómez-Carmona ◽

Javier García-Rubio ◽

Sergio J. Ibáñez

Keyword(s):

Basketball Players ◽

Internal Load ◽

Technical Performance ◽

Situational Variables ◽

Notational Analysis ◽

Planning Strategies ◽

Post Hoc ◽

Competitive Actions ◽

Final Round

Currently, most basketball research is focused on professional and elite players. Studies at the amateur level are important to explain the physical and technical demands of competition and thus improve players’ and teams’ performance. The purpose of the present study was to describe the competitive demands of an amateur-level basketball team and to analyze the influence of different situational variables on the physical and technical performance indicators. Eleven amateur senior basketball players participated in six official final-round games during the 2018/2019 season. External, internal load, and notational analysis were registered by inertial devices, heart rate bands, and video analysis. The Kruskal-Wallis H-test was applied for comparisons based on playing positions, periods, and final quarter game outcome, with the post hoc comparison accomplished by a Mann-Whitney U test. The Spearman correlation coefficient was realized for the relational analysis. The results showed that: (a) guards covered more volume of displacements (effective on-court time: p < 0.01, E R 2 = 0.05; steps/min: p < 0.01, E R 2 = 0.28) and the centers performed competitive actions of higher load ([>8G] Imp/min: p < 0.01, E R 2 = 0.20; jumps/min: p < 0.01, E R 2 = 0.33); (b) a performance decreasing was found between the first and second half of the game; (c) in balanced matches there was the most individual technical performance (PIR/min: p < 0.98, E R 2 = 0.01), while in the unbalanced games more high-intensity impacts were seen ([>8G] Imp/min: p < 0.01, E R 2 = 0.07). The situational variables analyzed had an influence on athletic performance in amateur senior basketball players and should be considered for designing training sessions and planning strategies during official matches.

Download Full-text