scholarly journals PlayerLoad Variables: Sensitive to Changes in Direction and Not Related to Collision Workloads in Rugby League Match Play

2018 ◽  
Vol 13 (9) ◽  
pp. 1136-1142 ◽  
Author(s):  
Billy T. Hulin ◽  
Tim J. Gabbett ◽  
Rich D. Johnston ◽  
David G. Jenkins
Keyword(s):  
Team Sport ◽  
Rugby League ◽  
Crossover Design ◽  
Match Play ◽  
Change Of Direction ◽  
Total Distance ◽  
Straight Line ◽  
The Difference ◽  
Pearson Correlations ◽  
Vector Magnitude

Purpose: To determine (1) how change-of-direction (COD) workloads influence PlayerLoad (PL) variables when controlling total distance covered and (2) relationships among collision workloads and PL variables during rugby league match play. Methods: Participants completed 3 protocols (crossover design) consisting of 10 repetitions of a 60-m effort in 15 s. The difference between protocols was the COD demands required to complete 1 repetition: no COD (straight line), 1° × 180° COD, or 3° × 180° COD. During rugby league matches, relationships among collision workloads, triaxial vector-magnitude PlayerLoad (PLVM), anteroposterior + mediolateral PL (PL2D), and PLVM accumulated at locomotor velocities below 2 m·s−1 (ie, PLSLOW) were examined using Pearson correlations (r) with coefficients of determination (R2). Results: Comparing 3° × 180° COD to straight-line drills, PLVM·min−1 (d = 1.50 ± 0.49, large, likelihood = 100%, almost certainly), PL2D·min−1 (d = 1.38 ± 0.53, large, likelihood = 100%, almost certainly), and PLSLOW·min−1 (d = 1.69 ± 0.40, large, likelihood = 100%, almost certainly) were greater. Collisions per minute demonstrated a distinct (ie, R2 < .50) relationship from PLVM·min−1 (R2 = .30, r = .55) and PL2D·min−1 (R2 = .37, r = .61). Total distance per minute demonstrated a very large relationship with PLVM·min−1 (R2 = .62, r = .79) and PL2D·min−1 (R2 = .57, r = .76). Conclusions: PL variables demonstrate (1) large increases as COD demands intensify, (2) separate relationships from collision workloads, and (3) moderate to very large relationships with total distance during match play. PL variables should be used with caution to measure collision workloads in team sport.

scholarly journals Officiating Role Influences the Physical Match Activity Profiles of Rugby League Touch Judges and Referees

2017 ◽  
Vol 58 (1) ◽  
pp. 225-231 ◽  
Author(s):  
Leesa Pearce ◽  
Carl Woods ◽  
Wade Sinclair ◽  
Anthony Leicht
Keyword(s):  
Performance Indicators ◽  
Maximum Velocity ◽  
Rugby League ◽  
Relative Distance ◽  
Walking Distance ◽  
Match Play ◽  
Total Distance ◽  
Main Effect ◽  
Univariate Analyses

Abstract This study investigated the effect of the officiating role on physical activity profiles of rugby league match officials during match-play. Physical performance indicators were collated from 23 match officials, resulting in 78 observations. Match officials were categorised into two groups: referees and touch judges. Microtechnology facilitated the quantification of total distance (m), relative distance (m⋅min-1), maximum velocity (m⋅s-1), the percentage of high intensity running distance (% total > 3.01 m⋅s-1), walking distance (<1 m⋅s-1), jogging distance (1.01 – 3 m⋅s-1), fast jogging distance (3.01 - 5 m⋅s-1), and sprinting distance (>5 m⋅s-1). Multivariate analysis modelled the main effect of the officiating role with follow up univariate analyses identifying significant differences. A significant effect was noted (V = 750; F(8, 66) = 24.71; p < 0.05) with referees covering a greater total distance (7767 ± 585 vs. 7022 ± 759 m), relative distance (90 ± 6 vs. 82 ± 8 m⋅min-1), jogging distance (3772 ± 752 vs. 3110 ± 553 m), and fast jogging distance (2565 ± 631 vs. 1816 ± 440 m) compared to touch judges. Touch judges covered greater distances while sprinting (1012 ± 385 vs. 654 ± 241 m). Results provide important guidance in the development of training programs for match officials.

Straight-Line and Change-of-Direction Intermittent Running in Professional Soccer Players

2018 ◽  
Vol 13 (5) ◽  
pp. 562-567 ◽  
Author(s):  
Mohamed S. Fessi ◽  
Fayçal Farhat ◽  
Alexandre Dellal ◽  
James J. Malone ◽  
Wassim Moalla
Keyword(s):  
Heart Rate ◽  
Test Performance ◽  
T Test ◽  
Rating Of Perceived Exertion ◽  
Soccer Players ◽  
Peak Heart Rate ◽  
Change Of Direction ◽  
Professional Soccer ◽  
Straight Line ◽  
The Difference

Purpose: To investigate the difference between straight-line (STL) and change-of-direction (COD) intermittent-running exercises in soccer players. Methods: Seventeen male professional soccer players performed the agility T test and 6 intermittent-running exercises: 10 s at 130% of maximal aerobic speed (MAS) alternated with 10 s of rest (10-10), 15 s at 120% of MAS alternated with 15 s of rest (15-15), and 30 s at 110% of MAS alternated with 30 s of rest (30-30) both in STL and with COD. All exercises were monitored using a global positioning system. Heart rate was measured during exercises, and rating of perceived exertion (RPE) was collected postexercise. The difference (Δ) between covered distance in STL and COD exercises at a similar load was calculated, and relationships between T test and Δ distance were analyzed. Results: COD intermittent exercises showed a significantly decreased distance covered and an increase in the number of accelerations, peak heart rate, and RPE compared with STL intermittent exercises at a similar load. High relationships were observed between T-test performance and Δ distance in 10-10 (r = .72, P < .01) and 15-15 (r = .77, P < .01), whereas no significant relationships were observed between T-test performance and Δ distance in 30-30 (r = −.37, P = .2). Conclusion: Intermittent COD exercises were associated with higher acceleration, peak heart rate, and RPE than STL during 10-10 and 15-15 exercises. The ability to rapidly change direction is crucial to perform intense sport-specific running in professional soccer players.

Metabolic Power Demands of Rugby League Match Play

2015 ◽  
Vol 10 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Tom Kempton ◽  
Anita Claire Sirotic ◽  
Ermanno Rampinini ◽  
Aaron James Coutts
Keyword(s):  
High Power ◽  
High Speed ◽  
Power Distance ◽  
Rugby League ◽  
Metabolic Power ◽  
Match Play ◽  
Global Positioning ◽  
High Power Distance ◽  
The Difference ◽  
Gps Devices

Purpose:To describe the metabolic demands of rugby league match play for positional groups and compare match distances obtained from high-speed-running classifications with those derived from high metabolic power.Methods:Global positioning system (GPS) data were collected from 25 players from a team competing in the National Rugby League competition over 39 matches. Players were classified into positional groups (adjustables, outside backs, hit-up forwards, and wide-running forwards). The GPS devices provided instantaneous raw velocity data at 5 Hz, which were exported to a customized spreadsheet. The spreadsheet provided calculations for speed-based distances (eg, total distance; high-speed running, >14.4 km/h; and very-highspeed running, >18.1 km/h) and metabolic-power variables (eg, energy expenditure; average metabolic power; and high-power distance, >20 W/kg).Results:The data show that speed-based distances and metabolic power varied between positional groups, although this was largely related to differences in time spent on field. The distance covered at high running speed was lower than that obtained from high-power thresholds for all positional groups; however, the difference between the 2 methods was greatest for hit-up forwards and adjustables.Conclusions:Positional differences existed for all metabolic parameters, although these are at least partially related to time spent on the field. Higher-speed running may underestimate the demands of match play when compared with high-power distance—although the degree of difference between the measures varied by position. The analysis of metabolic power may complement traditional speed-based classifications and improve our understanding of the demands of rugby league match play.

Physical Demands of Match Play in Successful and Less-Successful Elite Rugby League Teams

2015 ◽  
Vol 10 (6) ◽  
pp. 703-710 ◽  
Author(s):  
Billy T. Hulin ◽  
Tim J. Gabbett ◽  
Simon Kearney ◽  
Alex Corvo
Keyword(s):  
High Intensity ◽  
Rugby League ◽  
Success Rates ◽  
Peak Period ◽  
Match Play ◽  
Total Distance ◽  
Success Group ◽  
Competitive Success ◽  
The Mean ◽  
Rate Of Success

Purpose: To quantify activity profiles in approximately 5-min periods to determine if the intensity of rugby league match play changes after the most intense period of play and to determine if the intensity of activity during predefined periods of match play differ between successful and less-successful teams playing at an elite standard. Methods: Movement was recorded using a MinimaxX global positioning system (GPS) unit sampling at 10 Hz during 25 rugby league matches, equating to 200 GPS files. Data for each half of match play were separated into 8 equal periods. These periods represented the most intense phase of match play (peak period), the period after the most intense phase of match play (subsequent period), and the average demands of all other periods in a match (mean period). Two rugby league teams were split into a high-success and a low-success group based on their success rates throughout their season. Results: Compared with their less-successful counterparts, adjustables and hit-up forwards from the high-success team covered less total distance (P < .01) and less high-intensity-running distance (P < .01) and were involved in a greater number of collisions (P < .01) during the mean period of match play. Conclusions: Although a greater number of collisions during match play is linked with a greater rate of success, greater amounts of high-intensity running and total distance are not related to competitive success in elite rugby league. These results suggest that technical and tactical differences, rather than activity profiles, may be the distinguishing factor between successful and less-successful rugby league teams.

scholarly journals Variability of GPS Units for Measuring Distance in Team Sport Movements

2010 ◽  
Vol 5 (4) ◽  
pp. 565-569 ◽  
Author(s):  
Denise Jennings ◽  
Stuart Cormack ◽  
Aaron J. Coutts ◽  
Luke J. Boyd ◽  
Robert J. Aughey
Keyword(s):  
Measurement Error ◽  
Team Sports ◽  
Team Sport ◽  
Exercise Session ◽  
Match Trial ◽  
Percentage Difference ◽  
Straight Line ◽  
Reduce Measurement Error ◽  
Australian Football ◽  
The Difference

Purpose:To examine the difference in distance measured by two global positioning system (GPS) units of the same model worn by the same player while performing movements common to team sports.Methods:Twenty elite Australian football players completed two trials of the straight line movement (10, 20, 40 m) at four speeds (walk, jog, stride, sprint), two trials of the changes of direction (COD) courses of two different frequencies (gradual and tight), and five trials of a team sport running simulation circuit. To assess inter-unit variability for total and high intensity running (HIR) distance measured in matches, data from eight field players were collected in three Australian Hockey League (AHL) matches during the 2009 season. Each subject wore two GPS devices (MinimaxX v2.5, Catapult, Australia) that collected position data at 5 Hz for each movement and match trial. The percentage difference ±90% confidence interval (CI) was used to determine differences between units.Results:Differences (±90% CI) between the units ranged from 9.9 ± 4.7% to 11.9 ± 19.5% for straight line running movements and from 9.5 ± 7.2% to 10.7 ± 7.9% in the COD courses. Similar results were exhibited in the team sport circuit (11.1 ± 4.2%). Total distance (10.3 ± 6.2%) and HIR distance (10.3 ± 15.6) measured during the match play displayed similar variability.Conclusion:It is recommended that players wear the same GPS unit for each exercise session to reduce measurement error. The level of between-unit measurement error should be considered when comparing results from players wearing different GPS units.

scholarly journals The Validity and Reliability of GPS Units for Measuring Distance in Team Sport Specific Running Patterns

2010 ◽  
Vol 5 (3) ◽  
pp. 328-341 ◽  
Author(s):  
Denise Jennings ◽  
Stuart Cormack ◽  
Aaron J. Coutts ◽  
Luke Boyd ◽  
Robert J. Aughey
Keyword(s):  
High Speed ◽  
Sampling Rate ◽  
Team Sports ◽  
Team Sport ◽  
Validity And Reliability ◽  
Change Of Direction ◽  
Straight Line ◽  
Australian Football ◽  
Measured Distance ◽  
Gps Devices

Purpose:To assess the validity and reliability of distance data measured by global positioning system (GPS) units sampling at 1 and 5 Hz during movement patterns common to team sports.Methods:Twenty elite Australian Football players each wearing two GPS devices (MinimaxX, Catapult, Australia) completed straight line movements (10, 20, 40 m) at various speeds (walk, jog, stride, sprint), changes of direction (COD) courses of two different frequencies (gradual and tight), and a team sport running simulation circuit. Position and speed data were collected by the GPS devices at 1 and 5 Hz. Distance validity was assessed using the standard error of the estimate (±90% confidence intervals [CI]). Reliability was estimated using typical error (TE) ± 90% CI (expressed as coefficient of variation [CV]).Results:Measurement accuracy decreased as speed of locomotion increased in both straight line and the COD courses. Difference between criterion and GPS measured distance ranged from 9.0% to 32.4%. A higher sampling rate improved validity regardless of distance and locomotion in the straight line, COD and simulated running circuit trials. The reliability improved as distance traveled increased but decreased as speed increased. Total distance over the simulated running circuit exhibited the lowest variation (CV 3.6%) while sprinting over 10 m demonstrated the highest (CV 77.2% at 1 Hz).Conclusion:Current GPS systems maybe limited for assessment of short, high speed straight line running and efforts involving change of direction. An increased sample rate improves validity and reliability of GPS devices.

Automatic Tread Gaging Machine

1979 ◽  
Vol 7 (1) ◽  
pp. 31-39
Author(s):  
G. S. Ludwig ◽  
F. C. Brenner
Keyword(s):  
Experimental Tests ◽  
Automatic Machine ◽  
Wear Rates ◽  
Handling Device ◽  
Straight Line ◽  
Component Systems ◽  
Before And After ◽  
Good Repeatability ◽  
The Difference ◽  
Straight Lines

Abstract An automatic tread gaging machine has been developed. It consists of three component systems: (1) a laser gaging head, (2) a tire handling device, and (3) a computer that controls the movement of the tire handling machine, processes the data, and computes the least-squares straight line from which a wear rate may be estimated. Experimental tests show that the machine has good repeatability. In comparisons with measurements obtained by a hand gage, the automatic machine gives smaller average groove depths. The difference before and after a period of wear for both methods of measurement are the same. Wear rates estimated from the slopes of straight lines fitted to both sets of data are not significantly different.

scholarly journals Comparison of Energy Expenditure Observed between Scheduled Activities in Collegiate Team-Sport Female Athletes

Sports ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 50
Author(s):  
Jessica M. Moon ◽  
Hannah A. Zabriskie ◽  
Patrick S. Harty ◽  
Bradley S. Currier ◽  
Julia C. Blumkaitis ◽  
...  
Keyword(s):  
Energy Expenditure ◽  
Female Athletes ◽  
Team Sport ◽  
Activity Level ◽  
Ncaa Division Ii ◽  
Activity Monitors ◽  
Energy Needs ◽  
The Difference ◽  
Academic Year ◽  
Activity Energy

Energy needs of female team-sport athletes are poorly understood with no evidence highlighting differences present between scheduled activities. The purpose of this study was to examine the difference in energy expenditure between NCAA Division II female basketball (BBALL) and lacrosse (LAX) athletes during different scheduled team activities. Female BBALL (n = 13; 19.8 ± 1.3 yrs; 173.9 ± 13.6 cm; 74.6 ± 9.1kg; 27.1 ± 3.2%fat) and LAX (n = 20; 20.4 ± 1.8yrs; 168.4 ± 6.6cm; 68.8 ± 8.9kg; 27.9 ± 3.1%fat) athletes were outfitted with heart rate and activity monitors during four consecutive days on five different occasions (20 days total) across an entire academic year to assess differences in total daily activity energy expenditure (TDEE), activity energy expenditure (AEE), and physical activity level (PAL). Data were categorized by type of scheduled daily activities: Practice, Game, Conditioning, or Off. Independent of day type, TDEE, AEE, and PAL levels were greater (p < 0.05) in BBALL athletes. For each sport, TDEE, AEE, and PAL were significantly different (p < 0.05) between classified activity days. BBALL and LAX athletes experienced higher values on game days for TDEE, AEE, and PAL, with the lowest values experienced on off days. In conclusion, calculated levels of TDEE, AEE, and PAL in female collegiate BBALL and LAX athletes were determined to be different, irrespective of the scheduled activity.

scholarly journals XXIII.—On the Disruptive Discharge of Electricity: An Experimental Thesis for the Degree of Doctor of Science, Department A

1878 ◽  
Vol 28 (2) ◽  
pp. 633-671 ◽  
Author(s):  
Alexander Macfarlane
Keyword(s):  
Copper Wire ◽  
Late Summer ◽  
The Other ◽  
Straight Line ◽  
Summer Session ◽  
The Difference ◽  
A Chain ◽  
The One ◽  
Metallic Parts ◽  
The University

The experiments to which I shall refer were carried out in the physical laboratory of the University during the late summer session. I was ably assisted in conducting the experiments by three students of the laboratory,—Messrs H. A. Salvesen, G. M. Connor, and D. E. Stewart. The method which was used of measuring the difference of potential required to produce a disruptive discharge of electricity under given conditions, is that described in a paper communicated to the Royal Society of Edinburgh in 1876 in the names of Mr J. A. Paton, M. A., and myself, and was suggested to me by Professor Tait as a means of attacking the experimental problems mentioned below.The above sketch which I took of the apparatus in situ may facilitate tha description of the method. The receiver of an air-pump, having a rod capable of being moved air-tight up and down through the neck, was attached to one of the conductors of a Holtz machine in such a manner that the conductor of the machine and the rod formed one conducting system. Projecting from the bottom of the receiver was a short metallic rod, forming one conductor with the metallic parts of the air-pump, and by means of a chain with the uninsulated conductor of the Holtz machine. Brass balls and discs of various sizes were made to order, capable of being screwed on to the ends of the rods. On the table, and at a distance of about six feet from the receiver, was a stand supporting two insulated brass balls, the one fixed, the other having one degree of freedom, viz., of moving in a straight line in the plane of the table. The fixed insulated ball A was made one conductor with the insulated conductor of the Holtz and the rod of the receiver, by means of a copper wire insulated with gutta percha, having one end stuck firmly into a hole in the collar of the receiver, and having the other fitted in between the glass stem and the hollow in the ball, by which it fitted on to the stem tightly. A thin wire similarly fitted in between the ball B and its insulating stem connected the ball with the insulated half ring of a divided ring reflecting electrometer.

Speed Improves With Eccentric Hamstring Training in Athletes of Different Maturity Status

2021 ◽  
pp. 1-9
Author(s):  
Raouf Hammami ◽  
Javier Gene-Morales ◽  
Ammar Nebigh ◽  
Haithem Rebai ◽  
Juan C. Colado
Keyword(s):  
Factor Analysis ◽  
Mixed Model ◽  
Intervention Group ◽  
Team Sport ◽  
Sprint Performance ◽  
Height Velocity ◽  
Control Groups ◽  
Change Of Direction ◽  
Almost All ◽  
Shuttle Run

Purpose: To investigate the effects of an eccentric hamstring strength training program (EHT) on sprint performance (10-, 20-, and 30-m sprint times) and change of direction speed (4 × 5-m shuttle run and T-Half test) in male European handball athletes at 2 maturity statuses (prepeak and postpeak height velocity [PHV]). Methods: Forty-five participants (12.68 [1.58] y) were divided into pre-PHV and post-PHV and randomly allocated to a control or intervention group, which performed a guided 2 day per week 6-week EHT of 5 exercises. A mixed-model (within- and between-factor) analysis of variance was conducted. Results: A significant effect (P < .05) of the interaction time × maturity × training was observed in the T-Half, 10, and 30 m tests. Both intervention groups significantly improved in all the tests, except in the 20 m sprint and the post-PHV in the 10 m sprint. Improvements ranged between 0.93% and 5.74% (effect size: 0.07–0.79). Both control groups yielded no improvements in almost all the tests. The improvements of both groups undergoing the intervention (pre-PHV and post-PHV) were not significantly different (only a tendency in the 10 m sprint). Conclusion: An EHT program combined with European-handball training improve change of direction and sprint performance in pre-PHV and post-PHV male players. Professionals training European handball and similar team-sport athletes should consider including EHT regardless of athlete’s maturity.

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