Movement Demands of Elite Under-20s and Senior International Rugby Union Players

This study compared the movement demands of elite international Under-20 age grade (U20s) and senior international rugby union players during competitive tournament match play. Forty elite professional players from an U20 and 27 elite professional senior players from international performance squads were monitored using 10Hz global positioning systems (GPS) during 15 (U20s) and 8 (senior) international tournament matches during the 2014 and 2015 seasons. Data on distances, velocities, accelerations, decelerations, high metabolic load (HML) distance and efforts, and number of sprints were derived. Data files from players who played over 60 min (n = 258) were separated firstly into Forwards and Backs, and more specifically into six positional groups; FR–Front Row (prop & hooker), SR–Second Row, BR–Back Row (Flankers & No.8), HB–Half Backs (scrum half & outside half), MF–Midfield (centres), B3 –Back Three (wings & full back) for match analysis. Linear mixed models revealed significant differences between U20 and senior teams in both the forwards and backs. In the forwards the seniors covered greater HML distance (736.4 ± 280.3 vs 701.3 ± 198.7m, p = 0.01) and severe decelerations (2.38 ± 2.2 vs 2.28 ± 1.65, p = 0.05) compared to the U20s, but performed less relative HSR (3.1 ± 1.6 vs 3.2 ± 1.5, p < 0.01), moderate (19.4 ± 10.5 vs 23.6 ± 10.5, p = 0.01) and high accelerations (2.2 ± 1.9 vs 4.3 ± 2.7, p < 0.01) and sprint•min^-1 (0.11 ± 0.06 vs 0.11 ± 0.05, p < 0.01). Senior backs covered a greater relative distance (73.3 ± 8.1 vs 69.1 ± 7.6 m•min^-1, p < 0.01), greater High Metabolic Load (HML) distance (1138.0 ± 233.5 vs 1060.4 ± 218.1m, p < 0.01), HML efforts (112.7 ± 22.2 vs 98.8 ± 21.7, p < 0.01) and heavy decelerations (9.9 ± 4.3 vs 9.5 ± 4.4, p = 0.04) than the U20s backs. However, the U20s backs performed more relative HSR (7.3 ± 2.1 vs 7.2 ± 2.1, p <0.01) and sprint•min^-1 (0.26 ± 0.07 vs 0.25 ± 0.07, p < 0.01). Further investigation highlighted differences between the 6 positional groups of the teams. The positional groups that differed the most on the variables measured were the FR and MF groups, with the U20s FR having higher outputs on HSR, moderate & high accelerations, moderate, high & severe decelerations, HML distance, HML efforts, and sprints•min^-1. For the MF group the senior players produced greater values for relative distance covered, HSR, moderate decelerations, HML distance and sprint•min^-1. The BR position group was most similar with the only differences seen on heavy accelerations (U20s higher) and moderate decelerations (seniors higher). Findings demonstrate that U20s internationals appear to be an adequate ‘stepping stone’ for preparing players for movement characteristics found senior International rugby, however, the current study highlight for the first time that certain positional groups may require more time to be able to match the movement demands required at a higher playing level than others. Conditioning staff must also bear in mind that the U20s players whilst maintaining or improving match movement capabilities may require to gain substantial mass in some positions to match their senior counterparts.     

Monitoring external load in elite male handball players depending on playing positions

Monitoring workload is critical for elite training and competition, as well as preventing potential sports injuries. The assessment of external load in team sports has been provided with new technologies that help coaches to individualize training and optimize their team’s playing system. In this study we characterized the physical demands of an elite handball team during an entire sports season. Novel data are reported for each playing position of this highly strenuous body-contact team sport. Sixteen world top players (5 wings, 2 centre backs, 6 backs, 3 line players) were equipped with a local positioning system (WIMU PRO) during fourteen official Spanish first league matches. Playing time, total distance covered at different running speeds, and acceleration variables were monitored. During a handball match, wings cover the greater distance by high-speed running (> 5.0 m·s^-1): 410.3 ± 193.2 m, and by sprint (> 6.7 m·s^-1): 98.0 ± 75.4 m. Centre backs perform the following playing position that supports the highest speed intensities during the matches: high-speed running: 243.2 ± 130.2 m; sprint: 62.0 ± 54.2 m. Centre backs also register the largest number of high-intensity decelerations (n = 142.7 ± 59.5) compared to wings (n = 112.9 ± 56.0), backs (n = 105.2 ± 49.2) and line players: 99.6 ± 28.9). This study provides helpful information for professional coaches and their technical staff to optimize training load and individualize the physical demands of their elite male handball players depending on each playing position.     

Comparison of the most demanding scenarios during different in-season training sessions and official matches in professional basketball players

The purpose of this study was to compare physical demands during the most demanding scenarios (MDS) of different training sessions and official matches in professional basketball players across playing positions. Thirteen professional basketball players were monitored over a 9-week competitive season using a local positioning system. Peak physical demands included total distance, distance covered at > 18 km·h^-1, distance and number of accelerations (≥ 2 m∙s^-2) and decelerations (≤ -2 m∙s^-2) over a 60-second epoch. Analysis of variance for repeated measures, Bonferroni post-hoc tests and standardised Cohen’s effect size (ES) were calculated. Overall, almost all physical demands during the MDS of training were lower (-6.2% to -35.4%) compared to official matches. The only variable that surpassed competition demands was distance covered at > 18 km·h^-1, which presented moderate (ES = 0.61, p = 0.01) and small (ES = 0.48, p > 0.05) increases during training sessions four and three days before a competition, respectively. Conversely, the two previous practices before match day presented trivial to very large decreases (ES = 0.09–2.66) in all physical demands. Furthermore, centres achieved the lowest peak value in total distance covered during matches, forwards completed the greatest peak distance at > 18 km·h^-1, and guards performed the greatest distance and number of high-intensity accelerations and decelerations. In conclusion, physical demands during the MDS of different training sessions across the microcycle failed to match or surpass peak values during official matches, which should be considered when prescribing a training process intended to optimise the MDS of match play.     

Performance analysis of elite Rugby League match play using global positioning systems

The aim of this study was (a) to examine the physiological demands of competitive Rugby League match play using portable Global Positioning Systems (GPSs) to monitor players' movement patterns and heart rate (HR) and (b) examine positional comparisons to determine if players' physiological requirements are influenced by their playing position during Rugby League match play. Twenty-two elite male Rugby League players were monitored during 5 regular season competition matches using portable GPS software. There was no difference in the total distance traveled between backs (5,573 ± 1,128 m) and forwards (4,982 ± 1,185 m) during match play. Backs and forwards had an average HR of approximately 80% of their maximum (162 ± 11 and 165 ± 12 b · min(-1), respectively) throughout each match. Backs achieved greater maximum running speed (8.6 ± 0.7 m · s(-1)), completed a greater number of sprints (18 ± 6), had less time between sprints (3.2 ± 1.1 minutes), achieved a greater total duration of sprinting (44.7 ± 9.1 seconds), and covered more distance sprinting (321 ± 74 m) than forwards did (6.8 ± 0.7 m · s(-1), 11 ± 5, 5.2 ± 2.2 minutes, 25.8 ± 9.2 seconds, and 153 ± 38 m, respectively). The GPS successfully provided real-time feedback to identify significant positional differences in distances covered, running speed characteristics, and the physiological demands of competitive Rugby League match play.     

Predicting ratings of perceived exertion in youth soccer using decision tree models

The purpose of this study was to determine the effectiveness of white-box decision tree models (DTM) for predicting the rating of perceived exertion (RPE). The second aim was to examine the relationship between RPE and external measures of intensity in youth soccer training at the group and individual level. Training load data from 18 youth soccer players were collected during an in-season competition period. A total of 804 training observations were undertaken, with a total of 43 ± 17 sessions per player (range 12–76). External measures of intensity were determined using a 10 Hz GPS and included total distance (TD, m/min), high-speed running distance (HSR, m/min), PlayerLoad (PL, n/min), impacts (n/min), distance in acceleration/deceleration (TD ACC/TD DEC, m/min) and the number of accelerations/decelerations (ACC/DEC, n/min). Data were analysed with decision tree models. Global and individualized models were constructed. Aggregated importance revealed HSR as the strongest predictor of RPE with relative importance of 0.61. HSR was the most important factor in predicting RPE for half of the players. The prediction error (root mean square error [RMSE] 0.755 ± 0.014) for the individualized models was lower compared to the population model (RMSE 1.621 ± 0.001). The findings demonstrate that individual models should be used for the assessment of players’ response to external load. Furthermore, the study demonstrates that DTM provide straightforward interpretation, with the possibility of visualization. This method can be used to prescribe daily training loads on the basis of predicted, desired player responses (exertion).     

Training sessions with tackles impair upper-limb neuromuscular function in elite rugby union

The aim of this study was to investigate the response to non-tackle and tackle field-based training on upper- and lower-limb neuromuscular function in elite rugby union players. Nine elite senior elite rugby union players (mean age = 21 ± 2 years; height = 184 ± 7 cm; body mass 91.0 ± 9 kg) were evaluated before and immediately following 17 training sessions. A total of 306 assessments were performed. Data on neuromuscular function of plyometric push-up and countermovement jump were calculated from force signals using inverse dynamics. The change from pre- to post-session was investigated across non-tackle and tackle training using a linear mixed model. Considering upper-limb neuromuscular function, peak concentric power [P = 0.024; ES = 0.33 95%CI (0.04, 0.62)] was significantly lower after tackle compared to non-tackle training. In addition, peak countermovement jump eccentric power was significantly lower after non-tackle compared to tackle training [P = 0.044; ES = -0.4 95%CI (-0.69, -0.1)] in lower-limb neuromuscular function. Overall, the results indicated that the type of training influences upper- and lower-limb neuromuscular function differently immediately after training. Indeed, due to physical contact, the upper-body neuromuscular function increased during tackle training. In contrast, lower-body neuromuscular function emerged only in non-tackle training, due to the greater distance covered during this type of training session. Coaches and practitioners should plan adequate weekly training sessions according to this information.     

Relationship between aerobic fitness and metabolic power metrics in elite male soccer players

The aim was to assess the relationship between aerobic fitness and metabolic power metrics in elite male soccer players, and the possible differences that playing positions might impose during match play over new metabolic power metrics. Sixty-two elite professional male soccer players (13 central backs, 13 side backs, 22 midfielders, and 14 forwards) took part in the study. Players were monitored during eleven months of full training (including pre-season and in-season) and over all official matches (Serie A matches, Italy Cup matches). Aerobic fitness tests were conducted one week after the start of the preseason, and 8, 24 and 36 weeks after the beginning of the Championship. Players’ aerobic fitness and metabolic power metrics were considered as the mean of all seasonal testing and of pooling data of 38 championship matches and 3 or 6 Italy Cup matches for all the calculations respectively. The velocity at 4 mmol·L^-1 (VL₄) was significantly related to metabolic power metrics match variables with correlation ranging from trivial to very large (r = 0.32 to r = 0.89). Receiver-operating-characteristic (ROC) analysis showed that speed at VL₄ was sensitive in detecting high metabolic power distance (HMPD) changes in all but central back players as revealed by area under the curve (central back .78, 95%CI .47 to .95; full back .93, 95%CI .64 to 0.99; midfielder .88, 95%CI .67 to 0.98; forward .90, 95%CI .62 to 0.99). This study’s findings provide further evidence for the ecological validity of aerobic fitness in elite male soccer players. Players having a HMPD cut-off equal to or higher than > 1450 m for central backs, > 1990 m for full backs, > 2170 m for midfielders and > 1670 m for forwards may be considered as possessing superior aerobic fitness status. In light of this study’s findings, the VL₄ test may be considered a valid test to evaluate meaningful information for direct generic aerobic training in soccer players.     

Sprinting patterns of National Rugby League competition

The purpose of this study was to investigate the sprinting demands of National Rugby League (NRL) competition and characterize the sprinting patterns of different rugby league playing positions. Thirty-seven elite rugby league players (mean ± SE age: 23.6 ± 0.5 years) underwent global positioning satellite analysis during 104 NRL appearances. The majority (67.5%) of sprint efforts were across distances of <20 m. The most common sprint distance for hit-up forwards was 6-10 m (46.3%). Outside backs had a greater proportion (33.7%) of sprint efforts over distances of ≥21 m. The proportion of sprint efforts over 40 m or greater for hit-up forwards, wide running forwards, adjustables, and outside backs was 5.0, 7.4, 5.0, and 9.7%, respectively. Of the sprints performed, approximately 48.0% involved contact, approximately 58.0% were preceded by forward locomotion (forward walking, jogging, or striding), whereas over 24.0% occurred from a standing start. Hit-up forwards more commonly sprinted from a standing start, or after lateral movement, whereas forward striding activities more commonly preceded sprint efforts for the adjustables and outside backs. The majority of sprint efforts were performed without the ball (78.7 vs. 21.3%). Most sprint efforts (67.5%) were followed by a long recovery (i.e., ≥5 minutes). Outside backs had the greatest proportion (76.1%) of long duration recovery periods and the smallest proportion (1.8%) of short duration recovery periods (i.e., <60 seconds) between sprints. The results of this study demonstrate differences among rugby league playing positions for the nature of sprint efforts and the typical distances covered during these efforts. Furthermore, the activities preceding and the recovery periods after sprint efforts were different among playing positions. These findings suggest that rugby league sprint training should be tailored to meet the individual demands of specific playing positions.     

Changes in anthropometric and fitness profile of Italian regional academy rugby union players

In rugby union, physical characteristics may partially contribute to long-term career progression, especially during adolescence. Therefore, the primary purpose of the study was to evaluate Italian regional rugby union academy players’ (i.e., under-18) anthropometric and physical characteristics during a competitive season. Body mass, height, upper- and lower-body maximal strength, sprint, and high-intensity running ability were assessed in 29 elite players (backs, n = 13, forwards, n = 16). A mixed-design analysis of variance (ANOVA) for repeated measures showed that backs were shorter (ES = 0.59), lighter (ES = 0.94), stronger relative to body mass (bench press; ES = 0.60; deadlift; ES = 0.63; clean ES = 0.63; rowing ES = 0.67), and fitter (shuttle run max; ES = 0.38; shuttle run tot; ES = 0.79) than forwards. However, the forwards achieved greater sprint momentum (initial sprint momentum; ES = 0.97; maximal sprint momentum; ES = 0.98). During the season, players changed in stature, upper-body maximal strength, jumping, and high intensity running (p < 0.05), but not in body weight or lower-body maximal strength (p > 0.05). Maximal strength improved in the first part of the season, whereas jumping and sprinting performances increased in the last part of the season. Therefore, these findings highlight the importance of regularly monitoring the physical development in a long-term perspective, even suggesting that physiological adaptations are heterochronic between positional roles.     

Session-to-session variations in external load measures during small-sided games in professional soccer players

The aims of this study were 1) to analyse session-to-session variations in different external load measures and 2) to examine differences in within-session intervals across different small-sided game (SSG) formats in professional players. Twenty professional soccer players (mean ± SD; age 28.1 ± 4.6 years, height 176.7 ± 4.9 cm, body mass 72.0 ± 7.8 kg, and body fat 10.3 ± 3.8%) participated in 3v3, 4v4, and 6v6 SSGs under different conditions (i.e., touch limitations and presence of goalkeepers vs. free touch and ball possession drill) over three sessions. Selected external load measures—including total distance (TD), high-intensity running (HIR, distance covered > 14.4 km^.h^-1), high-speed running (HSR, distance covered > 19.8 km^.h^-1), and mechanical work (MW, accelerations and deceleration > 2.2 m^.s²)—were recorded using GPS technology during all SSG sessions. Small to large standardized typical errors were observed in session-to-session variations of selected measures across SSGs. TD^.min^-1 showed less variability, having a coefficient of variation (CV) of 2.2 to 4.6%, while all other selected external load measures had CV values ranging from 7.2% to 29.4%. Trivial differences were observed between intervals in TD^.min^-1 and HIR^.min^-1 for all SSGs, as well as in HSR^.min^-1 and MW^.min^-1 for most SSG formats. No reductions or incremental trends in session-to-session variations were observed when employing touch limitations or adding goalkeepers. The increased noise observed in higher speed zones (e.g., high-speed running) suggests a need for more controlled, running-based conditional drills if the aim is greater consistency in these measures.     

Physiological and anthropometric characteristics of elite women rugby league players

This study investigated the physiological and anthropometric characteristics of elite women rugby league players and developed physical performance standards for these athletes. Thirty-two elite women rugby league players underwent measurements of standard anthropometry (body mass, height, sum of 7 skinfolds), muscular power (vertical jump), speed (10-, 20-, and 40-m sprint), agility (505 test), glycolytic capacity (glycolytic agility test), and estimated maximal aerobic power (multistage fitness test). The skinfold thickness, speed, agility, vertical jump height, glycolytic capacity, and estimated maximal aerobic power results were 6.0-38.1% poorer than previously reported for elite women team sport athletes (e.g., rugby union, soccer, and hockey). Although no significant differences (p > 0.05) were detected between selected and nonselected players for any of the physiological or anthropometric characteristics, significant differences (p < 0.05) were detected between forwards and backs for body mass, skinfold thickness, 10-, 20-, and 40-m speed, and estimated maximal aerobic power. When data were analyzed according to positional similarities, it was found that the hit-up forwards positional group were heavier, had greater skinfold thickness, and had lower 10-, 20-, and 40-m speed, muscular power, glycolytic capacity, and estimated maximal aerobic power than the adjustables and outside backs positional groups. The results of this study show that elite women rugby league players have slower speed and agility, lower muscular power, glycolytic capacity, and estimated maximal aerobic power, and greater body mass and skinfold thickness than previously reported for other elite women team sport athletes. These findings show the need to develop all physiological parameters to allow elite women rugby league players to more effectively tolerate the physiological demands of competition, reduce fatigue-related errors in skill execution, and decrease the risk of injury.     

Training elite youth soccer players: area per player in small-sided games to replicate the match demands

The aim was to determine the area per player (ApP, m² × player) in small- or large-sided games to replicate the official match demands in elite youth soccer players. Two hundred and twenty-eight players (U15 = 36, U16 = 48, U17 = 49, U18 = 37 and U19 = 58) were monitored during both training (12 183 individual samples) and matches (683 individual samples) across five seasons. Relative (m × min^-1) total (TD), high-speed running (HSR), very high-speed running (VHSR), sprint and acceleration/deceleration (Acc/Dec) distance were collected. Between-category and between-position comparisons were performed. Area per player was moderately correlated (P < 0.05) with TD (r = 0.401), large (r = 0.621) with HSR, and very largely with VHSR (r = 0.744) and sprint (r = 0.723). An inverse small (r = -0.232; P = 0.039) correlation for Acc/Dec was found. The area per player to replicate the match demands was 158 ± 18, 182 ± 32, 197 ± 37, 212 ± 42 and 156 ± 25 m² × player for TD, HSR, VHSR, sprint and Acc/Dec, respectively. Moderate to very large (ES: 0.79 to 4.66) differences in the area per player across metrics were observed, with sprint > VHSR > HSR > TD = Acc/Dec. Trivial to very large (ES: 0.01 to 2.67) between-category differences in area per player across the same metric were found, with U15 and U16 requiring a larger area per player than other age categories. These findings may help practitioners to recreate the desired external load outcomes with regards to positional match-play demands using specific area per player in small- or large-sided games in youth elite soccer players from U15 to U19.     

The effects of defensive style and final game outcome on the external training load of professional basketball players

This study aimed to analyse the influence of different contextual factors (i.e., defensive style and game outcome) on basketball players’ external load during games-based drills using ultrawideband (UWB) technology. Fourteen male professional basketball players belonging to an elite reserve Spanish club (ACB) participated in this study. The games-based drills consisted of one bout of 10 min played 5vs5 in which players were instructed to use man-to-man defence (MMD) and/or zone defence (ZD). In addition, the final game outcome (i.e., winning or losing) of the game-based drill was registered. External load variables per minute were recorded: total distance covered, distance covered in different speed zones, distance covered while accelerating and decelerating, maximum speed, steps, jumps and player load. A two-way ANOVA with the Tukey post hoc test was used to assess the impact of defensive style and final game outcome and the interaction of both factors on the external load encountered by basketball players. No meaningful differences (unclear) were found in the external loads between playing with MMD and with ZD and between winning and losing teams except for greater distance at high-speed running (18.0–24.0 km·h^-1) in winning teams (p < 0.05, ES = 0.68, moderate). A significant interaction between defensive style and final game outcome was found for high decelerations (> -2 m·s^-2) (p = 0.041; ES = 0.70) and jumps (p = 0.037; ES = 0.68). These results could potentially help coaching staff in prescribing an appropriate workload during basketball-specific game-based drills, and ultimately enhance the match performance.     

Match running performance and exercise intensity in elite female Rugby Sevens

The purpose of this study was to describe the match-play demands of professional female rugby players competing in Rugby Sevens (Rugby 7's) matches. Time-motion analyses (global position system) were performed on 12 elite female rugby players during 5 competitive matches in a 2-day international tournament. Data revealed that players covered an average distance of 1,556.2 ± 189.3 m per game (14 minutes). Over this distance, 29.7% (462.6 ± 94.6 m) was spent standing and walking, 33.2% (515.9 ± 88.6 m) jogging, 11.6% (181.0 ± 61.4 m) cruising, 16.4% (255.7 ± 88.3 m) striding, 3.7% (57.1 ± 40.8 m) high-intensity running, and 5.4% (84.0 ± 64.8 m) sprinting. The average maximal distance of sprints, number of sprints, minimum distance of sprint, and mean sprint distance over the game were as follows: 25.8 ± 16.1 m, 5.3 ± 3.2 sprints, 6.5 ± 2.0 m, and 17.2 ± 8.8 m, respectively. The players' work-to-rest ratio was 1:0.4. For over 75% of the game, the players were exposed to heart rates (HRs) >80% of their maximal HR. There were no statistical differences between the first and second halves in any of the variables analyzed. This study suggests that the physical demands of Rugby 7's are quite different from those reported in other rugby codes. For players and teams to remain competitive in female Rugby Sevens, coaching, conditioning, and physical fitness testing should reflect these current demands.     

International field hockey players perform more high-speed running than national-level counterparts

This study compared the activity profile of national and international male field hockey athletes. Sixteen players (mean (±SD) age, stature, and body mass: 22 ± 4 y, 178 ± 8 cm, and 78 ± 9 kg, respectively) competing in the national-level Australian Hockey League (AHL) and 16 players [mean (±SD) age, stature, and body mass: 27 ± 4 y, 179 ± 5 cm, and 77 ± 5 kg, respectively] competing in the international Champions Trophy (CT) tournament participated in this study. Global positioning systems assessed total distance (TD), meters per minute (m·min(-1)), and high-speed running distance (HSR; >4.17 m·s(-1)). Differences in multistage fitness test performance, movement between competition, positions, and halves were assessed using effect size and percent difference ±90% confidence intervals. The CT players had a 10.1% greater multistage fitness test, 13.9% and 42.0% more TD and HSR, respectively, than AHL. During CT, strikers performed 10.1 ± 7.4% less HSR than midfielders and 26.6 ± 8.2% more HSR than defenders. The AHL defenders covered less TD and HSR distance compared with strikers and midfielders (8.1 ± 3.6% and 8.4 ± 2.6%; 36.1 ± 11.1% and 51.5 ± 12.1%, respectively). The AHL strikers, midfielders, and defenders (19.9 ± 8.8%, 32.1 ± 7.9%, and 30.3 ± 10.7%, respectively), all performed less HSR distance than their CT counterparts. Finally, TD decreased from the first to second halves across all positions (6.1-7.5%) in both competitions. International competition increases the running profile of hockey players, with greater HSR at the elite level and positional differences including decreased running during the second half in both competitions.     

Physiological and skill demands of 'on-side' and 'off-side' games

This study investigated the physiological and skill demands of 'on-side' and 'off-side' games in elite rugby league players. Sixteen male rugby league players participated in 'on-side' and 'off-side' games. Both small-sided games were played in a 40- × 40-m playing area. The 'off-side' game permitted players to have 3 'plays' while in possession of the ball. Players were permitted to pass backward or forward (to an 'off-side' player). The 'on-side' game also permitted players to have 3 'plays' while in possession of the ball. However, players were only permitted to pass backward to players in an 'on-side' position. Heart rate and movement patterns (via global positioning system) were recorded continuously throughout both games. Data were collected on the distance covered, number of high-acceleration and velocity efforts, and recovery between efforts. Video footage was also taken to track the performance of the players. Post hoc inspection of the footage was undertaken to count the number of possessions and the number and quality of disposals. In comparison to 'on-side' games, 'off-side' games had a greater number of involvements ("touches"), passes, and effective passes. However, the cognitive demands of 'on-side' games were greater than 'off-side' games. 'Off-side' games resulted in a greater total distance covered, greater distance covered in mild and moderate accelerations, and greater distance covered in low, moderate, and high-velocity efforts. There were also a greater number of short duration recovery periods between efforts in 'off-side' games. The results of this study demonstrate that 'off-side' games provide greater physiological and skill demands than 'on-side' games. 'Off-side' games may provide a practical alternative to 'on-side' games for the development of skill and fitness in elite rugby league players.     

The ratio and allometric scaling of speed, power, and strength in elite male rugby union players

This study compared the effectiveness of ratio and allometric scaling for normalizing speed, power, and strength in elite male rugby union players. Thirty rugby players (body mass [BM] 107.1 ± 10.1 kg, body height [BH] 187.8 ± 7.1 cm) were assessed for sprinting speed, peak power during countermovement jumps and squat jumps, and horizontal jumping distance. One-repetition maximum strength was assessed during a bench press, chin-up, and back squat. Performance was normalized using ratio and allometric scaling (Y/X), where Y is the performance, X, the body size variable (i.e., BM or BH), and b is the power exponent. An exponent of 1.0 was used during ratio scaling. Allometric scaling was applied using proposed exponents and derived exponents for each data set. The BM and BH variables were significantly related, or close to, performance during the speed, power and/or strength tests (p < 0.001-0.066). Ratio scaling and allometric scaling using proposed exponents were effective in normalizing performance (i.e., no significant correlations) for some of these tests. Allometric scaling with derived exponents normalized performance across all the tests undertaken, thereby removing the confounding effects of BM and BH. In terms of practical applications, allometric scaling with derived exponents may be used to normalize performance between larger rugby forwards and smaller rugby backs, and could provide additional information on rugby players of similar body size. Ratio scaling may provide the best predictive measure of performance (i.e., strongest correlations).     

Physical match performance of Japanese top-level futsal players in different categories and playing positions

To examine the substitution characteristics during official matches and the physical match performances of Japanese top-level futsal players in different categories and playing positions. Overall, 79 adult (age: 28.4 ± 4.6 years) and 59 youth (age: 17.1 ± 0.7 years) futsal players were classified into three groups based on the playing position (Pivot, Winger, and Defender). Physical match performance was assessed using active profiles from the semi-automatic tracking system. Speed and total distance covered were analysed for the in-play time. The in-play time was categorized based on the teams’ ball possession status. The average total playing time per substitution was significantly higher in the youth (6.2 ± 2.1 min) than in the adult players (3.8 ± 1.1 min; p < 0.05). Furthermore, the proportion of high intensity exercise during matches was significantly higher in adults (43.2 ± 5.2%) than in youth players (37.2 ± 5.4%; p < 0.05). There was no significant difference in the average total distance covered between different playing positions. However, the average total distance covered with ball possession by Pivot (140 ± 15 m/min) was significantly lower than that by Winger (151 ± 15 m/min; p < 0.05) in adult players. Furthermore, the proportion of high intensity exercise without ball possession as Defender (36.7 ± 6.1%) was lower than that as Winger (41.9 ± 6.1%; p < 0.05) in adults but not in the youth players. Adult futsal players have higher physiological demands than youth players. The physical match performances vary between playing positions with or without ball possession. These results could be useful for youth development and position-specific training information.     

Influence of field size on the physiological and skill demands of small-sided games in junior and senior rugby league players

The purpose of this study was to investigate the effect of changes in field size on the physiological and skill demands of small-sided games in elite junior and senior rugby league players. Sixteen elite senior rugby league players ([mean ± SE] age, 23.6 ± 0.5 years) and 16 elite junior rugby league players ([mean ± SE] age, 17.3 ± 0.3 years) participated in this study. On day 1, 2 teams played an 8-minute small-sided game on a small field (10-m width × 40-m length), whereas the remaining 2 teams played the small-sided game on a larger sized field (40-m width × 70-m length). On day 2, the groups were crossed over. Movement was recorded by a global positioning system unit sampling at 5 Hz. Games were filmed to count the number of possessions and the number and quality of disposals. The games played on a larger field resulted in a greater (p < 0.05) total distance covered, and distances covered in moderate, high, and very-high velocity movement intensities. Senior players covered more distance at moderate, high, and very-high intensities, and less distance at low and very-low intensities during small-sided games than junior players. Although increasing field size had no significant influence (p > 0.05) over the duration of recovery periods for junior players, larger field size significantly reduced (p < 0.05) the amount of short-, moderate-, and long-duration recovery periods in senior players. No significant between-group differences (p > 0.05) were detected for games played on a small or large field for the number or quality of skill involvements. These results suggest that increases in field size serve to increase the physiological demands of small-sided games but have minimal influence over the volume or quality of skill executions in elite rugby league players.     

Strength and power characteristics in English elite rugby league players

The aim of this article is to present data on the strength and power characteristics of forwards and backs in a squad of elite English rugby league players and compare these findings to previously published literature from Australia. Participants were elite English rugby league players (n = 18; height 184.16 ± 5.76 cm; body mass 96.87 ± 10.92 kg, age 21.67 ± 4.10 years) who were all regular first team players for an English Superleague club. Testing included 5-, 10-, 20-m sprint times, agility, vertical jump, 40-kg squat jump, isometric squat, concentric and eccentric isokinetic knee flexion and extension. Independent t-tests were performed to compare results between forwards and backs, with paired samples t-tests used to compare bilateral differences from isokinetic assessments and agility tests. Forwards demonstrated significantly (p < 0.05) greater body mass (102.15 ± 7.5 kg), height (186.30 ± 5.47 cm), power during the 40-kg jump squat (2,106 ± 421 W), isometric force (3,122 ± 611 N) and peak torque during left concentric isokinetic knee extension (296.1 ± 54.2 N·m) compared to the backs (86.30 ± 8.97 kg; 179.87 ± 3.72 cm; 1,709 ± 286 W; 2,927 ± 607 N; 241.7 ± 35.2 N·m, respectively). However, no significant differences (p > 0.05) were noted between forwards and backs during right concentric isokinetic knee extension (274.8 ± 37.7 and 246.8 ± 25.8 N·m), concentric isokinetic knee flexion for both left (158.8 ± 28.6 and 141.0 ± 22. 7 N·m) and right legs (155.3 ± 22.9 and 128.0 ± 23.9 N·m), eccentric isokinetic knee flexion and extension, hamstring quadriceps ratios, or vertical jump (37.25 ± 4.35 and 40.33 ± 6.38 cm). In comparison, relative measures demonstrated that backs performed significantly better compared to the forwards during the 40-kg jump squat (20.71 ± 5.15 and 19.91 ± 3.91 W·kg?1) and the isometric squat (34.32 ± 7.9 and 30.65 ± 5.34 N·kg?1). Bilateral comparisons revealed no significant differences (p > 0.05) between left and right leg performances in the agility test (3.26 ± 0.18 and 3.24 ± 0.18 seconds), or between left (0.7 ± 0.10) and right (0.71 ± 0.17) leg eccentric hamstring concentric quadriceps ratios. The results demonstrate that absolute strength and power measures are generally higher in forwards compared to in backs; however, when body mass is taken into account and relative measures compared, the backs outperform the forwards.