Rugby League Players Research Articles

Functional Movement Screening and injury risk in elite adolescent rugby league players

Research is limited as to whether Functional Movement Screen scores relate to non-contact injury risk in rugby league players. This cohort study investigates whether the Functional Movement Screen score predicts non-contact injuries in elite adolescent rugby league players. Australian adolescent rugby league players ( n = 52; mean age 16.0 ± 1.0 years) from one club participated in this study. Functional Movement Screen scores, height, and mass were collected at the beginning of the preseason. Training, match exposure, and injury incidence data (non-contact match and training injuries with three levels of severity) were recorded for each individual athlete throughout the season. Linear and logistic regression analyses were conducted to investigate the association between Functional Movement Screen score (continuous score, ≤ 14 or > 14, and three subscores) and injury risk, whilst controlling for exposure time. The mean Functional Movement Screen score for the sample was 13.4 (95% CI: 11.0–14.0). A total of 72 non-contact injuries were recorded (incidence rate: 18.7 per 1000 exposure hours; 95% CI: 11.6–24.8). There were no statistically significant associations between non-contact injury and Functional Movement Screen score for any of the analyses conducted. Our results suggest that the Functional Movement Screen does not reflect non-contact injury risk in elite adolescent rugby league players. Further research should investigate whether a more sport-specific movement screen in the preseason can more effectively predict injury risk in this population.

Peak movement and collision demands of professional rugby league competition

ABSTRACTTo quantify the peak movement and contact demands of National Rugby League (NRL) and European Super League (ESL) competition players were tracked during 10 NRL (166 files) and 10 ESL (143 files) matches using microtechnology devices. The peak 1- to 5-min periods were then calculated for average match speed (m·min−1), and acceleration (m·s−2) when 0, 1, 2, and ≥3 collisions per min occurred. Linear mixed effect models and Cohen’s effect size statistic (± 90%CI) were used to determine the differences in movement profiles when collisions occurred. Compared to no collision periods, as frequency of collisions per minute increased, there were progressive reductions in running speed for most positional groups. The addition of 1 or more collisions per min resulted in average effect size reductions in match speed of −0.14 for NRL forwards, −0.89 for NRL backs, −0.48 for ESL forwards, and −2.41 for ESL backs. ESL forwards had the highest frequency of peak periods involving 3 or more collisions per min, 22% of all periods, followed by NRL forwards (14%), NRL backs (10%) and ESL backs (8%). This study highlights the peak movement and collision demands of professional rugby league competition and allows practitioners to develop training drills that reflect worst case scenarios.

Pre-season training responses and their associations with training load in elite rugby league players

ABSTRACTObjective: Strength, power and endurance characteristics and their association with training load during a 7-week preseason training phase were assessed in elite rugby league players.Methods: Twenty-two players (age 23.3 ± 4.4 years) performed bench throw, one repetition maximum (1RM) bench press, squat jumps, three repetition maximum (3RM) squats, prone pull-ups and prone Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) before and after the 7-week preseason period. Training was classified into Gym, Field and Wrestle, with training load of each monitored using session rating of perceived exertion (sRPE) multiplied by training duration (sRPE-TL). Results: There were most likely improvements in 3RM back squat, prone pull-ups and Yo-Yo IR1 and likely improvements in the bench press, bench throw and squat jump after the 7-week training programme (ES = 0.3 to 1.2). Accumulated sRPE-TL for Gym, Field and Wrestle sessions were 9176 ± 1187, 10,906 ± 2162, and 1072 ± 315 AU, respectively. Relationships between mean weekly sRPE-TL and changes in physical qualities were trivial to large (r = −0.67 to 0.34). Conclusions: This study suggests sRPE-TL is unsuitable to detect dose–response relationships between training load and the changes in physical qualities of elite rugby league players during the pre-season period.

Differences in the Movement Skills and Physical Qualities of Elite Senior and Academy Rugby League Players.

Ireton, MRE, Till, K, Weaving, D, and Jones, B. Differences in the movement skills and physical qualities of elite senior and academy rugby league players. J Strength Cond Res 33(5): 1328-1338, 2019-The aim of this study was to investigate (a) the differences in the movement skills and physical qualities between academy and senior rugby league players and (b) the relationships between movement skills and physical qualities. Fifty-five male rugby league players (Senior, n = 18; Under 19 n = 23; Under 16, n = 14) undertook a physical testing battery, including anthropometric (stature and body mass), strength (isometric midthigh pull; IMTP), and power (countermovement jump; CMJ) qualities, alongside the athletic ability assessment (AAA; comprised of overhead squat, double lunge, single-leg Romanian deadlift, press-up, and pull-up exercises). Univariate analysis of variance demonstrated significant (p < 0.001) differences in body mass, IMTP peak force, CMJ mean power, and AAA movement skills between groups. The greatest observed differences for total movement skills, peak force, and mean power were identified between Under 16 and 19 academy age groups. Spearman's rank correlation coefficients demonstrated a significant moderate (r = 0.31) relationship between peak force and total movement skills. Furthermore, trivial (r = 0.01) and small (r = 0.13; r = 0.22) relationships were observed between power qualities and total movement skills. These findings highlight that both movement skills and physical qualities differentiate between academy age groups, and provides comparative data for English senior and academy rugby league players.

Carbohydrate and Caffeine Improves High-Intensity Running of Elite Rugby League Interchange Players During Simulated Match Play.

Clarke, JS, Highton, J, Close, GL, and Twist, C. Carbohydrate and caffeine improves high-intensity running of elite rugby league interchange players during simulated match play. J Strength Cond Res 33(5): 1320-1327, 2019-The study examined the effects of carbohydrate and caffeine ingestion on simulated rugby league interchange performance. Eight male elite rugby league forwards completed 2 trials of a rugby league simulation protocol for interchange players 7 days apart in a randomized crossover design, ingesting either carbohydrate (CHO; 40 g·h) or carbohydrate and caffeine (CHO-C) (40 g·h + 3 mg·kg) drink. Movement characteristics, heart rate, ratings of perceived exertion (RPE), and countermovement jump (CMJ) height were measured during the protocol. CHO-C resulted in likely to very likely higher mean running speeds (effect size [ES] 0.43-0.75), distance in high-intensity running (ES 0.41-0.64), and mean sprint speeds (ES 0.39-1.04) compared with CHO. Heart rate was possibly to very likely higher (ES 0.32-0.74), and RPE was likely to very likely lower (ES -0.53 to 0.86) with CHO-C. There was a likely trivial to possibly higher CMJ in CHO-C compared with CHO (ES 0.07-0.25). The coingestion of carbohydrate with caffeine has an ergogenic effect to reduce the sense of effort and increase high-intensity running capability that might be used to enhance interchange running performance in elite rugby league players.

Influence of Playing Standard on Upper- and Lower-Body Strength, Power, and Velocity Characteristics of Elite Rugby League Players.

Background: To compare load–velocity and load–power relationships among first grade (n = 26, age 22.9 ± 4.3 years), academy (n = 23, age 17.1 ± 1.0 years), and scholarship (n = 16, age 15.4 ± 0.5 years) Super League rugby league players. Methods: Participants completed assessments of maximal upper- and lower-body strength (1RM) and peak velocity and power at 20, 40, 60, and 80 kg during bench press and squat exercises, in a randomised order. Results: Bench press and squat 1RM were highest for first grade players compared with other standards (effect size (ES) = −0.43 to −3.18). Peak velocities during bench and squat were greater in the higher playing standards (ES = −0.39 to −3.72 range), except for the squat at 20 and 40 kg. Peak power was higher in the better playing standards for all loads and exercises. For all three groups, velocity was correlated to optimal bench press power (r = 0.514 to 0.766), but only 1RM was related to optimal power (r = 0.635) in the scholarship players. Only squat 1RM in the academy was related to optimal squat power (r = 0.505). Conclusions: Peak velocity and power are key physical qualities to be developed that enable progression from junior elite rugby league to first grade level. Resistance training should emphasise both maximal strength and velocity components, in order to optimise upper- and lower-body power in professional rugby league players.

Effect of Sampling Frequency on Isometric Midthigh-Pull Kinetics.

Skeletal-muscle function can be evaluated using force-times curves generated via the isometric midthigh pull (IMTP). Various sampling frequencies (500-1000Hz) have been used for IMTP assessments; however, no research has investigated the influence of sampling frequency on IMTP kinetics. Therefore, the purpose of this study was to investigate the influence of sampling frequency on kinetic variables during the IMTP, including peak force, time-specific force values (100, 150, and 200ms), and rate of force development (RFD) at 3 time bands (0-100, 0-150, 0-200ms). Academy rugby league players (n = 30, age 17.5 ± 1.1y, height 1.80 ± 0.06m, mass 85.4 ± 10.3kg) performed 3 IMTP trials on a force platform sampling at 2000Hz, which was subsequently down-sampled to 1500, 1000, and 500Hz for analysis. Intraclass correlation coefficients (ICC) and coefficients of variation (CV) demonstrated high within-session reliability for all force and RFD variables across all sampling frequencies (ICC ≥ .80, CV ≤ 14.4%) except RFD 0-100 and 0-150, which demonstrated slightly greater levels of variance (CV = 18.0-24.1%). Repeated-measures analysis of variance revealed no significant differences (P > .05, Cohen d ≤ 0.0171) in kinetic variables between sampling frequencies. Overall, high reliability was observed across all sampling frequencies for peak force, time-specific force, and RFD 0- to 200-ms variables, with no significant differences (P > .05) for each kinetic variable across sampling frequencies. Practitioners and scientists may consider sampling as low as 500Hz when measuring peak force, time-specific force values, and RFD at predetermined time bands during the IMTP for accurate and reliable data.

Verifying Head Impacts Recorded by a Wearable Sensor using Video Footage in Rugby League: a Preliminary Study

BackgroundRugby league is a full-contact collision sport with an inherent risk of concussion. Wearable instrumented technology was used to observe and characterize the level of exposure to head impacts during game play.PurposeTo verify the impacts recorded by the x-patch™ with video analysis.Study designObservational case series.MethodsThe x-patch™ was used on eight men’s semi-professional rugby league players during the 2016 Newcastle Rugby League competition (five forwards and three backs). Game day footage was recorded by a trained videographer using a single camera located at the highest midfield location to verify the impact recorded by the x-patch™. Videographic and accelerometer data were time synchronized.ResultsThe x-patch™ sensors recorded a total of 779 impacts ≥ 20 g during the games, of which 732 (94.0%) were verified on video. In addition, 817 impacts were identified on video that did not record an impact on the sensors. The number of video-verified impacts ≥ 20 g, per playing hour, was 7.8 for forwards and 4.8 for backs (range = 3.9–19.0). Impacts resulting in a diagnosed concussion had much greater peak linear acceleration (M = 76.1 g, SD = 17.0) than impacts that did not result in a concussion (M = 34.2g, SD = 18.0; Cohen’s d = 2.4).ConclusionsThe vast majority (94%) of impacts ≥ 20 g captured by the x-patch™ sensor were video verified in semi-professional rugby league games. The use of a secondary source of information to verify impact events recorded by wearable sensors is beneficial in clarifying game events and exposure levels.

Effects of a Rugby League Match Simulation on Decision-Making in Elite Junior Rugby League.

Redman, K, Steel, K, Kelly, V, and Siegler, J. Effects of a rugby league match simulation on decision-making in elite junior rugby league. J Strength Cond Res 35(7): 1972-1980, 2021-The paucity of research on decision-making in Rugby league within the context of a match, and the potential for age and playing experience to influence decision-making ability, warrants further investigation. Therefore, the aim of this study was to determine the effects of a simulated rugby league match on decision-making in elite junior rugby league players. Twenty male junior rugby league players (age 15.9 ± 0.9 years, body mass 87.3 ± 14.3 kg, height 1.82 ± 0.07 m, playing experience 10.2 ± 2.4 years) completed a match simulation protocol that replicated the physiological demands of an elite junior rugby league match. Decision-making performance was measured prematch, midmatch, and postmatch simulation through a reactive agility test and video-based temporal occlusion task. Upper- and lower-body neuromuscular measures as well as ratings of perceived exertion were obtained before decision-making assessments to quantify fatigue. A 2-way mixed analysis of variance with Bonferroni corrections was used to assess changes during the simulation, and significance was accepted at p < 0.05. The main finding of this study was despite observing a decline in neuromuscular function during the match simulation protocol (countermovement jump declined 1.9 ± 0.6 cm [95% confidence intervals 0.4-3.5]; p < 0.05), this decline did not significantly affect decision-making performance (reactive agility test [p = 0.58]; temporal occlusion [p = 0.88]). These results suggest elite junior rugby league players are capable of sustaining performance during a progressively fatiguing match simulation.

Transient Fatigue is Not Influenced by Ball-In-Play Time During Elite Rugby League Matches.

Waldron, M, Thomson, E, Highton, J, and Twist, C. Transient fatigue is not influenced by ball-in-play time during elite rugby league matches. J Strength Cond Res 33(1): 146-151, 2019-The capacity to sustain high-speed running is important for rugby league players. Transient fatigue, described as a reduction in high-speed running in the 5 minutes after a peak 5-minute period, is a phenomenon observed during rugby league matches. This concept has recently been questioned based on the proposed confounding influence of ball-in-play time during these periods. Therefore, this study examined the changes in high-speed running (>14 km·h) of elite rugby league players, and ball-in-play time, during the peak, subsequent, and mean 5-minute periods of 5 competitive matches using 5-Hz Global Positioning System devices. The suitability of ball-in-play time as a covariate was also evaluated. The high-speed running and ball-in-play time was different between peak (26.7 ± 5.5 m·min and 177 ± 37 seconds) and subsequent (12.1 ± 6.2 m·min and 147 ± 37 seconds) 5-minute periods (p ≤ 0.05; most likely ↓). However, there was no relationship (r = 0.01 to -0.13; p > 0.05) between ball-in-play time and high-speed running, and ball-in-play time was not independent of the match period. This study has reaffirmed the presence of transient fatigue during elite rugby league matches but questioned the influence of ball-in-play time as a confounding factor. These observations have implications for the design of appropriate training practices and informing tactical strategies used by coaches. Most importantly, any practitioner wishing to measure transient fatigue could follow a similar statistical approach taken herein and based on the current findings would not need to account for ball-in-play time as a confounding variable.

Modelling the relationships between volume, intensity and injury-risk in professional rugby league players

ObjectiveThis study aimed to: (a) identify the association between external-workloads and injury-risk in the subsequent week; and (b) understand the effectiveness of workload variables in establishing injury-risk. DesignRetrospective cohort study. MethodsWorkload and injury data (soft-tissue) were collected from forty-eight professional male rugby league players. Load variables included duration (min), total distance (m), relative distance (mmin−1), high speed distance ([m]>20kmh−1), very-high speed distance ([m]>25kmh−1), acceleration and deceleration efforts (count) and PlayerLoad (Arbitrary Unit: AU). Cumulative two-, three- and four-weekly loads; Acute:Chronic Workload Ratio (ACWR); Mean-Standard Deviation Workload Ratio (MSWR) and strain values were calculated and divided into three equally-sized bins (low, moderate and high). Generalised Estimating Equations analysed relationships between workload variables and injury probability in the subsequent week. ResultsInjury-risk increased alongside increases in the ACWR for duration, total distance and PlayerLoad. Conversely, injury-risk decreased (Area Under Curve: 0.569–0.585) with increases in the four-weekly duration, total distance, accelerations, decelerations and PlayerLoad. For relative distance, high four-weekly workloads (high: >60mmin−1) demonstrated a positive association with injury-risk, whilst high two-weekly loads (high: >82 mmin−1) were negatively associated. ConclusionsA range of external workload metrics and summary statistics demonstrate either positive or negative associations with injury-risk status. Such findings provide the framework for the development of decision-support systems in which external workload metrics (e.g. total or high speed distance) can be uniquely and routinely monitored across a range of summary statistics (i.e. cumulative weekly loads and ACWR) in order to optimise player performance and welfare.

Energetic Demands of Interchange and Full-Match Rugby League Players.

Cummins, CJ, Gray, AJ, Shorter, KA, Halaki, M, and Orr, R. Energetic demands of interchange and full-match rugby league players. J Strength Cond Res 32(12): 3456-3464, 2018-The purpose of this study was to describe and compare the metabolic demands of rugby league for interchange and full-match players in relation to positional groups. Eighteen elite rugby league players were recruited. A time-motion model was used to estimate the energy expenditure and metabolic demands of rugby league match-play using Global Positioning System (GPS) technology. This approach uses players' GPS velocity-time curves to examine running velocity. Players were categorized into positional groups (outside backs, adjustables, wide-running, and hit-up forwards) and then further categorized into full-match or interchange players. Compared with their full-match counterparts, interchange wide-running forwards expended greater energy (43.1 ± 6.1 vs. 28.6 ± 7.5 kJ·kg, p ≤ 0.001, effect size [ES] = -2.38) and produced a higher anaerobic index (p = 0.016, ES = 0.56) and mean power (7.4%, p = 0.003, ES = 0.66) per match. Full-match adjustables expended 94.8% more energy (p ≤ 0.001, ES = -2.3) and performed more moderate accelerations (10.1%, p = 0.014, ES = -0.57) and decelerations (7.6%, p = 0.017, ES = -0.8), than their interchange counterparts. Outside backs did not interchange and hit-up forwards rarely (n = 2) played an entire match. Differing metabolic demands were identified for interchange and full-match players across positional groups, suggesting position-specific conditioning drills are required to model the energetic demands of match-play.

Exploring British adolescent rugby league players’ experiences of professional academies and dropout

The purposes of this study were threefold: to explore former rugby league players’ experiences of professional academy environments, to understand their reasons for dropping out of the sport, and to explore their recommendations for optimising future talent development environments. Semi-structured interviews were conducted with nine ex-professional academy rugby league players up to one year after dropping out of playing rugby. A combination of inductive and deductive thematic analysis was employed to analyse the data. The thematic analysis revealed three general dimensions: talent development pathways, reasons for dropout, and recommendations. The findings suggest that players’ talent development experiences, and the reasons for dropout could be explained by a complex interaction of micro (e.g. negative academy experiences), meso (e.g. education), exo (e.g. player pathway structures), and macro systems (e.g. transitions to other clubs). It is concluded from these findings that talent development pathways which lack a long-term focus, and emphasise early success are likely to result in increased risk of burnout, de-motivation, and subsequent dropout. From an applied perspective, talent development pathways must consider the many personal and environmental factors which interact to determine an individual’s talent development trajectory. Furthermore, by recognising the multiple factors that may influence development, the effectiveness of development pathways may be enhanced by neither excluding “potential” through inappropriate early identification, nor ignoring crucial talent development variables that contribute toward the fulfilment of potential.

A Reliable Testing Battery for Assessing Physical Qualities of Elite Academy Rugby League Players.

Dobbin, N, Hunwicks, R, Highton, J, and Twist, C. A reliable testing battery for assessing physical qualities of elite academy rugby league players. J Strength Cond Res 32(11): 3232-3238, 2018-This study assessed the interday reliability of a testing battery for the assessment of physical qualities of rugby league players. Fifty players (age 17.1 ± 1.1 years; stature 181.3 ± 6.3 cm; and body mass 89.0 ± 11.6 kg) from 3 Super League academies participated in this study. Tests of countermovement jump performance, 10- and 20-m sprint performance, change of direction, medicine ball throw, and a modified Yo-Yo Intermittent Recovery Test Level 1 (prone Yo-Yo IR1) were completed on 3 separate occasions. Between-day intraclass correlation coefficient, typical error (TE), coefficient of variation, and the smallest worthwhile change (SWC) were calculated to determine the reliability and sensitivity of each measure. Individual tests (except medicine ball throw) were not systematically different between trials (p > 0.05), with an interday variability that was <10%. In all instances, the TE was larger than the calculated SWC change, although variability was less than that typically observed after a training intervention or specific training period (i.e. preseason). Using a magnitude-based inference approach, we present the required change for all performance tests to be 75% confident and the change is beneficial. This simple and time efficient testing battery is sufficiently reliable to detect previously observed changes in a range of physical qualities of rugby league players.

Changes in northern hemisphere male international rugby union players’ body mass and height between 1955 and 2015

ObjectivesWe sought to establish the effects of professionalism, which officially began in 1995, on the body mass and height of northern hemisphere male international rugby union (RU) players. We hypothesised...

Physical, Anthropometric, and Athletic Movement Qualities Discriminate Development Level in a Rugby League Talent Pathway.

Pearce, LA, Sinclair, WH, Leicht, AS, and Woods, CT. Physical, anthropometric, and athletic movement qualities discriminate development level in a rugby league talent pathway. J Strength Cond Res 32(11): 3169-3176, 2018-This study compared the physical, anthropometric, and athletic movement qualities of talent-identified rugby league (RL) players within a development pathway. From a total of 174 players, 3 developmental levels were defined: under 18 (U18; n = 52), under 20 (U20; n = 53), and state league (SL; n = 69). All players performed a test battery that consisted of 5 physical assessments, 2 anthropometric measurements, and an athletic movement assessment. A multivariate analysis of variance modeled the main effect of developmental level (3 levels: U18, U20, and SL) on test criterion variables. Receiver-operating characteristic (ROC) curves were then built for the criterion variables that showed a significant developmental level effect. A significant effect was noted (V = 0.775, F = 5.43, p ≤ 0.05), with the SL players outperforming their U18 and U20 counterparts for measures of body mass, peak and average lower limb power, double lunge (left side), single-leg Romanian deadlift (left and right sides), the push-up, and total athletic ability assessment score (p ≤ 0.05; d = 0.35-1.21). The ROC curves generated an area under the curve of greater than 65% for each test criterion, indicating greater than chance discrimination. These results highlight the physical, anthropometric, and athletic movement qualities discriminant of development level within a RL talent pathway. Practitioners are encouraged to consider the thresholds from the ROC curves as an objective guide to assist with the development of physical performance qualities that may augment player progression in Australian RL.

Are professional young rugby league players eating enough? Energy intake, expenditure and balance during a pre-season

Due to the unique energetic demands of professional young collision sport athletes, accurate assessment of energy balance is required. Consequently, this is the first study to simultaneously investigate the energy intake, expenditure and balance of professional young rugby league players across a pre-season period. The total energy expenditure of six professional young male rugby league players was measured via doubly labelled water over a fourteen-day assessment period. Resting metabolic rate was measured and physical activity level calculated. Dietary intake was reported via Snap-N-Send over a non-consecutive ten-day assessment period, alongside changes in fasted body mass and hydration status. Accordingly, energy balance was inferred. The mean (standard deviation) difference between total energy intake (16.73 (1.32) MJ.day−1) and total energy expenditure (18.36 (3.05) MJ.day−1) measured over the non-consecutive ten-day period was unclear (−1.63 (1.73) MJ.day−1; ES = 0.91 ± 1.28; p = 0.221). This corresponded in a most likely trivial decrease in body mass (−0.65 (0.78) kg; ES = 0.04 ± 0.03; p = 0.097). Resting metabolic rate and physical activity level across the fourteen-day pre-season period was 11.20 (2.16) MJ.day−1 and 1.7 (0.2), respectively. For the first time, this study utilises gold standard assessment techniques to elucidate the distinctly large energy expenditures of professional young rugby league players across a pre-season period, emphasising a requirement for equally large energy intakes to achieve targeted body mass and composition adaptations. Accordingly, it is imperative that practitioners regularly assess the energy balance of professional young collision-sport athletes to ensure their unique energetic requirements are achieved.

Effect of Velocity-Based Loading on Acceleration Kinetics and Kinematics During Sled Towing.

Bentley, I, Sinclair, JK, Atkins, SJ, Metcalfe, J, and Edmundson, CJ. Effect of velocity-based loading on acceleration kinetics and kinematics during sled towing. J Strength Cond Res 35(4): 1030-1038, 2021-Sled towing (ST) provides an external load in the form of a sled towed using a shoulder or waist harness and cord behind the athlete. Loading strategies have varied greatly between studies, and despite many investigations, there is little agreement on the optimum sled loading to develop the acceleration phase. The aim of this study was to investigate the kinetics and kinematics of velocity-based ST during the acceleration phase of sprinting. Twelve academy rugby league players performed a series of 6-m sprints in different conditions; uninhibited, 10, 15, and 20% velocity decrement (VDec). Sagittal plane kinematics and kinetic measures were examined using 1-way repeated-measures analysis of variance. Results indicated that ST affected trunk, knee, and ankle joint kinematics (p < 0.05). Peak knee flexion increased as sled loads increased (p < 0.05), which may enable athletes to lower their center of mass and increase their horizontal force application. Net horizontal and propulsive impulse measures were greater in all sled conditions (p < 0.05), which increased significantly because sled loadings were heavier. In conclusion, this study highlights the effects of differential loads to help coaches understand acute kinetics and kinematic changes to improve the planning of sprint training.

Impact of Accommodating Resistance in Potentiating Horizontal-Jump Performance in Professional Rugby League Players.

This study investigated the efficacy of deadlifts and box squats, with a combination of traditional and accommodating resistance, as a postactivation potentiating stimulus of standing broad jumps (SBJ) in a multiple-set contrast protocol. Twelve professional rugby league players (21.4 [2.5]y; 181.3 [8.3]cm, 91.9 [8.8]kg; 1-repetition-maximum [1RM] back squat/body mass 1.59 [0.21]; 1RM deadlift/body mass 2.11 [0.25]; ≥3-y resistance-training experience) performed baseline SBJ before a contrast postactivation potentiating protocol involving 2 repetitions of 85% 1RM box squat or deadlifts, loaded with a combination of traditional barbell weight (70% 1RM) and elastic-band resistance (∼15% 1RM), followed by 2 SBJs. Exercises were separated by 90 s, and 4 contrast pairs were performed in total. Using a repeated-measures design, all subjects performed the squat followed by the deadlift and finally the control (SBJ only) condition in the same order across consecutive weeks. Changes from baseline in SBJ distance were moderate for the box squat (effect size [ES] = 0.64-1.03) and deadlift (ES = 0.80-0.96) and trivial in the control condition (ES = 0.02-0.11). The magnitude of differences in postactivation potentiating effect were considered moderate (d = 0.61) for set 1, trivial for set 2 (d = 0.10) and set 3 (d = 0.05) in favor of box squats, and moderate for set 4 (d = 0.58) in favor of deadlifts. Accommodating resistance in either box squats or deadlifts is an effective means of potentiating SBJ performance across multiple sets of a contrast protocol with only 90-s rest.

The association between external workloads and injury risk in professional rugby league players

The association between external workloads and injury risk in professional rugby league players