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Darrall-Jones, J, Roe, G, Cremen, E, and Jones, B. Can team-sport athletes accurately run at submaximal sprinting speeds? Implications for rehabilitation and warm-up protocols. J Strength Cond Res 36(8): 2218-2222, 2022-The aim of this study is to examine the ability of team-sport athletes to accurately run at a range of submaximal sprint velocities (60-90% maximal velocity; Vmax) under verbal instruction without any objective feedback. Twelve professional male rugby union players (age 19.7 ± 0.9 years, body mass 98.3 ± 13.9 kg, height 184.0 ± 7.5 cm) were verbally instructed to complete three 40-m sprints at each of 60, 70, 80, and 90% of Vmax in a randomized order. Percentage Vmax achieved during each sprint was compared with criterion velocities calculated from Vmax testing undertaken a week prior. Players underestimated (ran faster) their sprint velocity when asked to run at 60% (very large to extremely large mean bias, 23%; range, 57-88% Vmax), 70% (large to very large, 11%; 67-93% Vmax), and 80% (small, 2%; 71-91% Vmax) of their Vmax, whereas overestimated (ran slower) their sprint velocity when asked to run at 90% Vmax (moderate, -4%; 77-95% Vmax). Team sport players may require objective feedback when performing submaximal sprinting to ensure that velocities achieved are similar to those prescribed. This may be particularly important where graded exposure to maximum velocities is required, for example during rehabilitation or warm-ups.

Small-sided games is a commonly used training method to develop technical, tactical and physical qualities concurrently. However, a review of small-sided games in rugby football codes (e.g. rugby union, rugby league) is not available. This systematic review aims to investigate the acute responses and chronic adaptations of small-sided games within rugby football codes considering the constraints applied. Four electronical databases were systematically searched until August 2020. Acute and chronic studies investigating rugby football codes small-sided games, with healthy amateur and professional athletes were included. Twenty studies were eventually included: 4 acute and 1 chronic in rugby union, 13 acute and 2 chronic in rugby league. Acute studies investigated task and individual constraints. Chronic studies showed that small-sided games would be an effective training method to improve physical performance. Current research in rugby football codes is heavily biased towards investigating how manipulating constraints can affect the physical characteristics of small-sided games, with limited literature investigating the effect on technical skills, and no studies investigating tactical behaviour. Future research is needed to evidence the effects of constraint manipulation on technical and tactical behaviour of rugby football players in small-sided games, in addition to physical characteristics.

Purpose: To identify which combination metrics of external and internal training load (TL) capture similar or unique information for individual professional players during skills training in rugby union using principal-component (PC) analysis. Methods: TL data were collected from 21 male professional rugby union players across a competitive season. This included PlayerLoad™, total distance, and individualized high-speed distance (>61% maximal velocity; all external TL) obtained from a microtechnology device (OptimEye X4; Catapult Innovations, Melbourne, Australia) that was worn by each player and the session rating of perceived exertion (RPE) (internal TL). PC analysis was conducted on each individual to extract the underlying combinations of the 4 TL measures that best describe the total information (variance) provided by the measures. TL measures with PC loadings (PCL) above 0.7 were deemed to possess well-defined relationships with the extracted PC. Results: The findings show that from the 4 TL measures, the majority of an individual’s TL information (first PC: 55–70%) during skills training can be explained by session RPE (PCL: 0.72–0.95), total distance (PCL: 0.86–0.98), or PlayerLoad (PCL: 0.71–0.98). High-speed distance was the only variable to relate to the second PC (PCL: 0.72–1.00), which captured additional TL information (+19–28%). Conclusions: Findings suggest that practitioners could quantify the TL of rugby union skills training with one of PlayerLoad, total distance, or session RPE plus high-speed distance while limiting omitted information of the TL imposed during professional rugby union skills training.

© 2018 Informa UK Limited, trading as Taylor & Francis Group Limited research has compared the physical qualities of adolescent rugby union (RU) players across differing playing standards. This study therefore compared the physical qualities of academy and school Under-18 RU players. One-hundred and eighty-four (professional regional academy, n = 55 school, n = 129) male RU players underwent a physical testing battery to quantify height, body mass, strength (bench press and pull-up), speed (10, 20 and 40 m), 10 m momentum (calculated; 10 m velocity * body mass) and a proxy measure of aerobic fitness (Yo-Yo Intermittent Recovery Test Level 1; IRTL1). The practical significance of differences between playing levels were assessed using magnitude-based inferences. Academy players were taller (very likely small), heavier (likely moderate) and stronger (bench press possibly large; pull-up plus body mass likely small) than school players. Academy players were faster than school players over 20 and 40 m (possibly and likely small), although differences in 10 m speed were not apparent (possibly trivial). Academy players displayed greater 10 m momentum (likely moderate) and greater IRTL1 performance (likely small) than school players. These findings suggest that body size, strength, running momentum, 40 m speed and aerobic fitness contribute to a higher playing standard in adolescent rugby union.

Weakley, JJS, Till, K, Darrall-Jones, J, Roe, GAB, Phibbs, PJ, Read, DB, and Jones, BL. The influence of resistance training experience on the between-day reliability of commonly used strength measures in male youth athletes. J Strength Cond Res 31(7): 2005-2010, 2017-The purpose of this study was to determine the between-day reliability of commonly used strength measures in male youth athletes while considering resistance training experience. Data were collected on 25 male athletes over 2 testing sessions, with 72 hours rest between, for the 3 repetition maximum (3RM) front squat, chin-up, and bench press. Subjects were initially categorized by resistance training experience (inexperienced; 6-12 months, experienced; >2 years). The assessment of the between-day reliability (coefficient of variation [CV%]) showed that the front squat (experienced: 2.90%; inexperienced: 1.90%), chin-up (experienced: 1.70%; inexperienced: 1.90%), and bench press (experienced: 4.50%; inexperienced: 2.40%) were all reliable measures of strength in both groups. Comparison between groups for the error of measurement for each exercise showed trivial differences. When both groups were combined, the CV% for the front squat, bench press, and chin-up were 2.50, 1.80, and 3.70%, respectively. This study provides scientists and practitioners with the between-day reliability reference data to determine real and practical changes for strength in male youth athletes with different resistance training experience. Furthermore, this study demonstrates that 3RM front squat, chin-up, and bench press are reliable exercises to quantify strength in male youth athletes.

The aim was to compare the physical characteristics of under-18 academy and schoolboy rugby union competition by position (forwards and backs). Using a microsensor unit, match characteristics were recorded in 66 players. Locomotor characteristics were assessed by maximum sprint speed (MSS) and total, walking, jogging, striding and sprinting distances. The slow component (

Weakley, JJS, Wilson, KM, Till, K, Read, DB, Darrall-Jones, J, Roe, GAB, Phibbs, PJ, and Jones, B. Visual feedback attenuates mean concentric barbell velocity loss and improves motivation, competitiveness, and perceived workload in male adolescent athletes. J Strength Cond Res 33(9): 2420-2425, 2019-It is unknown whether instantaneous visual feedback of resistance training outcomes can enhance barbell velocity in younger athletes. Therefore, the purpose of this study was to quantify the effects of visual feedback on mean concentric barbell velocity in the back squat and to identify changes in motivation, competitiveness, and perceived workload. In a randomized-crossover design (Feedback vs. Control), feedback of mean concentric barbell velocity was or was not provided throughout a set of 10 repetitions in the barbell back squat. Magnitude-based inferences were used to assess changes between conditions, with almost certainly greater differences in mean concentric velocity between the Feedback (0.70 ± 0.04 m·s) and Control (0.65 ± 0.05 m·s) observed. In addition, individual repetition mean concentric velocity ranged from possibly (repetition number 2: 0.79 ± 0.04 vs. 0.78 ± 0.04 m·s) to almost certainly (repetition number 10: 0.58 ± 0.05 vs. 0.49 ± 0.05 m·s) greater when provided feedback, whereas almost certain differences were observed in motivation, competitiveness, and perceived workload, respectively. Providing adolescent male athletes with visual kinematic information while completing resistance training is beneficial for the maintenance of barbell velocity during a training set, potentially enhancing physical performance. Moreover, these improvements were observed alongside increases in motivation, competitiveness, and perceived workload providing insight into the underlying mechanisms responsible for the performance gains observed. Given the observed maintenance of barbell velocity during a training set, practitioners can use this technique to manipulate training outcomes during resistance training.

Applied researchers (eg, academic researchers, PhD students) strive to undertake research that can inform practice in sport, and evidence ‘ impact.’ Conversely, practitioners (eg, coaches, physiotherapists, clinicians, sports scientists) strive to apply relevant up-to-date research findings to develop or optimise practice, adopting ‘ evidence based practice. ’ Despite the researcher and practitioner within a discipline having similar overall aims (eg, improve athletic performance, reduce injury risk, optimise return to play practices), their primary roles appear different due to various contextual factors.1 2 Researchers are able to work slowly, dedicating time to solving complex problems, whereas practitioners working in the field are required to work fast, to provide day-to-day support to coaches and athletes.1 The differences in how the researcher and practitioner work can be problematic and challenge the alignment of their respective priorities within their roles (eg, timescales required to deliver outcomes, specific expertise and experience, resources). Here we share a model demonstrating how the ‘working fast1 on-field brain3’, ‘working slow1 off-field brain3’ and ‘research-practitioner2’ can work together to undertake and integrate research into practice and solve the above problems. The alignment of (applied) research questions, expectations and usability of outcomes into practice …

Roe, G, Shaw, W, Darrall-Jones, J, Phibbs, PJ, Read, D, Weakley, JJ, Till, K, and Jones, B. Reliability and validity of a medicine ball-contained accelerometer for measuring upper-body neuromuscular performance. J Strength Cond Res 32(7): 1915-1918, 2018-The aim of the study was to assess the between-day reliability and validity of a medicine ball-contained accelerometer (MBA) for assessing upper-body neuromuscular performance during a throwing task. Ten professional rugby union players partook in the study. Between-day reliability was assessed from the best score attained during 2 sets of 3 throws, on 2 testing occasions separated by 7 days. Validity was assessed against a criterion measure (Optioelectronic system) during 75 throws from a subgroup of 3 participants. The MBA exhibited a small between-day error of 2.2% (90% confidence intervals; 2.0-4.6%) and an almost perfect relationship with a criterion measure (r = 0.91 [90% CIs; 0.87-0.94]). However, the mean bias and standard error were moderate (7.9% [90% CIs; 6.6-9.2%] and 4.9% [90% CIs; 4.2-5.7%], respectively). Practitioners using an MBA to assess neuromuscular performance of the upper body must take into account the overestimation and error associated with such assessment with respect to a criterion measure. However, as the error associated with between-day testing was small and testing is easy to implement in applied practice, an MBA may provide a useful tool for monitoring upper-body neuromuscular performance over time.

Phibbs, PJ, Jones, B, Roe, G, Read, DB, Darrall-Jones, J, Weakley, J, Rock, A, and Till, K. Organized chaos in late specialization team sports: weekly training loads of elite adolescent rugby union players. J Strength Cond Res 32(5): 1316-1323, 2018-The aim of this study was to quantify the mean weekly training load (TL) of elite adolescent rugby union players participating in multiple teams and examine the differences between playing positions. Twenty elite male adolescent rugby union players (17.4 +/- 0.7 years) were recruited from a regional academy and categorized by playing position: forwards (n = 10) and backs (n = 10). Global positioning system and accelerometer microtechnology was used to quantify external TL, and session rating of perceived exertion (sRPE) was used to quantify internal TL during all sessions throughout a 10-week in-season period. A total of 97 complete observations (5 +/- 3 weeks per participant) were analyzed, and differences between positions were assessed using Cohen's d effect sizes (ES) and magnitude-based inferences. Mean weekly sRPE was 1,217 +/- 364 arbitrary units (AU) (between-subject coefficient of variation [CV] = 30%), with a total distance (TD) of 11,629 +/- 3,445 m (CV = 30%), and PlayerLoad (PL) of 1,124 +/- 330 AU (CV = 29%). Within-subject CV ranged between 5 and 78% for sRPE, 24 and 82% for TD, and 19 and 84% for PL. Mean TD (13,063 +/- 3,933 vs. 10,195 +/- 2,242 m) and PL (1,246 +/- 345 vs. 1,002 +/- 279 AU) were both likely greater for backs compared with forwards (moderate ES); however, differences in sRPE were unclear (small ES). Although mean internal TLs and volumes were low, external TLs were higher than previously reported during preseason and in-season periods in senior professional players. Additionally, the large between-subject and within-subject variation in weekly TL suggests that players participate in a chaotic training system.

The aims of this study were to determine the variability of weekly match and training loads in adolescent rugby union players across a competitive season, and to investigate the effect of match frequency on load distribution across different activities. Internal match and training load data (i.e., session-rating of perceived exertion: sRPE) were collected daily from 20 players from a regional academy across a 14-week season. Data were analysed using a mixed-effects linear model, and variability was reported as a coefficient of variation (CV). Differences between 0-, 1-, 2-, and 3-match weeks were assessed using Cohen’s d effect sizes and magnitude-based inferences. Mean weekly total match and training sRPE load was 1425 ± 545 arbitrary units (AU), with a between-player CV of 10 ±6% and within-player CV of 37 ±3%. Mean week-to-week change in total sRPE load was 497 ± 423 AU (35%), and 40% of weekly observations were outside of the suggested acute:chronic workload ratio ‘safe zone’. Total weekly sRPE loads increased substantially with match frequency (1210 ± 571 AU, 1511 ± 489, and 1692 ± 517 AU, for 0-, 1-, and 2-match weeks, respectively), except for 3-match weeks (1520 ± 442 AU). Weekly match and training loads were highly variable for adolescent rugby players during the competitive season, and match frequency has a substantial effect on the distribution of loads. Therefore, match and training loads should be coordinated, monitored, and managed on an individual basis to protect players from negative training consequences, and to promote long term athlete development.

The aim of this study was to compare the physical and movement demands between training and match-play in schoolboy and academy adolescent rugby union (RU) players. Sixty-one adolescent male RU players (mean ± SD; age 17.0 ± 0.7 years) were recruited from four teams representing school and regional academy standards. Players were categorised into four groups based on playing standard and position: schoolboy forwards (n = 15), schoolboy backs (n = 15), academy forwards (n = 16) and academy backs (n = 15). Global positioning system and accelerometry measures were obtained from training and match-play to assess within-group differences between conditions. Maximum data were analysed from 79 match files across 8 matches (1.3 ± 0.5 matches per participant) and 152 training files across 15 training sessions (2.5 ± 0.5 training sessions per participant). Schoolboy forwards were underprepared for low-intensity activities experienced during match-play, with schoolboy backs underprepared for all movement demands. Academy forwards were exposed to similar physical demands in training to matches, with academy backs similar to or exceeding values for all measured variables. Schoolboy players were underprepared for many key, position-specific aspects of match-play, which could place them at greater risk of injury and hinder performance, unlike academy players who were better prepared.

The purpose of the present study was to evaluate the anthropometric and physical characteristics of English regional academy rugby union academy players by age category (under 16, under 18 and under 21s). Data were collected on 67 academy players at the beginning of the pre-season period and comprised anthropometric (height, body mass and sum of 8 skinfolds) and physical (5 m, 10 m, 20 m & 40 m sprint, acceleration, velocity & momentum; agility 505; vertical jump; yo-yo intermittent recovery test level 1; 30-15 Intermittent Fitness Test; absolute and relative 3 repetition maximum (3RM) front squat, split squat, bench press, prone row and chin; and isometric mid-thigh pull). One way analysis of variance demonstrated significant increases across the three age categories (p < 0.05) for height (e.g., 16s = 178.8 ± 7.1; 18s = 183.5 ± 7.2; 21s = 186.7 ± 6.61 cm), body mass (e.g., 16s = 79.4 ± 12.8; 18s = 88.3 ± 11.9; 21s = 98.3 ± 10.4kg), countermovement jump height and peak power, sprint momentum, velocity and acceleration; absolute, relative and isometric (e.g., 16s = 2157.9 ± 309.9; 18s = 2561.3 ± 339.4; 21s = 3104.5 ± 354.0 N) strength. Momentum, maximal speed and the ability to maintain acceleration were all discriminating factors between age categories, suggesting that these variables may be more important to monitor rather than sprint times. These findings highlight that anthropometric and physical characteristics develop across age categories and provide comparative data for English academy Rugby Union players.

The purpose of this study was to evaluate the annual and long-term (i.e., 4 years) development of anthropometric and physical characteristics in academy (16-20 years) rugby league players. Players were assessed at the start of preseason over a 6-year period and were required to be assessed on consecutive years to be included in the study (Under 16-17, n = 35; Under 17-18, n = 44; Under 18-19, n = 35; Under 19-20, n = 16). A subset of 15 players were assessed for long-term changes over 4 years (Under 16-19). Anthropometric (height, body mass, sum of 4 skinfolds) and physical (10- and 20-m sprint, 10-m momentum, vertical jump, yo-yo intermittent recovery test level 1, 1 repetition maximum [1RM] squat, bench press, and prone row) assessments were collected. Paired t-tests and repeated measures analysis of variance demonstrated significant annual (e.g., body mass, U16 = 76.4 ± 8.4, U17 = 81.3 ± 8.3 kg; p < 0.001, d = 0.59) and long-term (e.g., vertical jump, Under 16 = 44.1 ± 3.8, Under 19 = 52.1 ± 5.3 cm; p < 0.001, d = 1.74) changes in anthropometric and physical characteristics. Greater percentage changes were identified between the Under 16-17 age categories compared with the other ages (e.g., 1RM squat, U16-17 = 22.5 ± 19.5 vs. U18-19 = 4.8 ± 6.4%). Findings demonstrate the annual and long-term development of anthropometric and physical characteristics in academy rugby league players establishing greater changes occur at younger ages upon the commencement of a structured training program within an academy. Coaches should understand the long-term development of physical characteristics and use longitudinal methods for monitoring and evaluating player performance and development.

Weakley, JJS, Till, K, Read, DB, Phibbs, PJ, Roe, G, Darrall-Jones, J, and Jones, BL. The effects of superset configuration on kinetic, kinematic, and perceived exertion in the barbell bench press. J Strength Cond Res 34(1): 65-72, 2020-Training that is efficient and effective is of great importance to an athlete. One method of improving efficiency is by incorporating supersets into resistance training routines. However, the structuring of supersets is still unexplored. Therefore, the purpose of this study was to assess the effects of agonist-antagonist (A-A), alternate peripheral (A-P), and similar biomechanical (SB) superset configurations on rate of perceived exertion (RPE), kinetic and kinematic changes during the bench press. Ten subjects performed resistance training protocols in a randomized-crossover design, with magnitude-based inferences assessing changes/differences within and between protocols. Changes in rate of perceived exertion were very likely and almost certainly greater in the A-P and SB protocols when compared with the A-A, whereas all superset protocols had very likely to almost certain reductions in mean velocity and power from baseline. Reductions in mean velocity and power were almost certainly greater in the SB protocol, with differences between the A-A and A-P protocols being unclear. Decreases in peak force were likely and almost certain in the A-A and SB protocols respectively, with changes in A-P being unclear. Differences between these protocols showed likely greater decreases in SB peak forces when compared to A-A, with all other superset comparisons being unclear. This study demonstrates the importance of exercise selection when incorporating supersets into a training routine. It is suggested that the practitioner uses A-A supersets when aiming to improve training efficiency and minimize reductions in kinetic and kinematic output of the agonist musculature while completing the barbell bench press.

Weakley, JJS, Till, K, Darrall-Jones, J, Roe, GAB, Phibbs, PJ, Read, DB, and Jones, BL. Strength and conditioning practices in adolescent rugby players: relationship with changes in physical qualities. J Strength Cond Res 33(9): 2361-2369, 2019-Adolescent rugby players benefit from the implementation of resistance training. However resistance training practices and how they influence short-term physical change is unknown. Therefore, the purpose of this study was to quantify resistance training practices, evaluate physical development, and relate these changes to resistance training variables across 12 weeks in adolescent rugby union players. Thirty-five male adolescent rugby union players participated in the study with subjects completing an anthropometric and physical testing battery before and after a 12-week in-season mesocycle. Subjects recorded resistance training frequency, exercises, repetitions, load, minutes, and rating of perceived exertion for each session using weekly training diaries during the 12-week period. Paired sample t tests and Cohen's d effect sizes were used to assess change, whereas Pearson correlation coefficients assessed relationships between variables. Resistance training practices were variable, although significant (p ≤ 0.05) improvements in body mass, countermovement jump (CMJ) height, front squat, bench press, and chin-up strength were observed. Resistance training volume load had moderate to strong relationships with changes in CMJ (r = 0.71), chin up (r = 0.73), and bench press (r = 0.45). Frequency of upper and lower-body compound exercises had significant moderate to large relationships with changes in CMJ (r = 0.68), chin up (r = 0.65), and bench press (r = 0.41). Across a 12-week in-season period, adolescent rugby union players have varying resistance training practices, although anthropometric and physical characteristics seem to improve. Given the observed relationships, increased volume loads through the implementation of free-weight compound exercises could be an effective method for improving physical qualities in young rugby players.

© 2017 European College of Sport Science. Repeated physical contact in rugby union is thought to contribute to post-match fatigue; however, no evidence exists on the effect of contact activity during field-based training on fatigue responses. Therefore, the purpose of this study was to examine the effect of contact during training on fatigue markers in rugby union players. Twenty academy rugby union players participated in the cross-over study. The magnitude of change in upper- and lower-body neuromuscular function (NMF), whole blood creatine kinase concentration [CK] and perception of well-being was assessed pre-training (baseline), immediately and 24 h post-training following contact and non-contact, field-based training. Training load was measured using mean heart rate, session rating of perceived exertion (sRPE) and microtechnology (Catapult Optimeye S5). The inclusion of contact during field-based training almost certainly increased mean heart rate (9.7; ±3.9%) and sRPE (42; ±29.2%) and resulted in likely and very likely greater decreases in upper-body NMF (−7.3; ±4.7% versus 2.7; ±5.9%) and perception of well-being (−8.0; ±4.8% versus −3.4; ±2.2%) 24 h post-training, respectively, and almost certainly greater elevations in [CK] (88.2; ±40.7% versus 3.7; ±8%). The exclusion of contact from field-based training almost certainly increased running intensity (19.8; ±5%) and distance (27.5; ±5.3%), resulting in possibly greater decreases in lower-body NMF (−5.6; ±5.2% versus 2.3; ±2.4%). Practitioners should be aware of the different demands and fatigue responses of contact and non-contact, field-based training and can use this information to appropriately schedule such training in the weekly microcycle.

Purpose:To evaluate changes in performance of a 6-s cycle-ergometer test (CET) and countermovement jump (CMJ) during a 6-wk training block in professional rugby union players.Methods:Twelve young professional rugby union players performed 2 CETs and CMJs on the 1st and 4th mornings of every week before the commencement of daily training during a 6-wk training block. Standardized changes in the highest score of 2 CET and CMJ efforts were assessed using linear mixed modeling and magnitude-based inferences.Results:After increases in training load during wk 3 to 5, moderate decreases in CMJ peak and mean power and small decreases in flight time were observed during wk 5 and 6 that were very likely to almost certainly greater than the smallest worthwhile change (SWC), suggesting neuromuscular fatigue. However, only small decreases, possibly greater than the SWC, were observed in CET peak power. Changes in CMJ peak and mean power were moderately greater than in CET peak power during this period, while the difference between flight time and CET peak power was small.Conclusion:The greater weekly changes in CMJ metrics in comparison with CET may indicate differences in the capacities of these tests to measure training-induced lower-body neuromuscular fatigue in rugby union players. However, future research is needed to ascertain the specific modes of training that elicit changes in CMJ and CET to determine the efficacy of each test for monitoring neuromuscular function in rugby union players.

Purpose:The purpose of this study was to investigate the validity of timing gates and 10-Hz global positioning systems (GPS) units (Catapult Optimeye S5) against a criterion measure (50-Hz radar gun) for assessing maximum sprint velocity (Vmax).Methods:Nine male professional rugby union players performed 3 maximal 40-m sprints with 3 min rest between efforts with Vmax assessed simultaneously via timing gates, 10-Hz GPSOpen (Openfield software), GPSSprint (Sprint software), and radar gun. Eight players wore 3 GPS units, while 1 wore a single unit during each sprint.Results:When compared with the radar gun, mean biases for GPSOpen, GPSSprint, and timing gates were trivial, small, and small, respectively. The typical error of the estimate (TEE) was small for timing gate and GPSOpen while moderate for GPSSprint. Correlations with radar gun were nearly perfect for all measures. Mean bias, TEE, and correlations between GPS units were trivial, small, and nearly perfect, respectively, while a small TEE existed when GPSOpenfield was compared with GPSSprint.Conclusion:Based on these findings, both 10-Hz GPS and timing gates provide valid measures of 40-m Vmax assessment compared with a radar gun. However, as error did exist between measures, the same testing protocol should be used when assessing 40-m Vmax over time. Furthermore, in light of the above results, it is recommended that when assessing changes in GPS-derived Vmax over time, practitioners should use the same unit for each player and perform the analysis with the same software, preferably Catapult Openfield.

Read, DB, Jones, B, Phibbs, PJ, Roe, GAB, Darrall-Jones, J, Weakley, JJS, and Till, K. Physical demands of representative match-play in adolescent rugby union. J Strength Cond Res 31(5): 1290-1296, 2017-The purpose of this study was to quantify the physical demands of representative adolescent rugby union match-play and investigate the difference between playing positions and age groups. Players (n = 112) were classified into 6 groups by playing position (forwards and backs) and age group (U16, U18, and U20). The physical demands were measured using microsensor-based technology and analyzed using magnitude-based inferences to assess practical importance. Backs had a greater relative distance (except U16s) and a greater high-speed running distance per minute than forwards, with the magnitude of difference between the positions becoming larger in older age groups. Forwards had higher values of PlayerLoad (PL) per minute (accumulated accelerations from the 3 axes of movement) and PL slow per minute (accumulated accelerations from the 3 axes of movement where velocity is < 2 m[middle dot]s-1) than backs at all age groups. Relative distance, low-, and high-speed running per minute all had a trend to be lower in older age groups for both positions. PlayerLoad per minute was greater in U18 than that in U16 and U20 for both positions. PlayerLoad slow per minute was greater for older age groups besides the U18 and U20 comparisons, which were unclear. The contrasts in physical demands experienced by different positions reinforce the need for greater exposure to sprinting and collision-based activity for backs and forwards, respectively. Given PL metrics peak at U18 and locomotor demands seem to be lower in older ages, the demands of representative adolescent rugby union do not seem to be greater at U20 as expected.

Till, K, Darrall-Jones, J, Weakley, JJ, Roe, GA, and Jones, BL. The influence of training age on the annual development of physical qualities within academy rugby league players. J Strength Cond Res 31(8): 2110-2118, 2017-Previous research in academy rugby league players has evaluated the development of physical qualities according to chronological age. However, no study has considered the training age, defined as the number of formalized years of strength and conditioning training, of these players. Therefore, the purpose of this study was to present and compare the annual changes in physical qualities of academy rugby league players according to training age. Sixty-one academy players undertook a fitness testing assessment, including anthropometric (height, body mass, sum of 4 skinfolds) and physical (10 and 20 m sprint, 10m momentum, vertical jump, Yo-Yo intermittent recovery test level 1 [Yo-Yo IRTL1], one-repetition maximum [1RM] squat, bench press and prone row) measures at the start of preseason on 2 consecutive annual occasions. Players were categorized into one of 3 training age groups (i.e., 0, 1, or 2 years) and were analyzed using magnitude-based inferences. Almost certain, very likely or likely annual improvements were identified for body mass, 10m momentum, Yo-Yo IRTL1, vertical jump, and all strength measures for the 3 training age groups. When training age groups were compared, 1 year showed possibly or likely lower strength increases than 0 years training age. However, the 2 years training age group demonstrated possibly or likely increased strength changes compared with 1 year. These findings suggest that training age is an important consideration for strength and conditioning practitioners but it is likely to be a combination of chronological age, biological maturity, and training experience alongside dynamic interplayer variability that influences the physical development of academy rugby league players.

This study investigated the changes in measures of neuromuscular fatigue and physical performance in young professional rugby union players during a preseason training period. Fourteen young (age: 19.1 ± 1.2 years) professional rugby union players participated in the study. Changes in measures of lower body neuromuscular fatigue (countermovement jump (CMJ) mean power, mean force, flight-time) and physical performance (lower body strength, 40 m sprint velocity) were assessed during an 11-week preseason period using magnitude-based inferences. CMJ mean power was likely to very likely decreased during week 2 (-8.1 ± 5.5% to -12.5 ± 6.8%), and likely to almost certainly decreased from weeks 5 to 11 (-10 ± 4.3% to -14.7 ± 6.9%), while CMJ flight-time demonstrated likely to very likely decreases during weeks 2, and weeks 4-6 (-2.41 ± 1% to -3.3 ± 1.3%), and weeks 9-10 (-1.9 ± 0.9% to -2.2 ± 1.5%). Despite this, possible improvements in lower body strength (5.8 ± 2.7%) and very likely improvements in 40 m velocity (5.5 ± 3.6%) were made. Relationships between changes in CMJ metrics and lower body strength or 40 m sprint velocity were trivial or small (

The purpose of this study was to evaluate the anthropometric, sprint, and high-intensity running profiles of English academy rugby union players by playing positions, and to investigate the relationships between anthropometric, sprint, and high-intensity running characteristics. Data were collected from 67 academy players after the off-season period and consisted of anthropometric (height, body mass, sum of 8 skinfolds [∑SF]), 40-m linear sprint (5-, 10-, 20-, and 40-m splits), the Yo-Yo intermittent recovery test level 1 (Yo-Yo IRTL-1), and the 30-15 intermittent fitness test (30-15 IFT). Forwards displayed greater stature, body mass, and ∑SF; sprint times and sprint momentum, with lower high-intensity running ability and sprint velocities than backs. Comparisons between age categories demonstrated body mass and sprint momentum to have the largest differences at consecutive age categories for forwards and backs; whereas 20-40-m sprint velocity was discriminate for forwards between under 16s, 18s, and 21s. Relationships between anthropometric, sprint velocity, momentum, and high-intensity running ability demonstrated body mass to negatively impact on sprint velocity (10 m; r = -0.34 to -0.46) and positively affect sprint momentum (e.g., 5 m; r = 0.85-0.93), with large to very large negative relationships with the Yo-Yo IRTL-1 (r = -0.65 to -0.74) and 30-15 IFT (r = -0.59 to -0.79). These findings suggest that there are distinct anthropometric, sprint, and high-intensity running ability differences between and within positions in junior rugby union players. The development of sprint and high-intensity running ability may be impacted by continued increases in body mass as there seems to be a trade-off between momentum, velocity, and the ability to complete high-intensity running.

Roe, GAB, Phibbs, PJ, Till, K, Jones, BL, Read, DB, Weakley, JJ, and Darrall-Jones, JD. Changes in adductor strength after competition in academy rugby union players. J Strength Cond Res 30(2): 344-350, 2016-This study determined the magnitude of change in adductor strength after a competitive match in academy rugby union players and examined the relationship between locomotive demands of match-play and changes in postmatch adductor strength. A within-subject repeated measures design was used. Fourteen academy rugby union players (age, 17.4 +/- 0.8 years; height, 182.7 +/- 7.6 cm; body mass, 86.2 +/- 11.6 kg) participated in the study. Each player performed 3 maximal adductor squeezes at 45[degrees] of hip flexion before and immediately, 24, 48, and 72 hours postmatch. Global positioning system was used to assess locomotive demands of match-play. Trivial decreases in adductor squeeze scores occurred immediately (-1.3 +/- 2.5%; effect size [ES] = -0.11 +/- 0.21; likely, 74%) and 24 hours after match (-0.7 +/- 3%; ES = -0.06 +/- 0.25; likely, 78%), whereas a small but substantial increase occurred at 48 hours (3.8 +/- 1.9%; ES = 0.32 +/- 0.16; likely, 89%) before reducing to trivial at 72 hours after match (3.1 +/- 2.2%; ES = 0.26 +/- 0.18; possibly, 72%). Large individual variation in adductor strength was observed at all time points. The relationship between changes in adductor strength and distance covered at sprinting speed (V[Combining Dot Above]O2max >= 81%) was large immediately postmatch (p = 0.056, r = -0.521), moderate at 24 hours (p = 0.094, r = -0.465), and very large at 48 hours postmatch (p = 0.005, r = -0.707). Players who cover greater distances sprinting may suffer greater adductor fatigue in the first 48 hours after competition. The assessment of adductor strength using the adductor squeeze test should be considered postmatch to identify players who may require additional rest before returning to field-based training.

The purpose of this study was to evaluate (a) whether there were differences in sprint times at 5, 10, 20, 30, and 40 m between rugby union and rugby league players, (b) determine the reliability and usefulness of linear sprint testing in adolescent rugby players. Data were collected on 28 rugby union and league academy players over 2 testing sessions, with 3-day rest between sessions. Rugby league players were faster at 5 m than rugby union players, with further difference unclear. Sprint time at 10, 20, 30, and 40 m was all reliable (coefficient of variation [CV] = 3.1, 1.8, 2.0, and 1.3%) but greater than the smallest worthwhile change (SWC [0.2 × between-subject SD]), rating the test as marginal for usefulness. Although the test was incapable of detecting the SWC, we recommend that practitioners and researchers use Hopkins' proposed method; whereby plotting the change score of the individual at each split (±typical error [TE] expressed as a CV) against the SWC and visually inspecting whether the TE crosses into the SWC are capable of identifying whether a change is both real (greater than the noise of the test, i.e., >TE) and of practical significance (>SWC). Researchers and practitioners can use the TE and SWC from this study to assess changes in performance of adolescent rugby players when using single beam timing gates.

This study established the between-days reliability and sensitivity of a countermovement jump (CMJ), plyometric push-up, well-being questionnaire, and whole-blood creatine kinase concentration ([CK]) in elite male youth rugby union players. The study also established the between-days reliability of 1, 2, or 3 CMJs and plyometric-push-up attempts. Twenty-five players completed tests on 2 occasions separated by 5 d (of rest). Between-days typical error, coefficient of variation (CV), and smallest worthwhile change (SWC) were calculated for the well-being questionnaire, [CK], and CMJ and plyometric-push-up metrics (peak/mean power, peak/mean force, height, flight time, and flight-time to contraction-time ratio) for 1 maximal effort or taking the highest score from 2 or 3 maximal efforts. The results suggest that CMJ mean power (2 or 3 attempts), peak force, or mean force and plyometric-push-up mean force (from 2 or 3 attempts) should be used for assessing lower- and upper-body neuromuscular function, respectively, due to both their acceptable reliability (CV < 5%) and good sensitivity (CV < SWC). The well-being questionnaire and [CK] demonstrated between-days CVs >5% (7.1% and 26.1%, respectively) and poor sensitivity (CV > SWC). The findings from this study can be used when interpreting fatigue markers to make an objective decision about a player’s readiness to train or compete.

Purpose:To evaluate the difference in performance of the 30-15 Intermittent Fitness Test (30–15IFT) across 4 squads in a professional rugby union club in the UK and consider body mass in the interpretation of the end velocity of the 30-15IFT (VIFT).Methods:One hundred fourteen rugby union players completed the 30-15IFT midseason.Results:VIFT demonstrated small and possibly lower (ES = –0.33; 4/29/67) values in the under 16s compared with the under 21s, with further comparisons unclear. With body mass included as a covariate, all differences were moderate to large and very likely to almost certainly lower in the squads with lower body mass, with the exception of comparisons between senior and under-21 squads.Conclusions:The data demonstrate that there appears to be a ceiling to the VIFT attained in rugby union players that does not increase from under-16 to senior level. However, the associated increases in body mass with increased playing level suggest that the ability to perform high-intensity running increases with age, although not translating into greater VIFT due to the detrimental effect of body mass on change of direction. Practitioners should be aware that VIFT is unlikely to improve, but it needs to be monitored during periods where increases in body mass are evident.