The utilisation of the Rugby League Athlete Profiling battery for assessing the anthropometric and physical characteristics of rugby league players

The research described in this thesis used a standardised battery of tests called the ‘Rugby League Athlete Profiling (RLAP)’ battery for assessing the anthropometric and physical characteristics of UK-based rugby league players. The overall purpose of this research was to determine the utility of the RLAP battery, which involved establishing the use of RLAP across numerous professional clubs over a three-year period, determining the measurement properties of the tests included and investigating the factors associated with a change in the characteristics. An early version of the RLAP battery existed [called SPARQ] and was provided by the Rugby Football League with scope to alter this as part of this programme of research. Before determining if an alteration to the battery was required, it was essential to understand the tests that are currently used in rugby league for assessing the anthropometric and physical characteristics of players. As such, the systematic review initially sought to determine the volume of performance tests used in rugby league along with their measurement properties. Based on the results, it was evident that a shorter sprint distance (< 20 m) ought to be included in the battery. It was also clear that only one field-based method for measuring muscle strength was available, though had received minimal research. Furthermore, the review highlighted that no rugbyspecific intermittent running test had previously been used and that RLAP was the first battery to include such a test. Therefore, based on these results, the battery was rebranded to RLAP, which included a stature, body mass, a 10 m and 20 m sprint test, a rugby-specific intermittent test, a change of direction test, measures of lower- and whole-body power. With the RLAP battery confirmed, it was then used and the reliability (Chapter 4) and discriminant validity (Chapter 5) of its elements determined. Results indicated that the RLAP battery is reliable and does not require habituation. Furthermore, the calculation of the required change, which includes the worthwhile change and random error of each test, provides researchers and practitioners with a single value that can be used as an analytical goal to evaluate a true change in characteristics with confidence. All components of the RLAP battery (except 10 m sprint time) possessed adequate discriminant validity between youth, academy and senior rugby league players, suggesting this battery can accurately distinguish between playing standards. As noted in above, the review highlighted a rugby-specific intermittent test has yet to be established in the literature before its inclusion in the RLAP battery. Whilst it appeared to be suitable and, based on Chapters 3 and 4, is reliable and possesses discriminant validity, the test itself had received no previous attention. Given the novelty of this test, it was unknown if this test was better associated with the responses to rugby league match performance and what the physiological responses were to this test. As such, Chapter 5 sought to determine the concurrent validity of this test and compare it against the traditional Yo-Yo Intermittent Recovery test level 1 (Yo-Yo IR1). The results indicated the association between prone Yo-Yo IR1 distance and the external, internal and perceptual responses to simulated match-play was improved when compared to the Yo-Yo IR1. Chapter 6 demonstrated that starting each 40 m shuttle in a prone position increases the internal, external and perceptual loads whilst reducing the total distance achieved. The degree of shared covariance between the prone Yo-Yo IR1 and Yo-Yo IR1 suggest the rugby-specific test provided insight into additional characteristics associated with rugby league performance. In studies that have reported on the anthropometric and physical characteristics, few have considered the multiple factors that might influence these with no studies conducted in rugby league. Chapter 7 sought to determine the complex interaction between anthropometric and physical characteristics that requires careful consideration by those involved in developing youth and academy athletes. The results also revealed a number of contextual factors such as season phase, league ranking, playing age and playing position that can influenced the change in characteristics over the course of a competitive season. The findings of this study highlight how some characteristics are impaired towards the end of the season, thus providing a rationale for considering in-season training loads and the application of short training interventions to off-set these negative changes. Based on negative changes in some anthropometric and physical characteristics towards the end of the year, Chapter 8 reported on the efficacy of two in-season sprint interval interventions for enhancing the physical characteristics of rugby league players. Furthermore, the study provided insight into the sensitivity of the RLAP battery for detecting changes in the characteristics of rugby league players. The results highlighted that two weeks of rugby-specific and running-based sprint interval training appeared affective for promoting the physical characteristics of rugby league players with minimal deleterious effects on wellness and neuromuscular function. Using the reliability statistics from Chapter 1, the mean change for prone Yo-Yo IR1 in the rugbyspecific group met the required change whilst changes approached this value for the running-based group despite contrasting loads. In all, this study demonstrated that sprint interval training that includes sport-specific actions is a suitable and effective training modality that can be used in-season. In addition, the result demonstrated how the prone Yo-Yo IR1 was sensitive to change across the intervention period whilst others were not sensitive to sprint interval training due to the lack of specificity. This thesis provides a thorough evaluation of the RLAP battery that can be used by researcher and practitioners to assess the anthropometric and physical characteristics of rugby league players. The battery is reliable and possess discriminant validity, while the prone Yo-Yo IR1 has concurrent validity and is sensitive to change during a lowvolume in-season training intervention. Overall, this thesis provides justification for the tests included and comprehensively examines the utility of this battery for assessing the anthropometric and physical characteristics of rugby league players. Practically, this battery of tests can be used by researcher and applied practitioners in rugby league with an understanding of the reliability, validity and sensitivity of the tests along with some factors that might influence the characteristics of players across a season

The role of ‘Play Touch Rugby League’ and self-paced interval running for improving men’s health

Over recent years, the use of team sports for health promotion has become a topical area of interest. Previous research has investigated the impact of small-sided games (SSGs) on cardiovascular, metabolic and musculoskeletal fitness, body composition, chronic systemic inflammation, enjoyment, social capital and adherence. However, research has primarily focused on inactive and/or diseased populations using interventions ranging from 8- to 40-weeks. With ‘time’ often being perceived as a ‘barrier’ to sports participation, prolonged interventions, like those typically used, might not appropriate to promote public health. Therefore, the aim of this study was to assess the impact of 4-weeks of Play Touch Rugby League (PTRL) and self-paced interval running (RUN) on several health markers within an active population. Sixteen men were recruited into a PTRL (n = 8) or RUN (n = 8) group and completed four consecutive weeks of PTRL or RUN. Health markers (resting heart rate (RHR), systolic (SBP) and diastolic (DBP) blood pressure, body mass, fat mass (FM), percentage body fat (%BF), fat free mass (FFM), waist circumference (WC), hip circumference (HC), waist-to-hip ration (WHR), body mass index (BMI), stress and inflammatory markers) were measured before and after the intervention period. During each session, participants wore a global positioning system (GPS) and heart rate monitor to record the internal and external demands of each session. The external demands varied between interventions, with the RUN group covering a larger total, low intensity and moderate intensity distance at a higher average velocity compared to the PTRL group. In contrast, the PTRL covered more high intensity distance and achieved a greater maximum velocity. After 4-weeks of PTRL and RUN, RHR, SBP and FM were likely lower. In contrast, only the PTRL group reported a lower %BF and higher FFM after 4-weeks. WC and HC were possibly lower after the RUN intervention but were likely and possibly higher at the PTRL intervention. Changes in C-reactive protein (CRP) were unclear after 4-weeks of RUN and PTRL, but interleukin-6 (IL-6) concentration was very likely lower in the PTRL group. Between groups differences for positive well-being, psychological distress and fatigue were unclear, but session RPE (sRPE) was likely lower during the PTRL intervention. In conclusion, 4-weeks of PTRL or RUN performed once per week, in addition to habitual physical activity, was sufficient to improve several markers of health in an active male population

Predictors of time to return to play and reinjury following hamstring strain injuries with and without tendon involvement in professional football

Background: Hamstring strain injury (HSI) is the single most commonly (~12%) sustained injury in professional football. It is suggested HSIs extending into the intramuscular tendon are more prone to reinjury, resulting in greater time-loss and delayed time to return to play (TtRtP). Currently, there is a lack of evidence regarding the effects of HSI with and without intramuscular involvement as well as the impact of factors such as removal of a player and grade. Objectives: 1) Describe the number of HSIs using the British Athletics Muscle Injury Classification (BAMIC); 2) Determine if intramuscular tendon HSI results in extended TtRtP and higher reinjury risk; 3) Determine the predictors of TtRtP and reinjury. Methods: A retrospective study in one English Premier League football club over four seasons. Players included underwent an MRI within 7 days of injury and were graded by a Radiologist using the BAMIC (0a-4). TtRtP and injury recurrence rates were recorded along with information on whether the players were removed from play. Data were analysed using a Kruskal-Wallis test and linear regression. Results: Twenty-nine HSI across 24 players (age = 26.1 ± 3.8 years) were recorded over 4 seasons. There was a significant difference in TtRtP between grades 1a and 2c (P = 0.027). No significant difference was observed in TtRtP between 2b and 2c and no greater risk of reinjury. Grade of HSI (P = < 0.000) and removal of the player (P = 0.001) were significant predictors of TtRtP. An increase in grade of HSI resulted in an additional 4 days TtRtP and removal from the field of play (P = 0.001) resulted in an additional 10 days. Conclusion: HSIs extending into the intramuscular tendon (2b cf. 2c) do not influence TtRtP or reinjury, however TtRtP is affected by the removal of a player and overall grade

The subjective task load responses and movement characteristics associated with purposefully designed games in junior Touch players

This study sought to design five touch-specific modified games and evaluate the subjective task load responses and movement characteristics. Forty-two high performance junior Touch players completed five modified games during a single training session. Each game was designed to increase the physical, technical, mental, frustration or temporal load. Subjective task loads were measured after each game using the NASA task load index (NASA-TLX) questionnaire. Movement characteristics were recorded using global positioning systems. Data were analysed using a one-way repeated measures analysis of variance, and the association between movement characteristics and subjective task loads were assessed using linear mixed modelling. Clear between-game differences were observed in physical, technical, mental, frustration, temporal, and technical load, indicating that the load for which the game was designed to increase (e.g., physical load = physical game) was higher than all other games (p2=0.118 to 0.211, all P<0.001). No differences were observed across games for effort, performance, mean or total load (p2=0.004 to 0.030 P=0.178 to 0.947). Small to large differences in the movement characteristics were observed across the five games (p2=0.057 to 0.577, P<0.001 to 0.017). The most prominent movement characteristic associated with the NASA-TLX responses was relative distance; it was positively associated with physical and temporal load (r=0.16 to 0.24, both P<0.05) and negatively associated with technical, mental and effort load (r=-0.29 to -0.06, P <0.001 to 0.353). Overall, coaches and sport scientists can design games for Touch players that increase loads through the rules, intention of the game, and by altering relative distance

The effect of an immersive environment on basic life support quality in trained clinicians

Introduction and purpose: With an emergence of new technology being used in medicine and medical teams practicing key skills in immersive environments, the purpose of this study was to assess the impact of an immersive environment on medical professionals’ ability and experience of giving basic life support. Materials and Methods: Seven medical professionals (minimum qualification of ITMMIF) completed basic life support in an immersive (CAVE; football pitch with audio) and classroom environment. The trials were completed in a randomised order and interspersed by 5 minutes. The basic life support included reacting to a sudden collapse with no signs of life. Outcomes included an observational analysis, quantitative cardiopulmonary resuscitation (QCPR), feeling scale, felt arousal scale, and attentional focus questionnaire. Quantitative data was analysed using standardised mean difference (SMD) and 95% confidence intervals. Results: In immersion, participants feeling scale score was lower (SMD=-0.490.69, small) and state of arousal was moderately higher (SMD=0.750.77). The results from the attentional focus questionnaire suggested immersion induced higher association (SMD=-0.360.64) and lower distress (SMD=-0.960.83). The immersive environment results in a higher QCRP total score (SMD=0.330.63), suggesting a small beneficial effect. Observational notes revealed a rushed approach and multiple key errors (e.g., delayed application of the AED) when in immersion. Participants expressed the view that the immersion enabled them to “focus on the task at hand” and feel “switched on”, whilst in the classroom, some felt under pressure and as though they were “put under a spotlight”. Conclusion: Our results suggest that an immersive environment alters participants’ feelings towards the scenario, has a small effect of QCPR scores, and is perceived to be beneficial for focusing on an emergency scenario despite resulting in some errors. These findings might have important implication for future training of medical professionals working in sporting environments where visual and audible stimulus is high

The effect of neck strength and anthropometric properties of academy football players on the linear and rotational accelerations experienced during heading

Introduction and purpose: Research on heading a football ball has gained interest in recent years due to the proposed association with long-term brain health and rule changes at a governing body level. Currently, evidence exploring linear and rotational accelerations is largely limited to standardised and lab-based headers and use of a hand-held dynamometer to assess neck strength, thus potentially lack ecological and concurrent validity. Therefore, this study examined the association between anthropometric properties and neck strength with linear and rotational accelerations during typical football activity. Materials and Methods: Eleven football players from a single category one academy underwent an anthropometric assessment (stature, body mass, neck length, neck circumference, and estimated head mass) and had isometric neck strength (allometrically scaled forward, lateral flexion, and extension force) determined using a fixed dynamometer. Linear and rotational accelerations were measured using instrumented mouthguards. To assess the associations, two separate linear mixed models were constructed. Results: A total of 259 ‘player observations’ were included. A small negative association was observed between neck length, head-neck segment mass and side flexion strength with linear acceleration. A positive association was observed between neck circumference, head mass, and strength in forward flexion and extension. Neck length, neck circumference and side flexion strength were negatively associated with rotational accelerations whilst head mass, head-neck segment mass, and strength in forward flexion and extension was positively associated. The magnitude of the association and effect on the estimate for a one standard deviation change is presented in Figure 1 and 2. Conclusion: The findings in this study highlight an association between anthropometric and neck strength properties with linear and rotational accelerations experienced by players during typical football activity. These findings could have important implications when managing young athlete returning to heading activity as they progress and when developing individualised neck strengthening programmes

The effects of an 8-week off-season period on the mechanical properties of sprinting in professional rugby league players: implications for training considerations

Objectives: To determine the change in mechanical properties of sprinting performance across an 8-week off-season period in professional rugby league players. Design: Repeated measures Methods: Twenty-six professional rugby league players from a single rugby league team competing in Super League completed two assessments of linear sprint performance during final week of the season and second week of preseason. Linear split times were used to model the horizontal force-velocity profile and determine theoretical maximal force (F0), velocity (V0) and power (Pmax). Results: Our result indicated moderate-to-large increases in split times was observed at each distance across the off-season period (ES = 0.86 to 1.24; most likely), indicative of a reduced sprinting ability. Furthermore, small reductions in F0 (ES -0.34 to -0.57; likely to very likely) were observed, whilst the reduction in V0 (ES = -0.81; most likely) and Pmax (ES = -0.62 to -1.03; most likely) were considered moderate in magnitude. Conclusions: An 8-week off-season period elicited negative changes in linear sprint times and the horizontal force-velocity profile of professional rugby league players. Such findings might have implications for preseason training loads and therefore, the off-season period requires careful consideration by practitioners and clinicians with regards to content and monitoring

Factors associated with non-specific low back pain in field hockey: a cross-sectional study of Premier and Division One players

Introduction and purpose: Several risk factors have been identified that alter risk of developing non-specific low back pain (LBP) in the general population. However, there is a lack of evidence around general and sport-specific factors associated with the odds of developing LBP in field hockey players, despite the prevalence being high (33-67%). Therefore, the purpose of this study was to determine what factors are associated with the risk of reporting non-specific LBP in field hockey. Materials and Methods: Using a cross-sectional study, a questionnaire was distributed to those who competed in the men’s and women’s Premier Division, Division 1 North and Division 1 South for field hockey. The questionnaire consisted of a participant information sheet, definitions sheet, participant characteristics, injury history, training-related factors, and work and personal factors. Univariable and multivariable logistic regression was used to identify the key factors associated with the odds of reporting LBP. Results: A total of 194 responses were received. Results from the logistic regression indicated that age (>25 years), playing internationally, use of a smaller stick, partaking in the drag flick, experiencing stiffness/tightness after hockey, training 0-2 and 3-5 hours per week, competing in two matches per week, lifting heavy objects at work, perceiving work to impact recovery, and experiencing a stressful life event were associated 1.43-7.39 greater odds of LBP. In contrast, being a male, being of smaller stature, perceived work to increase fatigue, perceiving sleep to be good quantity, and experiences less frequent job stress were associated with lower odds of non-specific LBP (odds ratio (OR) = 0.11 to 0.60). A summary of key factors is presented in Table 1. Conclusion: The results of this study provide seven prominent factors that medical professionals involved in field hockey can consider when identifying individual at greater or lesser risk of LBP, when developing screening processes, and when developing training practices

Selected Physiological, Perceptual, and Physical Performance Changes During Two Bouts of Prolonged High-Intensity Intermittent Running Separated by 72 Hours

Dobbin, N, Lamb, KL, and Twist, C. Selected physiological, perceptual, and physical performance changes during two bouts of prolonged high-intensity intermittent running separated by 72 hours. J Strength Cond Res 31(12): 3474–3481, 2017—This study investigated the effects of performing a second 90-minute intermittent running protocol 72 hours after an initial trial on selected physiological, perceptual, and sprint running measures. Eight subelite soccer players provided measures of isokinetic muscle function, countermovement jump (CMJ), 10-m sprinting, and muscle soreness before, and at 0, 24, 48, and 72 hours after a 90-minute intermittent high-intensity running bout (IHIR-1). A second 90-minute IHIR bout (IHIR-2) was performed 72 hours after the first. Heart rates, ratings of perceived exertion (RPE), blood lactate concentration [Bla], and 10-m sprint times were recorded periodically during both IHIR. Analysis of effects revealed that in the 72-hour period after IHIR-1, there were most likely increases in muscle soreness and likely to very likely deteriorations in CMJ, 10-m sprint, and isokinetic muscle function. During IHIR-2, heart rates (possibly to likely) and [Bla] (possibly to very likely) were lower than IHIR-1, whereas RPE remained unchanged. Sprint times during IHIR-2 were also likely to very likely higher than in IHIR-1. It was evident that these team sport players exposed to repeat bouts of prolonged high-intensity running within 72 hours downregulated their sprint performan- ces in the second bout despite no change in perceived effort. These findings have implications for managing training and match loads during periods of intense scheduling

Effects of a 12% carbohydrate beverage on tackling technique and running performance during rugby league activity: a randomised, placebo-controlled trial

The purpose of this study was to investigate the effects of a 12% carbohydrate (CHO) beverage on tackling technique and running performance during rugby league activity. Using a double-blind, placebo-controlled, randomised, crossover design, 15 academy rugby league players ingested a 250 ml bolus of a 12% CHO solution (30 g maltodextrin and 30 g sucrose in 500 ml) 15 minutes before two bouts of rugby activity. The rugby league match simulation for interchange players was used to standardise the movement patterns of activity and provide reliable outcome measures, whilst also reflecting the duration of a typical field-based conditioning session. Measures of tackling technique, external responses (e.g., fatigue index from sprint data) and rating of perceived exertion (RPE) were recorded throughout. Gut discomfort was measured before each bout. The interaction effect was largely compatible with the hypothesis for relative distance (P<0.001, η2 = 0.217) and fairly compatible for tackling technique (P = 0.068, η2 = 0.0640). The time effect for tackling technique, relative and high-intensity distance, sprint, and sprint to contact velocity, time at high metabolic power, PlayerLoad™, and RPE (all P<0.05; η2 = 0.131–0.701) was compatible with the hypothesis. Data for tackling technique, relative and high-intensity distance, sprint, and sprint to contact velocity, sprint, and sprint to contact fatigue index (all P<0.05; η2 = 0.189–0.612) was compatible with a supplement effect overall despite few differences in the pattern of change (interaction). Minimal gut discomfort was reported for the CHO (bout 1 = 27 ± 17; bout 2 = 23 ± 17 AU) and placebo (bout 1 = 23 ± 18 AU; bout 2 = 24 ± 13) trials. This study shows that a 12% CHO beverage before two bouts of standardised rugby activity is a practical and effective strategy for retaining tackling technique, increasing external responses, and reducing RPE without compromising gut comfort