RESUMEN

Background: Athlete exposure to contact could be a risk factor for injury. Governing bodies should provide guidelines preventing overexposure to contact. Objectives: Describe the current contact load practices and perceptions of contact load requirements within men's and women's rugby league to allow the Rugby Football League (RFL) to develop contact load guidelines. Methods: Participants (n=450 players, n=46 coaching staff, n=32 performance staff, n=23 medical staff) completed an online survey of 27 items, assessing the current contact load practices and perceptions within four categories: "current contact load practices" (n=12 items), "perceptions of required contact load" (n = 6 items), "monitoring of contact load" (n=3 items), and "the relationship between contact load and recovery" (n=6 items). Results: During men's Super League pre-season, full contact and controlled contact training was typically undertaken for 15-30 minutes per week, and wrestling training for 15-45 minutes per week. During the in-season, these three training types were all typically undertaken for 15-30 mins per week. In women's Super League, all training modalities were undertaken for up to 30 minutes per week in the pre- and in-season periods. Both men's and women's Super League players and staff perceived 15-30 minutes of full contact training per week was enough to prepare players for the physical demands of rugby league, but a higher duration may be required to prepare for the technical contact demands. Conclusion: Men's and women's Super League clubs currently undertake more contact training during pre-season than in-season, which was planned by coaches and is deemed adequate to prepare players for the demands of rugby league. This study provides data to develop contact load guidelines to improve player welfare whilst not impacting performance.

RESUMEN

INTRODUCTION: Habitual smoking is highly prevalent in military populations despite its association with poorer training outcomes. Smoking imposes challenges on the immune and endocrine systems which could alter how smokers acutely respond to, and recover from, intensive exercise particularly over multiple days of training. METHODS: Over a two-day period, 35 male British Army recruits (age 22±3 years; mass 76.9±8.0 kg; height 1.78±0.06 m; 15 smokers) completed a 16.1 km loaded march (19.1 kg additional mass) on the first morning and a best-effort 3.2 km 'log race' (carrying a 60 kg log between six and eight people) on the subsequent morning. Blood samples were obtained on waking and immediately postexercise on both days and analysed for C reactive protein (CRP), interleukin 6 (IL-6), testosterone to cortisol ratio and insulin-like growth factor 1 (IGF-1). RESULTS: Independent of smoking group, the exercise bouts on both days evoked significant increases in IL-6 (p<0.001) and decreases in testosterone to cortisol ratio (p<0.05). CRP concentrations on day 2 were significantly higher than both time points on day 1 (p<0.001), and a 9% decline in IGF-1 occurred over the two-day period, but was not significant (p=0.063). No significant differences were observed between smokers and non-smokers (p>0.05). CONCLUSIONS: Military-specific tasks elicited inflammatory and endocrine responses, with systemic CRP and IGF-1 indicating that the physiological stress generated during the first training day was still evident on the second day. Despite the well-established impacts of smoking on resting levels of the markers examined, responses to two days of arduous military-specific training did not differ by smoking status.

Asunto(s)

RESUMEN

Background: One strategy to prevent and manage concussion is to reduce head impacts, both those resulting in concussion and those that do not. Because objective data on the frequency and intensity of head impacts in rugby union (rugby) are sparse, stakeholders resort to individual perceptions to guide contact training. It is unknown whether there is a level of contact training that is protective in preparing elite players for contact during matches. Objectives: This study aimed to describe how contact training is managed in elite male rugby, and how staff and players perceive contact training load and head impact load. Methods: This was a sequential explanatory mixed-methods study. Forty-four directors of rugby, defence coaches, medical and strength/conditioning staff and 23 players across all 13 English Premiership Rugby Union clubs and the National senior team participated in semi-structured focus groups and completed two bespoke questionnaires. Results: The study identified the varied understanding of what constitutes head impact exposure across all stakeholder groups, resulting in different interpretations and a range of management strategies. The findings suggest that elite clubs conduct low levels of contact training; however, participants believe that some exposure is required to prepare players and that efforts to reduce head impact exposure must allow for individualised contact training prescription. Conclusion: There is a need for objective data, possibly from instrumented mouthguards to identify activities with a high risk for head impact and possible unintended consequences of reduced exposure to these activities. As data on head impact exposure develop, this must be accompanied with knowledge exchange within the rugby community.

RESUMEN

Background: Impact forces during rugby can contribute to scapula dysfunction and shoulder pain. Reliable assessment of static and dynamic scapula position is paramount in managing athletes with, and those at risk of developing, shoulder pain. Objectives: To determine the reliability of static scapular posture (SP), clavicular tilt angle (CTA) and the scapular dyskinesis (SD) assessments by expert and student therapists. Methods: The study design was an inter-rater and intra-rater reliability study in male university level rugby union players. Four sport rehabilitation students and one experienced physiotherapist evaluated the position of the scapular and clavicle of male university-level rugby union players (inter-rater participants: session 1: n=17, session 2: n=12 and session 3: n=16; (intra-rater participants: n = 12). Participants attended 3 testing sessions, each 1 week apart. Scapular orientation and motion were assessed in five planes of movement and using the Scapular Dyskinesis Test (SDT) respectively. The inter-rater analysis included all participants from each session, while in the intra-rater analysis included only the 12 participants who attended all three testing sessions. Results: Kappa coefficient values and percentage agreement ratings for students compared to the experienced therapist were: SP=poor to fair (-0.01 to 0.33), (27% - 94%); SDT=slight (0.16; 41%); CTA=fair (0.21; 59%). Test-retest (intra-rater) agreement was fair to moderate (0.22 - 0.44; 69% - 95%), slight (0.12; 47%), and fair (0.39; 77%) for the SP, SDT, and CTA, respectively. Conclusion: Static and dynamic evaluation of the shoulder by students and an experienced therapist has poor to moderate reliability and should not be used to make clinical decisions based on observation alone.

RESUMEN

Background: Rugby union demands a multifaceted approach to training, given the multiple physical and technical attributes required to play the sport. Objectives: The aim of this study is to describe the distribution of training throughout the week and investigate how this may be influenced by match-related factors. Methods: Training load data (session Rating of Perceived Exertion [sRPE], total distance and high-speed running [HSR]) were collected from six professional English rugby teams during the 2017/18 season. Five contextual factors were also recorded including: standard of opposition, competition type, result of previous fixture, surface type, and match venue. Results: The day prior to matches demonstrated the lowest training load (101 AU (95% CIs: 0-216 AU), 1 047 m (95% CIs:1 128-1 686 m) and 59 m (95% CIs: 0-343 m), respectively), while four days prior to the match demonstrated the highest training load (464 AU (95% CIs: 350-578), 2 983 m (95% CIs: 2 704-3 262m) and 234m (95% CIs: 0-477m), respectively). Of the five contextual factors, competition type was the only variable that demonstrated greater than trivial findings, with training before European fixtures the lowest stimulus across the four different competition types. Standard of opposition, previous result, surface type and venue had only trivial effects on training load (effect sizes = -0.13 to 0.15). Conclusion: Future studies should outline the distribution of other training metrics, including contact and collision training. This study provides a multi-club evaluation that demonstrates the variety of loading strategies prior to competitive match play and highlights competition type as the most influential contextual factor impacting the average training load.

RESUMEN

Background: The use of artificial turf on rugby pitches is increasingly commonplace but there is limited evidence around its effects on injury, recovery, and performance. It is unclear whether this uncertainty influences player management strategies in professional clubs. Objectives: To understand how professional rugby union clubs in England approach player management for artificial turf, to explore how the beliefs of medical and strength/conditioning staff influence these decisions, and to determine whether differences exist between clubs with different levels of exposure to artificial surfaces. Methods: The study was a cross-sectional mixed methods study. Twenty-three medical and strength/conditioning staff members from 12 English Premiership Rugby Union clubs completed two bespoke questionnaires and participated in a semi-structured interview. Results: Two-thirds of the participants described formal club-level approaches to artificial turf. All participants from low-exposure clubs (<50% training and match time on artificial pitches) reported adjusting player recovery strategies following games on artificial turf to mitigate elevated muscle soreness and fatigue. Clubs with artificial surfaces at their home venues were less likely to adapt recovery than clubs with natural turf pitches. Regardless of exposure participants believed switching between surface types was a risk factor for injury. Medics reported that acute injuries associated with artificial turf exposure typically occurred at the foot or ankle, whereas abrasions and overuse injuries were more common and often affected the knees, hips and lower back. Players with compromised joints were less likely to be selected for matches on artificial surfaces. Conclusion: Player management around artificial turf is a focus for staff at professional rugby union clubs. Club practices vary by exposure and may consequently influence injury risk estimates.

RESUMEN

Evidence supporting use of the Functional Movement Screen (FMSTM) to identify athletes' risk of injury is equivocal. Furthermore, few studies account for exposure to risk during analysis. This study investigated the association of FMSTM performance with incidence and burden of match-injuries in adult community rugby players. 277 players performed the FMSTM during pre-season and in-season time-loss injuries and match exposure were recorded. The associations between FMSTM score, pain, and movement-pattern asymmetries with match-injury incidence (≥8-days time-loss/1000hours), severe match-injury incidence (>28-days time-loss/1000hours), and match-injury burden (total time-loss days/1000hours for ≥8-days match-injuries) were analysed using Poisson regression. Multivariate analysis indicated players with pain and movement-pattern asymmetry during pre-season had 2.9 times higher severe match-injury incidence (RR, 90%CI = 2.9, 0.9-9.7) and match-injury burden (RR, 90%CI = 2.9, 1.3-6.6). Players with a typically low FMSTM score (mean - 1SD threshold) were estimated to have a 50% greater match-injury burden compared to players with a typically high FMSTM score (mean + 1SD threshold) as match-injury burden was 10% lower per 1-unit increase in FMSTM score. As the strongest association with injury outcome was found for players with pain and asymmetry, when implementing the FMSTM it is advisable to prioritise these players for further assessment and subsequent treatment.

Asunto(s)

Asunto(s)

RESUMEN

Herein, we report the formation of silicon, germanium and more complex Si-SixGe1-x and Si-Ge axial 1D heterostructures, at low temperatures in solution. These nanorods/nanowires are grown using phenylated compounds of silicon and germanium as reagents, with precursor decomposition achieved at substantially reduced temperatures (200 °C for single crystal nanostructures and 300 °C for heterostructures), through the addition of a reducing agent. This low energy route for the production of these functional nanostructures as a wet chemical in high yield is attractive to meet the processing needs for next generation photovoltaics, batteries and electronics.

RESUMEN

AIM: Residual ß-cell function is present at the time of diagnosis with Type 1 diabetes. Preserving this ß-cell function reduces complications. We hypothesized that exercise preserves ß-cell function in Type 1 diabetes and undertook a pilot trial to address the key uncertainties in designing a definitive trial to test this hypothesis. METHODS: A randomized controlled pilot trial in adults aged 16-60 years diagnosed with Type 1 diabetes within the previous 3 months was undertaken. Participants were assigned to control (usual care) or intervention (exercise consultation every month), in a 1 : 1 ratio for 12 months. The primary outcomes were recruitment rate, drop out, exercise adherence [weeks with ≥ 150 min of self-reported moderate to vigorous physical activity (MVPA)], and exercise uptake in the control group. The secondary outcomes were differences in insulin sensitivity and rate of loss of ß-cell function between intervention and control at 6 and 12 months. RESULTS: Of 507 individuals who were approached, 58 (28 control, 30 intervention) entered the study and 41 completed it. Participants were largely white European males, BMI 24.8 ± 3.8 kg/m2 , HbA1c 75 ± 25 mmol/mol (9 ± 2%). Mean level of objectively measured MVPA increased in the intervention group (mean 243 to 273 min/week) and 61% of intervention participants reached the target of ≥ 150 min/week of self-reported MVPA on at least 42 weeks of the year. Physical activity levels fell slightly in the control group (mean 277 to 235 min of MVPA/week). There was exploratory evidence that intervention group became more insulin sensitive and required less insulin. However, the rate of loss of ß-cell function appeared similar between the groups, although the change in insulin sensitivity may have affected this. CONCLUSION: We show that it is possible to recruit and randomize people with newly diagnosed Type 1 diabetes to a trial of an exercise intervention, and increase and maintain their exercise levels for 12 months. Future trials need to incorporate measures of greater adherence to exercise training targets, and include more appropriate measures of ß-cell function. (Clinical Trials Registry No; ISRCTN91388505).

Asunto(s)

RESUMEN

BACKGROUND: Injuries to youth rugby players have become an increasingly prominent health concern, highlighting the importance of developing and implementing appropriate preventive strategies. A growing body of evidence from other youth sports has demonstrated the efficacy of targeted exercise regimens to reduce injury risk. However, studies have yet to investigate the effect of such interventions in youth contact sport populations like rugby union. OBJECTIVE: To determine the efficacy of an evidence-based movement control exercise programme compared with a sham exercise programme to reduce injury risk in youth rugby players. Exercise programme compliance between trial arms and the effect of coach attitudes on compliance will also be evaluated. SETTING: School rugby coaches in England will be the target of the researcher intervention, with the effects of the injury prevention programmes being measured in male youth players aged 14-18 years in school rugby programmes over the 2015-2016 school winter term. METHODS: A cluster-randomised controlled trial with schools randomly allocated to either a movement control exercise programme or a sham exercise programme, both of which are coach-delivered. Injury measures will derive from field-based injury surveillance, with match and training exposure and compliance recorded. A questionnaire will be used to evaluate coach attitudes, knowledge, beliefs and behaviours both prior to and on the conclusion of the study period. OUTCOME MEASURES: Summary injury measures (incidence, severity and burden) will be compared between trial arms, as will the influence of coach attitudes on compliance and injury burden. Additionally, changes in these outcomes through using the exercise programmes will be evaluated. TRIAL REGISTRATION NUMBER: ISRTCNN13422001.

RESUMEN

The aim of this study was to describe the incidence, severity and type of shoulder injuries resulting from match play in adult community rugby union between 2009-2013. A total of 254 time-loss shoulder injuries were reported, an overall incidence of 2.2 per 1 000 h (95% CI: 1.9 to 2.4), and a mean injury severity of 9.5 weeks missed (95% CI: 8.2 to 10.8). The semi-professional group had an incidence of 2.8 injuries per 1 000 h (95% CI: 2.2 to 3.5), which was higher than the recreational group at 1.8 injuries per 1 000 h (95% CI: 1.4 to 2.2, p=0.004). The incidence of acromioclavicular joint injury for semi-professional players was 1.2 per 1 000 h (95% CI: 0.8 to 1.6); which was significantly higher than the incidence of this injury type in recreational players (0.5 per 1 000 h 95% CI: 0.3 to 0.7, p=0.002). Overall, back row players sustained the highest incidence of all shoulder injuries for a given playing position, 2.9 injuries per 1 000 h (95% CI: 2.2 to 3.6). The tackle was the main event associated with injury. Injury prevention programs and coaching strategies that consider tackle technique and physical conditioning of the shoulder region are therefore considered important.

Asunto(s)

RESUMEN

A minimum cardiorespiratory fitness standard was derived for firefighters following a metabolic demands analysis. Design and minimal acceptable performance of generic firefighting task simulations (i.e. hose running, casualty evacuation, stair climb, equipment carry, wild-land fire) were endorsed by a panel of operationally experienced experts. Sixty-two UK firefighters completed these tasks wearing a standard protective firefighting ensemble while being monitored for peak steady-state metabolic demand and cardiovascular strain. Four tasks, endorsed as valid operational simulations by ≥90% of participants (excluding wild-land fire; 84%), were deemed to be a sufficiently valid and reliable basis for a fitness standard. These tasks elicited an average peak steady-state metabolic cost of 38.1 ± 7.8 ml kg-1 min-1. It is estimated that healthy adults can sustain the total duration of these tasks (~16 min) at ≤90% maximum oxygen uptake and a cardiorespiratory fitness standard of ≥42.3 ml kg-1 min-1 would be required to sustain work. Practitioner Summary: A cardiorespiratory fitness standard for firefighters of ≥42.3 ml kg-1 min-1 was derived from monitoring minimum acceptable performance of essential tasks. This study supports the implementation of a routine assessment of this fitness standard for all UK operational firefighters, to ensure safe physical preparedness for occupational performance.

Asunto(s)

RESUMEN

This prospective cohort study investigated the influence of an artificial playing surface on injury risk and perceptions of muscle soreness in elite English Premiership Rugby Union players. Time loss (from 39.5 matches) and abrasion (from 27 matches) injury risk was compared between matches played on artificial turf and natural grass. Muscle soreness was reported over the 4 days following one match played on each surface by 95 visiting players (i.e., normally play on natural grass surfaces). There was a likely trivial difference in the overall injury burden relating to time-loss injuries between playing surfaces [rate ratio = 1.01, 90% confidence interval (CI): 0.73-1.38]. Abrasions were substantially more common on artificial turf (rate ratio = 7.92, 90% CI: 4.39-14.28), although the majority of these were minor and only two resulted in any reported time loss. Muscle soreness was consistently higher over the 4 days following a match on artificial turf in comparison with natural grass, although the magnitude of this effect was small (effect sizes ranging from 0.26 to 0.40). These results suggest that overall injury risk is similar for the two playing surfaces, but further surveillance is required before inferences regarding specific injury diagnoses and smaller differences in overall injury risk can be made.

Asunto(s)

RESUMEN

We investigated the effect of a "PreBind" engagement protocol on the biomechanics of contested Rugby Union scrummaging at different playing levels. "PreBind" requires front-row props to take a bind on opposing players prior to the engagement, and to maintain the bind throughout the scrum duration. Twenty-seven teams from five different playing levels performed live scrums under realistic conditions. Video analysis, pressures sensors, and inertial measurement units measured biomechanical outcomes as teams scrummaged following different engagement protocols: the CTPE (referee calls "crouch-touch-pause-engage"), the CTS ("crouch-touch-set"), and the PreBind ("crouch-bind-set") variants. PreBind reduced the set-up distance between the packs (-27%) and the speed at which they came into contact by more than 20%. The peak biomechanical stresses acting on front rows during the engagement phase were decreased in PreBind by 14-25% with respect to CTPE and CTS, without reducing the capability to generate force in the subsequent sustained push. No relevant main effects were recorded for playing level due to within-group variability and there were no interaction effects between playing level and engagement protocol. Pre-binding reduced many mechanical quantities that have been indicated as possible factors for chronic and acute injury, and may lead to safer engagement conditions without affecting subsequent performance.

Asunto(s)

RESUMEN

PURPOSE: We have previously shown that 6 weeks of reduced-exertion high-intensity interval training (REHIT) improves VO2max in sedentary men and women and insulin sensitivity in men. Here, we present two studies examining the acute physiological and molecular responses to REHIT. METHODS: In Study 1, five men and six women (age: 26 ± 7 year, BMI: 23 ± 3 kg m(-2), VO2max: 51 ± 11 ml kg(-1) min(-1)) performed a single 10-min REHIT cycling session (60 W and two 20-s 'all-out' sprints), with vastus lateralis biopsies taken before and 0, 30, and 180 min post-exercise for analysis of glycogen content, phosphorylation of AMPK, p38 MAPK and ACC, and gene expression of PGC1α and GLUT4. In Study 2, eight men (21 ± 2 year; 25 ± 4 kg·m(-2); 39 ± 10 ml kg(-1) min(-1)) performed three trials (REHIT, 30-min cycling at 50 % of VO2max, and a resting control condition) in a randomised cross-over design. Expired air, venous blood samples, and subjective measures of appetite and fatigue were collected before and 0, 15, 30, and 90 min post-exercise. RESULTS: Acutely, REHIT was associated with a decrease in muscle glycogen, increased ACC phosphorylation, and activation of PGC1α. When compared to aerobic exercise, changes in VO2, RER, plasma volume, and plasma lactate and ghrelin were significantly more pronounced with REHIT, whereas plasma glucose, NEFAs, PYY, and measures of appetite were unaffected. CONCLUSIONS: Collectively, these data demonstrate that REHIT is associated with a pronounced disturbance of physiological homeostasis and associated activation of signalling pathways, which together may help explain previously observed adaptations once considered exclusive to aerobic exercise.

Asunto(s)

RESUMEN

Temperature can have a profound effect on the phenotype of reptilian offspring, yet the bulk of current research considers the effects of constant incubation temperatures on offspring morphology, with few studies examining the natural thermal variance that occurs in the wild. Over two consecutive nesting seasons, we placed temperature data loggers in 57 naturally incubating clutches of loggerhead sea turtles Caretta caretta and found that greater diel thermal variance during incubation significantly reduced offspring mass, potentially reducing survival of hatchlings during their journey from the nest to offshore waters and beyond. With predicted scenarios of climate change, behavioral plasticity in nest site selection may be key for the survival of ectothermic species, particularly those with temperature-dependent sex determination.

Asunto(s)

RESUMEN

This study investigated machine scrummaging at different playing levels in rugby union and analysed kinetic factors that might influence performance and injury risk. Thirty-four forward packs from six different playing levels scrummaged against an instrumented scrum machine under real environmental conditions. Applied forces were measured in three orthogonal directions. The peak (SD) of the overall compression forces during engagement ranged between 16.5 (1.4) kN (International-Elite) and 8.7 (0.1) kN (Women), while sustained compression forces spanned between 8.3 (1.0) kN (International) and 4.8 (0.5) kN (Women). The peak of the overall vertical force during the initial engagement phase was between -3.9 (0.7) kN (Elite) and -2.0 (1.0) kN (School), and the range of lateral forces was between 1.8 (0.3) kN (International) and 1.1 (0.3) kN (School). Forces measured across all playing levels, particularly during initial engagement, were generally higher than those measured in the most commonly cited previous studies. This increase may be due to a combination of changes in modern scrummaging technique, changes in players' anthropometrics, and experimental conditions that better respect ecological validity. The magnitude of the measured forces is in the range of values that studies on cadaveric specimens have indicated as potentially hazardous for (chronic) spine injuries.

Asunto(s)

RESUMEN

Speciation usually is conceptualized as occurring via three biogeographic modes: allopatry, parapatry, and sympatry. Sympatric speciation has been the most controversial because of the difficulty of developing plausible theoretical models in which the homogenizing effects of gene flow are sufficiently overcome to permit genetic divergence to occur in the absence of geographic barriers restricting gene flow. Recently, a number of hypothetical models for sympatric speciation have been advanced and several candidate study systems have provided evidence of sympatric divergence, although many of the systems so identified involve introduced species, especially in the cases of host-race formation in phytophagous insects, which expand their host range and use a novel host. Although these cases demonstrate the reality of sympatric divergence, they do not address which mode of speciation predominates in indigenous communities. Asphondylia borrichiae Rossi & Strong has been proposed as a potential example of sympatric divergence in a fully indigenous system, based on the results of a host-choice experiment involving three host-plant species. In the current study, we report significant differences in the genetic composition of midge populations collected from each host in situ, supporting the hypothesis of sympatric genetic divergence among the morphologically identical host-associated populations of A. borrichiae and consistent with host fidelity in oviposition choice.

Asunto(s)