Risk of injury associated with rugby union played on artificial turf

Abstract

The aim of this study was to compare the incidence, nature, and cause of injuries sustained in rugby union played on artificial turf and grass. The study comprised a two-season investigation of match injuries sustained by six teams competing in Hong Kong's Division 1 and training injuries sustained by two teams in the English Premiership. Injury definitions and recording procedures were compliant with the international consensus statement on epidemiological studies of injuries in rugby union. There were no significant differences in the overall incidence (rate ratio = 1.42; P = 0.134) or severity (P = 0.620) of match injuries sustained on the two surfaces. The lower limb and joint (non-bone)/ligament injuries were the most common location and type of match injury on both surfaces; the incidence of anterior cruciate ligament injuries was nearly four times higher on artificial turf than grass but the difference was not statistically significant (rate ratio = 3.82; P = 0.222). There were no significant differences in the overall incidence (rate ratio = 1.36; P = 0.204) or severity (P = 0.302) of training injuries sustained on artificial turf and grass. The lower limb and muscle/tendon injuries were the most common location and type of training injury on both surfaces. The results indicate that the overall risks of injury on artificial turf are not significantly different from those experienced on grass; however, the difference in the incidence of anterior cruciate ligament injuries on the two surfaces is worthy of further study.     

Sport-specific biomechanical responses to an ACL injury prevention programme: A randomised controlled trial

Anterior cruciate ligament (ACL) injury prevention programmes have not been as successful at reducing injury rates in women’s basketball as in soccer. This randomised controlled trial (ClinicalTrials.gov #NCT02530333) compared biomechanical adaptations in basketball and soccer players during jump-landing activities after an ACL injury prevention programme. Eighty-seven athletes were cluster randomised into intervention (6-week programme) and control groups. Three-dimensional biomechanical analyses of drop vertical jump (DVJ), double- (SAG-DL) and single-leg (SAG-SL) sagittal, and double- (FRONT-DL) and single-leg (FRONT-SL) frontal plane jump landing tasks were tested before and after the intervention. Peak angles, excursions, and joint moments were analysed using two-way MANCOVAs of post-test scores while controlling for pre-test scores. During SAG-SL the basketball intervention group exhibited increased peak knee abduction angles (p = .004) and excursions (p = .003) compared to the basketball control group (p = .01) and soccer intervention group (p = .01). During FRONT-SL, the basketball intervention group exhibited greater knee flexion excursion after training than the control group (p = .01), but not the soccer intervention group (p = .11). Although women’s soccer players exhibit greater improvements in knee abduction kinematics than basketball players, these athletes largely exhibit similar biomechanical adaptations to ACL injury prevention programmes.     

Effects of treadmill versus overground soccer match simulations on biomechanical markers of anterior cruciate ligament injury risk in side cutting

This study aimed to investigate whether treadmill versus overground soccer match simulations have similar effects on knee joint mechanics during side cutting. Nineteen male recreational soccer players completed a 45-min treadmill and overground match simulation. Heart rate (HR) and rating of perceived exertion (RPE) were recorded every 5 min. Prior to exercise (time 0 min), at “half-time” (time 45 min) and 15 min post-exercise (time 60 min), participants performed five trials of 45° side-cutting manoeuvres. Knee abduction moments and knee extension angles were analysed using two-way repeated measures analysis of variance (α = 0.05). Physiological responses were significantly greater during the overground (HR 160 ± 7 beats ? min^?1; RPE 15 ± 2) than the treadmill simulation (HR 142 ± 5 beats ? min^?1; RPE 12 ± 2). Knee extension angles significantly increased over time and were more extended at time 60 min compared with time 0 min and time 45 min. No significant differences in knee abduction moments were observed. Although knee abduction moments were not altered over time during both simulations, passive rest during half-time induced changes in knee angles that may have implications for anterior cruciate ligament injury risk.     

The influence of playing surface on physiological and performance responses during and after soccer simulation

The aim of this study was to investigate the effect of playing surface on physiological and performance responses during and in the 48 h after simulated soccer match play. Blood lactate, single-sprint, repeated-sprint and agility of eight amateur soccer players were assessed throughout a 90-min soccer-simulation protocol (SSP) completed on natural turf (NT) and artificial turf. Counter-movement jump, multiple-rebound jump, sprint (10 m, 60 m), L-agility run (L-AR), creatine kinase (CK) and perception of muscle soreness (PMS) were measured before, immediately after, 24 h and 48 h after exercise. Analyses revealed significant changes in blood lactate and single-sprint performance (both P < 0.05) during the SSP but with no significant differences between surfaces. Conversely, repeated-sprint performance demonstrated an interaction effect, with reductions in performance evident on NT only (P < 0.05). Whilst L-AR and 10-m sprint performance remained unchanged, 60-m sprint and multiple-rebound jump performance were impaired, and PMS and CK were elevated immediately following the SSP (all P < 0.05) but with no surface effects. Although performance, CK and PMS were negatively affected to some degree in the 48 h after the SSP, there was no surface effect. For the artificial and natural surfaces used in the present study, physiological and performance responses to simulated soccer match play appear to be similar. Whilst a potential for small differences in performance response exists during activity, surface type does not affect the pattern of recovery following simulated match play.     

Acute responses of soccer match play on hip strength and flexibility measures: potential measure of injury risk

Abstract

Regular measurements of groin risk factors may offer a preventive measure against injury. Therefore, the aim of this study was to (1) determine minimal detectable change (MDC) and reliability of hip flexibility and strength measures and to (2) identify the effect soccer match play load has on these measures. Reliability was determined for bent knee fall out test, hip abduction and adduction (hand-held dynamometry (HHD)) in 20 trained youth male soccer players. Reliability was evaluated with the intra-class correlation coefficient (ICC_[2,1]), 95% confidence intervals (CI). Hip strength and flexibility measures were taken before and after an international friendly match. Intra-rater reliability ICC ranges were bent knee fall out (0.75–0.90), abduction (0.83–0.90) and adduction (0.72–0.96). Inter-rater ICCs (95% CI) were bent knee fall out test [0.75 (0.39–0.90) right, 0.71 (0.27–0.89) left hip]; abduction [0.80 (0.50–0.92) right, 0.81 (0.53–0.92) left hip] and adduction [0.72 (0.31–0.89) right, 0.70 (0.26–0.88) left hip]. MDCs were as low as 20.7% of the mean for hip flexibility and 12.5% for strength. In conclusion, HHD and the bent knee fall out test are reliable tools to measure changes in hip strength and flexibility. Finally, a threshold may exist in which match play load negatively impacts hip flexibility.     

The mechanics of American football cleats on natural grass and infill-type artificial playing surfaces with loads relevant to elite athletes

This study quantified the mechanical interactions of 19 American football cleats with a natural grass and an infill-type artificial surface under loading conditions designed to represent play-relevant manoeuvres of elite athletes. Variation in peak forces and torques was observed across cleats when tested on natural grass (2.8–4.2 kN in translation, 120–174 Nm in rotation). A significant (p < 0.05) relationship was found between the peak force and torque on natural grass. Almost all of the cleats caused shear failure of the natural surface, which generated a divot following a test. This is a force-limiting cleat release mode. In contrast, all but one of the cleat types held fast in the artificial turf, resulting in force and torque limited by the prescribed input load from the test device (nom. 4.8 kN and 200 Nm). Only one cleat pattern, consisting of small deformable nubs, released on the artificial surface and generated force (3.9 kN) comparable to the range observed with natural grass. These findings (1) should inform the design of cleats intended for use on natural and artificial surfaces and (2) suggest a mechanical explanation for a higher lower-limb injury rate in elite athletes playing on artificial surfaces.     

Comparative analysis of sequentiality using SDIS-GSEQ and THEME: A concrete example in soccer

Abstract

Within an observational design aimed at studying what type of soccer is better adapted to the possibilities of the 11–12 year-old child, a comparison was made of the results obtained using two fully consolidated analysis techniques in observational methods, and which form the basis in the development of two respective software programs: SDIS-GSEQ and THEME, which allow one to detect the existence of sequential patterns hidden in a data set. This work is intended to shed light on the comparison of results obtained using these two analysis techniques. In particular, the data used for the analysis are multicode event data (using the lexicon of the sequential analysis), and do not incorporate the duration parameter. Accordingly, for the detection of regular structures using the THEME program (T-patterns), a constant duration has conventionally been assigned to each occurrence. Using THEME, among the greatest number of sequential structures detected, diachronic and synchronic correspondence was observed (T-patterns reflecting identical multi-events) with each and every one of the sequential patterns obtained using the lag technique, by the SDIS-GSEQ software. This coincidence strengthens the link between the algorithms that support SDIS-GSEQ and THEME. The results indicate that 7-a-side soccer and 9-a-side soccer types facilitate the spatial mastery of the game by the child, compared with the adult form, 11-a-side soccer.     

中长跑运动员胫骨疲劳性损伤的生物力学机制分析及预防

从解剖学和生物力学的角度,对长跑运动员运动中胫骨所受应力进行了动态分析,进而阐述中长跑运动员常发性胫骨疲劳性损伤的生物力学原因。并对此提出针对性的预防措施。     

Body composition assessment of English Premier League soccer players: a comparative DXA analysis of first team,U21 and U18 squads

Professional soccer players from the first team (1st team, n = 27), under twenty-one (U21, n = 21) and under eighteen (U18, n = 35) squads of an English Premier League soccer team were assessed for whole body and regional estimates of body composition using dual-energy X-ray absorptiometry (DXA). Per cent body fat was lower in 1st team (10.0 ± 1.6) compared with both U21 (11.6 ± 2.5, P = 0.02) and U18 (11.4 ± 2.6, P = 0.01) players. However, this difference was not due to variations (P = 0.23) in fat mass between squads (7.8 ± 1.6 v 8.8 ± 2.1 v 8.2 ± 2.4 kg, respectively) but rather the presence of more lean mass in 1st team (66.9 ± 7.1 kg, P < 0.01) and U21 (64.6 ± 6.5 kg, P = 0.02) compared with U18 (60.6 ± 6.3 kg) players. Accordingly, fat mass index was not different (P = 0.138) between squads, whereas lean mass index was greater (P < 0.01) in 1st team players (20.0 ± 1.1 kg · m^?2) compared with U18 players (18.8 ± 1.4 kg · m^?2). Differences in lean mass were also reflective of higher lean tissue mass in all regions, for example, upper limbs/lower limbs and trunk. Data suggest that training and nutritional interventions for younger players should therefore be targeted to lean mass growth as opposed to body fat loss.     

The influence of hand positions on biomechanical injury risk factors at the wrist joint during the round-off skills in female gymnastics

The aim of this study was to examine the biomechanical injury risk factors at the wrist, including joint kinetics, kinematics and stiffness in the first and second contact limb for parallel and T-shape round-off (RO) techniques. Seven international-level female gymnasts performed 10 trials of the RO to back handspring with parallel and T-shape hand positions. Synchronised kinematic (3D motion analysis system; 247 Hz) and kinetic (two force plates; 1235 Hz) data were collected for each trial. A two-way repeated measure analysis of variance (ANOVA) assessed differences in the kinematic and kinetic parameters between the techniques for each contact limb. The main findings highlighted that in both the RO techniques, the second contact limb wrist joint is exposed to higher mechanical loads than the first contact limb demonstrated by increased axial compression force and loading rate. In the parallel technique, the second contact limb wrist joint is exposed to higher axial compression load. Differences between wrist joint kinetics highlight that the T-shape technique may potentially lead to reducing these bio-physical loads and consequently protect the second contact limb wrist joint from overload and biological failure. Highlighting the biomechanical risk factors facilitates the process of technique selection making more objective and safe.     

Hill on a mountaintop: A longitudinal and cross-sectional analysis of the relative age effect in competitive youth football

ABSTRACT

The aim of this study was to examine the origin and persistence of the relative age effect (RAE) in competitive youth football. To examine its origin, birthdates of 121 category one Premier League academy players recruited over 6 years were compared with 691 Under 8 (U8) players in one of the regional grassroots leagues from which academy players are selected. To examine the persistence of the RAE we conducted a longitudinal comparison of retention rates in early-birth and late-birth academy players from U9 to U15, and made a cross-sectional comparison of birthdate distributions from U7 to U18 in 10,857 regional league players. The results revealed birthdate asymmetry in both the academy and grassroots players but a much larger RAE in the academy. Longitudinal analysis revealed that the cumulative probability of retention at the academy was higher for early-birth than late-birth players. A small to medium RAE persisted across grassroots football age groups though it declined somewhat from U15 to U18. The implication of these results for academy player recruitment is discussed.     

胰岛素对缺血再灌注心肌的保护作用及其机制与运动干预的研究进展

目的:通过探讨胰岛素对缺血再灌注心肌的保护作用及其机制,分析运动干预的应用前景。方法:采用文献资料法、前瞻性分析与逻辑推理相结合的方法,总结胰岛素对缺血再灌注心肌的保护作用及其机制的研究进展以及在运动医学领域中所发挥的重要作用。结论:胰岛素可减轻缺血再灌注心肌细胞的炎症反应,增强心室肌细胞的收缩及钙的瞬变,减少心肌细胞凋亡,提高NO的含量,改善心肌超微结构的改变,从而抑制缺血再灌注过程中脂质过氧化物的升高,清除氧自由基,同时增加Akt的表达及活化,促进再灌注后心肌细胞功能的恢复,在此过程中激活PI3k途径,发挥对缺血再灌注心肌的保护作用。运动干预则与其发挥协同作用,增强对心肌的保护作用,有效地缓解缺血再灌注后心肌的损伤。     

The relationship between performance of a single-leg squat and leap landing task: moving towards a netball-specific anterior cruciate ligament (ACL) injury risk screening method

ABSTRACT

Field-based screening methods have a limited capacity to identify high-risk postures during netball-specific landings associated with anterior cruciate ligament (ACL) injuries. This study determined the biomechanical relationship between a single-leg squat and netball-specific leap landing, to examine the utility of including a single-leg squat within netball-specific ACL injury risk screening. Thirty-two female netballers performed single-leg squat and netball-specific leap landing tasks, during which three-dimensional (3D) kinematic/kinetic data were collected. One-dimensional statistical parametric mapping examined relationships between kinematics from the single-leg squat, and the 3D joint rotation and moment data from leap landings. Participants displaying reduced hip external rotation, reduced knee flexion, and greater knee abduction and knee internal rotation angles during the single-leg squat exhibited these same biomechanical characteristics during the leap landing (p < 0.001). Greater ankle dorsiflexion during the single-leg squat was associated with greater knee flexion during landing (p < 0.001). Ankle eversion during the single-leg squat was associated with frontal and transverse plane knee biomechanics during landing (p < 0.001). Biomechanics from the single-leg squat were associated with landing strategies linked to ACL loading or injury risk, and thus may be a useful movement screen for identifying netball players who exhibit biomechanical deficits during landing.     

The role of ultrasonography in the diagnosis of anterior cruciate ligament injury: A systematic review and meta-analysis

To evaluate the value of ultrasonography in the diagnosis of anterior cruciate ligament injury (ACL injury) by conducting a systematic review and meta-analysis. A literature search was carried out in the Cochrane Library, Embase, Pubmed databases and included studies prior to April 2017. Based on inclusion and exclusion criteria, studies evaluating ultrasound to diagnose ACL injury were selected. MRI, arthroscopy and clinical-follow were considered the reference standards. The diagnostic accuracy of ultrasound was assessed using a combination of sensitivity, specificity, likelihood ratio (LR), post-test probability, diagnostic odds ratio (DOR) and by summarizing the area under the receiver operating characteristic (SROC) curve. A total of 4 studies involving 246 patients were eventually included in the analysis. In these four studies, the combined sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, post-test probability and DOR were 90.0% (95% CI: 77–96), 97% (95% CI: 90–99), 31.08 (95% CI: 8.75–110.41), 0.11 (95% CI: 0.05–0.24), 89% (3%) and 288.81 (95% CI: 78.51–1062.48), respectively. The area under the SROC curve was 0.98 (95% CI: 0.97–0.99). Our meta-analysis showed that ultrasound can play an important role in the diagnosis of ACL injury. Because of its high sensitivity, high specificity and high diagnostic ability, ultrasound should be a part of the standard diagnostic work-up of an ACL injury.     

The effect of smartphones and playing video games on decision-making in soccer players: A crossover and randomised study

ABSTRACT

The objective of this study was to analyse the effect of the use of social networks in smartphones or playing video games on the passing decision-making performance in professional soccer athletes. Participants were 25 male professional soccer athletes (mean ± SD: age 23.4 ± 2.8 years). The participants performed three randomised conditions divided into three groups: control (CON), smartphone (SMA), and video game (VID). Before and after each experimental condition, the Stroop Task assessed the level of induced mental fatigue. Then, the athletes performed a simulated soccer match. A CANON® camera recorded the matches for further analysis on passing decision-making performance. A group effect was identified (p < .01) with impairment on passing decision-making performance for the SMA (p = .01, ES = 0.5) and VID (p = .01, ES = 0.5) conditions. We concluded that the use of social networks on smartphones and/or playing video games right before official soccer matches might impair the passing decision-making performance in professional soccer athletes.     

A season long investigation into the effects of injury,match selection and training load on mental wellbeing in professional under 23 soccer players: A team case study

Abstract

This study examined the influence of injury, match selection and training load on mental wellbeing (MW) in a squad of professional soccer players. Using a longitudinal design, twenty-five male soccer players (age, 20?±?1 years, height, 1.80?±?5.79 m, body mass 76.33?±?7.52?kg) from the under 23 squad playing in the Premier League 2 division in the UK completed the Warwick–Edinburgh Mental Well-being Scale (WEMWBS) each week of the 2017/2018 season (37 weeks in total). Injury and non-selection for the match squad were the only significant predictors of MW (P?<?0.05). Injury had the biggest influence on MW that was lower when injured vs. not injured (43.6?±?5.0 vs. 49.9?±?3.5, respectively, P?=?0.001, ES?=?1.48), accounting for 40% of the variation in MW. This increased to 50% when not being selected to play games was also considered. Weekly training loads measured by GPS (total distance, sprint distance and total duration) and individual player win rate did not influence MW (P?>?0.05). These findings highlight the importance of monitoring MW in professional soccer players and suggest that injured players and those rarely selected for the match squad should be educated on the strategies available for managing their mental health and wellbeing.     

海南省7～18岁汉、黎族女生身体形态3项指标的比较

在2000年体质调研的基础上，对海南7-18岁、汉、黎族女生身体形态中身高、体重、胸围3项指标进行统计分析，试图了解海南不同地域、不同种族女生身体形态发育基本规律和特征，为在今后体育教学和营养方面的改进提供依据。     

对中外体育教师继续教育模式的研究——兼谈学校在职本位模式

运用献资料、比较分析、逻辑分析、专家访谈的方法，探讨了国内外几种体育教师继续教育模式的特点，通过对比，提出了我国体育教师继续教育模式的不足。在借鉴发达国家继续教育模式的基础上，提出了改进现有的学校在职本位模式的建议。     

第23届亚锦赛中国男篮与对手守转攻状况比较研究

通过对中国男篮在第23届亚洲篮球锦标赛上与对手的守转攻获球方式和进攻效果的统计分析，发现中国男篮由防守转入进攻的获球方式以抢获篮板球方式为最多，但二次进攻的外围得分却明显低于对手；进攻时犯规相对较多；在固定进攻战术配合方法和时机的选择及技术的合理运用上尚显不足。因此本文针对其现存的问题提出相关建议。     

The effect of biofeedback training on affective regulation and simulated car-racing performance: A multiple case study analysis

Abstract

In this study, we wished to investigate the factors that determine the direction of the spin axis of a pitched baseball. Nineteen male baseball pitchers were recruited to pitch fastballs. The pitching motion was recorded with a three-dimensional motion analysis system (1000 Hz), and the orientations of the hand segment in a global coordinate system were calculated using Euler rotation angles. Reflective markers were attached to the ball, and the direction of the spin axis was calculated on the basis of their positional changes. The spin axis directions were significantly correlated with the orientations of the hand just before ball release. The ball is released from the fingertip and rotates on a plane that is formed by the palm and fingers; the spin axis of the ball is parallel to this plane. The lift force of the pitched baseball is largest when the angular and translational velocity vectors are mutually perpendicular. Furthermore, to increase the lift forces for the fastballs, the palm must face home plate.