Biomechanical analysis of traction at the shoe-surface interface on third-generation artificial turf

The existing knowledge of traction on artificial turf is based almost exclusively on mechanical devices. While most attention has traditionally been concentrated on rotational traction, sports such as soccer predominantly involve translational movements. The aim of the study was to investigate whether translational traction at the shoe-surface interface differed between various third-generation artificial turf systems in combination with different cleat configurations in vivo. Twenty-two male soccer players performed five short sprints with a 90° cut over a turf-covered force plate for each combination of three turf systems and three cleat configurations. The results showed that, despite various differences in other traction measures, traction coefficients were almost identical across turf systems and cleat configurations.     

Mechanical behaviour of natural turf sports pitches across a season

A study assessing the mechanical behaviour of six natural turf pitches of varying sporting level and surface construction was undertaken over a period of 10?months, spanning a sporting season (August 2010 to May 2011). Penetration resistance and shear resistance were measured with the GoingStick^?, impact hardness and surface energy absorption were measured with the 2.25?kg Clegg Impact Soil Tester and the Dynamic Surface Tester device, respectively. The two sand rootzone pitches were more resistant to deformation and less variable in their impact behaviour (impact hardness and energy absorption) through the season than the native soil pitches containing greater proportions of silt and clay. Greater consistency was shown for penetration resistance and shear resistance on one of the sand rootzone pitches, with the other behaving similar to the native soil pitches for these parameters. The sand rootzone surfaces exhibited greater (P?<?0.05) impact hardness than the native soil pitches in the winter period of the season (November to mid-March) compared to the beginning or end periods of the season, where data were statistically similar (P?>?0.05). The greater consistency of sand rootzone surfaces should be considered for the effect it may have on player and team performance, and injury potential. Analysis of data against Performance Quality Standard benchmarks indicated that all data on the sand rootzones exceeded preferred values for impact hardness, indicating these ranges may be obsolete for the modern elite natural turf surface.     

The predicted risk of head injury from fall-related impacts on to third-generation artificial turf and grass soccer surfaces: A comparative biomechanical analysis

The risk of soccer players sustaining mild traumatic brain injury (MTBI) following head impact with a playing surface is unclear. This study investigates MTBI by performing headform impact tests from varying heights onto a range of third-generation artificial turf surfaces. Each turf was prepared as per manufacturers specifications within a laboratory, before being tested immediately following installation and then again after a bedding-in period. Each turf was tested dry and when wetted to saturation. Data from the laboratory tests were compared to an in situ third-generation surface and a professional grass surface. The surface performance threshold was set at a head impact criterion (HIC) = 400, which equates to a 10% risk of the head impact causing MTBI. All six third-generation surfaces had a >10% risk of MTBI from a fall >0.77 m; the inferior surfaces required a fall from just 0.46 m to have a 10% MTBI risk. Wetting the artificial turf did not produce a statistically significant improvement (P > 0.01). The in situ third-generation playing surface produced HIC values within the range of bedded-in experimental values. However, the natural turf pitch was the superior performer – necessitating fall heights exceeding those achievable during games to achieve HIC = 400.     

Does soccer cleat design influence the rotational interaction with the playing surface?

Non-contact injuries in soccer players may be related to the interplay between cleat type and playing surface, and bladed shoes were often blamed for non-contact injuries with no research support. The aim of this study was to compare the rotational resistance (stiffness and peak sustainable torque) among three types of soccer cleats (metal studs, molded rubber studs, and bladed) in a controlled laboratory environment. The shoes were tested on both natural and artificial turfs under a compressive preload of 1000 N and with internal and external rotations. The three shoe models showed comparable performances with a good repeatability for each individual test on both playing surfaces. A less stiff behavior was observed for the natural turf. A tendency toward highest peak torque was observed in the studded model on natural surface. The bladed cleats provided peak torque and rotational stiffness comparable to the other models. Studded and bladed cleats did not significantly differ in their interaction with the playing surface. Therefore, soccer shoes with bladed cleats should not be banned in the context of presumed higher risk for non-contact injuries.     

Footwear traction at different areas on artificial and natural grass fields

Footwear traction has been linked to lower-extremity injuries with the theory that higher traction leads to an increased incidence of injury. Recent studies have challenged this showing similar injury rates on artificial turf, which has higher traction than natural grass. This could suggest that the magnitude of traction may not be as relevant for injury as relative changes from one location to another, due to inconsistencies in the surface. The purpose of this study was to compare the traction at various locations on an in-fill artificial turf and natural grass surface. A portable traction tester measured the traction of three shoes at six locations on both surfaces. The results indicate that over the course of a season the traction on natural grass changes considerably, especially rotational traction. Surprisingly the artificial turf surface also had areas of high and low traction due to the movement of the in-fill material during play.     

Influence of the composition of artificial turf on rotational traction and athlete biomechanics

Artificial turf advances have enabled surfaces to behave like natural grass, however, debate remains as to whether artificial turf is as safe as natural grass. To reduce injury risk, sport surfaces should have low rotational traction with artificial surfaces having a potential advantage as components can be manipulated to change surface properties and traction. The purpose of this study was to investigate the influence that different components of artificial turf have on rotational traction and athlete lower extremity joint loading. Twelve surfaces underwent mechanical testing to determine the influence of fibre density, fibre length, infill composition and compaction on rotational traction. Following mechanical testing, Control, Low and High Traction surfaces were selected for biomechanical analysis, where sixteen athletes performed maximum effort v-cuts while kinematic/kinetic data were recorded on each surface. Mechanically, fibre density, type of infill and compaction of the surface each independently influenced traction. The traction differences were substantial enough to alter the athlete kinematics and kinetics. Low traction surfaces reduced ankle and knee loading, while high traction surfaces increased ankle and knee loading . Reducing the rotational traction of sport surfaces is possible through alterations of individual components, which may reduce the joint loading at the knee and ankle joint.     

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.     

Does variability within natural turfgrass sports fields influence ground-derived injuries?

Natural turfgrass sports fields exhibit within-field variations due to climatic conditions, field construction, field management, and foot traffic patterns from field usage. Variations within a field could influence the playing surface predictability and require athletes to make abrupt or frequent adjustments that lead to increased ground-derived injury occurrence. This study introduces a new methodology aimed at evaluating the potential relationship between within-field variations of turfgrass sports field properties and ground-derived athlete injuries. Collegiate Club Sport athletes self-reported ground-derived injuries over two years. Soil moisture, turfgrass quality, surface hardness, and turfgrass shear strength were quantified from their two home fields. Hot spot analysis identified significantly high (hot spots) and low (cold spots) values within the fields. Injury locations were compared to hot spot maps each month. Binomial proportion tests determined if there were differences between observed injury proportions and expected proportions. Twenty-three ground-derived injuries were reported overall. The observed injury proportions occurring in turfgrass quality cold spots [0.52 (95% CI 0.29–0.76)] and soil moisture hot spots [0.43 (95% CI 0.22–0.66)] was significantly higher than expected [0.20 (p?p?相似文献   

Dynamic behaviour of soils used for natural turf sports surfaces

The modulus and damping properties of soils in compression are a function of soil type, water content, stress history and loading rate. To model human–surface interaction with natural turf sports surfaces, stiffness and damping properties must be determined at dynamic loading rates. Two contrasting soil types, a Sand and a Clay Loam, commonly used in sports surfaces were loaded uniaxially to 2 kN at loading rates between 0.6 and 6 kN s⁻¹ in modified dynamic soil testing apparatus. Soils were compacted prior to loading but initial cycles resulted in viscoplastic deformation, with strain accumulation with repeated cycles of loading. Ultimately a resilient, viscoelastic steady-state equilibrium with loading was established. Resilient modulus and damping ratio varied with soil type, water content, stress history and increased significantly with loading rate. The resilient modulus of the Sand soil, typical of modern free-draining sand construction natural turf sports surfaces, was significantly greater than that of a Clay Loam soil more characteristic of traditional natural turf surfaces; reducing water content caused an increase in modulus and a decrease in damping ratio in the Clay Loam soil. Determination of these properties provides initial data for the modelling natural turf surface behaviour in terms of both ball and human interactions, with further research required to determine the effect of both grass roots and leaves on mechanical behaviour.     

Spatial characterisation of natural and third-generation artificial turf football pitches

In contrast to the situation with early artificial turf pitches, little information has previously been published on the characterisation of third-generation artificial surfaces. The spatial variation of ball rebound resilience and rotational resistance were measured here under dry conditions, late in the season, for two natural turf football pitches and a recently laid third-generation artificial turf pitch. Data for the natural turf pitches show a wider variation with position on the pitch than for the artificial pitch. The latter surface showed remarkable consistency in both quantities measured. Surprisingly, all ball rebound resilience data and some of the rotational resistance values were found to lie outside current FIFA specifications, possibly due to the level of wear in natural turf at this stage of the season. For the artificial turf, the deterioration in properties over a period of 6 months is significant and suggests more frequent testing is needed. Taking data from various pitch positions, the two measured quantities were shown for the first time, as far as we are aware, to be inversely related for both natural turf pitches. This correlation may be largely attributed to differences in the extent of grass cover and/or soil compaction. For artificial turf, the lack of variation in measured quantities with pitch position precluded the determination of any correlation.     

Effect of turf on the cutting movement of female football players

PurposeThe globalisation of artificial turf and the increase in player participation has driven the need to examine injury risk in the sport of football. The purpose of this study was to investigate the surface–player interaction in female football players between natural and artificial turf.MethodsEight university level female football players performed an unanticipated cutting manoeuvre at an angle of 30° and 60°, on a regulation natural grass pitch (NT) and a 3G artificial turf pitch (AT). An automated active maker system (CodaSport CXS System, 200 Hz) quantified 3D joint angles at the ankle and knee during the early deceleration phase of the cutting, defined from foot strike to weight acceptance at 20% of the stance phase. Differences were statistically examined using a two-way (cutting angle, surface) ANOVA, with an α level of p < 0.05 and Cohen's d effect size reported.ResultsA trend was observed on the AT, with a reduction in knee valgus and internal rotation, suggesting a reduced risk of knee injury. This findings highlight that AT is no worse than NT and may have the potential to reduce the risk of knee injury. The ankle joint during foot strike showed large effects for an increase dorsiflexion and inversion on AT. A large effect for an increase during weight acceptance was observed for ankle inversion and external rotation on AT.ConclusionThese findings provide some support for the use of AT in female football, with no evidence to suggests that there is an increased risk of injury when performing on an artificial turf. The ankle response was less clear and further research is warranted. This initial study provides a platform for more detailed analysis, and highlights the importance of exploring the biomechanical changes in performance and injury risk with the introduction of AT.     

The effect of stud configuration on rotational traction using the studded boot apparatus

Due to its associated injury risk, rotational traction is a frequently measured natural turf surface property. The most commonly used equipment, the studded boot apparatus (SBA), consists of a circular stud configuration that does not replicate the stud pattern on a regular football boot and may under or over estimate the surface traction. The aim of this study was to establish potential differences in the rotational traction measured between the current stud configuration on the SBA and the stud configuration on the most commonly used Australian football boots. The original studded boot had significantly higher rotational traction than the moulded stud sole or bladed sole. Location, quality and time tested all interacted significantly with the rotational traction measured. The current SBA may not accurately represent the rotational traction experienced by football players, and consequently may not be the most appropriate configuration to assess the relationship between rotational traction and injuries.     

解析足球全球化对世界足球运动的发展

全球化是近年流行的一个概念,在政治、经济和文化领域的影响深远,特别是经济的全球化带动了其他各领域全球化的发展．本文从足球与社会、经济、管理体制等方面的相互影响以及足球的全球化趋势角度出发,着重分析和论述了足球全球化对世界足球运动所带来的机遇和挑战,并提出了认清全球化发展的趋势,处理好各种矛盾,科学地应对各种挑战,使足球运动更好地完善发展的观点。     

Modifying landing mat material properties may decrease peak contact forces but increase forefoot forces in gymnastics landings

This study investigated how changes in the material properties of a landing mat could minimise ground reaction forces (GRF) and internal loading on a gymnast during landing. A multi-layer model of a gymnastics competition landing mat and a subject-specific seven-link wobbling mass model of a gymnast were developed to address this aim. Landing mat properties (stiffness and damping) were optimised using a Simplex algorithm to minimise GRF and internal loading. The optimisation of the landing mat parameters was characterised by minimal changes to the mat's stiffness (<0.5%) but increased damping (272%) compared to the competition landing mat. Changes to the landing mat resulted in reduced peak vertical and horizontal GRF and reduced bone bending moments in the shank and thigh compared to a matching simulation. Peak bone bending moments within the thigh and shank were reduced by 6% from 321.5 Nm to 302.5Nm and GRF by 12% from 8626 N to 7552 N when compared to a matching simulation. The reduction in these forces may help to reduce the risk of bone fracture injury associated with a single landing and reduce the risk of a chronic injury such as a stress fracture.     

Modifying landing mat material properties may decrease peak contact forces but increase forefoot forces in gymnastics landings

This study investigated how changes in the material properties of a landing mat could minimise ground reaction forces (GRF) and internal loading on a gymnast during landing. A multi-layer model of a gymnastics competition landing mat and a subject-specific seven-link wobbling mass model of a gymnast were developed to address this aim. Landing mat properties (stiffness and damping) were optimised using a Simplex algorithm to minimise GRF and internal loading. The optimisation of the landing mat parameters was characterised by minimal changes to the mat's stiffness ( < 0.5%) but increased damping (272%) compared to the competition landing mat. Changes to the landing mat resulted in reduced peak vertical and horizontal GRF and reduced bone bending moments in the shank and thigh compared to a matching simulation. Peak bone bending moments within the thigh and shank were reduced by 6% from 321.5 Nm to 302.5 Nm and GRF by 12% from 8626 N to 7552 N when compared to a matching simulation. The reduction in these forces may help to reduce the risk of bone fracture injury associated with a single landing and reduce the risk of a chronic injury such as a stress fracture.     

Single Functional Movement Screen items as main predictors of injury risk in amateur male soccer players

The Functional Movement Screen (FMS) has been applied to identify predisposed players, mainly in professional sports, and their injury risk. Empirical evidence on the FMS in amateur soccer is scant. Furthermore, the composite FMS score contains upper, lower, and core-related body items, which might be related differently in soccer-specific injury incidences. The aim of this study was twofold: to investigate the relationship between the composite FMS score and the injury incidence of amateur soccer players and to analyze the contribution of single FMS test items to the injury state. In all, 83 amateur male soccer players (23?±?4 years old) were evaluated using the FMS prior to the preparation period of the 2016/2017 season. Injuries (lower extremities, non-contact, time loss) were continuously documented throughout the first competition period. The composite FMS score differed significantly (p?=?0.017) between injured (15.1?±?2.5) and non-injured (16.5?±?2) players. A twofold increase in the risk of injury was found for a composite FMS score of 14 or less. Significant correlations between single test items with a score?≤?2 and injured players were found for the trunk stability push-up exercise (χ²?=?17.4, df?=?1, p?<?0.001, φ?=?0.5) and the rotary stability exercise (χ²?=?6.7, df?=?1, p?=?0.009, φ?=?0.3). The composite FMS score seems to be an indicator of injury risk in amateur soccer with injured players having lower core stability and lower core strength.     

中、日、韩青少年足球运动员培养体系的比较研究

采用对比分析方法,对中、日、韩青少年足球运动员的培养体系中的培养途径、培养目标、教练员队伍建设、训练和教学理念、竞赛体系等诸多因素进行全面的比较研究,深入认识中、日、韩青少年足球运动员培养体系的异同,分析各自的优点与不足,提出了中国青少年足球运动员培养应制定符合我国实际的培养体系,以推动我国青少年足球工作的不断改善。     

Quasi-static mechanical behaviour of soils used for natural turf sports surfaces and stud force prediction

The quasi-static testing of soils used in natural turf pitches yields key parameters in soil modelling, including elastic moduli, Poisson’s ratio and Mohr–Coulomb parameters for shearing resistance and cohesion in soil. The bulk strength of a Sand soil used in the construction of elite sports surfaces was found to increase initially and then decrease with increasing water content due to apparent cohesion effects. For a Clay Loam soil, more common in recreational facilities, shear strength decreased with water content. Reducing density resulted in a reduction of shear strength and elastic moduli in both soils due to reduced packing of particles reducing particle–particle contact surface area. The effect of roots on the shear strength of a Sand soil was not significant but reduced elastic moduli significantly. Horizontal forces measured during running and turning in a biomechanics laboratory were in good agreement with forces predicted using a simple quasi-static soil model for coarse-grained (Sand) soils although this was not the case with the Clay Loam soil.     

纳米材料在体育工程中的应用及其生物安全性研究

纳米材料已广泛应用于体育场馆、运动草坪、田径跑道、运动服装、体育器材及运动补剂等方面,同时纳米材料进入机体也可能对细胞、肺组织、肝肾组织、脑组织带来负面影响,存在一定的生物安全隐患。在充分利用纳米材料对体育工程发展积极效应的同时,应该重视和加强对纳米材料的生物性研究。     

Association of different types of playing surfaces with bone mass in growing girls

The aim of this cross-sectional study was to compare bone mass in young female athletes playing ball games on different types of playing surfaces. About 120 girls, 9–13 years of age (10.6 ± 1.5 years old Tanner I–III) were recruited and divided into prepubertal and pubertal groups. The sample represented 3 groups of athletes: soccer (N = 40), basketball (N = 40), and handball (N = 40); and 6 different playing surfaces (soccer – ground, soccer – artificial turf, basketball – synthetic, basketball – parquet, handball – synthetic, and handball – smooth concrete). Total and regional body composition (bone mass, fat mass, and lean mass) were measured by dual-energy X-ray absorptiometry (DXA). The mechanical properties of the surfaces (force reduction, vertical deformation, and energy return) were measured with the Advanced Artificial Athlete (Triple A) method. The degree of sexual development was determined using Tanner test. The pubertal group showed that soccer players on the ground, basketball players on synthetic, and handball players on smooth concrete had higher values of bone mineral content (BMC) and bone mineral density (BMD) (P < 0.05) than the soccer players on the artificial turf, basketball players on parquet, and handball players on synthetic. In conclusion, a hard playing surface, with less vertical deformation and force reduction, and greater energy return, is associated with higher levels of BMD and BMC in growing girls, regardless of the sport they practice.