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Energy storage and return in sport surfaces
Abstract
The purpose of this paper was to determine the energy input, return and dissipation of sport surfaces using the FE analysis based on actual ground reaction forces. A three-dimensional finite element model of an existing running track was created. A viscoelastic material model was implemented using experimentally determined parameters from existing surface samples. Ground reaction forces collected during forefoot running were input into the model and used to determine the associated energetics of the surface. This method has the advantage, over previous experimental methods, of characterising the energy associated with sport surfaces under actual loading conditions experienced during human movement.
... Obviously, this brought an associated change in the typology and frequency of injuries, as already recognized long ago (e.g. in [5]). More recent studies investigated surface -athlete's body interactions [6][7] and particularly the energy exchange aspects, making use of of numerical analysis techniques such as finite element (FE) modelling [8]. ...
... Loading rate is also known to be more sensitive than the maximum force to changes in cushioning [19]. As for the impact energy, its absorption and restitution by a surface are of paramount importance for optimizing cushioning and performance, respectively [8]. ...
... The fitting of equation (8) to all the data points (both experimental and numerical) reported in Figure 6 yields the dashed line drawn in black, with a best fit value K = 1430 kN/s. Referring to this apparently 'universal' relationship between ALR and FR one can note that the Table 1. ...
In this work, finite element simulations of typical sports surfaces were performed to evaluate parameters, such as the loading rate and the energy absorbed by the surface, in relation to its characteristics (surface structure and material properties). Hence, possible relations between these quantities and the standard parameters used to characterize the shock absorbing characteristics of the athletics track (in particular, its force reduction) were investigated. The samples selected for this study were two common athletics tracks and a sheet of natural rubber. They were first characterized by quasi-static compression tests; their mechanical properties were extrapolated to the strain rate of interest and their dependence on the level of deformation was modelled with hyperelastic constitutive equations. Numerical simulations were carried out for varying sample thicknesses to understand the influence of track geometry on force reduction, loading rate and stored energy. A very good correlation was found between force reduction and the other relevant parameters, with the exception of the loading rate at the beginning of the impact.
... Besides, synthetic surfaces for sport and recreational usage have been manufactured. One of the important aspects in construction of sport surfaces is to improve athletic performance [4,12,23]. It has been suggested that the main feature of a sport surface that can affect the athletic performance is the energy storage and return [4,12] These studies have argued that if some of the energy that an athlete requires for each step, stride, jump, landing, etc. can be reused, through energy return from the surface, the athlete can perform the same movement more efficiently. ...
... One of the important aspects in construction of sport surfaces is to improve athletic performance [4,12,23]. It has been suggested that the main feature of a sport surface that can affect the athletic performance is the energy storage and return [4,12] These studies have argued that if some of the energy that an athlete requires for each step, stride, jump, landing, etc. can be reused, through energy return from the surface, the athlete can perform the same movement more efficiently. In other words, one can achieve a given physical activity by using less energy and, therefore, he continues his activity during a longer period. ...
... This finding is in consistent with the previous ones [3,24]. Unpublished energy return values quantified with drop tests (material testing using a shot) provided values between 40 and 70% for athletic surfaces and close to 0% for asphalt [4]. The order of the other surfaces used in this study was, from hardest to most compliant, as follows: synthetic grass, tile powder, soil, EPDM, full polyurethane, parquet and natural grass. ...
The aim of the present study was to examine the effects of different sport surfaces on sportive performance by means of muscle performance. 112 elite athletes, aged between 17 and 26, participated in this study. This study was executed on 8 different sport surfaces: asphalt, synthetic grass, natural grass, tile powder, soil, wooden parquet, full polyurethane and EPDM (Ethylene Propylene Diene Monomer). Leg strength (LS), back strength (BS) and vertical jumping height (VJH) were measured at rest and after a given training protocol on each surface. Asphalt and synthetic grass were the most fatiguing, natural grass, soil and tile powder were moderately fatiguing, parquet and polyurethane were the least fatiguing surfaces. Then the surface compliance was evaluated with a drop test using a medicine ball and it was observed that achived results were consistent with those obtained in LS, BS and VJH tests. According to the test results as the hardness of the surface increased the performance of the athletes was decreased. The results of the present study suggest that it is better to use parquet and polyurethane in construction of indoor sport surfaces.
... So far, the contribution of materials engineering to the design of products that can reduce the risk of such injuries has been relatively minor. Studies of system dynamics and energy aspects of impact have been performed with computer aided modelling [8][9][10]. ...
... This also triggers the data acquisition system of the load cell (3) mounted on the base plate (4). The mass impacts onto another plate (5) placed on top of a spring (6) which transmits the force to the base plate and thence to the surface sample under test (7), and ultimately to the substrate (8). The load cell lying between the spring and the sample measures the force acting on the sample; the maximum force during impact, F max , being identified from the force vs. time record. ...
... The results obtained on track surfaces are reported in Figure 7. To do that, the asymptotic value of FR for each sample was determined by best fitting the experimental data set of Figure 8 with the following empirical equation: ( 8) in which, the asymptotic value of FR, corresponds to thicknesses, s, adequately larger than a characteristic value, s 0 . Both parameters are obviously material dependent. ...
The present paper is aimed at clarifying the dependence of the force reduction ability of sport surfaces used in athletic tracks on the material's viscoelastic properties and on the geometry of the sample. The study is based on laboratory tests carried out with an “artificial athlete” apparatus and dynamic mechanical analysis. Seven different sport surfaces were tested; other polymeric materials were also examined in order to widen the property ranges covered. The results show a prominent effect of sample thickness on the measured value of force reduction; a method to relate it to the intrinsic properties of the material is proposed.
... Andena, Ciancio et al, 37 Andena, Briatico-Vangosa, Cazzoni et al, 48 Andena, Farhang et al, 42 Baroud et al, 53 and Rens ...
... The AA or human foot model is regarded as the impact load and loaded on the synthetic surface when the simulation was performed previously. 42,48,53 A 2-D numerical model considered the AA device in detail in work by Andena et al. 48 Farhang et al made a 3-D FE model where a simplified model of the human foot was applied. ...
Repeated impact loading during running is a risk factor in the etiology of overuse injuries. Shock absorption can reflect the degree of force attenuation when the heel lands first during movement. This study summarizes the major achievements in the existing literature regarding shock absorption from the engineering perspective and then suggests directions for further investigation. Studies have explained the influencing factors related to shock absorption from the synthetic sports surface itself. Some special measurement methods that can be used to assess vertical and horizontal shock absorption simultaneously are discussed. Numerical simulations related to shock absorption are reviewed, including how to acquire a constitutive model of the sports surface and simulate the manner of loading. Future work should aim to build “player movement‐surface structure and material‐player performance” relationship systems, with more accurate measurements of shock absorption properties in the vertical and horizontal directions and numerical models that can truly reflect actual movements. Solving these problems can strengthen the theoretical and practical understanding of the relationship between synthetic sports surfaces and injury, and athletes can develop more expert performance with fewer injuries.
... Predictions of the numerical model were validated against results of impact experiments performed using a drop tower and an Artificial Athlete Berlin on a variety of tracks possessing different mechanical characteristics. The model became a tool to explore the behaviour of existing as well as virtual tracks, investigating the relationship between FR and other quantities of potential biomechanical interest, such as loading rate and energy absorption [9][10][11]. ...
... To overcome this limitation, a few simple 3D FE cases of sports surfaces have been developed [6,10,13]. The present work describes the validation of a 3D extension of the numerical models already developed for athletic tracks in [7][8]14]. ...
In this work, a three-dimensional finite-element model of athletic tracks is presented. The model is based on data from quasi-static compression tests performed on small laboratory samples, to tune the constitutive parameters. The model was validated on three different athletic tracks, considering their top and bottom layers. Model predictions compared well with the results of shock absorption tests performed using a standard artificial athlete system, with relative errors of a few percent in terms of shock absorption. The model was then used to investigate the effect of the geometric structure of different tracks on their shock absorption capabilities. In particular, a reduction in size of the bottom layer cell pattern increased cushioning; the same property was shown to depend on the pattern voids depth in a non-monotonic way. A maximum in shock absorption was found for a void depth value about 40% higher than the one currently used in the analysed track patterns.
... Using a discrete non-linear viscoelastic model, the energy return from a running shoe during one step was estimated to be in the order of 10 J (Shorten, 1993). A recent pilot study using a 3-D finite element model (Baroud et al., 1999) has confirmed the above results. Approximately 95% of the energy conserved in a sport surface and/or shoe can be returned to the athlete. ...
... The numerical results were experimentally verified using a conventional surface design, and a very good agreement with the force-displacement curves was found. 3-D FE simulations using the new surface also confirmed the results of studies regarding the improvement of energy return (Baroud et al., 1999). A normalized typical energy conservation curve for a sport surface is illustrated infig 2. The conventional shoe/surface system exhibited a rather limited capacity to deform and consequently, to store and return energy. ...
... The top one is responsible for the aesthetics, the frictional behavior and wear/environmental resistance. The bottom one, whose characteristics govern the dynamic behavior of the track, affects instead the safety and performance of the athletes [2][3][4][5][6][7][8]. The production process of prefabricated tracks allows the introduction of honeycomb patterns or similar geometries to further enhance surface properties of a given material [9,10]. ...
This investigation deals with the problem of identifying the mechanical behaviour of rubbers from compression tests, performed on specimens having unfavorable geometry. A typical situation is that of flat specimens obtained from high-friction sports surfaces. To this purpose, experimental tests were conducted, aimed at measuring friction under various conditions and evaluating its effect on the compressive behavior of different rubber samples. The experimental results have been interpreted in view of an existing analytical model proposed by Gent and coworkers. The method was shown to be valid within a relatively broad range of conditions (in terms of materials, lubrication and aspect ratio). Its application allowed the creation of virtual “frictionless” curves, by rescaling experimental data for the stiffening factor predicted by Gent model. These curves represent more closely the intrinsic material behaviour, removing the large frictional contribution present in the experimental tests, and can be used as a more reliable input for numerical simulations.
... Yet, the lack of a dissipative component in the model limits its ability to correctly evaluate the energy return characteristics of the surface, which are essential in determining the athletes' perform ance (Baroud et al. 1999, McMahon et al. 1979, Nigg & Yeadon 1987. To overcome this limitation, the existing constitutive model has been enriched in the present work with a dissipative, viscoelastic component. ...
... Yet, the lack of a dissipative component in the model limits its ability to correctly evaluate the energy return characteristics of the surface, which are essential in determining the athletes' perform ance (Baroud et al. 1999, McMahon et al. 1979, Nigg & Yeadon 1987. To overcome this limitation, the existing constitutive model has been enriched in the present work with a dissipative, viscoelastic component. ...
... Yet, the lack of a dissipative component in the model limits its ability to correctly evaluate the energy return characteristics of the surface, which are essential in determining the athletes' perform ance (Baroud et al. 1999, McMahon et al. 1979, Nigg & Yeadon 1987. To overcome this limitation, the existing constitutive model has been enriched in the present work with a dissipative, viscoelastic component. ...
... risk of sports related injuries and enhance sports performance in this population. The best playing surface is essential elements for school children to conduct sports competitions as well as the activities during regular physical education classes. One of the important aspects in construction of sports surfaces is to improve athletic performance. (Baroud et. al. 1999 ...
Background: Sports surfaces not only play a significant role in influencing sports performance but also determining the risk of injury. The best running surface should be moderately soft & smooth and widely used in a variety of games & sports in schools. Aim: The aim of this study was to compare the shuttle run performance induced injury rates of school boys on five different sport surfaces in physical education classes. Method: Thirty six healthy school boys (Age: 14.06±0.41 years, Height: 1.60±0.08 meters, Weight: 47.17±7.13 kilograms, BMI: 18.59±3.21 kg/m²) performed 4x10m shuttle run on five different sport surfaces (PVC, asphalt, turf, concrete bed & soft clay) to evaluate speed-agility and subjective symptoms to determine injury rates. Result: The best average result of shuttle run performance was achieved on asphalt surface followed by PVC, soft clay, turf and concrete bed surface was found weak average result. In addition to safety, PVC surface provided greater security with reduced incidence of sports injuries and better performance of school boys. Conclusion: The impact of possible difference among the sport surfaces to obtain optimum shuttle run performance for school boys during competition, test and regular physical education activities under the condition of safety & reduced risk of sports injuries.
... When the athlete contacts the sport surface, there is some work done by the athlete on the sport surface [5]. Energy is transferred from the athlete to the surface through the foot and the shoe [6]. An athletes performance can be highly regulated by the interaction between the foot and sports surface [7,8]. ...
Energy can be represented in the form of deformation obtained by the applied force. Energy transfer is defined in physics as the energy is moved from one place to another. To make the energy transfer functional, energy should be moved into the right direction. If it is possible to make a better use of the energy in the right direction, the energy efficiency of the structure can be enhanced. This idea leads to the concept of directional energy transfer (DET), which refers to transferring energy from one direction to a specific direction. With the recent development of additive manufacturing and topology optimization, complex structures can be applied to various applications to enhance performances, like a wheel and shoe midsole. While many works are related to structural strength, there is limited research in optimization for energy performance. In this study, a theoretical approach is proposed to measure the directional energy performance of a structure, which can be used to measure the net energy in an intended direction. The purpose is to understand the energy behavior of a structure and to measure if a structure is able to increase energy in the desired direction.
... The main function of a sport surface is to ensure safety and adequate player performance during physical exercise practice [1]. One of the most important goals in sport surface construction is to improve sport performance [2]. The constant improvement of sport surfaces like artificial turf is motivated by the demands of the sport sector, as the quality of sport surfaces is considered a determining factor for achieving results [3]. ...
The aim of this study was to analyze the influence of natural turf, artificial turf, and sand on sprint performance in different sports and to determine how the sport surface affects sprint performance. A systematic search was conducted in Pubmed, Web of Sciences, and SPORTDiscus databases. Out of 5644 studies, 11 studies were included in the meta-analysis. The studies were very heterogeneous, as they examined different structural characteristics or quality parameters. The studies on natural turf and sand showed significant improvements on sprint speed during training. On the other hand, the analysis of fatigue did not reveal significant differences in the deterioration of sprint speed on both natural and artificial turf. Significance was set at p < 0.05. In conclusion, although lower performance in sprint was reported on sand, further studies are needed to explain the differences in sprint on natural and artificial turf.
... Existing literature largely bases experimental findings on the "law of conservation, " which states that energy cannot be destroyed, merely transferred among bodies or changed into another form (Baroud et al., 1999). Limited to time-independent assumptions, footwear research conventionally evaluates results in terms of total or max values of energy, force and deformation (Zhang et al., 2005). ...
Etiologic factors associated to running injuries are reviewed, with an emphasis on the transient shock waves experienced during foot strike. In these terms, impact mechanics are analyzed from both, a biomechanical and medical standpoint and evaluated with respect injury etiology, precursors and morbidity. The complex interaction of runner specific characteristics on the employed footwear system are examined, providing insight into footwear selection that could act as a preventive measure against non-acute trauma incidence. In conclusion, and despite the vast literature on running-related injury-risks, only few records could be identified to consider the effect of shoe cushioning and anthropometric data on injury prevalence. Based on this literature, we would stress the importance of such considerations in future studies aspiring to provide insight into running related injury etiology and prevention.
... Finally, energy restitution (in %) is determined by the energy input minus the amount of energy that has been lost in the surface. The area under the unloading force-deformation curve obtained from acceleration-signals describes the energy return of the surface (Baroud et al., 1999). This value represents the surface ability to return energy after being deformed with 100% corresponding to zero energy loss (i.e., no hysteresis). ...
Interactions between human movement and surfaces have previously been studied to understand the influence of surface properties on the mechanics and energetics of jumping. However, little is known about the muscle-tendon unit (MTU) mechanics associated with muscle activity and leg adjustments induced by different surfaces during this movement. This study aimed to examine the effects of three surfaces with different properties (artificial turf, hybrid turf, and athletic track) on the muscle mechanics and muscle excitation of the gastrocnemius medialis (GM) and vastus lateralis (VL) during maximal countermovement jumping (CMJ). Twelve participants performed maximal CMJs on the three sport surfaces. GM and VL muscle fascicles were simultaneously imaged using two ultrafast ultrasound systems (500 Hz). MTUs lengths were determined based on anthropometric models and two-dimensional joint kinematics. Surface electromyography (EMG) was used to record GM and VL muscle activity. Surface mechanical testing revealed systematic differences in surface mechanical properties (P = 0.006, η²: 0.26–0.32, large). Specifically, the highest force reduction and vertical deformation values have been observed on artificial turf (65 ± 2% and 9.0 ± 0.3 mm, respectively), while athletic track exhibited the lowest force reduction and vertical deformation values (28 ± 1% and 2.1 ± 0.1 mm, respectively) and the highest energy restitution (65 ± 1%). We observed no significant difference in CMJ performance between the three surfaces (∼35–36 cm, P = 0.66). GM and VL fascicle shortening (P = 0.90 and P = 0.94, respectively) and shortening velocity (P = 0.13 and P = 0.65, respectively) were also unaffected by the type of surface. However, when jumping from greater deformable surface, both GM muscle activity (P = 0.022, η² = 0.18, large) and peak shortening velocity of GM MTU (P = 0.042, η² = 0.10, medium) increased during the push-off phase. This resulted in a greater peak plantar flexion velocity late in the jump (P = 0.027, η² = 0.13, medium). Our findings suggest that maximal vertical jumping tasks in humans is not affected by common sport surfaces with different mechanical properties. However, internal regulatory mechanisms exist to compensate for differences in surface properties.
... Several factors affect the final behaviour of sports surfaces, including composition, geometrical structure and arrangement of their constituting layers [4][5][6]. The complex interplay between these variables prompted the development of numerical models as a tool to understand the behaviour of sports surfaces, predict their performance and allow their optimization [7][8][9]. ...
Continuous outdoor exposure of athletics tracks can lead to an important degradation of their mechanical and aesthetical properties. In this work, flat laboratory samples prepared from rubber blends of different colours were subjected to natural and artificial ageing, to investigate their effect on the surface properties. Compositional variations demonstrated a generalized oxidization of the outer (top) material layer, together with surfacing of inorganic additives; a small increase of the degradation temperature of the natural rubber component was reported, similar to the one previously observed on bulk track samples. The smooth surface of the present samples allowed their testing using a microscratching technique, able to mechanically probe the material within a few hundred microns below the top surface. The formation of a significantly harder outer crust layer was reported, potentially impacting the track performance since it is exactly the locus of interaction between the athlete and the sport surface. In particular, the increase in scratch hardness is accompanied by a significant reduction in the apparent friction coefficient. These surface modifications, previously unreported in the literature, are independent phenomena with respect to generalized bulk ageing. Microscratch data supported by microscopy evidenced a significantly varying sensitivity to ageing for the different colours (red, blue, green, neutral). Moreover, this sensitivity appeared strongly dependent on the applied ageing protocol (natural vs. artificial). In view of these results, care must be taken when accelerated artificial weathering is used to simulate long-term natural ageing of these materials.
... Indeed, surface compliance-that is, the ability of the surface to deform when subjected to an applied force [2]-influences ground contact time, step length, ground reaction forces, and running speed [1]. As such, surface compliance is also a potential determinant of the energetic cost of running and ultimately, of running performance, as well as of injury risk [3][4][5]. ...
The aim of this study was to define a reliable and sensitive test method for assessing Shock Absorption (SA), Vertical Deformation (VD), and Energy Restitution (ER) in treadmill surfaces. A total of 42 treadmills belonging to four different models were included in the study: (a) Technogym Jog700 Excite (n = 10), (b) Technogym Artis Run (n = 12), (c) LifeFitness Integrity Series 97T (n = 11), and (d) LifeFitness Integrity Series DX (n = 9). An advanced artificial athlete (AAA) device was used to assess SA, VD, and ER at three different locations along the longitudinal axis of each treadmill and in the support area of the athletes’ feet. For each location, our results show that the error assumed when performing one impact with the AAA instead of three (SA ≤ |0.1|%, VD ≤ |0.0| mm, and ER ≤ |0.2|%) is lower than the smallest changes that can be detected by the measuring device (SA = 0.4%, VD = 0.2 mm, and ER = 0.9%). Also, our results show the ability of the test method to detect meaningful differences between locations once the one-impact criterium is adopted, since absolute minimum differences between zones (SA: |0.6|%, VD: |0.3| mm, and ER: |1.2|%) were above the uncertainty of the measuring device. Therefore, performing a single impact with the AAA in each of the three locations described in this study can be considered a representative and reliable method for assessing SA, VD, and ER in treadmill surfaces.
... Surface properties can influence endurance running performance. [1][2][3] Indeed, athletes adjust their leg stiffness when running on surfaces of differing mechanical properties, 4,5 resulting in subtle changes in lower-limb kinematic patterns, landing style, stride length, ground reaction force dynamics, and peak impact accelerations. [6][7][8][9][10] Thus, surface properties have been reported to affect physiological responses during endurance running. ...
Purpose:
To characterize, for the first time, the mechanical properties of treadmill surfaces along with a practical interpretation of their influence on physiological and perceived demands during endurance running compared with other widely used surfaces such as asphalt and tartan tracks.
Methods:
Ten experienced male endurance runners performed a 40-minute running bout at a preferred constant speed on 3 different surfaces (after a randomized, counterbalanced order with a 7-d interval between trials): asphalt, tartan, or treadmill. Shock absorption, vertical deformation, and energy restitution were measured for the 3 surfaces. Intensity (based on heart rate data) and rating of perceived exertion were monitored.
Results:
The values of shock absorption averaged 0.0% (asphalt), 37.4% (tartan), and 71.3% (treadmill), while those of vertical deformation and energy restitution averaged 0.3, 2.2, and 6.5 mm and 90.8%, 62.6%, and 37.0%, respectively. Running intensity (as determined by heart rate data) was higher overall on the treadmill than tartan but not asphalt running. Except for the first 10 minutes, all mean rating of perceived exertion values were significantly higher in asphalt and treadmill than in tartan. No significant differences were identified between treadmill and asphalt.
Conclusions:
The considerably higher shock absorption of the treadmill than the tartan surface leads to a reduction in the amount of energy returned to the athlete, which in turn increases physiological stress and rating of perceived exertion during endurance running.
... Regarding players' performance, several studies of other sports have shown that the mechanical heterogeneity of playing surfaces can affect the ability of players when performing CODs or linear runs, as a result of differences in the storage and return of energy from the sports surface (Sánchez-Sánchez et al., 2016;Sánchez-Sánchez, García-Unanue, et al., 2014). Indeed, it is widely reported that part of the energy produced during these actions is returned to the players through the surface (Baroud, Nigg, & Stefanyshyn, 1999). ...
The ability to effect a change of direction (COD) when performing high-speed actions is essential in team sports like futsal. Nevertheless, the interaction effect of sports surfaces on this ability remains unknown. This research aimed to analyze the plantar pressures and time performance of 15 youth futsal players when performing CODs on two playing surfaces with different mechanical properties. The shock absorption and vertical deformation of one synthetic flooring surface and one wooden flooring surface were assessed. CODs were evaluated using a modified version of the Agility T-Test, while total time of the test, time of CODs, and plantar pressure in CODs were all recorded. The wooden flooring surface displayed higher values of shock absorption (35.70 ± 2.87%) and vertical deformation (2.77 ± 0.38 mm) compared with the synthetic flooring (p <0.01). Faster CODs were performed on the wooden flooring than on the synthetic flooring (-0.05 s, 95% confidence interval [CI]: -0.10 to -0.007, effect size [ES]: 0.07, p <0.05), but no differences in total test time were found (p >0.05). Finally, no differences in plantar pressures by playing surface were found. In sum, the differences in the mechanical properties of the two futsal surfaces affected the performance of futsal players in the modified agility test. However, these differences were not great enough to generate different plantar pressures on players, probably due to playerś own adaptations.
... The denser the playing surface, the more muscular force in the last phase of the SSC is needed to alter the ground reaction forces that are returned to the body with each stride or landing movement, such as a vertical jump (8,9,(12)(13)(14) However, previous findings are primarily based on speed and acceleration performance, which fail to correctly assess an athlete's full potential of stored energy (10). The level of the stored energy returned to the athlete when touching the ground depends on elastic properties of muscles and potentially the physical properties of a playing surface (5,6,48). At the start of testing, Clegg surface density analysis suggested that the surface densities of the peat loam (NT1) and sandy loam (NT2) both increased their level of hardness similarly over the course of the study, and NT1 and NT2 were not statistically different when compared to each other. ...
Hatfield, DL, Murphy, KM, Nicoll, JX, Sullivan, WM, and Henderson, J. Effects of different athletic playing surfaces on jump height, force, and power. J Strength Cond Res 33(4): 965-973, 2019-Artificial turfs (ATs) have become more commonplace. Some aspects of performance such as speed seem to be better on ATs, but there are few published studies on the effects of playing surfaces on performance. Furthermore, there is no research that compares performance on ATs, hard surfaces (HSs), and different composite natural surfaces. Forty-three subjects, 21 men (age: 20 ± 1.82 years; height: 177.53 ± 5.87 cm; body mass: 78.44 ± 11.59 kg; and body fat: 11.17 ± 4.45%) and 22 women (age: 25 ± 1.32 years; height: 161.37 ± 6.47 cm; body mass: 60.94 ± 10.24 kg; and body fat: 27.16 ± 7.08%) performed a single countermovement jump (SCMJ), repeated CMJs (RCMJs), and single depth jump (SDJ) on 4 different playing surfaces (peat soil composition turf [NT1], sandy loam composition turf [NT2], 1 AT, and 1 HS. Repeated-measures analysis of variance with Bonferroni post hoc was used to calculate differences in performance across playing surfaces. Statistical significance was set at p ≤ 0.05. Force and jump height were not different across different surfaces. Men had significantly higher force, power, and jump height on all surfaces. Only SCMJ power was lower on NT1 compared with all other surfaces. The difference in power between surfaces was not reproduced when RCMJ and SDJ were performed, and may be due to the increased reactiveness of the stretch-shortening cycle during those jumps. Because of marginal differences between athletic performance and playing surface type, future research comparing playing surface type and other aspects of athletic success such as rate of injury should be considered.
... Performance is strictly related to the mechanical behavior of the surface in connection with the athlete. The three most important properties are shock absorption [3], energy restitution and friction [4][5]. The elastic properties of polymers and their excellent capability of absorbing shocks greatly contribute to the enhancement of athletics track qualities, thus guaranteeing the athletes' safety and performance. ...
This is an extensive study of the ageing of athletics tracks, approached with a variety of
experimental techniques. The effects of environmental variables, such as UV radiation, relative
humidity, water immersion and temperature, were investigated using several artificial ageing
protocols, applied to six prefabricated tracks of different color and chemical formulation. A few
effective techniques capable of detecting and monitoring the changes occurring in track materials
because of ageing were identified among a broad range of available experimental tests.
In particular, semi-quantitative colorimetric analysis and dispersive electron spectroscopy were
successfully employed to investigate surface degradation phenomena, while uniaxial compression
and thermo-gravimetric analysis allowed characterization of the underlying bulk material. The
combination of accelerated ageing protocols and monitoring techniques proved to be a powerful tool
to study ageing in athletics tracks, with the aim of developing new products with improved durability
for installations in critical areas.
... Soccer players are required to move in a high-intensity, intermittent fashion that includes multiple sprints of varying distances and durations, acceleration, deceleration, agility, jumping and other locomotive movements (Little and Williams, 2005). A feature of a surface that affects athletic performance is the energy stored and returned (Baroud et al., 1999). The energy that an athlete requires for each jump, stride, step and landing movement is influenced by reused and returned energy from the surface (Katkat et al., 2009). ...
Sporting performance and outcomes are affected by surface type and hardness. Natural grass surface characteristics can vary considerably at amateur level sport which can influence technical skills and locomotive movements. Surface hardness and human responses need to be objectively measured in order to fully understand movement responses and subsequent performance. In the present study, one academy u-19 soccer player played in eleven competitive matches. Surface hardness was measured using a Clegg Impact Hammer and pitches were categorised into either harder or softer groups (67.7 to 93.0 Gmax and 41.4 to 58.3 Gmax respectively). The frequency of high intensity shuffling was significantly greater on softer grass (11.2±2.1) when compared to harder grass (6.1±3.8) (p < 0.05). A large effect size was revealed with running, dribbling, low and high intensity activities as greater frequencies were evident on softer grass when compared to harder grass. There were no significant differences for any of the game events, but there was a large effect size for aerial challenges and headed clearances which were performed more often on softer surfaces than on harder surfaces. There was a greater frequency of moderate intensity, sharp path changes to the right and v-cut path change performed on softer surfaces than on harder surfaces and the effect sizes were large. To conclude, movement activity and game events performed were influenced by natural grass surface hardness. Future research should endeavour to explore differences in the physical work-rate in terms of the biomechanical and physiological demands.
... Soccer players experience different kinds of forces on the tissues depending on the surface, which has an impact on the type and frequency of the injuries among players (Kordi, Hemmati, Heidarian, & Ziaee, 2011). Another important factor in the surface-player interaction is the energy return (Baroud, Nigg, & Stefanyshyn, 1999) that associates the force applied against the surface with the returned energy, which has an influence on elastic behaviour of the surface and its interaction with athletes. According to Kerdok, Biewener, McMahon, Weyand, and Herr (2002), greater energy return enhances player performance. ...
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.
... The scientific literature offers some examples [5][6] of very simple three-dimensional (3D) FE models of sports surfaces; in the present study, a new one was developed to accurately describe the structure of such multi-layered tracks and, consequently, allow an optimization of the track impact performance, which is not limited to the vertical direction. ...
In previous works, a finite element model of the shock absorbing characteristics of athletics tracks was developed, able to give sufficiently reliable predictions from laboratory tests performed on suitable material samples. The model proved to be effective in discriminating the effects of geometry (i.e. thickness) and material properties (essentially the elastic characteristics) on force reduction, thus allowing a first optimization of the tracks in view of their approval by the International Association of Athletics Federations (IAAF).
... There is a clear gap between what is now understood about player loading during different movements on a surface and what the (simple) industry/sport governing body standard tests can and do replicate in light of this. The drop-weight tests used to determine the mechanical properties of sport surfaces under vertical constant energy impacts have the shortcomings that the impact force peaks, rate of loading and contact duration show little correlation with actual player movements (Nigg and Yeadon, 1987;Nigg et al., 1984;Baroud et al., 1999). Furthermore the tests usually only report peak force or displacement magnitudes (Dura et al., 2002) and have little flexibility in test method to simulate differing foot loading styles or movement patterns (Dixon et al., 1999). ...
Artificial turf sport surface systems are comprised of a number of different materials. Improving the understanding of the sports surface system's response to actual player loading is important for developing enhanced products and system designs for improving play performance and durability. Previous research has tested and compared the mechanical properties of artificial turf systems with relatively simple mechanical tests intended to simulate loading from the player or ball. However, these test methods have known shortcomings in representing real in-service loading and it is often assumed a peak value of force or peak deformation is sufficient to describe the surface behaviour. Little literature exists that describes the force-deflection or stress- strain behaviour of artificial turf system under mechanical or player loading. This paper outlines methodologies developed for surface response measurement under real-time player movements including: the advanced measurement systems and data analysis methods for determining surface deflection/strain under player foot strike during a ground contact, and further evaluating the force-deflection and stress-strain relationships of the synthetic carpet-shockpad composite surface systems. The results show the ability of the surface system to accommodate the player applied loads by deforming to large strains with strong non-linearity and rate-dependent energy loss (hysteresis) in the load-unload phases. The contrast between the surface systems’ response to player loading using different shockpads is also presented and discussed. By combining these findings from the development of measurement techniques and the data analysis methods a new surface system evaluation regime is proposed for future studies into mechanical behaviour and cushioning response of artificial turf systems under player loading.
... Considering athletics, a significant body of literature debates about the effects of shoe and track surface materials on running or jumping impacts, focusing primarily on the athletes' physiology and the prevention of sports injuries [3][4][5][6][7]. The contribution of materials engineering to the design of products that can reduce the risk of such injuries while securing high performance, has been relatively minor; only a few studies on system dynamics and energy aspects have been performed with computer aided modeling [8][9][10][11]. Obviously, such studies cannot neglect the properties of the constituent polymeric materials and the structure of the tracks, as different stress levels can be reached during impact on the surface on varying the characteristics of the shoe [11] and of the surface itself [6]. ...
In this work, the possibility of predicting the force reduction (FR) characterizing the shock absorption capability of track surfaces by finite element modeling was investigated. The mechanical responses of a typical sport surface and of a reference material were characterized by quasi-static uniaxial compression experiments and fitted by Neo-Hookean and Mooney–Rivlin’s hyperelastic models to select the more appropriate one. Furthermore, in order to examine the materials behavior at strain rates typical of athletics applications, the rate dependence of the constitutive parameters was investigated. A finite element model, taking into consideration the post-impact nonlinear dynamics of the track surface and of the system (track surface + artificial athlete), was developed and validated through comparison with the results of FR tests. The simulations showed a very good agreement with the experiments and allowed to interpret the experimentally observed combined effect of track thickness and material intrinsic properties on the overall surface behavior.
... risk of sports related injuries and enhance sports performance in this population. The best playing surface is essential elements for school children to conduct sports competitions as well as the activities during regular physical education classes. One of the important aspects in construction of sports surfaces is to improve athletic performance. (Baroud et. al. 1999 ...
... This relationship also existed between the AAA FR and ER outputs. The calculation of ER used by the BSEN 14808 [10] has some support [22,23], although it is unclear how the ER test apparatus and protocols should be developed in order to obtain a valid measurement for human-surface interactions. The inclusion of the spring in the AAA test apparatus may provide an explanation for the inverse relationship reported in this study. ...
Dance floor surfaces are important environmental factors in dance activity andhave been suggested to be a factor in the aetiology of dance injury. Measurement of the injury risk associated with floor surfaces is difficult as the validity of the relationship between mechanical surface measures and human–surface interactions is unclear. Dancer perceptions of the mechanical properties of floor surfaces were investigated with reference to mechanical quantification measures. Student (n = 27) and professional (n = 27) dancers completed a questionnaire investigating their perceptions of the force reduction, vertical deformation, energy restitution and overall ratings of five sample dance floors. Dance floor mechanical properties were quantified using sport surface testing apparatus, the Advanced Artificial Athlete (AAA) (Metaalmaatwerk, Netherlands). Student and professional cohort perceptions were not significantly different for 18 of the 20 perception variables. Vertical deformation was the only mechanical variable to differ between cohort perceptions. Dancers demonstrated a preference for floors with greater force reduction magnitudes than specified by European sport surface standards, suggesting that bespoke floor standards for dance may be beneficial. Considerable discrepancies were found between particular dancer perceptions and related AAA outputs, highlighting the need for further investigation of valid mechanical tests that are used to represent human–surface interactions.
... This relationship also existed between the AAA FR and ER outputs. The calculation of ER used by the BSEN 14808 [10] has some support [22,23], although it is unclear how the ER test apparatus and protocols should be developed in order to obtain a valid measurement for human-surface interactions. The inclusion of the spring in the AAA test apparatus may provide an explanation for the inverse relationship reported in this study. ...
Dance floor surfaces are important environmental factors in dance activity and have been suggested to be a factor in the aetiology of dance injury. Measurement of the injury risk associated with floor surfaces is difficult as the validity of the relationship between mechanical surface measures and human–surface interactions is unclear. Dancer perceptions of the mechanical properties of floor surfaces were investigated with reference to mechanical quantification measures. Student (n = 27) and professional (n = 27) dancers completed a questionnaire investigating their perceptions of the force reduction, vertical deformation, energy restitution and overall ratings of five sample dance floors. Dance floor mechanical properties were quantified using sport surface testing apparatus, the Advanced Artificial Athlete (AAA) (Metaalmaatwerk, Netherlands). Student and professional cohort perceptions were not significantly different for 18 of the 20 perception variables. Vertical deformation was the only mechanical variable to differ between cohort perceptions. Dancers demonstrated a preference for floors with greater force reduction magnitudes than specified by European sport surface standards, suggesting that bespoke floor standards for dance may be beneficial. Considerable discrepancies were found between particular dancer perceptions and related AAA outputs, highlighting the need for further investigation of valid mechanical tests that are used to represent human–surface interactions.
... This quotient is a real number between 0 and 1, which measures the correlation between e and r at the frequency x. If this quotient were not near to 1, the linear supposition could not be assumed. The linear viscoelastic model is easier to handle mathematically and for this reason is implemented in most ®nite element analysis software packages. Baraud et al. (1999) have shown that the application on viscoelastic lineal behaviour in ®nite element analysis (FEA) could be a good technique for designing sports surfaces with shock absorbing properties tuned to athletes necessities. One of the shortcomings for applying FEA with viscoelastic materials is to check the linear behaviour. Then, the Coherence ...
The purpose of this paper is to show a test method which measures the possibility of using the viscoelastic linear model in shock absorbing materials and its advantages regarding to actual standard tests. Applying the viscoelastic linear model and frequency analysis it is possible to study the behaviour of the dynamic rigidity and loss tangent as function of the frequency. The practical case described in the paper shows how it is possible to obtain the same results with the standard test used by IAAF (International Amateur Athletic Federation) and european standards for measuring shock absorption with materials which have different loss tangent and different dynamic rigidity.
... This finding is in consistent with the previous ones [31]. Unpublished energy return values quantified with drop tests (material testing using a shot) provided values between 40 and 70% for athletic surfaces and close to 0% for asphalt [4]. The order of the other surfaces used in this study was, from hardest to most compliant, as follows: synthetic grass, tile powder, soil, EPDM, parquet and natural grass. ...
The aim of the present study was to examine the effects of different sport surfaces on athletic performance by means of muscle performance. Twenty two elite male basketball players, aged between 17 and 28, participated in this study. This study was executed on 7 different sport surfaces: asphalt, synthetic grass, natural grass, tile powder, soil, wooden parquet and EPDM (Ethylene Propylene Diene Monomer). Leg strength (LS) and vertical jumping height (VJH) were measured at rest and after a given training protocol on each surface. Surface compliance was evaluated with a drop test using a medicine ball. Asphalt and synthetic grass were the most fatiguing, natural grass, soil and tile powder were moderately fatiguing, parquet and EPDM were the least fatiguing surfaces. The results of surface compliance were inconsistent with those obtained in LS and VJH tests. As the compliance of the surface increased LS and VJH increased, i.e. performance was decreased. The results of the present study suggest that it is better to use parquet and EPDM in construction of indoor sport surfaces. On the other hand, it may be appropriate to build outdoor surfaces with natural grass because of its aesthetic and visual impacts and its contribution to the amount of urban green area.
... To support physiological studies of the effect of surface compliance on running economy, Grant et al. (1998) measured the quasi-static force-de¯ection response of two different treadmill running surfaces; both were found to be nonlinear-elastic. Baroud et al. (1999) chose a viscoelastic material model in studies of energy return from running surfaces but Walker (1998) has argued that the time constants of the materials studied are too large for viscosity to play any role in the short-duration impacts typical in running. In addition, the duration of the stance phase of running is always of the order ...
Accurate, 3-D analyses of running impact require a constitutive model of the running surface that includes the material nonlinearity shown by many modern surfaces. This paper describes a hyperelastic continuum that mimics the experimentally measured response of a particular treadmill surface. The material model sacrifices a little accuracy to admit a robust, low-order hyperelastic strain-energy functional. This helps prevent the premature termination of finite element simulations, due to numerical or material instabilities, that can occur with higher-order functionals. With only two free constants, it is also a more practical design tool. The best fit to the quasi-static response of the treadmill was achieved with an initial shear modulus =2 MPa and a power-stiffening index =25. The paper outlines the method used to derive the material constants for the treadmill, a device that is not amenable to the usual materials laboratory tests and must be reverse-engineered. Finite element analyses were then performed to ensure that the treadmill model interacts with the other components of the multibody running system in a numerically stable and physically realistic manner. The model surface was struck by a rigid heel, cushioned by a hyperfoam material that represents a shoe midsole. The results show that, while the ground reaction force is similar to that obtained with a rigid surface, the maximum principal stress in the shoe is reduced by 15%. Such a reduction, particularly when endured over many load cycles, may have a significant effect on comfort and damage to nearby tissue.
Bu araştırmanın amacı, genç futbolcularda doğal çim ve suni çim saha üzerinde gerçekleştirilen sprint, çeviklik ve top sürme performanslarının karşılaştırılmasıdır. Araştırmaya 16 sağlıklı genç futbolcu (yaş:14,01 ± 0,29 yıl; antrenman yaşı: 4,31 ± 1,74 yıl; boy uzunluğu 166,68 ± 6,93 cm.; vücut ağırlığı 55,48 ± 8,16 kg.) gönüllü olarak katılmıştır. Araştırma grubuna 5 ölçüm gününde suni çim ve doğal çim üzerinde sprint, çeviklik (yön değiştirme) ve top sürme testleri uygulanmıştır. Değişkenlerine ait değerlerin, normal dağılıma sahip olup olmadığını tespit etmek için ShapiroWilk testi kullanılmıştır. Tüm verilerin karşılaştırmalarında, grup içi karşılaştırmalar için eşleştirilmiş t-testi (The Paired Samples t Test) uygulanmıştır. İstatistiksel anlamlılık düzeyi p < ,05 olarak belirlenmiştir. Araştırma grubunun suni çim- doğal çim sprint değerleri (3,17 ± 0,13sn; 3,26 ± 0,14sn) ve çeviklik değerleri (11,11 ± 0,33sn; 11,24 ± 0,38sn) arasında istatistiksel olarak anlamlı bir farklılık bulunurken (p < ,05); top sürme değerleri (21,17 ± 1,29sn; 21,52 ± 0,89sn) arasında istatistiksel olarak anlamlı bir farklılık bulunamamıştır (p > ,05). Sonuç olarak genç futbolcularda suni çim ve doğal çim üzerinde gerçekleştirilen sprint ve çeviklik performansı verileri suni çim lehine anlamlı bir farklılık olduğunu gösterirken top sürme performansları arasında anlamlı bir fark olmadığını göstermiştir.
The mechanical properties of the surfaces used for exercising can affect sports performance and injury risk. However, the mechanical properties of treadmill surfaces remain largely unknown. The aim of this study was, therefore, to assess the shock absorption (SA), vertical deformation (VD) and energy restitution (ER) of different treadmill models and to compare them with those of other sport surfaces. A total of 77 treadmills, 30 artificial turf pitches and 30 athletics tracks were assessed using an advanced artificial athlete device. Differences in the mechanical properties between the surfaces and treadmill models were evaluated using a repeated-measures ANOVA. The treadmills were found to exhibit the highest SA of all the surfaces (64.2 ± 2; p < 0.01; effect size (ES) = 0.96), while their VD (7.6 ± 1.3; p < 0.01; ES = 0.87) and ER (45 ± 11; p < 0.01; ES = 0.51) were between the VDs of the artificial turf and track. The SA (p < 0.01; ES = 0.69), VD (p < 0.01; ES = 0.90) and ER (p < 0.01; ES = 0.89) were also shown to differ between treadmill models. The differences between the treadmills commonly used in fitness centers were much lower than differences between the treadmills and track surfaces, but they were sometimes larger than the differences with artificial turf. The treadmills used in clinical practice and research were shown to exhibit widely varying mechanical properties. The results of this study demonstrate that the mechanical properties (SA, VD and ER) of treadmill surfaces differ significantly from those of overground sport surfaces such as artificial turf and athletics track surfaces but also asphalt or concrete. These different mechanical properties of treadmills may affect treadmill running performance, injury risk and the generalizability of research performed on treadmills to overground locomotion.
The aim of the study was to examine different sport surfaces in term of on life-long sports. 196 sedanter, aged between 25 and 40, participated in this study. This study was executed on 8 different sport surfaces: asphalt, synthetic grass, natural grass, tile powder, soil, wooden parquet, full polyurethane and EPDM (Ethylene Propylene Diene Monomer). Leg strength (LS), back strength (BS) and vertical jumping height (VJH) were measured at rest and after a given training protocol on each surface. The results of the study, wooden parquet, EPDM, natural grass and polyurethane are ergonomi{dotless}c sport surfaces in terms of life-long sports.
The purposes of this study were to a analysis of friction relation between tennis outsole and tennis playing surfaces. Tennis footwear is an important component of tennis game equipment. It can support or damage players performance and comfort. Most importantly athletic shoes protect the foot preventing abrasions and injuries. Footwear stability in court sports like tennis is incredibly important since it is estimated that as many as 45% of all lower extremity injuries occur in the foot and ankle. The friction force is the force exerted by a surface as an object moves across it or makes an effort to move across it. The friction force opposes the motion of the object. Friction results when two surfaces are pressed together closely, causing attractive intermolecular forces between the molecules of the two different surfaces. The outsole provides traction and reduces wear on the midsole. Today`s outsoles address sport specific movements (running versus pivoting) and playing surface types. Different areas of the outsole are designed for the distinct frictional needs of specific movements. Traction created by the friction between the outsole and the surface allows the shoe to grip the surface. As surfaces, conditions and player motion change, traction may need to vary. An athletic shoe needs to grip well when running but not when pivoting. Laboratory tests have demonstrated force reductions compared to impact on concrete. There is a correlation between pain, injury and surface hardness. These are a variety of traction patterns on the soles of athletic shoes. Traction like any other shoe characteristic must be commensurate and balanced with the sport. The equal and opposite force does not necessarily travel back up your leg. The surface itself absorbs a portion of the force converting it to other forms of energy. Subsequently, tennis court surfaces are rated not only for pace but also for the percentage of force reduction.
Artificial turf is increasingly being used in the construction of football pitches. One of its characteristics is an infill of sand and rubber granules. At present, different materials and layer thicknesses, as well as grain sizes are used for the sand and mainly for the rubber, but they are chosen with little scientific evidence about their influence on the mechanical and biomechanical properties of the pitch. Based on knowledge from materials science, it is reasonable to suggest that grain morphology may have a large influence on pitch performance. This paper presents research conducted to assess the influence of different parameters related to infill grain morphology on the mechanical properties of artificial turf (force reduction (%), vertical deformation (mm) and vertical ball bounce (m)), as well as on their wear with use, measured according to the Fédération Internationale de Football Association (FIFA) procedures. The results show a significant reduction of pitch performance with use and a significant influence of grain morphology in mechanical response of artificial turf with respect to impact forces and ball rebound.
The changing nature of sports, and the need to play different sports in a wide range of climactic conditions, has led to sports being played on synthetic surfaces in place of natural surfaces. In recent years, there has been a trend towards the creation of multi-sport facilities and surfaces, where facility utilization is increased by offering a variety of sports such as netball, basketball, indoor soccer, volleyball, inline hockey and martial arts, all being played on the same surface. The “one size fits all” approach to multi-sport surfaces may not however be appropriate from an injury prevention perspective, due to the different performance needs of different sports. For this reason, sports are now played on a variety of point elastic, multi-layer, synthetic sports surfaces. Sports surfaces can therefore be highly complex structures, often constructed from many elements which contribute to compound behaviour patterns. Despite such a wide range of playing surfaces, there is a lack of knowledge relating to the suitability and performance of various surfaces for specific sports. In order to improve the understanding of sports surfaces and help quantify their performance characteristics and injury prevention potential, an angular, mechanical impact device has been developed in this research, which can strike a sports surface with a controlled mass at different angles to measure the resultant horizontal and vertical forces generated. It is the aim of this paper to review the performance of this impact device, illustrate its effectiveness and validity in determining horizontal and vertical reaction force attenuation effectiveness and assess the potential to evaluate injury risk on different sports surfaces, and in particular for netball.
Tennis was originally played on grass courts, but developments in technology have allowed play to take place on a larger variety
of surfaces than any other sport. In parks throughout the UK, players of ranging ability are playing on Macadam surfaces.
In similar public park settings in the USA, the general public are found playing tennis on clay surfaces. At Wimbledon we
see the famous, traditional turf surface being used. At the elite level across the World, players perform on natural turf,
clay, acrylic hardcourts and carpet. Players at all levels have their favoured surface. Whilst hardcourt is the prevalent
surface in professional tennis, we see players such as Tim Henman performing above par on the grass of Wimbledon, and Andre
Agassi adapting effectively to clay courts.
Artificial turf is increasingly being used in the construction of football pitches. Characteristic for this product is the
infill, usually consisting of sand and rubber granulates. A significant role is attributed to it in the Performance of the
surface. At present, different materials and thicknesses, as well as grain sizes are used with little scientific support about
their influence in mechanical and biomechanical properties. However, knowledge from materials science makes reasonable to
think that grain morphology will also have a great influence in the field Performance. This paper presents a research condueted
to assess the influence of different parameters related to infill grain morphology on the mechanical properties of artificial
turf, as well as on their wear with use.
To advance the engineering of natural turf sports surfaces it is necessary to characterize the stress states and paths of
the loads applied by athletes during activity. Such loads are transitory and dynamic. In order to characterize the pressure
distribution in a natural soil sports(?) surface a novel experiment was conducted in the 20 m long, 1.8 m wide, 1.0 m deep
soil dynamics laboratory at Cranfield University. Two soil surfaces of 1460 kg m−3 and 1590 kg m−3 were constructed from a sandy loam soil (66% sand, 17% silt and 17% clay). Hardness (0.5 kg Clegg impact hammer) was 125
and 235 g, and maximum penetration resistance 1200 and 1800 kPa, respectively. Seven subjects (57–85 kg body mass) were asked
to run at a constant speed of 4 m s−1 (±5%) over each surface, three times, in three different types of footwear used in soccer. Loading and unloading of the soil
surface was measured using a ceramic membrane pressure transducer of 19 mm diameter, aligned to the vertical and buried at
100, 200 and 350 mm below the surface. Pressure data were recorded at 5 kHz and processed to determine peak pressure and loading
and unloading behaviour of the soil surface. ANOVA determined maximum pressure for the two surfaces was significantly lower
at 350 mm (7–15 kPa) and 200 mm (2–3 kPa) than at 100 mm (52–61 kPa) depth (p=0.05) but that there was no significant difference
between the two surfaces at any particular depth. Maximum pressure at 100 mm depth was linearly correlated with subject weight
(for Subjects 3–7). Loading and unloading behaviour of the soil showed a pattern of bimodality, caused by heel strike and
push-off, similar to biomechanics running experiments conducted with force plates. These results suggest that in soil surfaces,
pressure distribution at and below 200 mm is independent of surface density or subject, but that mechanical properties such
as density and stiffness must be considered in the top 100 mm of a surface. This research also demonstrates the applicability
of in-surface pressure transducers in integrated soil mechanics and biomechanics testing.
The energy return characteristics of an impacted surface are important for human impacts such as a child falling onto a play surface or an athlete landing on a gymnastic mat. The amount of energy dissipated or returned to the impacting body will contribute to the surface's injury-minimizing or performance-enhancing potential. We describe a simple approach for selecting a rheological computer model to simulate a human-surface impact. The situation analyzed was of a head form impact onto gymnastic tumbling mats. The approach can be used to characterize other surfaces and impacts. The force-time-displacement characteristics of the mats were determined from laboratory drop tests. Various spring-damper models were evaluated for their ability to reproduce the experimental acceleration-time and force-displacement impact curves. An exponential spring and depth damper combination was found to best replicate the surface characteristics of the mats tested here, and to demonstrate their energy flow and exchange properties. Rheological modeling is less complex than finite element modeling but still accounted for the depth, velocity, and energy characteristics of the impacted surfaces. This approach will be useful for reproducing the characteristics of surfaces when the impacting body cannot be instrumented, and for predicting force and energy flow in nonrigid impacts.
Impact forces have been associated with the development of musculoskeletal injuries. However, results of epidemiologic studies that assess the association between impact loading and the development of acute or chronic injuries do not support this notion. There is agreement that excessive impact force may produce damage to the human musculoskeletal system and that there is a window of loading in which biologic tissue reacts positively to the applied impact load. However, it seems that the impact forces and stresses acting on cartilage, bones, ligaments, and tendons during running are typically within an acceptable range. Running on soft or hard surface materials creates different feelings of comfort. A muscle-tuning model suggests that muscles in general attempt to avoid vibrations using a tuning strategy to establish a critically damped mechanical system. Thus, the different feeling may manifest itself in the form of changed comfort or performance, a concept that is certainly not in agreement with the previous paradigm of impact forces and cushioning.
(C) Lippincott-Raven Publishers.
A model of running is proposed in which the leg is represented as a rack-and-pinion element in series with a damped spring. The rack-and-pinion element emphasizes the role of descending commands, while the damped spring represents the dynamic properties of muscles and the position and the rate sensitivity of reflexes. This model is used to predict separately the effect of track compliance on step length and ground contact time. The predictions are compared with experiments in which athletes ran over tracks of controlled spring stiffness. A sharp spike in foot force up to 5 times body weight was found on hard surfaces, but this spike disappeared as the athletes ran on soft experimental tracks. Both ground contact time and step length increased on very compliant surfaces, leading to moderately reduced running speeds, but a range of track stiffness was discovered which actually enhances speed.
Two sets of concepts for sport shoe construction are discussed, based on anatomical, orthopedic, and epidemiological considerations: one for the prevention of excessive load and related injuries, and one for the improvement of performance. The proposed concepts for prevention of excessive load and related injuries in the foot and the lower extremities are cushioning, support, and guidance. The goals outlined in the concepts can be achieved by altering the material properties or the construction of the shoe. It is suggested that the concept "cushioning" is not well understood yet and needs further research. The discussed concepts for improving performance are first, that energy should be returned at the right location, at the right time, with the right frequency, and second, that loss of energy should be minimized. Reduction of energy loss is an important concept for performance. The concept "return of energy" seems inappropriate for sport shoes.
The purpose of this paper is to discuss some biomechanical aspects of playing surfaces with special focus on (a) surface induced injuries, (b) methodologies used to assess surfaces and (c) findings from various sports. The paper concentrates primarily on questions related to load on the athlete's body. Data from epidemiological studies suggest strongly that the surface is an important factor in the aetiology of injuries. Injury frequencies are reported to be significantly different for different surfaces in several sports. The methodologies used to assess surfaces with respect to load or performance include material tests and tests using experimental subjects. There is only little correlation between the results of these two approaches. Material tests used in many standardized test procedures are not validated which suggests that one should exercise restraint in the interpretation of these results. Point elastic surfaces are widely studied while area elastic surfaces have received little attention to date. Questions of energy losses on sport surfaces have rarely been studied scientifically.
A method of measuring impact absorbing capacity of athletic playing surfaces is described. Four impact parameters were measured of grass fields, asphalt and Astro Turf. It is concluded that the new Astro Turf surface approximates, but does not equal a grass field in impact absorption capability. The 5 yr old Astro Turf surface has significantly decreased ability to absorb impact compared to the new Astro Turf layer. Replacing the Astro Turf surface layer significantly improves the impact quality of the field; therefore the diminished impact absorbing quality of the field appears to be directly related to the alterations in the grass like surface layer secondary to continued use and exposure to atmospheric conditions.
The study was designed to determine the energy cost of walking over sandy and firm surfaces, and to compare the physiological responses of recruits recorded while walking over these surfaces.
The average oxygen intake of 11 young men walking over loose sand at 3 m.p.h. and carrying loads of about 50 lbs each (inclusive of clothes) was 1.973 litre/min. as compared with 1.101 litre/min. for walking on a firm surface, an increase of 80 per cent. The average pulse rate and rectal temperature were significantly higher during the march over sand (150 beats/min. and 101.5 °F respectively) than while walking over firm surfaces (127 beats/min. and 100.5 °F). The increased physiological strain was obvious. Most of the men were working at more than 50 per cent of their estimated maximum oxygen intakes while walking on sand, as a result of which their heart rates and rectal temperatures would have increased progressively with time.
Ground reaction forces and center of pressure (C of P) patterns were studied in 17 subjects running at 4.5 ms−1. The subjects were classified as rearfoot or midfoot strikers according to the location of the C of P at the time of first contact between foot and ground. The C of P path in the rearfoot group showed a continuous anterior movement during support while the C of P in most of the midfoot group migrated posteriorly during the first 20 ms of the support phase. Variability in both groups was most marked during early support. The mean peak to peak force components were 3 BW, 1 BW and 0.3 BW in the vertical, anteroposterior and mediolateral directions respectively. Consistent differences between groups were noted in all three components, but individual differences within a given group were also considerable. The C of P patterns are presented in conjunction with ground reaction force data, and the implications of the results in the areas of running mechanics, shoe design and sports injury are discussed.
Biomechan-ical Aspect of Sport Shoes and Playing Surfaces Die Methode der Finiten Elemente (Band I, II III). Friedr. Vieweg & Sohn Materialeigenschaften von Sportboeden und Schuhen Impact absorption, new and old turf at west virginia university Ground reaction force in distance running
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Functional standards for playing surfaces
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The in¯uence of the shoe on foot movement and shock attenuation in running
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