Shoe-surface Interaction Research Articles

Primary Anterior Cruciate Ligament Injury: Extrinsic and Intrinsic Risk Factors.

Anterior cruciate ligament (ACL) injuries continue to increase in incidence despite extensive research into prevention strategies. Many extrinsic and intrinsic risk factors for sustaining ACL injuries have been identified and continue to be investigated. Extrinsic risk factors for ACL injury relate to the athlete's environment, such as the shoe-surface interaction, weather conditions, and sport played. Intrinsic risk factors relate to the athlete's sex, hormones, knee anatomy, landing and pivoting biomechanics, and neuromuscular control. Recent research has highlighted the role of the bony morphology of the proximal tibia and distal femur on primary ACL injury risk, as well as the risk for ACL graft failure. Sex differences in bony and ligamentous morphology of the knee, neuromuscular control, and hormonal factors, such as serum relaxin levels and variations within the menstrual cycle, have been correlated with a higher risk of noncontact primary ACL injuries in female athletes compared with male athletes.

A mechanical study of the influence of ankle joint angle on translational traction of soccer boots

The shoe–surface interaction for soccer players has both safety and performance implications. This interaction has been widely researched in terms of outsole configuration and surface type. However, these investigations, particularly those involving translational traction, often neglect the approach angle of the foot in terms of a real-world setting. This investigation considers the foot position prior to injuries such as anterior cruciate ligament tears, and observes how the translational traction alters with various angles for simulated plantarflexion, dorsiflexion, calcaneal inversion and calcaneal eversion. It was hypothesised that, as these angles increased, the translational traction would decrease as there would be less contact area between the boot and the surface compared to the neutral, flat footform. A custom-built testing apparatus recorded the translational traction of a soccer boot moving in four different directions at different loading angles on both a natural grass and artificial grass playing surface. A one-way ANOVA was performed, with a post-hoc Tukey Test to determine the significant differences between the translational traction between each angle. It was found that the geometry of the outsole configuration, more specifically, the apparent contact area between the shoe and surface played a significant role in the level of traction obtained. These results highlight the importance of stud geometry, particularly with respect to movements when the foot is angled as it would be in a potential injury scenario. Manufacturers should consider the profile of studs relative to the expected movements to not induce excessive traction, which could lead to potential foot fixation and injury.

A biomechanical report of an acute lateral ankle sprain during a handball-specific cutting movement

ABSTRACT Biomechanical measurements of accidental ankle sprain injuries are rare but make important contributions to a more detailed understanding of the injury mechanism. In this case study, we present the kinematics and kinetics of a lateral ankle sprain of a female athlete performing handball-specific fake-and-cut manoeuvres. Three-dimensional kinematics and kinetics were recorded and six previously performed trials were used as reference. Plantarflexion, inversion, and internal rotation angles were substantially larger than the reference trials and peaked between 190 and 200 ms after initial ground contact. We observed a highly increased inversion and internal rotation moment. However, compared to the non-injury trials the data also revealed a reduction in the second dorsiflexion moment peak. Ground reaction forces were lower throughout the injury trial. Other parameters at initial ground contact including ankle and hip position, step length, and the traction coefficient indicate that a preparatory maladjustment occurred. This study adds valuable contributions to the understanding of lateral ankle sprains by building upon previously published reports and considering the shoe-surface interaction as an important factor for injury.

The development of mandatory practices for the testing and maintenance of synthetic turf fields in the National Football League

AbstractSynthetic turf has become an increasingly common playing surface in athletics. Synthetic turf maintenance and athlete health are related and are important considerations at all levels of play. As part of the development of testing practices for the National Football League (NFL) game‐day surfaces, a literature search of MEDLINE and PubMed between the years 1990 and 2018 was conducted. Additionally, a taskforce was convened, and expert opinion was solicited from members through systematic interviews regarding synthetic turf design and maintenance practices in the NFL. All game‐day synthetic turf manufacturers were routinely solicited for input during development and implementation of the mandatory practices. Appropriate maintenance practices can improve the consistency of a synthetic playing surface. Methods for evaluating surface hardness and other aspects of synthetic turf have been developed. The relationships between current hardness testing methods and injury outcomes have been studied but are not well established. Consensus methods for evaluating surface traction and cleat release at potentially injurious loading levels are currently unavailable and needed. Mandatory practices were developed and have been implemented by the NFL, which have resulted in more consistent playing surfaces over the course of a season. Despite the extant gaps in knowledge, a formalized set of testing practices and maintenance has proven effective for reducing surface variability across synthetic surfaces in the NFL. Characteristics such as surface hardness, traction, and shoe–surface interaction, and the effects of surface maintenance procedures should be the focus of future research.

The effect of horseshoes and surfaces on horse and jockey centre of mass displacements at gallop.

Horseshoes influence how horses' hooves interact with different ground surfaces, during the impact, loading and push-off phases of a stride cycle. Consequently, they impact on the biomechanics of horses' proximal limb segments and upper body. By implication, different shoe and surface combinations could drive changes in the magnitude and stability of movement patterns in horse-jockey dyads. This study aimed to quantify centre of mass (COM) displacements in horse-jockey dyads galloping on turf and artificial tracks in four shoeing conditions: 1) aluminium; 2) barefoot; 3) GluShu; and 4) steel. Thirteen retired racehorses and two jockeys at the British Racing School were recruited for this intervention study. Tri-axial acceleration data were collected close to the COM for the horse (girth) and jockey (kidney-belt), using iPhones (Apple Inc.) equipped with an iOS app (SensorLog, sample rate = 50 Hz). Shoe-surface combinations were tested in a randomized order and horse-jockey pairings remained constant. Tri-axial acceleration data from gallop runs were filtered using bandpass Butterworth filters with cut-off frequencies of 15 Hz and 1 Hz, then integrated for displacement using Matlab. Peak displacement was assessed in both directions (positive 'maxima', negative 'minima') along the cranio-caudal (CC, positive = forwards), medio-lateral (ML, positive = right) and dorso-ventral (DV, positive = up) axes for all strides with frequency ≥2 Hz (mean = 2.06 Hz). Linear mixed-models determined whether surfaces, shoes or shoe-surface interactions (fixed factors) significantly affected the displacement patterns observed, with day, run and horse-jockey pairs included as random factors; significance was set at p<0.05. Data indicated that surface-type significantly affected peak COM displacements in all directions for the horse (p<0.0005) and for all directions (p≤0.008) but forwards in the jockey. The largest differences were observed in the DV-axis, with an additional 5.7 mm and 2.5 mm of downwards displacement for the horse and jockey, respectively, on the artificial surface. Shoeing condition significantly affected all displacement parameters except ML-axis minima for the horse (p≤0.007), and all displacement parameters for the jockey (p<0.0005). Absolute differences were again largest vertically, with notable similarities amongst displacements from barefoot and aluminium trials compared to GluShu and steel. Shoe-surface interactions affected all but CC-axis minima for the jockey (p≤0.002), but only the ML-axis minima and maxima and DV-axis maxima for the horse (p≤0.008). The results support the idea that hoof-surface interface interventions can significantly affect horse and jockey upper-body displacements. Greater sink of hooves on impact, combined with increased push-off during the propulsive phase, could explain the higher vertical displacements on the artificial track. Variations in distal limb mass associated with shoe-type may drive compensatory COM displacements to minimize the energetic cost of movement. The artificial surface and steel shoes provoked the least CC-axis movement of the jockey, so may promote greatest stability. However, differences between horse and jockey mean displacements indicated DV-axis and CC-axis offsets with compensatory increases and decreases, suggesting the dyad might operate within displacement limits to maintain stability. Further work is needed to relate COM displacements to hoof kinematics and to determine whether there is an optimum configuration of COM displacement to optimise performance and minimise injury.

Ground reaction force estimation in football using inertial measurement units during alternate lateral bounding

Ground reaction force (GRF) is of interest to understand the mechanics of football shoe-surface interactions and the consequences for athletic performance (Luo & Stefanyshyn, 2011 Luo, G., & Stefanyshyn, D. (2011). Identification of critical traction values for maximum athletic performance. Footwear Science, 3, 127–138. doi:10.1080/19424280.2011.639807 [Taylor & Francis Online] , [Google Scholar] ; Pedroza, Fernandez, Heidt, & Kaeding, 2010 Pedroza, A., Fernandez, S., Heidt, R., & Kaeding, C. (2010). Evaluation of the shoe-surface interaction using an agility maneuver. Medicine and Science in Sports and Exercise, 42, 1754–1759. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] ). Force platforms (FP) are the gold standard for measuring GRF; however, they are expensive devices, athletes may adjust their movements to target a specific area and installation is difficult outside the laboratory under football specific surfaces. Potential candidates to overcome these limitations and estimate GRFs in-field are inertial measurement units (IMU).

مخاطر الإصابة بالرباط الصليبي الأمامي: مراجعة أدبية

الرباط الصليبي الأمامي هو أحد أربطة الركبة الهامة التي تلعب دوراً هاماً في الحفاظ على ثبات مفصل الركبة. وآلية الإصابة غالبا ما تكون جراء عدم الاحتكاك المباشر بنسبة65% مع الخصم أثناء الأنشطة البدنية التي تتطلب تغييراً مفاجئًا لاتجاه اللعب، مثل: القفز والهبوط، وحركات دوران القدم. أن معدل الإصابة بقطع الرباط الصليبي ما زال عاليا بين عموم الناس والرياضيين بشكل خاص للفئة العمرية ما بين 15 إلى 25 سنة. إن الهدف من هذه المراجعة الأدبية هو تحليل ودراسة اأصسباب والمخاطر المحتملة للإصابة بقطع الرباط الصليبي الأمامي في عدة متغيرات و تسليط الضوء عليها منها: العلاقة بين أرضية الملعب والحذاء، وزاوية العضلة ذات الأربعة رؤوس الفخذية، ارتخاء مفصل الركبة، التقوس الخارجي للركبة، كتلة الجسم، وغيرها. وزيادة فرص الإصابة عادة ما يكون من خلال تداخل واشتراك عدة عوامل بعضها مع بعض أثناء النشاط البدني؛ لذلك يجب الأخذ بعين الاعتبار جميع المعطيات المتعلقة بخطر الإصابة عند تصميم وتخطيط البرامج التدريبية والتأهيلية أثناء التدريب والمنافسات من أجل تقليل فرص الإصابة.

Incidence, Mechanisms, and Severity of Game-Related High School Football Injuries Across Artificial Turf Systems of Various Infill Weights.

Background:Artificial turf surfaces are developed to duplicate playing characteristics of natural grass. With the newer generations of sand and rubber infill systems, the infill is a common component that varies between fields and is a critical factor that could influence the player-surface interaction. Because the influence of infill weight on sport trauma is unknown, this study quantified football trauma in high schools in the United States across artificial turf systems of various infill weights.Hypothesis:Athletes would not experience differences in game-related injuries across artificial turf systems of various infill weights.Study Design:Cohort study; Level of evidence, 2.Methods:Artificial turf systems were divided into 4 sand/rubber infill weight groups by pounds per square foot: ≥9.0, 6.0-8.9, 3.0-5.9, and 0.0-2.9. A total of 57 high schools in 4 states participated over the course of 5 seasons. Outcomes of interest included injury severity, as a function of infill weight, across head, knee, and shoulder traumas; injury category; primary type of injury; tissue type; specific body location of injury; cleat design; environmental factors; and turf age. Data were subject to multivariate analyses of variance (MANOVAs) and Wilks λ criteria through use of general linear model procedures.Results:Of 1837 games documented, 528 games were played on infill weights of ≥9.0 lb/ft2, 521 on 6.0-8.9 lb/ft2, 525 on 3.0-5.9 lb/ft2, and 263 on 0.0-2.9 lb/ft2, with 4655 total injuries reported. MANOVAs indicated significant infill weight effects across injury severity (F 2,4648 = 5.087; P = .0001), with significant main effects also observed by injury category, tissue injured, lower extremity joint and muscle, cleat design, environmental factors, and turf age. Post hoc analyses indicated significantly lower (P < .05 to .0001) total and substantial traumas, concussions, shoe-surface interaction during contact trauma, surface impacts, muscle-tendon overload, cleat design influence, adverse weather trauma, lower extremity injuries, and turf age effect while athletes were competing on the 6.0 to ≥9.0 lb/ft2 infill weight systems compared with the lighter infill weight systems.Conclusion:As infill surface weight decreased, football trauma significantly increased across numerous playing conditions. Based on findings, high school football fields should minimally contain 6.0 pounds of infill per square foot.

Is There an Economical Running Technique? A Review of Modifiable Biomechanical Factors Affecting Running Economy.

Running economy (RE) has a strong relationship with running performance, and modifiable running biomechanics are a determining factor of RE. The purposes of this review were to (1) examine the intrinsic and extrinsic modifiable biomechanical factors affecting RE; (2) assess training-induced changes in RE and running biomechanics; (3) evaluate whether an economical running technique can be recommended and; (4) discuss potential areas for future research. Based on current evidence, the intrinsic factors that appeared beneficial for RE were using a preferred stride length range, which allows for stride length deviations up to 3 % shorter than preferred stride length; lower vertical oscillation; greater leg stiffness; low lower limb moment of inertia; less leg extension at toe-off; larger stride angles; alignment of the ground reaction force and leg axis during propulsion; maintaining arm swing; low thigh antagonist–agonist muscular coactivation; and low activation of lower limb muscles during propulsion. Extrinsic factors associated with a better RE were a firm, compliant shoe–surface interaction and being barefoot or wearing lightweight shoes. Several other modifiable biomechanical factors presented inconsistent relationships with RE. Running biomechanics during ground contact appeared to play an important role, specifically those during propulsion. Therefore, this phase has the strongest direct links with RE. Recurring methodological problems exist within the literature, such as cross-comparisons, assessing variables in isolation, and acute to short-term interventions. Therefore, recommending a general economical running technique should be approached with caution. Future work should focus on interdisciplinary longitudinal investigations combining RE, kinematics, kinetics, and neuromuscular and anatomical aspects, as well as applying a synergistic approach to understanding the role of kinetics.

Shoe–surface interaction and lower extremity injury in the football codes: A systematic review and meta-analysis

Shoe–surface interaction and lower extremity injury in the football codes: A systematic review and meta-analysis

Higher shoe-surface interaction is associated with doubling of lower extremity injury risk in football codes: a systematic review and meta-analysis

BackgroundTurning or cutting on a planted foot may be an important inciting event for lower limb injury, particularly when shoe-surface traction is high. We systematically reviewed the relationship between shoe-surface...

Rotational stiffness of American football shoes affects ankle biomechanics and injury severity.

While previous studies have investigated the effect of shoe-surface interaction on injury risk, few studies have examined the effect of rotational stiffness of the shoe. The hypothesis of the current study was that ankles externally rotated to failure in shoes with low rotational stiffness would allow more talus eversion than those in shoes with a higher rotational stiffness, resulting in less severe injury. Twelve (six pairs) cadaver lower extremities were externally rotated to gross failure while positioned in 20 deg of pre-eversion and 20 deg of predorsiflexion by fixing the distal end of the foot, axially loading the proximal tibia, and internally rotating the tibia. One ankle in each pair was constrained by an American football shoe with a stiff upper, while the other was constrained by an American football shoe with a flexible upper. Experimental bone motions were input into specimen-specific computational models to examine levels of ligament elongation to help understand mechanisms of ankle joint failure. Ankles in flexible shoes allowed 6.7±2.4 deg of talus eversion during rotation, significantly greater than the 1.7±1.0 deg for ankles in stiff shoes (p = 0.01). The significantly greater eversion in flexible shoes was potentially due to a more natural response of the ankle during rotation, possibly affecting the injuries that were produced. All ankles failed by either medial ankle injury or syndesmotic injury, or a combination of both. Complex (more than one ligament or bone) injuries were noted in 4 of 6 ankles in stiff shoes and 1 of 6 ankles in flexible shoes. Ligament elongations from the computational model validated the experimental injury data. The current study suggested flexibility (or rotational stiffness) of the shoe may play an important role in both the severity of ankle injuries for athletes.

The Development of a Translational Traction Rig to Investigate the Mechanisms of Traction in 3G Turf

During football specific movements a high translational traction is desired at the shoe-surface interface to facilitate player movement. Translational traction is commonly assessed through bespoke mechanical test devices which provide a more repeatable tool for characterising the shoe-surface interaction compared to player testing. Following development, application of the rig is demonstrated through an initial investigation into the effect of the number of studs and stud orientation on translational traction. The translational rig consists of a tray attached to two trails, with surface samples of varying specification placed in the tray. A number of stud configurations were chosen and tested on a 3G artificial turf sample. The initial stiffness response of the surface as well as larger displacements were considered to help inform the mechanisms of traction. The study showed the increasing force as the number of studs increased and how the positions of the studs also relate to the forces produced in the infill and the effect on the mechanism of traction.

Measurement of studded shoe–surface interaction metrics during in situ performance analysis

Interaction between studded footwear and performance surfaces plays an important role in sport. Discretising this interaction into quantifiable measurements can help optimise design of outsoles and identify parameters for performance testing in situ. Here, we describe the development and validity of an image-based three-dimensional (3D) measurement system to investigate shoe–surface interactions during locomotion performance in situ by eight skilled footballers. By calculating individual stud positions, results revealed that the 3D kinematic data could be distilled to a number of shoe–surface interaction metrics such as orientation, velocity, translation distance and location of the centre of rotation. Findings show how the measurement system and simple analysis methods can be used to provide informative shoe–surface interaction metrics from in situ performance capture for the footwear community.

Shoe traction and surface compliance affect performance of soccer-related movements

Purpose: To determine how shoe-surface interaction, specifically traction and compliance, affects performance and biomechanics of soccer-related movements.Methods: Third generation artificial turf was installed in the laboratory to allow for kinetic and kinematic data collection both on the turf and on a laboratory surface (Pulastic sports surface). Twelve male athletes performed five 5 m sprint accelerations and five 180° sprint turns in three different shoe-surface conditions (indoor soccer shoe on the laboratory surface, indoor soccer shoe on the turf surface, soccer cleat on turf surface). Comparisons between the indoor shoe across surfaces indicated compliance effects and comparisons between the cleat and indoor shoe on turf indicated traction effects.Results: Performance increased for the sprint acceleration in the indoor shoe on the turf compared to the laboratory (1.04 s vs. 1.08 s); however, no further increase in acceleration performance occurred with the soccer cleat. For the turn movement, no change in performance occurred comparing the indoor shoe across surfaces however an increase in turn performance was seen when using the soccer cleat on turf compared to the indoor shoe (2.67 s vs. 2.56 s). The cleat had both increased utilised translational and rotational traction compared to the indoor shoe on turf for the turn movement. The cleat also resulted in increased ankle eversion moments as well as increased knee abduction and external rotation moments compared to the indoor shoe on the turf surface for the turn movement.Conclusion: Both compliance and traction shoe-surface characteristics affect performance; however, the effects of the different characteristics are different depending on the movement type.

Effect of Varying the Volume Infill Sand on Synthetic Clay Surfaces in Terms of the Shoe-surface Friction

The friction developed by the shoe-surface interface on artificial clay has not been widely studied, and can influence player's performance and injury risk. The aim of this research was to investigate the effect of varying the quantity of infill sand on shoe- surface friction on an artificial clay court tennis surface. A laboratory-based mechanical test rig was used to measure the friction force developed at the shoe-surface interface. Additionally, the perception of a group of participants, performing a turning movement on the same surface under dry conditions, was collected in order to compare against the mechanical results. The relationship between the normal force and friction generated by the shoe-surface interaction was examined for surfaces with different sand in-fill volumes. The mechanical testing was performed under dry and wet conditions, showing strong and significant differences. Results indicated that the normal force significantly influenced the static and dynamic frictional forces. For lower sand infill volumes, as normal loading increased, the dry condition was found to exhibit the lowest peak static friction force and highest average dynamic friction force. However, for higher sand infill volume conditions, the opposite behaviour was observed. Strong and significant positive linear relationships were found between peak friction force and average dynamic friction force for all infill sand volumes and conditions. The mechanical results were in agreement with the perception data, which suggests that the participants were sensitive to the small changes in sand infill volumes.The findings of this study will therefore aid the understanding of tennis players’ perceived response to a tennis court surface. In order to get a better understanding of friction behaviour, further testing needs to be performed, and once the mechanisms involved are understood, surface properties could be modified to increase performance and reduce injury risk.

Friction at the Tennis Shoe-court Interface: How Biomechanically Informed Lab-based Testing can Enhance Understanding

This paper presents some of the methodology, observations and findings from a 30-month study, aiming to improve the understanding of tennis shoe-court interactions and the biomechanical implications of changes in friction between the shoe and surface. A detailed programme of biomechanical player testing on different court surfaces provided the boundary conditions with which to develop a lab-based rig capable of simulating the key aspects of shoe-surface interaction that are required for acceptable performance (e.g. push-off to accelerate) within expected levels of consistency (e.g. for a controlled slide). Large- scale parametric testing could then be carried out for a variety of surface types and components under a range of loading conditions, without the risk of injury to human participants. Two case studies are described to demonstrate the value of a combined approach of biomechanical field testing and lab-based rigs that simulate shoe-court interactions. These include a study that compared different artificial clay court designs; and a study that examined the effect of different acrylic hard court parameters on friction and the tribological mechanisms that explain the observed interaction

Influence of Clay Properties on Shoe-kinematics and Friction During Tennis Movements

Tennis is a sport characterised by being played on different surfaces: hard court, grass and clay. These surfaces influence the style of play and tennis specific movements. Specifically on clay, most of the common movements performed by players (e.g. accelerating, side stepping and braking), are performed with some level of controlled sliding. In order to reduce the player's injury risk, and assess the shoe-surface requirements on clay surfaces, there is a need for a scientific understanding of the player's kinematics and tribological mechanisms occurring at the shoe-surface interface. The purpose of this study was to identify the kinematics of the shoe during the sliding phase, and to assess the friction that is present. Baseline areas of both ends of a clay court were prepared with two different mixes of clay, varying the particle size. Eight experienced clay players participated in this study which took place during the Conde de Godó tennis tournament in Barcelona, Spain. 3D kinematic data data was collected using two synchronised high speed video cameras, and after the tests, perception questionnaires were applied to the players. Additionally, three different mechanical devices were utilised to measure the friction of the two clay surfaces. Displacement and velocity data of the shoe in contact with the surface were correlated with the friction measurements from both clay surfaces. Results indicated that significant differences occurred between the two clay surfaces for some shoe kinematic data, and mechanical friction. However, the perception scores suggest the opposite behaviour stated by the mechanical test and shoe-kinematic data. The present study has provided evidence that shoe kinematics and friction of the shoe-surface interaction are affected by the surface conditions, specifically particle size.

Tribology, friction and traction: understanding shoe-surface interaction

Friction has been studied since the early investigations of Leonardo da Vinci, Amontons, Coulomb, and Euler, and many experimental investigations have been used to measure the friction force between contact surfaces. However, in the case of non-homogenous and different surfaces commonly experienced in sports, all of the laws of friction are violated. The area of tribology provides an opportunity to describe the relationship between footwear and the surface in engineering terms and explain how traction is generated on sports surfaces. The paper firstly examines the mechanisms used to explain dry friction, and uses these to explain the complex mechanisms associated with field footwear-surface interaction.

Effects of artificial turf on performance and ground contact kinetics during a sprint acceleration

Athletic footwear companies strive to optimise shoe-surface interaction characteristics for different sports, resulting in different shoes for different play conditions. An obvious example of this ...