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We aimed to clarify the effect of different futsal playing surface structural properties on the resultant change of direction (COD) performance, perceived traction and frictional properties. Twenty experienced male university soccer players performed a COD slalom-course test and perceived traction evaluation on three different types of playing surfaces (area-elastic: AE, point-elastic no.1: PE1 and point-elastic no.2: PE2). Frictional properties of these surfaces were mechanically evaluated against a futsal shoe, using a hydraulic moving force platform, and expressed as available friction coefficient (AFC). In the COD performance test, the participants performed significantly better on the point-elastic surfaces (PE1 and PE2) when compared to the area-elastic surface (AE) (p

Previous studies have compared slip resistance of commercially available footwear, however, often lacking the ability to isolate factors such as material and surface properties, or/and geometry. The aim of this study was to compare slip resistance of geometrically identical shoes with varying outsole materials. Three left Ecco Xpedition III shoes were constructed out of three different outsole materials: polyurethane (PU), thermoplastic polyurethane (TPU) and vulcanised rubber (RU). The shoes were tested for dynamic coefficient of friction (DCOF) on a steel and a tile surface, without contamination and with glycerine and canola oil as contaminants. The shoes were significantly (p < 0.001) different from each other across all surface/contaminant conditions/combinations, with the PU having a significantly 61–125% (p < 0.001) higher DCOF on contaminated surfaces compared to the RU outsole. Practitioner summary: Previous research has suggested the importance of studying individual parameters separately of footwear in relation to slip resistance. In this study, we managed to construct geometrically identical shoes and compare the slip resistance between three different outsole materials. We found that the polyurethane outsole was the least slippery choice of material for this specific footwear model on contaminated surfaces.

Lateral ankle sprains are a commonly incurred injury in sports. They have a high recurrence rate and can lead to the development of persistent injury associated symptoms. We performed a quantitative synthesis of published case reports documenting the kinematics of acute lateral ankle sprains and episodes of 'giving-way' of the ankle joint to provide a comprehensive description of the mechanisms. A systematic literature search was conducted to screen records within MEDLINE® and EMBASE®. Additional strategies included manual search of specific journals, as well as contacting researchers in relevant communities to retrieve unpublished data. Twenty-four cases were included in the quantitative synthesis, 11 from individual case reports and 13 from four separate case series. Two authors independently reviewed all the articles and extracted ankle joint kinematic data. Excessive ankle inversion was the most pronounced kinematic pattern observed across all included cases, with a mean peak inversion angle of 67.5° (range 2.0 to 142) and a mean peak inversion velocity of 974°/s (range 468 to 1752). This was followed by internal rotation and plantar flexion, respectively. A homogeneous linear function revealed a mean inversion velocity across all cases of 337°/s (range 117 to 1400; R2 = 0.78; p < 0.0001).

Det gjorde det muligvis for Brøndbys Kevin Mensah. Og han er langt fra den eneste fodboldspiller, der spiller i forkerte støvler.

Lateral ankle sprains are common in indoor sports, and most of these injuries occur via a ‘non-contact’ injury mechanism in which the only contact is between the shoe and the floor.1 2 Shoe–surface friction is generally high in indoor sports, and this attribute is considered a risk factor for non-contact lower extremity injuries.3 Spraino is a novel low-friction patch that is attached to the outside of sports shoes, specifically designed to prevent ‘friction-related’ ankle sprains in indoor sports by minimising friction at the lateral edge of the shoe sole. The minimised friction causes a reorientation of the ground reaction force vector, bringing it closer towards the joint centre, resulting in a lower joint torque, which could mitigate the risk and severity of lateral ankle sprains.4 In our recent pilot randomised controlled trial (RCT), published in British Journal of Sports Medicine …

BackgroundLateral ankle sprains are common in indoor sports. High shoe–surface friction is considered a risk factor for non-contact lateral ankle sprains. Spraino is a novel low-friction patch that can be attached to the outside of sports shoes to minimise friction at the lateral edge, which could mitigate the risk of such injury. We aimed to determine preliminary effectiveness (incidence rate and severity) and safety (harms) of Spraino to prevent lateral ankle sprains among indoor sport athletes.MethodsIn this exploratory, parallel-group, two-arm pilot randomised controlled trial, 510 subelite indoor sport athletes with a previous lateral ankle sprain were randomly allocated (1:1) to Spraino or ‘do-as-usual’. Allocation was concealed and the trial was outcome assessor blinded. Match and training exposure, number of injuries and associated time loss were captured weekly via text messages. Information on harms, fear-of-injury and ankle pain was also documented.Results480 participants completed the trial. They reported a total of 151 lateral ankle sprains, of which 96 were categorised as non-contact, and 50 as severe. All outcomes favoured Spraino with incidence rate ratios of 0.87 (95% CI 0.62 to 1.23) for all lateral ankle sprains; 0.64 (95% CI 0.42 to 0.98) for non-contact lateral ankle sprains; and 0.47 (95% CI 0.25 to 0.88) for severe lateral ankle sprains. Time loss per injury was also lower in the Spraino group (1.8 vs 2.8 weeks, p=0.014). Six participants reported minor harms because of Spraino.ConclusionCompared with usual care, athletes allocated to Spraino had a lower risk of lateral ankle sprains and less time loss, with only few reported minor harms.Trial registration numberNCT03311490.

Adequate friction between footwear and surface is essential to reduce the risk of slipping (Chang et al., 2001) and maximise athletic performance (Luo & Stefanyshyn, 2011). Footwear outsole materia...

Introduction: The contact mechanism between shoe and surface is crucial in order to avoid slipping and falling, enhance sporting performance or minimize the risk of sport injuries. However, studying this contact mechanism, between footwear and surface, is challenging and violates the traditional Amontons–Coulomb’s law of friction, due to the viscoelastic outsole materials. Hence, replicating the biomechanical test conditions are of great importance, when determining the friction properties of footwear. The aim of this study is to present a test-setup able to replicate biomechanical relevant test conditions.Approach/Methods: The test-setup consisted of a steel frame designed to maintain the position of a shoe, mounted above a force plate. The force plate is attached on top of a hydraulic platform, which makes it possible to move vertical and horizontal. Discussion & Significance: This study presents a new test setup that can characterize the tribological behavior of shoe and surface in a traditional way, by following the traditional ISO 13287 standards, but more importantly also being able to add a novel impacting approach to the test of footwear, which is arguably more biomechanically relevant.

Sprains to the lateral ligaments of the ankle joint are the most common type of acute musculoskeletal injuries (Vuurberg et al., 2018). These injuries are especially prevalent in indoor sports wher...

PURPOSE: The sudden rise in the injury incidence during adolescence is also evident in soccer-related injuries to the groin. Submaximal passing applies high stress on the adductor muscles and pubic symphysis and is therefore likely to be connected to the occurrence of groin injuries. Therefore, the purpose of the study was to compare hip joint kinematics and adductor muscle forces of different adolescent age groups during submaximal soccer passing. METHODS: Sixty participants, in four groups, younger than 12, 15, 16. and 23 yr (U12, U15, U16, U23), were analyzed. A Footbonaut, equipped with a 3D motion capture system consisting of 16 cameras, was used to capture kinematic data of short passes. Inverse dynamic analysis was performed to calculate muscle forces of 10 passes of each subject. RESULTS: The U15 group showed reduced angular velocities. A rise in hip adductor muscle forces was evident from the youngest group up to the oldest groups. The largest increase (49%) was found between U12 and U15. Lower-limb mass was identified as the best predictor for the increasing adductor force. CONCLUSIONS: The reduced angular velocities of the U15 and the increase in muscle forces between all age groups were attributed to the increasing segment masses and length. This increases the moments of inertia of the leg segments thereby demanding higher forces to accelerate the segments. Most likely, the stress put upon the adductors apophyses increases during adolescence, as tendons are known to adapt slower than muscles, increasing the risk for overuse injuries. Coaches could use lower-limb mass as an indicator for fast increases in the force demand to identify players who would benefit from a reduced training volume.

Traction is widely regarded as essential to sporting performance. However, high traction also increases lower limb injury risk (Pasanen, Parkkari, Rossi, & Kannus, 2008). Indoor sports shoes are ge...

Ankle sprain injuries account for up to 30% of all sport-related injuries80-90% are of a lateral nature caused by a sudden excessiveinversion of the footAnkle sprains are extremely common in indoor sportsAthletes with a previous ankle sprain are 4.9 to 8.2 times more likely to sustain another ankle sprain injuryCurrent best practice prescribes a combined use of an externalmeasure and neuromuscular training for 1-2 years

Groin injuries are common in soccer and often cause time-loss from training. While groin injuries have been linked to full effort kicking, the role of inside passing is unclear. Therefore, the purpose of this study was to investigate hip joint kinematics and muscle force, stress and contraction velocity for adductor longus and gracilis during inside passing. 3D kinematics of ten soccer players (23.4 yrs; 77.5 kg; 1.81 m) were captured with a motion capture system inside a Footbonaut. Muscle force and contraction velocity were determined with AnyBody Modelling System. Gracilis muscle forces were 9% lower compared to adductor longus (p = 0.005), but muscle stress was 183% higher in gracilis (p = 0.005). Contraction velocity reveals eccentric contraction of gracilis in the last quarter of the swing phase. Considering the combination of eccentric contraction, high muscle stress and the repetitive nature of inside passing, gracilis accumulates high loads in matches and training. These results indicate that the high incidence of groin injuries in soccer could be linked to isolated pass training. Practitioners need to be aware of the risk and refrain from sudden increases in the amount of pass training. This gives the musculoskeletal system time to adapt and might avoid career threatening injuries.

Ankle injuries are among the most frequent injuries sustained in sports with approximately 75% being lateral sprains (Fong, Hong, Chan, Yung, & Chan, 2007). Prevention of ankle sprains is a broad f...

It has previously been speculated that the occurrence and severity of lateral ankle sprain injuries is linked to excessive shoe-surface friction. The purpose of this study was to assess the amount of lateral edge friction in indoor sports shoes, and evaluate the variation from the traditional forefoot traction test. Therefore, we modified the ISO:12387:2019 test for slip resistance and positioned the shoe on its lateral edge while simulating a sideways movement. All tests were conducted on an indoor surface. In general, we found that lateral edge friction on average was 22% lower than forefoot friction (p

It has previously been speculated that the occurrence and severity of lateral ankle sprain injuries is linked to excessive shoe–surface friction. Especially, the lateral parts of the shoe outsole are suggested to play an important role in such scenarios but have never been quantified in a systematic manner. Therefore, the purpose of this study was to investigate the variation of friction of indoor sport shoes with foot orientation and compare it to the traditional industry forefoot friction test standard. We modified the ISO:13287:2019 test for footwear slip resistance and positioned the shoe on its forefoot and lateral edge while replicating medio-lateral movements similar to previously reported ankle sprain incidents. All tests were conducted on an indoor vinyl/sport surface. The results from the modified setups were compared to those following the anterior-posterior orientated ISO standard. Medio-lateral friction was on average 17% lower and lateral edge friction 24% lower than anterior-posterior forefoot friction (p