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Brauner T.,TU Munich | Zwinzscher M.,TU Chemnitz | Sterzing T.,Li Ning Sports Science Research Center
Footwear Science | Year: 2012

Introduction: Basketball contains numerous types of movements and highly specific playing positions, and hence the anthropometric profile of players varies considerably. To date, the subjective demands of basketball footwear have not been investigated in depth, either biomechanically or from the players' perspective. This study aimed to investigate players' subjective demands of basketball footwear according to playing position and respective physical game requirements. Methods: A supervised questionnaire survey of 165 basketball players of heterogeneous skill level was carried out. The questionnaire was divided into three sections enquiring about characteristics of (a) subject profile, (b) athletic demands of playing positions, and (c) basketball footwear. The χ 2 test and the Kruskal-Wallis test were used for statistical evaluation of the non-parametric data.Results: The three playing positions have very different physical profiles: (1) guards require speed and agility, (2) centres require strength and strong leaping ability, and (3) forward players are versatile all-rounders. Overall, ankle stability was rated the most important shoe characteristic and mid-cut uppers were favoured by the majority of players. Shoe preferences differed only marginally between playing positions: guards put more emphasis on low-weight and more flexible shoes whereas centre players prefer shoes with high stability and injury protection. Accordingly, centre player favoured high-cut uppers.Conclusions: The findings reveal the potential for two position-specific basketball shoe models: (1) a low- to mid-cut agility shoe model for guards and small forwards that has high traction and is supportive during acceleration and cutting movements, and (2) a mid- to high-cut stability shoe for power forwards and centres with the focus on ankle stability and jumping performance. The stability shoe could easily be complemented with additional ankle braces. © 2012 Copyright Taylor and Francis Group, LLC.

Brauner T.,TU Munich | Sterzing T.,Li Ning Sports Science Research Center | Wulf M.,TU Munich | Horstmann T.,TU Munich
Human Movement Science | Year: 2014

Leg stiffness is a predictor of athletic performance and injury and typically evaluated during bilateral hopping. The contribution of each limb to bilateral leg stiffness, however, is not well understood. This study investigated leg stiffness during unilateral and bilateral hopping to address the following research questions: (1) does the magnitude and variability of leg stiffness differ between dominant and non-dominant legs? (2) Does unilateral leg stiffness differ from bilateral leg stiffness? and (3) Is bilateral leg stiffness determined by unilateral leg stiffness? Thirty-two physically active males performed repeated hopping tests on a force platform for each of the three conditions: bilateral hopping, unilateral hopping on the dominant leg, and unilateral hopping on the non-dominant leg. Leg stiffness was estimated as the ratio of the peak vertical force and the maximum displacement using a simple 1-D mass-spring model. Neither the magnitude nor variability of leg stiffness differed between dominant and non-dominant limbs. Unilateral leg stiffness was 24% lower than bilateral stiffness and showed less variability between consecutive hops and subjects. Unilateral leg stiffness explained 76% of the variance in bilateral leg stiffness. We conclude that leg stiffness estimates during unilateral hopping are preferable for intervention studies because of their low variability. © 2013 Elsevier B.V.

Wang L.,Beihang University | Wang L.,Hong Kong Polytechnic University | CheungJason J.T.-M.,Li Ning Sports Science Research Center | Pu F.,Beihang University | And 3 more authors.
PLoS ONE | Year: 2011

Head injury is a leading cause of morbidity and death in both industrialized and developing countries. It is estimated that brain injuries account for 15% of the burden of fatalities and disabilities, and represent the leading cause of death in young adults. Brain injury may be caused by an impact or a sudden change in the linear and/or angular velocity of the head. However, the woodpecker does not experience any head injury at the high speed of 6-7 m/s with a deceleration of 1000 g when it drums a tree trunk. It is still not known how woodpeckers protect their brain from impact injury. In order to investigate this, two synchronous high-speed video systems were used to observe the pecking process, and the force sensor was used to measure the peck force. The mechanical properties and macro/micro morphological structure in woodpecker's head were investigated using a mechanical testing system and micro-CT scanning. Finite element (FE) models of the woodpecker's head were established to study the dynamic intracranial responses. The result showed that macro/micro morphology of cranial bone and beak can be recognized as a major contributor to non-impact-injuries. This biomechanical analysis makes it possible to visualize events during woodpecker pecking and may inspire new approaches to prevention and treatment of human head injury. © 2011 Wang et al.

Cong Y.,Hong Kong Polytechnic University | Tak-Man Cheung J.,Li Ning Sports Science Research Center | Leung A.K.L.,Hong Kong Polytechnic University | Zhang M.,Hong Kong Polytechnic University
Journal of Biomechanics | Year: 2011

Abnormal and excessive plantar pressure and shear are potential risk factors for high-heeled related foot problems, such as forefoot pain, hallux valgus deformity and calluses. Plantar shear stresses could be of particular importance with an inclined supporting surface of high-heeled shoe. This study aimed to investigate the contact pressures and shear stresses simultaneously between plantar foot and high-heeled shoe over five major weightbearing regions: hallux, heel, first, second and fourth metatarsal heads, using in-shoe triaxial force transducers. During both standing and walking, peak pressure and shear stress shifted from the lateral to the medial forefoot as the heel height increased from 30 to 70. mm. Heel height elevation had a greater influence on peak shear than peak pressure. The increase in peak shear was up to 119% during walking, which was about five times that of peak pressure. With increasing heel height, peak posterolateral shear over the hallux at midstance increased, whereas peak pressure at push-off decreased. The increased posterolateral shear could be a contributing factor to hallux deformity. It was found that there were differences in the location and time of occurrence between in-shoe peak pressure and peak shear. In addition, there were significant differences in time of occurrence for the double-peak loading pattern between the resultant horizontal ground reaction force peaks and in-shoe localized peak shears. The abnormal and drastic increase of in-shoe shear stresses might be a critical risk factor for shoe-related foot disorders. In-shoe triaxial stresses should therefore be considered to help in designing proper footwear. © 2011.

Yu J.,Hong Kong Polytechnic University | Cheung J.T.M.,Li Ning Sports Science Research Center | Wong D.W.C.,Hong Kong Polytechnic University | Cong Y.,Hong Kong Polytechnic University | Zhang M.,Hong Kong Polytechnic University
Journal of Biomechanics | Year: 2013

Footwear serves to protect the foot in various activities, to enhance athletic performance in sports and in many cases to fulfill aesthetic and cultural needs of urban society. Most women like wearing high-heeled shoes (HHS) for the benefit of sensuous attractiveness, while foot problems are often associated. Computational modeling based on finite element (FE) analysis is a useful tool for deep understanding of foot and footwear biomechanics and incorporating footwear with foot in the model is the prerequisite. In this study, a three-dimensional FE model of coupled foot-ankle-shoe complex and preceding gait simulation were established. Interfacial contact simulation was employed to complete the donning process of foot and shoe upper contact. Three major stance phases namely heel strike, midstance and push off were simulated to investigate the biomechanical response of high-heeled shod walking. It was found that the contact pressure at all metatarsophalangeal (MTP) joints intensified and reached their maximum at push off phase during locomotion, meanwhile the first MTP had the largest magnitude. The first and fifth MTP joints had larger movements in transverse plane among all MTP joints, indicating that these two joints bended more significantly by toe box restraint during locomotion. The dorsal contact pressure at the first toe increased by four times from heel strike to push off. The established HHS donning and walking simulation in this study proved the versatility and promising potential of computational approach for realistic biomechanical evaluation and optimization of footwear design in a virtual environment. © 2013 Elsevier Ltd.

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