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Apps C.,Nottingham Trent University | Apps C.,Li Ning China Sports Goods Co. | Apps C.,Liverpool John Moores University | Sterzing T.,Li Ning China Sports Goods Co. | And 3 more authors.
Footwear Science | Year: 2017

A shoe with unsystematic perturbations, similar to natural uneven terrain, may offer an enhanced training stimulus over current unstable footwear technologies. This study compared the instability of a shoe with unpredictably random midsole deformations, an irregular surface and a control shoe-surface while treadmill walking and running. Three-dimensional kinematics and electromyography were recorded of the lower limb in 18 active males. Gait cycle characteristics, joint angles at initial ground contact and maximum values during stance, and muscle activations prior to initial contact and during loading were analysed. Perceived stability, injury-risk and energy consumption were evaluated. Instability was assessed by movement variability, muscular activations and subjective ratings. Posture alterations at initial contact revealed active adaptations in the irregular midsole and irregular surface to maintain stability while walking and running. Variability of the gait cycle and lower limb kinematics increased on the irregular surface compared to the control across locomotion types. Similarly increased variability (coefficient of variation) were found in the irregular midsole compared to the control for frontal ankle motion (walk: 31.1 and 14.9, run: 28.1 and 11.6), maximum sagittal knee angle (walk: 7.6 and 4.8, run: 2.8 and 2.4), and global gait characteristics during walking only (2.1 ± 0.5 and 1.6 ± 0.3). Tibialis anterior pre-activation reduced and gastrocnemius activation increased in the irregular midsole compared to the control across locomotion types. During running, peroneus longus activation increased in the irregular midsole and irregular surface. Results indicate random shoe midsole deformations enhanced instability relative to the control and simulated certain locomotion adaptations of the irregular surface, although less pronounced. Thus, a shoe with unpredictable instability revealed potential as a novel instability-training device. © 2017 Informa UK Limited, trading as Taylor & Francis Group


Sterzing T.,Li Ning China Sports Goods Co. | Barnes S.,Li Ning China Sports Goods Co. | Barnes S.,Victoria University | Althoff K.,University of Duisburg - Essen | And 2 more authors.
Footwear Science | Year: 2014

Background: Tennis is played globally across genders, skill levels, and surfaces. However, there is a lack of knowledge of athletes' footwear requirements regarding wearing habits, importance of shoe properties, desired degree of shoe properties, shoe problems, and foot discomfort. Therefore, this survey aimed to analyse these aspects comprehensively in China, USA, and Germany.Methods: Our survey involved 1524 competitive tennis players who provided their perspective on tennis footwear by answering supervised hard copy questionnaires. Data was analysed by descriptive statistics for the total population and for subgroups of country, gender, and skill level.Results: Across countries the most important shoe properties were fit, comfort, traction, injury protection, and outsole durability. However, the desired degree of shoe properties between countries was slightly different for some features. Chinese ask for comparatively narrower fit, Americans and Germans require comparatively higher traction. Durability and foot sweating are the most common shoe problems among all players and the plantar ball area is predominantly prone to foot discomfort.Conclusion: Although differences between countries, genders and skill level were observed, footwear requirements are comparable across groups. Observations provide evidence-based guidance for tennis footwear design, manufacturing and respective research areas. © 2014 © 2014 Taylor & Francis.


Sterzing T.,Li Ning China Sports Goods Co. | Custoza G.,Li Ning China Sports Goods Co. | Custoza G.,German Sport University Cologne | Ding R.,Li Ning China Sports Goods Co. | Cheung J.T.-M.,Li Ning China Sports Goods Co.
Footwear Science | Year: 2015

Purpose: Dual density midsole constructions at the lateral rearfoot and medial midfoot provide opportunities to improve cushioning and stability of running shoes. By similar mechanisms, non-uniform midsole density across the medio-lateral direction at the midfoot to forefoot may allow better negotiation of different loading magnitudes of the medial and lateral midfoot to forefoot during running. Thus, the effect of segmented midsole hardness at the midfoot to forefoot of running shoes on perception and biomechanics was examined. Methods: Four custom-made running shoes featured a three section longitudinal hardness pattern at midfoot to forefoot. The central section as well as the rearfoot section always had consistent medium hardness, whereas medial and lateral sections were systematically softer or harder. A sample of 24 runners participated in visual analogue scale based perception measurements and in recording of in-shoe plantar pressures, ground reaction forces, and multi-segment foot kinematics. Shoe effects were analysed by repeated measures analyses of variance (ANOVA) (p<.05), followed by least significant difference (LSD) and Bonferroni adjusted post-hoc tests (p<.05) for discrete variables. Interaction of shank and foot segments was also analysed using motion-time curves. Results: Runners distinguished midsole hardness at the medial (p =.009) but not at the lateral midfoot to forefoot and indicated a trend (p =.069) preferring softer medial hardness. Plantar peak pressure (medial: p =.006, lateral: p =.000) and relative loads (medial: p =.000, lateral: p =.000) were increased when midsole sections were harder. Ground contact time (p =.045) and maximum loading rate I (p =.016) were higher for shoes having softer medial hardness, while rearfoot (p =.040) and forefoot (p =.001) showed increased maximum ankle eversion for these conditions. Conclusion: Segmented running shoe midsole hardness across the medio-lateral direction of the midfoot to forefoot influences subjective comfort and biomechanical forefoot stability. Findings allow systematic approaches to improve both features, thereby creating enhanced running footwear. © 2015 Taylor & Francis.


Hong Y.,Chengdu University of Technology | Hong Y.,Chinese University of Hong Kong | Lam W.K.,Li Ning China Sports Goods Co. | Wang S.,Beifang University of Nationalities | Cheung J.T.-M.,Li Ning China Sports Goods Co.
Footwear Science | Year: 2016

This study examined whether the shoe usage time influences the comfort perception and direction change performance of badminton shoes. Fifteen university badminton players performed direction change trials with maximum-effort at new and extensively worn shoe conditions. Two professional badminton shoe models (Shoe Y and Shoe L) were selected to examine if both tested shoes would have similar usage time effect on comfort perception and direction change performance. Comfort perception of in-shoe climate, overall fit, medial-lateral stability, overall cushioning, shoe-ground traction, and overall comfort were measured using a 150 mm Visual Analogue Scales, immediately after the direction change trials. After finishing data collection of new shoe condition (day 1), the tested shoes were assigned to the university badminton team players to simulate the extensively worn condition that normally used during badminton training for eight weeks (i.e., 96 hours in total). The identical testing procedure was performed by the same experimenter for the extensively worn shoe condition (day 2). Paired t-tests were performed to investigate if there were any significant differences between new and extensively worn condition in each of the variables. Significance level was set at P < 0.05. No difference in direction change performance between new and extensively worn conditions was determined in each shoe (P > 0.05). Y shoe indicated significant poorer perception of medial-lateral stability, overall fit, and in-shoe climate (P < 0.05) while L shoe indicated significant poorer perception of overall fit and in-shoe climate for the extensively worn shoe condition, compared to the new shoe condition (P < 0.05). Prolonged shoe usage time plays a role in footwear comfort perception, but not in direction change performance. Changing with a new pairs of shoes would be considered to attain better comfort perception for badminton players during practice and competition. © 2016 Informa UK Limited, trading as Taylor & Francis Group.


Apps C.,Li Ning China Sports Goods Co. | Apps C.,Liverpool John Moores University | Liu H.,Beijing Sports University | Pykett J.,Liverpool John Moores University | Sterzing T.,Li Ning China Sports Goods Co.
Footwear Science | Year: 2015

Background: Exercising in gyms is popular worldwide, among diverse populations and with different types of training applied. However, there is a lack of knowledge about general gym training footwear requirements of gym goers. Therefore, the purpose of this study was to survey the requisites of gym footwear.Methods: Our survey comprised of 935 regular gym goers from China and England who completed supervised hard copy questionnaires of gym footwear. The questionnaire included gym footwear wearing habits, importance of shoe properties, desired degree of shoe properties, shoe problems, and foot discomfort. Data was analysed using descriptive statistics for the total population and for subgroups of country, gender, and fitness level.Results: Notably, most gym goers did not use gym-specific footwear, but running shoes. Across all gym goers fit and comfort were regarded as the most important gym shoe features, followed by outward appearance and breathability. English males considered performance enhancing shoe properties more important and English females comfort ones, with no such gender differences in China. The plantar foot region was most prone to discomfort across the total population. In China the largest shoe problem was durability, whereas in England it was foot sweating. Gym goers typically desired a rather wide, soft cushioned, flexible, light gym shoe, also providing arch support and rather high traction.Conclusion: Footwear requirements were generally comparable across countries, genders, and fitness levels, although some differences were observed. Universally, shoe comfort and appearance features were more important than features directly enhancing athletic performance, reflecting the rather moderate movements of gym exercises. Our results provide comprehensive and evidence-based guidance for gym training footwear design and related research. © 2014, © 2014 Taylor & Francis.


PubMed | Li Ning China Sports Goods Co. and Beijing Sports University
Type: | Journal: Research in sports medicine (Print) | Year: 2017

This study examined the effects of collar height and heel counter-stiffness of basketball shoes on ankle stability during sidestep cutting and athletic performance. 15 university basketball players wore customized shoes with different collar heights (high and low) and heel counter-stiffness (regular, stiffer and stiffest) for this study. Ankle stability was evaluated in sidestep cutting while athletic performance evaluated in jumping and agility tasks. All variables were analysed using two-way repeated ANOVA. Results showed shorter time to peak ankle inversion for both high collar and stiff heel counter conditions (P<0.05), while smaller initial ankle inversion angle, peak inversion velocity and total range of inversion for wearing high collar shoes (P<0.05). No shoe differences were found for performance variables. These findings imply that the collar height might play a larger role in lateral stability than heel counter-stiffness, while both collar height and counter-stiffness have no effect on athletic performance.


PubMed | Li Ning China Sports Goods Co. and Liverpool John Moores University
Type: | Journal: Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology | Year: 2016

Unstable shoes (US) continually perturb gait which can train the lower limb musculature, but muscle co-contraction and potential joint stiffness strategies are not well understood. A shoe with a randomly perturbing midsole (IM) may enhance these adaptations. This study compares ankle and knee joint stiffness, and ankle muscle co-contraction during walking and running in US, IM and a control shoe in 18 healthy females. Ground reaction forces, three-dimensional kinematics and electromyography of the gastrocnemius medialis and tibialis anterior were recorded. Stiffness was calculated during loading and propulsion, derived from the sagittal joint angle-moment curves. Ankle co-contraction was analysed during pre-activation and stiffness phases. Ankle stiffness reduced and knee stiffness increased during loading in IM and US whilst walking (ankle, knee: p=0.008, 0.005) and running (p<0.001; p=0.002). During propulsion, the opposite joint stiffness re-organisation was found in IM whilst walking (both joints p<0.001). Ankle co-contraction increased in IM during pre-activation (walking: p=0.001; running: p<0.001), and loading whilst walking (p=0.003), not relating to ankle stiffness. Results identified relative levels of joint stiffness change in unstable shoes, providing new evidence of how stability is maintained at the joint level.


Sterzing T.,Li Ning China Sports Goods Co. | Wulf M.,TU Munich | Qin T.Y.,Li Ning China Sports Goods Co. | Brauner T.,TU Munich
Footwear Science | Year: 2014

Purpose: Soccer shoes influence agility running due to traction properties. Shoe upper fit was identified to effect stability perception of players. However, its influence on agility running performance is unclear. This study examined whether soccer shoe ball girth dimension affects fit perception, agility running, and running speed perception. It was hypothesised that a narrower shoe ball girth would improve running performance.Methods: Thirty male soccer players performed agility runs in three experimental shoe conditions, featuring the same length but different ball girth (narrow, medium, wide). Fit perception, running time, and running speed perception were measured by a timing gate and perception protocols. One-way repeated measures analysis of variance (ANOVA) and Friedman tests were used to identify differences among shoe conditions, complemented by least significant difference (LSD) post-hoc and Wilcoxon signed rank tests.Results: Fit perception scores revealed that the medium and the wide shoe condition were perceived to have wider ball girth compared to the narrow condition (p < 0.05). No agility running performance and running speed perception differences were detected among shoe conditions. Anatomical foot measures were only weakly, or not correlated to fit perception at corresponding shoe locations.Conclusion: Fit differences of soccer shoes, only regarding their ball girth, did not influence agility running performance. This indicates a lesser importance of fit properties for achieving best running performance compared to traction properties, when ball girth is varied in shoes featuring a given shoe length. Individual lacing procedures were used in this study and may have compensated for the fit differences of the experimental shoes of this research. © 2014 © 2014 Taylor & Francis.


Lam W.K.,Li Ning China Sports Goods Company | Ding R.,Li Ning China Sports Goods Company | Qu Y.,Li Ning China Sports Goods Company
Journal of Sports Sciences | Year: 2016

Repeated movement (RM) lunge that frequently executed in badminton might be used for footwear evaluation. This study examined the influence of single movement (SM) and RM lunges on the ground reaction forces (GRFs) and knee kinetics during the braking phase of a badminton lunge step. Thirteen male university badminton players performed left-forward lunges in both SM and RM sessions. Force platform and motion capturing system were used to measure GRFs and knee kinetics variables. Paired t-test was performed to determine any significant differences between SM and RM lunges regarding mean and coefficient of variation (CV) in each variable. The kinetics results indicated that compared to SM lunges, the RM lunges had shorter contact time and generated smaller maximum loading rate of impact force, peak knee anterior-posterior force, and peak knee sagittal moment but generated larger peak horizontal resultant forces (Ps < 0.05). Additionally, the RM lunges had lower CV for peak knee medial-lateral and vertical forces (Ps < 0.05). These results suggested that the RM testing protocols had a distinct loading response and adaptation pattern during lunge and that the RM protocol showed higher within-trial reliability, which may be beneficial for the knee joint loading evaluation under different interventions. © 2016 Informa UK Limited, trading as Taylor & Francis Group


PubMed | Li Ning China Sports Goods Company
Type: Journal Article | Journal: Journal of sports sciences | Year: 2016

Repeated movement (RM) lunge that frequently executed in badminton might be used for footwear evaluation. This study examined the influence of single movement (SM) and RM lunges on the ground reaction forces (GRFs) and knee kinetics during the braking phase of a badminton lunge step. Thirteen male university badminton players performed left-forward lunges in both SM and RM sessions. Force platform and motion capturing system were used to measure GRFs and knee kinetics variables. Paired t-test was performed to determine any significant differences between SM and RM lunges regarding mean and coefficient of variation (CV) in each variable. The kinetics results indicated that compared to SM lunges, the RM lunges had shorter contact time and generated smaller maximum loading rate of impact force, peak knee anterior-posterior force, and peak knee sagittal moment but generated larger peak horizontal resultant forces (Ps < 0.05). Additionally, the RM lunges had lower CV for peak knee medial-lateral and vertical forces (Ps < 0.05). These results suggested that the RM testing protocols had a distinct loading response and adaptation pattern during lunge and that the RM protocol showed higher within-trial reliability, which may be beneficial for the knee joint loading evaluation under different interventions.

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