Impact phase kinematics of instep kicking in soccer

The purpose of this study was to capture the lower limb kinematics before during and after ball impact of soccer kicking by examining the influence of both sampling rate and smoothing procedures. Nine male soccer players performed maximal instep kicks and the three-dimensional leg movements were captured at 1000 Hz. Angular and linear velocities and accelerations were determined using four different processing approaches: processed using a modified version of a time-frequency filtering algorithm (WGN), smoothed by a second-order low-pass Butterworth filter at 200 Hz cut-off (BWF), re-sampled at 250 Hz without smoothing (RSR) and re-sampled at 250 Hz but filtered by the same Butterworth filter at 10 Hz cut-off (RSF). The WGN approach appeared to establish representative kinematics, whereas the other procedures failed to remove noisy oscillation from the baseline of signal (BWF), lost the peaks of rapid changes (RSR) or produced totally distorted movement patterns (RSF). The results indicate that the procedures used by some previous studies may have been insufficient to adequately capture the lower limb motion near ball impact. We propose a new time-frequency filtering technique as a better way to smooth data whose frequency content varies dramatically.     

Primary mechanical factors contributing to foot eversion moment during the stance phase of running

Rearfoot external eversion moments due to ground reaction forces (GRF) during running have been suggested to contribute to overuse running injuries. This study aimed to identify primary factors inducing these rearfoot external eversion moments. Fourteen healthy men ran barefoot across a force plate embedded in the middle of 30-m runway with 3.30 ± 0.17 m · s^–1. Total rearfoot external eversion/inversion moments (Mtot) were broken down into the component Mxy due to medio-lateral GRF (Fxy) and the component Mz due to vertical GRF (Fz). Ankle joint centre height and medio-lateral distance from the centre of pressure to the ankle joint centre (a_cop) were calculated as the moment arm of these moments. Mxy dominated Mtot just after heel contact, with the magnitude strongly dependent on Fxy, which was most likely caused by the medio-lateral foot velocity before heel contact. Mz then became the main generator of Mtot throughout the first half of the stance phase, during which a_cop was the critical factor influencing the magnitude. Medio-lateral foot velocity before heel contact and medio-lateral distance from the centre of pressure to the ankle joint centre throughout the first half of the stance phase were identified as primary factors inducing the rearfoot external eversion moment.     

Ankle taping can reduce external ankle joint moments during drop landings on a tilted surface

Ankle taping is commonly used to prevent ankle sprains. However, kinematic assessments investigating the biomechanical effects of ankle taping have provided inconclusive results. This study aimed to determine the effect of ankle taping on the external ankle joint moments during a drop landing on a tilted surface at 25°. Twenty-five participants performed landings on a tilted force platform that caused ankle inversion with and without ankle taping. Landing kinematics were captured using a motion capture system. External ankle inversion moment, the angular impulse due to the medio-lateral and vertical components of ground reaction force (GRF) and their moment arm lengths about the ankle joint were analysed. The foot plantar inclination relative to the ground was assessed. In the taping condition, the foot plantar inclination and ankle inversion angular impulse were reduced significantly compared to that of the control. The only component of the external inversion moment to change significantly in the taped condition was a shortened medio-lateral GRF moment arm length. It can be assumed that the ankle taping altered the foot plantar inclination relative to the ground, thereby shortening the moment arm of medio-lateral GRF that resulted in the reduced ankle inversion angular impulse.     

The effect of muscle fatigue on instep kicking kinetics and kinematics in association football

The aim of this study was to examine the effect of leg muscle fatigue on the kinetics and kinematics of the instep football kick. Fatigue was induced by repeated, loaded knee extension (40% body weight) and flexion (50% body weight) motions on a weight-training machine until exhaustion. The kicking motions of seven male players were captured three-dimensionally at 500 Hz before and immediately after the fatigue protocol. The significantly slower ball velocity observed in the fatigue condition was due to both reduced lower leg swing speed and poorer ball contact. The reduced leg swing speed, represented by a slower toe linear velocity immediately before ball impact and slower peak lower leg angular velocity, was most likely due to a significantly reduced resultant joint moment and motion-dependent interactive moment during kicking. These results suggest that the specific muscle fatigue induced in the present study not only diminished the ability to generate force, but also disturbed the effective action of the interactive moment leading to poorer inter-segmental coordination during kicking. Moreover, fatigue obscured the eccentric action of the knee flexors immediately before ball impact. This might increase the susceptibility to injury.     

Subsidy and networking: The effects of direct and indirect support programs of the cluster policy

Industrial clusters have attracted considerable attention worldwide for their expected contribution to regional innovation. Recently, policymakers in various countries have developed specific cluster policies. However, there exist few empirical studies on cluster policies. Focusing on the Industrial Cluster Project (ICP) in Japan initiated by the Ministry of Economy, Trade and Industry in 2001, we address two research questions on the support programs of the cluster policies: if the project participants who exploit various support programs are more successful in network formation within the cluster than others, and which kind of support program contributes to firm performance. We pay special attention to the differences between direct R&D support and indirect networking/coordination support. The estimation results, which are based on recent original survey data, suggest that cluster participants who exploit support programs (especially indirect support measures) expand the industry-university-government network after participating in the ICP. Moreover, we find that not every support program contributes to firm performance; firms should therefore select the program that is most aligned with their aims. Indirect support programs have an extensive and strong impact on output whereas direct R&D support has only a weak effect.     

Object similarity bootstraps young children to action-based verb extension

Young children often fail to generalize a novel verb based on sameness of action since they have difficulty focusing on the relational similarity across events while at the same time ignoring the objects that are involved. Study 1, with Japanese-speaking 3- and 4-year-olds (N = 28 in each group), found that similarity of objects involved in action events plays a scaffolding role in children's extraction of relational similarity across events when they extend a verb. Study 2, with 4-year-olds (N = 47), further showed that repeated experience of action-based verb extension supported by object similarity leads children to be better able to extend a novel verb based on sameness of action, even without support from object similarity.     

A novel comparison between standard and new testing procedures to assess shock absorbency of third generation artificial turfs

This study aims to re-examine to what extent the testing procedure of the Artificial Athlete Berlin (DIN18032) is a valid evaluation method to assess the shock absorbency of third generation artificial turf (3-g turf) and to establish a new testing procedure, which precisely reflects the acute load by human sports action. The DIN test was conducted for 3-g turfs with different infill component. The baseline of the load of acute human sports action was obtained from the ground reaction force underneath the standard type of 3-g turf sample during landing from a 55-cm height with minimal shock attenuation. For reproducing the force similar to such a hard landing, a testing rig was developed and the same 3-g turf samples were tested. The DIN test failed to distinguish most types of 3-g turf and was found to be inappropriate to evaluate the shock absorbency of the 3-g turf mainly due to bouncing actions of the test foot on measured samples. In contrast, the newly developed testing rig succeeded in illustrating the differences of shock attenuation properties among most types of 3-g turfs in a high loading condition. In terms of players’ safety, the necessity of high loading test using an alternative testing procedure was highlighted.     

Key motion characteristics of side-step movements in hip-hop dance and their effect on the evaluation by judges

In hip-hop dance, the elements of motion that discriminate the skill levels of dancers and that influence the evaluations by judges have not been clearly identified. This study set out to extract these motion characteristics from the side-step movements of hip-hop dancing. Eight expert and eight non-expert dancers performed side-step movements, which were recorded using a motion capture system. Nine experienced judges evaluated the dancers’ performances. Several parameters, including the range of motion (ROM) of the joint angles (neck, trunk, hip, knee, and face inclination) and phase delays between these angular motions were calculated. A quarter-cycle phase delay between the neck motion and other body parts, seen only in the expert dancers, is highlighted as an element that can distinguish dancers’ skill levels. This feature of the expert dancers resulted in a larger ROM during the face inclination than that for the non-expert dancers. In addition, the experts exhibited a bottom-to-top segmental sequence in the horizontal direction while the non-experts did not demonstrate any such sequential motion. Of these kinematic parameters, only the ROM of the face inclination was highly correlated to the judging score and is regarded as being the most appealing element of the side-step movement.     

What Children Have Lost by the Modernisation of Education: A Comparison of Experiences in Western Europe and Eastern Asia

The discovery of the proper value of childhood during the 18th century in Europe was an important break-through. People began to respect childhood as a sacred world that should not be judged from the standpoint of adults. However, in today' world many children are subjected to all kinds of physical and mental pain, including the so-called examination hell in some Asian countries. Children now live in a paradoxical situation. Theoretically they have obtained the right to enjoy their own world, approved and protected by adults, but in practice they cannot adapt themselves smoothly to the world mainly ruled by the logic of grown-ups. This paper argues that it is time to re-evaluate what has been lost under the slogan of modernisation. The solution is not simply to return to the pre-modern situation but rather to consider what elements from the past could be re-activated to the benefit of children today.