James Ren

Effects of different unstable sole construction on kinematics and muscle activity of lower limb

Unstable sole construction can change biomechanics of lower extremity as highlighted by some previous studies, which could potentially help developing special training or rehabilitation schemes. In this study, unstable elements are fixed in heel and forefoot zone to exert unstable perturbations, and the position changes (medial, neutral and lateral) of unstable elements in forefoot coronal plane are adjusted to analyze changes of lower extremity kinematics and muscle activities. Twenty-two healthy male subjects participated in the test, walking with control shoes and experimental shoes randomly under self-selected speed. Kinematics and surface electromyography measurements were carried out simultaneously. It is found that experimental shoes can lead to the reduction of knee abduction and internal rotation and hip internal rotation, with p<.05. Ankle inversion and internal rotation amplitude were also reduced, which are associated with significantly increased activation levels of muscles (TA-tibialis anterior, PL-peroneus longus, LG-lateral gastrocnemius) in order to compensate perturbations. It is suggested that a training equipment incorporating unstable elements would enhance postural control by adjusting lower extremity kinematics and reorganizing muscle activity. More research can be conducted to testify the feasibility of unstable shoes construction on human postural control and gait, even guide training regime design, injury prevention and rehabilitation.

PLANTAR PRESSURE DISTRIBUTION CHARACTER IN YOUNG FEMALE WITH MILD HALLUX VALGUS WEARING HIGH-HEELED SHOES

Young females with mild hallux valgus (HV) have been identified as having an increased risk of first ray deformation. Little is known, however, about the biomechanical changes that might contribute to this increased risk. The purpose of this study was to compare kinetics changes during walking for mild HV subjects with high-heel-height shoes. Twelve female subjects (six with mild HV and six controls) participated in this study with heel height varying from 0 cm (barefoot) to 4.5 cm. Compared to healthy controls, patients had significantly higher peak pressure on the big toe area during barefoot walking. When the heel height increased, loading was transferred to medial side of the forefoot, and the big toe area suffered more impact compared to barefoot in mild HV. This study also demonstrated that the center of pressure (COP) inclines to medial side alteration after high-heeled shoes wearing. These findings indicate that mild HV people should be discouraged from wearing high-heeled shoes.

Comparison of center of pressure trajectory characteristics in table tennis during topspin forehand loop between superior and intermediate players

The purpose of this study was to investigate the characteristics of center of pressure (COP) trajectory during table tennis topspin forehand loop between superior and intermediate players. Twenty-six male table tennis players with two different skilled level participated in this test. Novel Pedar insole plantar pressure measurement system was used to record COP displacement. Subjects were asked to perform crosscourt forehand loop against the topspin ball with maximal power. The motion was divided into two phases as backswing and forward swing. Compared to intermediate players, superior players showed significantly larger medial–lateral COP displacement at backward-end and significantly smaller anterior–posterior displacement at both backward and forward ends. In addition, the ratio of COP velocity between forward swing and backswing was much higher for superior subjects. Results indicated that superior players possessed better foot drive technique and ability of foot motion control during forehand loop. These characteristics are beneficial for coaches to develop special training schemes in improving forehand loop performance.

The Transition into University: What Engineering Students Know

The overall aim of this preliminary project is to develop a set of web-based diagnostic and support tools designed to identify more clearly the attributes of students entering engineering programmes in 2010 and to support their transition into university.

Experimental studies and effective finite element modelling of foot deformation in standing

In this work, a full scale subject specific FE foot model is developed to simulate the deformation of human foot under a standing position similar to a Navicular Drop Test. The model used a full bone structure and effective embedded structure method to increase the modelling efficiency. Navicular drop tests have been performed and the displacement of the navicular bone is measured using 3D image analysing system. The experimental results show a good agreement with the numerical models and published data. The model is verified by comparing the numerical data for simple standing against subject specific navicular drop test. The detailed deformation of the navicular bone and factors affecting the navicular bone displacement and measurement are discussed.

Stress distribution of metatarsals during forefoot strike versus rearfoot strike: A finite element study

Due to the limitations of experimental approaches, comparison of the internal deformation and stresses of the human man foot between forefoot and rearfoot landing is not fully established. The objective of this work is to develop an effective FE modelling approach to comparatively study the stresses and energy in the foot during forefoot strike (FS) and rearfoot strike (RS). The stress level and rate of stress increase in the Metatarsals are established and the injury risk between these two landing styles is evaluated and discussed. A detailed subject specific FE foot model is developed and validated. A hexahedral dominated meshing scheme was applied on the surface of the foot bones and skin. An explicit solver (Abaqus/Explicit) was used to stimulate the transient landing process. The deformation and internal energy of the foot and stresses in the metatarsals are comparatively investigated. The results for forefoot strike tests showed an overall higher average stress level in the metatarsals during the entire landing cycle than that for rearfoot strike. The increase rate of the metatarsal stress from the 0.5 body weight (BW) to 2 BW load point is 30.76% for forefoot strike and 21.39% for rearfoot strike. The maximum rate of stress increase among the five metatarsals is observed on the 1st metatarsal in both landing modes. The results indicate that high stress level during forefoot landing phase may increase potential of metatarsal injuries.