In soccer, sports science aims to prevent injuries and improve performance by biomechanically analyzing a series of the kick processes. In order to understand the kick processes biomechanically, studies on kinematic, kinetic, and EMG have been conducted. However, these studies have limitations due to absence of integrated theory defining interactions between the segments. In the present work, we propose a model to understand dynamic characteristics of the kicking leg based on the biomechanical features of the instep kick. Five healthy men participated in an experiment to perform four-level instep kick. We collected kinematic and kinetic information of the hip and knee joints. Based on the passive dominance of the knee joint, we devised the knee joint torque model proportional to angle and angular velocity. RMSE between simulated and real torque was 4.17%, and exhibited a tendency to decrease linearly with the kick speed. Henceforth, it is apparent that the faster the kick, the greater the load on the hip; and the slower the kick, the greater the load on the knee joint. We anticipate that this model will be applied to the kick monitoring equipment and for the prevention of injuries by measuring the load.

Walking on split-belt treadmill has been applied to study walking disabilities, such as osteoarthritis (OA), to show asymmetric walking characteristics. In this study, we compared asymmetric walking in OA patients with healthy subjects under split-belt conditions and examined the reproduction of walking asymmetry in OA. Seven OA patients were instructed to walk at four frequencies, while four healthy subjects walked on a treadmill with tied-belt and split-belt conditions. To compare walking asymmetries, kinetic and kinematic measurements were made using force-plates and motion capture cameras, and subsequently center of mass (CoM) velocity, mechanical work and potential energy were calculated. Horizontal velocity change during split-belt walking of healthy subjects was similar to OA patients. Difference of mechanical work during single support phase occurred due to fall of CoM in fast belt. OA walking asymmetry could be reproduced by reducing differences of belt speeds to prevent rapid fall of CoM.

When one sensor cannot provide information by sensory deficit or loss, the sensory information can be provided by substituting other sensors for the defected sensor. This sensory substation might be influence on the deteriorated motion perception that consists of multi-sensory information such as visual, vestibular and somatosensory information. In this study, to investigate whether the additional sensation by sensory substitution could be integrated into the motion perception, we examined the effect of substituted postural sway sensation on the directional perception of body movement. Deteriorated motion perception by the reduced plantar sensation was enhanced under sensory substitution condition that provided the body sway information as the plantar vibratory stimulus. These results imply that the additional sensation might be integrated into and improve the motion perception.