Three-dimensional kinematics analysis of blind football kicking.

The purpose of this study was to identify critical technical points that lead to increased ball speed in a maximal toe kick with no run-up (a 'static kick') in blind football. Six visually impaired male players and eight sighted male players participated in the experiment. All participants wore a blindfold to fully remove visual information and performed the static kick. The motion was captured three-dimensionally using an optical motion analysis system. Our results demonstrated that ball speed, maximum linear velocity of the kicking-side thigh, and maximum angular velocity of the kicking-side shank for the sighted player group were significantly greater than those for the visually impaired player group. The sighted players tended to perform the static kick in a similar motion pattern, which was characterised by a backwards rotation of the torso to adequately extend the kicking-side hip joint during the back-swing phase and a stable posture of the lower torso on the frontal plane during the forward-swing phase. This motion pattern is critical to both acceleration of the kicking-side foot and orientation of the foot for a more precise ball contact position.

Influence of a Foot Insole for a Down Syndrome Patient with a Flat Foot: A Case Study.

Background and Objectives: Patients with Down syndrome have many orthopedic problems including flat foot. Insertion of an insole for a flat foot provides support to the medial longitudinal arch; thus, insole therapy is often used to treat a flat foot. However, the influence of an insole insertion on the knee joint kinematics for a patient with Down syndrome is unknown. This study aimed to elucidate the influence of an insole for a flat foot on the knee kinematics during gait for a patient with Down syndrome. Materials and Methods: The subject was a 22-year-old male with Down syndrome who had a flat foot. The knee joint angle during the gait was measured using a 3D motion capture system that consisted of eight infrared cameras. Results: The gait analysis demonstrated a reduction in the knee flexion angle during double knee action. The knee valgus and tibial internal rotation angles also decreased during the loading response phase while wearing shoes that contained the insole. Conclusions: As the angle of the knee joint decreased during the gait, it was considered that the stability of the knee joint improved by inserting the insole. In particular, there was a large difference in the tibial internal rotation angle when the insole was inserted. It is thus hypothesized that the insole contributes to the rotational stability of the knee joint. This study suggests that knee stability may improve and that gait becomes more stable when a Down syndrome patient with a flat foot wears an insole.

Differences in skill level influence the effects of visual feedback on motor learning.

[Purpose] No previous studies have confirmed whether the effects of visual feedback on motor learning vary according to learner skill level for a learning task. The purpose of this study was to clarify whether differences in skill influence the effects of visual feedback on motor learning. [Participants and Methods] Sixty-four participants were assigned to one of four different feedback groups (concurrent-100%, concurrent-50%, terminal-100%, or terminal-50%). The learning task was to adjust the load amount continuously to the left lower limb in accordance with sound stimulation at intervals of 1 Hz. The four groups performed a pretest, practice sessions, and a retention test 24 hours after practice. After completing these measurements, the participants were classified as either high- or low-skilled based on the results of the pretest. [Results] Only the groups of low-skilled participants who used concurrent feedback showed lower root mean square errors in the retention test compared to in the pretest. [Conclusion] Differences in skill level for the same task influenced the effects of visual feedback on motor learning. Furthermore, concurrent visual feedback can help improve motor learning in low-skilled learners for the same task.

Long-term sustained effect of gait training using a hybrid assistive limb on gait stability via prevention of knee collapse in a patient with cerebral palsy: a case report.

[Purpose] The hybrid assistive limb was developed to improve the kinematics and muscle activity in patients with neurological and orthopedic conditions. The purpose of the present study was to examine the long-term sustained effect of gait training using a hybrid assistive limb on gait stability, kinematics, and muscle activity by preventing knee collapse in a patient with cerebral palsy. [Participant and Methods] A 17 year-old male with cerebral palsy performed gait training with a hybrid assistive limb 12 times in 4 weeks. After completion of 12 sessions of hybrid assistive limb training, monthly follow-up was conducted for 8 months. The improvement was assessed on the basis of joint angle and muscle activity during gait. [Results] The degree of knee collapse observed at baseline was improved at 8-month follow-up. Regarding muscle activity, electromyography revealed increased activation of the vastus lateralis at 8-month follow-up. Moreover, the hip and knee angles were expanded during gait. In particular, the knee extension angle at heel contact was increased at 8 months after follow-up. [Conclusion] Gait training with a hybrid assistive limb provided improvement of gait stability such as kinematics and muscle activity in a patient with cerebral palsy. The improved gait stability through prevention of knee collapse achieved with hybrid assistive limb training sustained for 8 months.

Kinematic comparison of the seoi-nage judo technique between elite and college athletes.

This study sought to identify biomechanical factors that determine fast and skilful execution of the seoi-nage (shoulder throw) technique by comparing kinematics between elite and college judo athletes. Three-dimensional motion data were captured using a VICON-MX system with 18 cameras operating at 250 Hz as three male elite and seven male college judo athletes performed seoi-nage. No significant difference was found in motion phase time of the turning phase between the two groups, indicating that motion phase time is not necessarily a factor contributing quickness in seoi-nage. The maximum relative velocity of the whole body centre of mass along the anterior-posterior direction was significantly greater in the elite athletes (2.74 ± 0.33 m/s) than in the college athletes (1.62 ± 0.47 m/s) during the turning phase (p = 0.023). The overall angular velocity of the body part lines, particularly the arm line, tended to be greater in the elite athletes (p = 0.068). The results imply that the velocity of the thrower relative to the opponent in the forward drive and turning motion reflects high skill seoi-nage. Coaches should recognise the relative forward velocity as a factor that may contribute to a successful seoi-nage when teaching the judo throw technique.

Kinetics of throwing arm joints and the trunk motion during an overarm distance throw by skilled Japanese elementary school boys.

The purpose of this study was to investigate joint kinetics of the throwing arms and role of trunk motion in skilled elementary school boys during an overarm distance throw. Throwing motions of 42 boys from second, fourth, and sixth grade were videotaped with three high-speed cameras operating at 300 fps. Seven skilled boys from each grade were selected on the basis of throwing distance for three-dimensional kinetic analysis. Joint forces, torques, and torque powers of the throwing arm joints were calculated from reconstructed three-dimensional coordinate data smoothed at cut-off frequencies of 10.5-15 Hz and by the inverse dynamics method. Throwing distance and ball velocity significantly increased with school grade. The angular velocity of elbow extension before ball release increased with school grade, although no significant increase between the grades was observed in peak extension torque of elbow joint. The joint torque power of shoulder internal/external rotation tended to increase with school grade. When teaching the overarm throw, elementary school teachers should observe large backward twisting of trunk during the striding phase and should keep in mind that young children, such as second graders (age 8 years), will be unable to effectively utilise shoulder external/internal rotation during the throwing phase.