ESTIMATION OF THE MOVING JOINT AXIS IN THE KNEE JOINT BY MOTION ANALYSIS DATA

It is essential to use individually parameterized models for the knee joint as well as for the patellofemoral joint while analyzing the correlations between external and internal loads and the efficiency of specific training exercises for the lower extremities. A new approach to estimate the moving joint axis within the knee joint using motion analysis data was evaluated. The results of this single case study show that this approach might offer a possibility to parameterize an individualized knee joint model without using MRI scans

ASPECTS OF A THREE DIMENSIONAL MOTION ANALYSIS OF THE VOLLEYBALL SPIKE IN HIGH LEVEL COMPETITION

The purpose of the study was a three dimensional motion analysis of the volleyball spike from position four during competition. Spikes were analysed at a tournament of the European league. Regarding the jump technique, only few athletes performed the discussed coordination pattern of the impulses within the body. It may be concluded that there exists reserves within the training process concerning the coordination in the takeoff phase even in high level athletes

BODY ANGLES IN VOLLEYBALL SPIKE INVESTIGATED BY MODELING METHODS

In order to understand how specific movements are performed, it is important to describe the specific movement under consideration with high accuracy. Assets and drawbacks of these movements can only be understood, if it is possible to describe movements with close-toreality and artifact-poor time histories for the inner co-ordinates. By modelling it is possible to gain further information about movement. For example it is possible to forecast effects of changes in coordination techniques. Another advantage is the quantification of motion details using inverse kinematics. Therefore, joint angles can be analyzed more accurately in a competition setting without using marker sets. The aim of this study was to perform inverse kinematics for a volleyball spike under competitive conditions and to investigate the shoulder angles by modelling methods

ANALYSIS OF SKELETAL MOTION KINEMATICS FOR A KNEE MOVEMENT CYCLE

This study estimated the skeletal motion for a knee motion cycle. The surface markers on the thigh and the shank showed the computed displacement during in vivo motion analysis. This error was minimized using optimization procedure. The displacement was generally greater on the thigh than the shank. The minimization of error produced by this procedure was more successful on the thigh than the shank. The purpose of this study was to require high value motion data. These results provide the basis to calculate the instantaneous knee axis of rotation in a follow up stud

INVESTIGATION OF SHOULDER KINEMATICS IN VOLLEYBALL SPIKES

This study investigated the shoulder kinematics of volleyball spikes, performed during European League Games. For the kinematic description of the shoulder movement quaternions and the axis-angle approach was used to avoid the gimbal lock. The orientation of the resulting axis of rotation in the shoulder joint and the rotational angle were calculated. Additionally, the 3D coordinates of the elbow movement around the shoulder and the internal and external rotation were investigated. The results show that specific movement strategies for the humerus could be detected using these methods. Interdependencies of internal and external rotation with abduction and adduction were found for shoulder movements during volleyball spikes

ACCURACY OF CALCULATED KNEE JOINT MOVEMENTS DEPENDING ON MARKER SETS AND LEG POSITION

This study investigated the influence of different marker sets and different leg positions on time histories of skeletal kinematics of the lower limb. Surface markers were attached to the thigh and the shank to reproduce their kinematics during a knee movement cycle. Certain selections of posture and marker sets minimised the expected measurement errors without further optimisation procedures. However, the results showed an approximation to skeletal movement, only. The results lead to recommendations for the use of skin based marker systems

INFLUENCE OF FOOTWEAR ON FOOT SENSITIVITY: A COMPARISON BETWEEN BAREFOOT AND SHOD SPORTS

The purpose of this study was to compare the vibration thresholds of the sensor of the plantar foot between athletes that practice sport with shoes and athletes that practice sport without shoes. Fourty female subjects were divided in two groups: Shod group (SG) with 20 volleyball players and barefoot group (BG) with 20 gymnasts. Vibration thresholds were measured by the use of a vibration exciter at five points of the foot sole: Heel; Midfoot; Metatarsal Head I; Metatarsal Head V and Hallux. The amplitude of the vibration stimulus was raised until it could be perceived by the subjects, which responded with a verbal sign. The amplitude read at the verbal sign was taken as the vibration threshold. The results show significantly lower vibration threshold values for the BG (p< 0.001) when calculating the mean values of the five foot points. The vibration thresholds measured at each of the five selected foot points were lower for the BG in comparison with the SG. However those differences were not statistically significant. The results indicate that the higher vibration sensitivity at the plantar foot for the BG may be explained by the sport practice without footwear as well as by the technical demands of the sport

Effects of active and passive warming of the foot sole on vibration perception thresholds

Objective Skin temperatures are known to increase cutaneous sensitivity. However, it is unclear whether the amount of improved sensitivity differs depending on the protocol of heat application. Therefore, this study aimed to investigate the effects of active (treadmill walking) and passive (infrared radiator) warming of the foot sole on vibration perception thresholds. Methods Sixty healthy and injury-free subjects voluntarily participated in this study. Vibration perception thresholds (200 Hz) and plantar temperatures were measured at the hallux and 1st metatarsal head. In experiment 1, warming and mechanically stimulating the skin was achieved by walking on a treadmill for 30 min. In a follow-up study (experiment 2), external plantar heat was administered via an infrared radiator (30 min). Results In both experiments, increasing temperatures led to increased plantar sensitivity. However, the amount of improved sensitivity was greater in experiment 1, although plantar temperature increases were lower compared to experiment 2. Conclusions Warming in conjunction with mechanical stimulation seems to have a greater potential to enhance plantar sensitivity compared to external heat supply only. Significance The possible influence of mechanical stimulation and warming towards superior plantar afferent feedback highlights its importance regarding human posture and fall prevention