IDENTIFICATION OF MOVEMENT PATTERNS BY TIME DISCRETE VARIABLES AND ANALYSIS OF TIME COURSES

Though movement is a process, it is unusual for adequate process oriented methods to be applied for movement analysis. Therefore the purpose of this study was to provide a comparison of movement pattern analysis based on time courses and time discrete variables. The subject was an experienced female basketball player, who practiced jump shots from different distances which were filmed in the sagital plane. The distance depending movement pattern changes of the successful shots were described by process oriented methods and time discrete variables. The comparison of the results obtained by the two methods show that it is necessary to describe movement pattern by time discrete variables and time courses. This takes into consideration the fact that it is possible to start a movement from the same initial position and to achieve an identical final position with different partial movements

A Jones matrix formalism for simulating three-dimensional polarized light imaging of brain tissue

The neuroimaging technique three-dimensional polarized light imaging (3D-PLI) provides a high-resolution reconstruction of nerve fibres in human post-mortem brains. The orientations of the fibres are derived from birefringence measurements of histological brain sections assuming that the nerve fibres - consisting of an axon and a surrounding myelin sheath - are uniaxial birefringent and that the measured optic axis is oriented in direction of the nerve fibres (macroscopic model). Although experimental studies support this assumption, the molecular structure of the myelin sheath suggests that the birefringence of a nerve fibre can be described more precisely by multiple optic axes oriented radially around the fibre axis (microscopic model). In this paper, we compare the use of the macroscopic and the microscopic model for simulating 3D-PLI by means of the Jones matrix formalism. The simulations show that the macroscopic model ensures a reliable estimation of the fibre orientations as long as the polarimeter does not resolve structures smaller than the diameter of single fibres. In the case of fibre bundles, polarimeters with even higher resolutions can be used without losing reliability. When taking the myelin density into account, the derived fibre orientations are considerably improved.Comment: 20 pages, 8 figure

ANALYSIS OF LOCOMOTION VELOCITY AND LATERAL DIFFERENCES OF STRENGTH PARAMETERS OF FOOTBALL (SOCCER) PLAYERS

The aim of this study was the analysis of lateral differences of strength parameters of the lower limbs and locomotion velocity of right and left turns in football. Nineteen junior athletes from a Brazilian National League football (soccer) club participated in this study. The locomotion velocity was analysed by a sprint test with and without 90° turns using double light barriers. In order to identify lateral differences of muscular strength characteristics, squat jumps (SJ) with one leg were performed on a force plate. Except for the maximal rate of force development and the time dependent variables of the SJ, all coefficients of retest-reliability were higher than 0.85. A reference table for the evaluation of specific locomotion velocity characteristics and strength of the lower limbs was developed. Significant correlation was found between the maximal force and the dominant leg (preferred kicking leg)

ACUTE EFFECT OF QUADRICEPS STRETCHING ON PERFORMANCE AND MOVEMENT TECHNIQUE DURING SQUAT JUMPS

The aim of this study was to analyze the acute effects of stretching on jumping performance (vertical velocity of the center of mass), vertical ground reaction force (peak force, rate of force development and impulse) and movement technique (joint angles and angular velocities) during the squat jump (SJ). Thirty male individuals performed the SJ test before and after one quadriceps stretching session. This session consisted of four 20-second repetitions of passive static stretching of quadriceps. The results indicated no significant difference in the performance, vertical ground reaction force or movement technique

Development of an Actuator for Ambient to Cryo Application

During the qualification campaign of the NIRSpec Instrument Mechanism, the actuator could not achieve the expected life time which was extended during the development phase. The initial design could not be adapted to the requested number of revolutions during that phase. Consequently the actuator needed to be modified such that the function of the mechanism would not be endangered and thus the overall function of the NIRSpec instrument. The modification included the change of the overall actuator design - internal dimensions, tolerances, materials, lubrication and assembly process - while keeping the interface to the mechanism, mass, and function. The lessons learned from the inspection of the failed actuator have been implemented in order to ensure the development and qualification success. The initially available time for this activity was in the range of 6 months to meet the overall program schedule

ACUTE EFFECT OF QUADRICEPS PASSIVE-STATIC STRETCHING ON KINEMATIC VARIABLES DURING LANDING

Stretching exercises are a widespread preparation practice before sport activities that involve landings. Therefore the purpose of this study was to verify the instantaneous effect of quadriceps passive-static stretching on kinematic variables of landings after a fall of different heights (30, 50 e 70 cm). Thirty male physical education students were divided into an experimental (with previous stretching exercises) and a control group (without previous stretching exercises) and landed after falls from a box with 30 cm, 50 cm and 70 cm height. In the experimental group alterations of the movement technique after stretching were found for the landings of 50 and 70 cm. These changes of kinematic parameters seem to be an adaptation of the motor system in order to optimize the absorption of the ground reaction forces during landings

INFLUENCE OF STRETCHING EXERCISE ON PERFORMANCE AND MOVEMENT TECHNIQUE DURING DROP JUMPS

The aim of this study was to verify the influence of a single flexibility training session on drop jump performance (vertical velocity at take off) and movement technique (joint angles and joint angular velocities). Thirty male subjects performed two drop jumps before and after four sets of quadriceps static stretching. A control session was made without stretching. The results showed an increase in ground contact time, an increase in knee and ankle joint flexion as well as an increase in knee maximal angular velocity during the eccentric and concentric phases. However, these changes in the movement technique have not affected the performance

IDENTIFICATION OF BILATERAL ASYMMETRIES IN LOWER LIMBS OF SOCCER PLAYERS BY VERTICAL JUMPS ON A DOUBLE FORCE PLATFORM

The purpose of this study was to identify bilateral dynamic asymmetries of the lower limbs of forty six Brazilian professional soccer players by countermovement jumps on a double force platform. Maximal ground reaction force, impulse and maximal power output were registered and bilateral asymmetries identified if the bilateral difference was greater than 15%. A two factor structure of bilateral differences was found represented by maximal force and impulse production/maximal power output. Impulse production and maximal power output are more reliable indicators for bilateral asymmetries than maximal ground reaction force. In order to analyze dynamic bilateral asymmetries more completely, it seems to be necessary to apply a combination of different test procedures which consist of vertical jumps, isokinetic tests and maximal isometric contractions