INFLUENCE OF CRANK LENGTH ON PEDALLING ECONOMY IN THE ACCELERATION PHASE IN TRACKCYCLING – A SINGLE CASE STUDY

The purpose of this study was to identify different effects of crank-length on cycling performance in track cycling. Two different crank lengths (162,5mm and 170mm) were used in a single-blind and balanced order at a wooden indoor cycling track. Saddle height and the position of the handlebar were kept constant during all trials. The subject was asked to complete 100m with maximum load with every crank length in each test session. To avoid test effects and effects from fatigue, the order of crank length was changed throughout all test sessions. Measured variables were torque (Nm), power output (W), Force (F), Cadence (rpm) and time (s). Results showed that force output stayed constant, while the 170mm condition had advantages in time, torque and power output due to the longer lever arm. Longer distances than 100m were not analysed

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

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

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

LOWERING VELOCITY OF THE CENTRE OF MASS DURING THE APPROACH AFFECTS JUMP HEIGHT IN VOLLEYBALL SPIKE JUMPS

It is assumed that a high impact height and therefore a high jump height is a relevant factor for success in volleyball spikes. The purpose of the study was to investigate whether the speed of the vertical movement of the centre of mass during the approach phase affects the jump height or not. Therefore, spikes from position IV were analysed at a tournament of the European League. Results showed that the faster the COM can be lowered and the faster the direction of the COM movement can be turned into an upward movement, the higher the jump height can be. This should be addressed within the training process

Identifizierung leistungsrelevanter Parameter für die biomechanische Leistungsdiagnostik am Beispiel des Angriffsschlages im Volleyball

Die vorliegende Arbeit beschäftigt sich mit der Analyse des Volleyballangriffsschlages von der Position vier unter Wettkampfbedingungen. Der Angriffsschlag von dieser Position ist oft die spielentscheidende Einflußgröße, da die meisten Punkte von dieser Position aus erzielt werden. Es handelt sich um einen komplexen Bewegungsablauf und es gibt eine Vielzahl an Untersuchungen, die sich mit der bewegungsanalytischen Untersuchung des Angriffsschlages befassen. Eine Herausforderung der generellen Problemstellung liegt darin, den Bewegungsablauf adäquat zu parametrisieren. Verschiedene Studien beschäftigten sich beispielsweise ausschließllich mit der Armbewegung während der Schlagphase oder mit der Beinbewegung während der Absprungphase. Die Dissertation ist darauf ausgerichtet eine breite Datenbasis für die Analyse von Volleyballangriffsschlägen zu schaffen. Der innovative Charakter der Arbeit liegt dabei in drei wesentlichen Punkten: - Definition leistungsrelevanter Parameter - Analyse von Angriffsschlägen unter Wettkampfbedingungen . große Stichprobe Insbesondere die Analyse von Angriffsschlägen während internationaler Wettkämpfe stellt dabei eine Herausforderung dar und hebt diese Arbeit von anderen Studien in der Literatur ab. Einerseits bietet dieser Ansatz die Möglichkeit "reale" Bewegungsabläufe im Spiel zu betrachten, andererseits verringert sich dadurch die Standardisierbarkeit der Umgebungsbedingungen. Die methodische Innovation liegt darin, zu untersuchen, welche Bewegungsabläufe unter echten Wettkampfbedingungen ausgeführt werden. Die wissenschaftliche Innovation liegt in der Identifikation und Definition leistungsrelevanter Parameter, die den Bewegungsablauf quantifizieren können. Damit kann ein Einblick gewonnen werden, was unter Spielbedingungen einen erfolgreichen Angriffsschlag ausmacht