CHANGES IN RACE WALKING STYLE FOLLOWED BY APPLICATION OF ADDITIONAL LOADS

The purpose of this study was to compare the effects of different loads in specific power training of race walkers on movement control. Essential aspects of movement control are avoidance of high impact forces and adequate core stability. We investigated three different forms of special power training (walking with 1.8 kg weight waistcoat, walking with 1.6 kg hand-held weights and tethered walking- 2.0-2.5 kg). The clearest changes were caused by tethered walking. We found that additional loads may significant reduce impact forces (-17 %) as well as the duration of the flight phase (-19 %). Additional core training supports the effects on movement control

EFFECTS OF VISUAL GAIT-RETRAINING ON DIFFERENT RUNNING CONDITIONS AND SPEEDS

In running athletes suffer a certain amount of injuries in a given year. Gait-Retraining therefore has been a proposed method to decrease impact loads in runners. Consequently, the purpose of this study was to confirm the effectiveness of gaitretraining, observe kinematic changes and establish transfer between overground (OG) and treadmill (TD) running as well as different velocities. Results confirmed that gaitretraining can reduce tibial impact shock. This was found during TD running (pre/post) across 3 different speeds with lower effect in OG running. Kinematics changes were found in footstrike (TD and OG), ankle (TD) and trunk (TD) angles. To increase transfer effects, we should poof new methods for motor learning and/or improve the devices for feedback training in overground running

A COMPARISON OF TWO BODY SEGMENT PARAMETER MODELS VIA ANGULAR MOMENTUM AT TAKEOFF IN DIVING

The angular momentum production during the takeoff phase in diving was computed in two ways: The first approach used the Hanavan model based on 15 landmarks. The second one was an image-based individual model. The remote angular momenta of the body segments were computed and compared. It turned out that both methods yield almost the same angular momenta of the total body. Depending on the body mass the arm segments amount to 52 ± 6 % to the total angular momentum for the individual model and 57 ± 9 % for the Hanavan model. The leg contribution was 33 ± 6 % and 33 ± 7 %, the head contribution was 19.1 ± 4 % and 14.2 ± 4 % for the individual model resp. for the Hanavan model

ARE THERE GENDER-SPECIFIC DIFFERENCES IN ELEMENTARY MOTOR SPEED ABILITY?

The purpose of this study was to analyse gender-specific differences in elementary motor speed ability. The reliability of 7 tests with 15 items was investigated using intra-classcoefficients. Gender-specific differences of performance were analysed using independent samples t-tests. There were no differences between men and women in elementary motor speed. The structure of the elementary motor speed ability (reaction time, tapping, reactive speed and arbitrarily initiated speed) was investigated with confirmatory factor analysis. Here, we identified gender-specific differences in the structure using structural equation models. The models are characterized with a good model fit. Based on the present findings, conclusions for a gender-specific training of elementary motor speed abilities are derived

THE ROLE OF THE INTERNAL ROTATION OF THE UPPER ARM IN JAVELIN THROWING

We performed a kinematic and inverse dynamic study with javelin throwers in order to assess the role of the internal rotation of the upper arm in javelin throwing and then compare the findings to baseball throwing. On the one hand, the results show an equal behaviour of the angular velocity, torque and power curves compared to baseball pitching. The evaluated peak values differ on the other hand. Hence, the different release velocities in baseball pitching and this study could serve as an explanation for the different values, which can vary enormously

INFLUENCE OF TRUNK MODEL DoF ON SHOULDER KINEMATICS IN JAVELIN THROWING - A CASE STUDY

A case study was conducted to clarify the influence of different body-models and modelling approaches on shoulder joint kinematics. Therefore, a single subject performed a javelin throw. The recorded movement was analyzed using two different modeling approaches using two different body models each. Results from the two different body models are highly comparable, while comparability of model approach specific results depend on the movement direction. Source of the difference between movement directions may be the model specific location of center of rotation in the shoulder joint

COMPUTER SIMULATIONS OF BACK SOMERSAULTS IN PLATFORM DIVING

The purpose of this study was to simulate the flight phase of a back 3½ somersault tuck (207 C) for a female elite diver. Starting with the analysis of a real performance initial conditions as angular momentum, takeoff velocity and trunk position were fixed. A multisegmental angle-driven 3D model was used to study different knee and hip angle patterns. Hip and knee angle modifications were moderate variations of the real performance. Coming quickly into a more compact position and keeping this tight position until come-out produced an advantage up to 130° total rotation and 50°/s mean angular velocity. This advantage obtained in the first flight phases could be used to improve the come-out or to reduce strength requirements at takeoff

Concurrent validity of VmaxPro, Kinovea, and Speedograph for the assessment of peak barbell velocity during the bench press: A comparison of technological approaches and historical evolutions

Measurement of barbell velocity is a simple and effective way to control strength training. To assess the concurrent validity of different technological approaches measuring barbell velocity, video-analysis (Kinovea), linear velocity transducer (Speedograph), and an inertial measurement unit (VmaxPro) were compared. Sixty-eight female and male sport science students lifted two repetitions in the bench press exercise at self-selected barbell loads. Peak vertical barbell velocity (Vmax) was parallel measured during the concentric phase of the lift using the aforementioned devices. Concordance correlation coefficient (CCC), Deming regression (DR) and Bland-Altman analysis (BA) were used to assess relative and absolute concurrent validity of Vmax measured with Kinovea, Speedograph, and VmaxPro. Results confirmed high concurrent validity of Speedograph and VmaxPro (CCC = 0.99, standard deviation of differences [SDD] = 0.04 m∙s-1) without detecting proportional or constant bias. In contrast, Vmax measured with Kinovea showed poor concurrent validity to Speedograph (CCC = 0.83) and VmaxPro (CCC = 0.81) with significant proportional and constant bias. Regression based re-calibration of Vmax from Kinovea resulted in an SDD = 0.09 m∙s-1 compared to Speedograph and an SDD = 0.08 m∙s-1 compared to VmaxPro. Among the three tested devices, Vmax assessed using Kinovea showed poor concurrent validity. Furthermore, as Kinovea showed proportional bias compared to Speedograph and VmaxPro, application-specific re-calibration of Kinovea should be applied when barbell velocity data is compared to Speedograph and VmaxPro

THREE METHODS TO DETERMINE MASS CHARACTERISTICS OF HUMAN BODY SEGMENTS

Three approaches to estimate body segment parameters (BSP) are compared, a volumescanning photographic method, a force plate technique and a geometric method. First approach: a 3D body scanner was used to obtain a closed surface mesh of a subject. Closed loops were employed to divide the mesh into head, thorax, pelvis and limbs. Volume and center of mass (CM) of each segment were computed. Second approach: a triangular reaction board with two force sensors was used to measure the position of the CM. Third approach: The multi-body simulation software dynamicus/alaska models the segments by geometric shapes like elliptic solids, ellipsoids, and semi-ellipsoids. The results indicate that the body scanner method is highly accurate and an integration into dynamicus/alaska would increase simulation accuracy

RESULTS OF INVERSE DYNAMICS CALCULATIONS IN JAVELIN THROWING ARE STRONGLY INFLUENCED BY INDIVIDUAL BODY SEGMENT PROPERTIES

The calculation of inverse dynamics (ID) solutions is widely used to examine potential injury risks and sources for performance enhancement. The results of these calculations are influenced, among others, by the chosen set of body segment inertia parameters (BSIP). While throwing movements are frequently analyzed via ID and there exists a broad variety of BSIP models, the influence of the BSIP sets on the outcome is not well examined. Therefore, the aim of this study was to clarify the influence of different BSIP sets on the modelling results in javelin throwing. For this purpose the kinematics of ten male javelin throwers were recorded. Six available models were used to estimate the BSIP values of the upper limp for each thrower. The chosen BSIP model had large influence on the derived BSIP parameters which showed variations between 8% and 120%. Also, the maximum net joint moment varied between 6% and 21%. Hence, our study suggests that for modelling joint kinetics in throwing movements the model should be chosen carefully