MODELLING AND PROGNOSIS OF COMPETITIVE PERFORMANCES IN ELITE SWIMMING

The study demonstrates that the performance of an elite female swimmer in the finals of the 200 m backstroke at the Olympic Games 2000 in Sydney can be predicted by means of the nonlinear mathematical method of a neural back-propagation network. The analysis included the performance output data of 19 competitions prior to the Olympics within a time period of 95 successive weeks and the training input data of the last four weeks prior to each competition. The training data were divided into two phases: (1) a two-week taper cycle, and (2) an earlier two-week high load cycle. The trained neural network was not only able to model the 19 competitive performances, but also to predict the performance in the semi final of the Olympic Games in Sydney on the basis of the two sets of training data during the preparation before that specific competition

TIME-VARIANT SPECTRAL ANALYSIS OF SURFACE EMG SIGNALS – EXEMPLARILY SHOWN FOR ARCHERY

To analyse the spectral density of electromyographic (EMG) signals Fourier transforms are commonly used. The prerequisite of this transform is that the analysed signal is stationary. Generally, this can not be assumed for the electromyograms of muscle contractions of human movement. A new method to analyse non-stationary biological signals is the time-variant spectral analysis. The aim of this paper is to use the timevariant spectral analysis in a realistic sport application to show connections of the athlete’s level and the spectral density of the EMG. Five top-level archers participated in the study. The results suggest, that a higher level of performance generally corresponds to lower median-frequencies and a smaller variability of the median-frequencies of the EMG-signals

MOTION OF THE BOW DURING AIMING AND RELEASING THE SHOT

The range of motion of a recurve bow during aiming and releasing the shot is very small. Thus on-target-trajectories are used. To measure the on-target-trajectories of bows a system originally designed for gun shooting was modified. The system can be fitted onto the archer’s personal bow. 15 highly skilled archers of the German National Teams of women and men participated in the study. Two intraindividual typical strategies of aiming were found: 11 archers try to hold the aim on sight for at least 2 seconds whereas 4 archers tend to “slide” on the target and release the shot at once when the target is on sight. For 14 of 15 archers the “hold boxes” disclose an asymmetry in aiming: The horizontal magnitude of the hold box is larger than the vertical dimension. From release to when the arrow leaves the string, the right handed archers tend to move to the left and the left handed archers tend to move right

APPLICABILITY OF A FULL BODY INERTIAL MEASUREMENT SYSTEM FOR KINEMATIC ANALYSIS OF THE DISCUS THROW

The aim of the study was the application of a full body inertial measurement system (IMS) for a kinematic analysis of the discus throw and the evaluation of its applicability. For this purpose, one male sports student performed three discus throws equipped with the IMS. All trials were additionally filmed by high-speed video. The results indicate that perfor-mance-relevant information can be obtained regarding the temporal coordination of the body segments and body joint angles. Limitations exist for the accurate detection of the last foot contact related instant and the discus release instant by solely using the IMS data

FEEDBACK SYSTEM FOR PHYSIOTHERAPY AND POPULAR ATHLETES

Background: Feedback systems give support to athletes or patients and have a positive effect on training control. A feedback system, the virtual coach (VC), was developed. Methods: Two different studies in both fields of application (popular sport, rehabilitation) were conducted. The pushup-study was done to investigate the effect of the VC during a 6-week-training. Results: The results show the positive impact on different parameters, such as motion duration which is closer (EG: 3.13 (± 0.28) s, CG: 1.88 (± 0.4) s) to the three seconds motion duration prescribed in the training routine for the EG (using the VC) compared to the CG (without feedback). The second study addressed the second field of application - the rehabilitation. Eight subjects (transfemoral amputees) conducted an 8-week-training with a particular training device added by mobile sensors and the VC (com-bined system). The gait, the maximum power of hip muscles and the weight distribution war registered before and after the intervention. The results are individual as the subjects are. The improvement of the maximum power (range: 18.6 to 26 %) and the gait velocity (range: 0.05 to 12.39 %) are the most remarkable results. Positive changes in other gait parameters as well as in the weight distribution were observed for the individuals. Conclusion: Summarizing both studies, a positive effect of using the feedback system (VC) can be found. Due to the small sample size and the heterogeneity of the amputee group, a generalized statement cannot be given from the second study with the transfemoral amputees