CONTOUR ANALYSIS, A NOVEL APPROACH IN MOVEMENT SCIENCE

Contour Analysis is a novel way for analyzing movements, which is specifically developed for daily use in high performance sports. The Contour Analysis is part of an automatic video capture and playback system, the CoachCockPit. Parameters like position, velocity and average body angle are obtained and also less straightforward parameters as step length or step frequency or 3D discus trajectory and speed can be investigated with Contour Analysis. The system is designed to operate fully automatic with a minimum of user input. Performance parameters obtained from the Contour Analysis can be used for direct feedback and to monitor progress over longer periods of time. To illustrate this several examples in different sports are discussed. The CoachCockPit is developed with primarily the coach perspective in mind: it does not interfere with daily training

MONITORING TRAINING LOAD OF ELITE TRAMPOLINISTS; FIRST RESULTS; AN AUTOMATIC ANALYSIS SYSTEM FOR DAILY USE

We developed a video-based analysis system to monitor and analyze performance in technical sports, the CoachCockPit. The CoachCockPit captures footage of a performance, stores and presents it instantly. Footage can automatically be analyzed and fed back. We show how daily training activity of trampolinists is monitored and parameters like number of routines, number of jumps per routine, or jump height, can be extracted. Over weeks and month these parameters display trends that provide information about training progress in relation to the aimed-for training results. Overtraining and stress fractures are crucial risk factors in trampoline jumping. The deployment of the CoachCockPit in trampoline jumping will, in the future, help to predict these risk factors at an early stage

VALIDATION OF A 5-DOF INSTRUMENTED SPEED SKATE; TOWARDS A POWER METER FOR SPEED SKATING

Speed skates are the most important part of equipment of a speed skater, where weight, rocker and bend are just a few characteristics that are to a high degree individualized. This poses a challenge for any type of research in speed skating where forces have to be measured in a reliable manner. For this purpose, a 5 degrees of freedom (DoF) instrumented speed skate (VU-Skate) has been designed and validated, weighing only 130 gram extra. Skaters use their own blades and shoes, something skaters are very keen on. A calibration tool has been developed to calibrate the 5 DoF. The quality of the data has been validated in 2 ways: 1. With the use of force plates and 2. By comparing the signals to another (also newly developed) Ultra-light Forces sensor. The results are remarkably good. This is the first step in being able to measure power continuously during each stroke

OPTIMAL VELOCITY PROFILES FOR VAULT

The aim of this study was to determine which kinematic characteristics may be used as a performance indicator(s) for vault. Over 600 vaults (299 men and 216 Women, see Table 1) were recorded and analyzed using footage of 3 high-speed cameras taken at the 2010 Rotterdam Artistic Gymnastics World Championships. The kinematics were correlated with the judge’s outcome score: type of vault, difficulty and final score. The correlation coefficients between velocity at takeoff and final judges’ scores were r = 0.60 for men and r = 0.52 for women

COMPETITION ANALYSIS OF SPEED SKATING USING IMU’S

For feedback to be effective, we must first identify relevant performance indicators for speed skating. We instrumented the skating of 10 junior elite Dutch speed skaters with two inertial measurement units during two competition events. Contact time, stroke frequency and other parameters were derived from collected IMU data and related to performance (finish times). The manner and timing in which the skater initiates a race in the first 100 m, is predictive of the final finish time. A significant correlation was found between finish times and 1) a decrease in stroke frequency and 2) an increase of the contact time of the skate and the ice over the first 100 m of a race. These relations were robust against variations in race distances (i.e., 100, 300, 500 and 1500 m), while the directionality of the relation differed qualitatively between the 100 m sprint and the other distances. We concluded that progression in stroke frequency and contact time are relevant feedback parameters for enhancing performance in speed skating

Muscular and kinematic features in speed skaters indicate a task-specific dystonia

Objective: Skater's cramp is a movement disorder in speed skaters. We investigated whether affected skaters matched the disease profile of task-specific dystonia, specifically whether there was evidence of maladaptive muscle activity occurring simultaneously with aberrant movements (jerking). We further examined different skating intensities, positing no change would be more indicative of task-specific dystonia. Methods: We analyzed video, kinematic and muscle activity in 14 affected skaters. We measured the angular velocity and electromyographic activity of normalized speed skating strokes using one dimensional statistical non-parametric mapping. Skaters were matched with comparably skilled controls, and filled out a bespoke clinical questionnaire. Results: Skaters’ impacted leg showed over-activation in the peroneus longus, tibialis anterior and gastrocnemius that coincided with higher foot movement compared to their healthy leg and controls. This pattern persisted regardless of skating intensity. Clinical features indicated it was task-specific and painless with common trigger factors including stress, equipment change, and falling. Conclusions: We showed aberrant muscular and kinematic activity in a movement disorder in speed skaters indicative of task-specific dystonia. Significance: Understanding skater's cramp as a task-specific dystonia could reduce the damage that misdiagnosis and unsuccessful invasive operations have caused. Our quantitative method has value in testing future treatment efficacy.</p

Effects of fatigue on trunk stability in elite gymnasts

The aim of the present study was to test the hypothesis that fatigue due to exercises performed in training leads to a decrement of trunk stability in elite, female gymnasts. Nine female gymnasts participated in the study. To fatigue trunk muscles, four series of five dump handstands on the uneven bar were performed. Before and after the fatigue protocol, participants performed three trials of a balancing task while sitting on a seat fixed over a hemisphere to create an unstable surface. A force plate tracked the location of the center of pressure (CoP). In addition, nine trials were performed in which the seat was backward inclined over a set angle and suddenly released after which the subject had to regain balance. Sway amplitude and frequency in unperturbed sitting were determined from the CoP time series and averaged over trials. The maximum displacement and rate of recovery of the CoP location after the sudden release were determined and averaged over trials. After the fatigue protocol, sway amplitude in the fore-aft direction was significantly increased (p = 0.03), while sway frequency was decreased (p = 0.005). In addition, the maximum displacement after the sudden release was increased (p = 0.009), while the rate of recovery after the perturbation was decreased (p = 0.05). Fatigue induced by series of exercises representing a realistic training load caused a measurable decrement in dynamic stability of the trunk in elite gymnasts

Cerium, one of nature's purest puzzles

Cerium is one of the most fascinating elements of the periodic system. In its elemental form it exhibits several phases like an antiferromagnetic-, a paramagnetic- and asuperconducting-phase. It is the only element with a solid-solid critical point and Kondo scatteringt. Many of these properties are attributed to the single localized 4f electron close to the Fermi level. Zie: Abstracts