Coordination variability and skill development in expert triple jumpers

The aim of this study was to examine the influence of skill of expert triple jumpers on the coordination variability of lower extremity intra-limb couplings. In contrast to the traditional motor learning perspective, we hypothesized that as skill and thus performance increases, movement coordination variability will also increase. Three-dimensional kinematic and ground reaction force data were collected during the hop-step transition phase of the triple jump. Relative motion plots and a modified vector coding technique were used to quantify the coordination variability across the trials. The results were consistent with a U-shaped curve, representing coordination variability, as skill increases. The high coordination variability in less skilled athletes is present while the appropriate characteristics defining the movement coordination patterns are acquired. This coordination variability may not be beneficial to performance. As the refinement of these characteristics is achieved, coordination variability decreases, resulting in a more consistent or regulated performance. In the final stages of developing a skilled performance, a functional variability is accessed that brings flexibility to the system allowing it to cope with perturbations. This study highlights the need to address the learning effect when analysing coordination variability from a dynamical systems perspective.     

Stürze im Alter

The consequences of falls can be considerable for elderly people. They often lead to fractures or other injuries, immobility, curtailed independence, need for long-term care, and even death. They decrease the quality of life and can exert a negative influence on self-esteem, activity level, and the number of social contacts. The annual rate of falls in people over 65 is approximately 30%. This number increases to about 50% up to the age of 80 years and almost half of those who fall do so more than once during the course of a year. More than 90% of all falls occur in everyday situations, mostly resulting from movement errors. All studies demonstrated a significant correlation between muscle weakness and the incidence of falls, thus representing a major risk factor for a fall. Gait disorders, hip fractures, and the loss of functional autonomy are closely related to falls and associated with age to a similar extent. Almost 90% of hip fractures in Germany are the result of a fall. From the individual and economic points of view, a fracture near the hip has serious consequences in old age. Based on research findings to date, vibration training could constitute an interesting alternative to classic methods of strength training in fall prevention programs. The aim of this contribution is to provide fundamental facts regarding epidemiology and prevention and to present a potential approach to implementing vibration training in multimodal programs designed to prevent falls.     

Dynamical analysis of winter terrain park jumps

Jump features in winter terrain parks frequently pose a hazard to patrons and may represent a significant liability risk to winter resorts. By performing a simple dynamic analysis of terrain park jumps, the relative risk to impact injuries for any proposed jump design can be quantified thereby allowing terrain park designers to minimize the risk from this class of injury.     

Acknowledgements

Acknowledgement

Acknowledgements     

The Russian avant-garde painting palette: Documentary and physicochemical codification of organic colorants

In the present article an attempt is made to elucidate the organic colorants commonly encountered in the Russian avant-garde painting palette by a combined art historical, documentary and physicochemical investigation, and to examine the influence of environmental factors on the chromatic profile originally sought by the artist. The overall approach based on written sources is confirmed by measurements on relevant paintings. The documentary research deals with the influences of Orthodox iconography, folkloric art, and occidental modernist tendencies on the Russian avant-garde palette, and studies the effects of contradictory historical processes in the chromatic profile of individual paintings. In the experimental section a series of colorants are investigated concerning the effects of accelerated ageing on experimental painting tables, prepared as watercolor and gouache layers on paper ground. The resulting samples are subjected to colorimetric and spectroscopic measurements, and analogous analytical procedures are applied on samples taken from selected paintings. A systematic comparative study of all data permits evaluation of the materials used in terms of their stability towards extrinsic factors, and proposal of degradation routes in order to assist museum curators and conservators in every concrete case related to the broad spectrum of pigments examined.     

Trial-by-trial analysis or averaging: implications for electromyographic models of rapid limb control

The control of human limb movement has been the focus of research for more than a century. A major issue to emerge from this work is the manner in which the central nervous system regulates electromyographic (EMG) activity to produce movements that differ in distance, velocity, and movement time. However the different methods of analysis often used to analyze EMG data could result in different kinematic-EMG relationships. In this study, participants performed an elbow flexion task to one of five distance goals (between 5 degrees and 50 degrees) using three movement speeds. EMG data from the right elbow flexors were compared using a trial-by-trial analysis and one based on averaged data. Averaging across trials underestimated biceps EMG amplitude at all movement distances and speeds compared to a trial-by-trial analysis. Averaging overestimated EMG burst duration compared to the trial-by-trial analysis. Peak agonist EMG amplitude was positively related to distance and inversely related to movement time. Agonist EMG duration was constant for movement distances less than 30 degrees but increased in the 50 degrees condition. The results support the view that peak EMG amplitude and duration can be controlled independently, but EMG duration changes only for longer distance movements when additional force is required.     

Effect of a pedometer-based intervention on daily step counts of community-dwelling older adults

This study investigated the effect of a 12-week pedometer-based intervention on daily step counts of 147 older adults randomly assigned to an intervention or wait-list control group (M age = 72.9 years, SD = 8.8). The intervention group significantly increased their daily step counts after 12 weeks (M=639, SD=2239) and continued to significantly increase during a 12-week maintenance period (M=680, SD=1721). The control group exhibited no change during the control period (M = -393, SD=2050) but had a significant increase in daily step counts (M=1580, SD=2305) when enrolled in the intervention. The pedometer-based intervention was effective in increasing participants' daily step counts.     

Development and validation of the moral disengagement in sport scale

A sport-specific measure of moral disengagement was developed in 2 studies. In Study 1, a 59-item questionnaire was developed and tested with 308 athletes from 5 team sports. A series of confirmatory factor analyses (CFA) testing different models suggested the model that best fitted the data had 6 first-order factors that could be represented by 1 second-order factor. Study 2 involved 305 athletes from the same 5 sports. CFA confirmed the 6-factor, second-order structure for the final 32-item measure. Results from Study 2 supported the construct validity of the scale, providing evidence for the factorial, concurrent, convergent, and discriminant validity. The Moral Disengagement in Sport Scale (MDSS) is proposed as a valid and reliable measure of moral disengagement for use in the sport context.