A METHOD FOR THE PERFORMANCE EVALUATION OF JUMPING HEADERS IN SOCCER

The aim of the present work was to develop a method for the evaluation of soccer heading performance in jumping headers by means of a stereophotogrammetric system. Three non-professional players were involved in this pilot study. The attention was focused on the following variables: the player’s jump height at the impact instant, the ball velocity variation and the initial ball angle after the impact with the forehead of the player. The analysis of these parameters permitted to characterize the biomechanical technique and the performance ability of each player in such a way that a trainer can define individual procedures to improve the efficacy of this fundamental skill in soccer. Finally an Elevation Index (E.I.) was developed to compare the players performances and to draft a ranking between them

Biomechanical comparison of shorts with different pads: An Insight into the Perineum Protection Issue

An intensive use of the bicycle may increase the risk of erectile dysfunction and the compression of the perineal area has been showed to be a major mechanism leading to sexual alterations compromising the quality of life. Manufacturers claim that pads contribute to increase cyclists perineal protection ensuring a high level of comfort. To investigate the influence of various cycling pads with regard to perineal protection and level of comfort. Nine club road cyclists rode 20 min on a drum simulator, located at the Nutrition and Exercise Physiology Laboratory, at a constant speed and gear ratio wearing the shorts with 3 cycling pads of different design and thickness: basic (BAS), intermediate (INT), and endurance (END). Kinematics and pressure data were recorded at min 5, 15, and 20 of the test using a motion capture system and a pressure sensor mat. The variables of interest were: 3-dimensional pelvis excursions, peak pressure, mean pressure, and vertical force. The comfort level was assessed with a ranking order based on the subjects' perception after the 20-min trials and measuring the vertical ground reaction force under the anterior wheel as well as the length of the center of pressure (COP) trajectory on the saddle. Results showed that the vertical force and the average value of mean pressure on the saddle significantly decreased during the 20-min period of testing for BAS and END. Mean peak pressure on the corresponding perineal cyclist area significantly increased only for BAS during the 20-min period. Interestingly objective comfort indexes measured did not match cyclists subjective comfort evaluation. The lower capacity of BAS to reduce the peak pressure on the corresponding perineal area after 20 min of testing, together with its positive comfort evaluation, suggest that a balance between protection and perceived comfort should be taken into account in the choice of the pad. Hence, the quantitative approach of objective comfort indexes introduced in this study could be helpful for manufacturers in the development of their protective pads

It\u2019s a Matter of Mind! Cognitive Functioning Predicts the Athletic Performance in Ultra- Marathon Runners

The present study was aimed at exploring the influence of cognitive processes on performance in ultra-marathon runners, providing an overview of the cognitive aspects that characterize outstanding runners. Thirty runners were administered a battery of computerized tests right before their participation in an ultra-marathon. Then, they were split according to the race rank into two groups (i.e., faster runners and slower runners) and their cognitive performance was compared. Faster runners outperformed slower runners in trials requiring motor inhibition and were more effective at performing two tasks together, successfully suppressing the activation of the information for one of the tasks when was not relevant. Furthermore, slower runners took longer to remember to execute pre-defined actions associated with emotional stimuli when such stimuli were presented. These findings suggest that cognitive factors play a key role in running an ultra-marathon. Indeed, if compared with slower runners, faster runners seem to have a better inhibitory control, showing superior ability not only to inhibit motor response but also to suppress processing of irrelevant information. Their cognitive performance also appears to be less influenced by emotional stimuli. This research opens new directions towards understanding which kinds of cognitive and emotional factors can discriminate talented runners from less outstanding runners

CORRELATION BETWEEN SUPPORT FOOT PLACEMENT AND GOAL ACCURACY FOR INSTEP KICKS IN THE SOCCER FIELD

The aim of the present work was to evaluate the correlation between the placement of the support foot on the ground and the precision of the shot: the placement of the support foot relative to the ball was supposed to have an effect on the shot precision for a given target. The goal was divided with a visual grid enabling to identify six possible targets of the shot, high/low for vertical placement and left/center/right for horizontal placement. Skilled players were asked to perform repetitive penalty instep kicking in the soccer field with a defined target such as high/left or low/right: ground reaction loads were recorded by means of a force platform installed in a suitable board and the movement was video recorded. The position of COP at the kick instant with respect to the ball and the average trajectory of COP on the platform resulted to be correlated with successful target in such a way that training procedures can be defined to improve the player coordination for precision shooting. Finally, differences between free kicking and kicking with a goalkeeper were recorded, enabling to analyze a realistic player behaviour in the study

Prediction of ACL and PCL Loads During Isokinetic Knee Exercises using Experimental Tests and Musculoskeletal Simulations

Abstract Aim of the study is to investigate the tension acting on the anterior cruciate ligament, ACL, and posterior cruciate ligament, PCL, during the knee isokinetic flexion-extension in a not-invasive way. Two different approaches were used: a numerical approach using OpenSim and an analytical approach. After having calculated the shear acting on the tibial plateau, it was possible to evaluate the tension at cruciates. After comparing the results with other studies in literature, the numerical approach resulted more correct than the analytical in flexion, whereas the analytical approach gave better results in extension. Results of the present work can suggest development directions for the ACL & PCL loads prediction from numerical muscololoskeletal models as well as indications of clinical relevance in isokinetik training or rehabilitation

Behaviour of an instrumented anthropomorphic dummy during full scale drop tests

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EVALUATION OF SPRINT BIOMECHANICS BY MEANS OF AN INSTRUMENTED TRAINING SLEDGE IN SOCCER

The aim of the study was the functional evaluation of sprint biomechanics by means of an instrumented training sledge in a soccer field. In particular, peak values of the horizontal ground reaction force generated in the first 6 thrusts were estimated after measuring the instantaneous cable tension and the sledge acceleration with a data acquisition system installed on the sledge. Three soccer players were asked to perform 3 couples of 30m sprints (starting once with the left and once with the right leg) while pulling the training sledge: the sledge mass increased in three levels (11.5kg, 16.5kg, 21.5kg). The athletes performed also Bosco tests in monolateral CMJ. Differences in force values between the two legs were more evident after the sledge functional testing in the field than after Bosco monolateral CMJ: the method can suggest functional training procedures to improve the strength of the weak leg and running coordination

Service offshoring and export experience

Service inputs are a key component of the costs of exporting, and contribute to explain the process of internationalization of firms. A new dataset on the participation of French firms in global value chains reveals that firms with longer export experience in a market are more likely to source service inputs from there. We rationalize this fact in a model where firms are initially uncertain about how successful they are as exporters, but learn their export profitability as they keep selling abroad. Because offshoring requires larger sunk costs than domestic sourcing, some firms decide to offshore only when they become sufficiently confident about their export prospects, i.e., once they acquire enough export experience. More export experience in a foreign destination also induces firms to offshore within the boundaries of the firm rather than at arm's length. The model further implies that firms are more likely to offshore when frictions in the provision of services between the domestic and the foreign market are greater. In turn, offshoring firms sell greater volumes, display less volatility, and are less likely to exit foreign markets. Exploiting our novel dataset, we provide strong empirical support for each of these predictions

Comparative analysis of muscle activation patterns between skiing on slopes and on training devices

Abstract The increasing popularity of ski as winter sport and the difficulties related to its accessibility and environmental conditions led to the development of specific training devices for practise, both for improving technique and for training after injuries. In particular the aim of this work was to study the efficacy of two training devices: Skimagic ® and Skier's Edge ® , comparing their functionality to ski on natural snow. The efficacy of training devices was investigated after comparing the EMG activation patterns of snow skiing with the other two training conditions; good correlation of activation patterns should correspond to a better simulation of the skiing movement