Imagerie de la trachée de l'adulte

Imaging of normal and pathologic trachea at the thoracic and cervical levels is described extensively. Beside congenital abnormalities discovered in adulthood, acquired tracheal abnormalities are artificially divided in two subgroups. One group consists of diffuse abnormalities, with all but one diseases associated with a diffuse narrowing of the tracheal lumen. The other group comprises focal abnormalities that lead to tracheal stenoses of various lengths, with a postintubation stenosis as probably the most frequent cause, followed by tumours. The main modality for tracheal imaging is now multidetector-row spiral CT. This technique allows for faster volume coverage and higher spatial and temporal resolution. The improved spatial resolution impacts on both axial images and all reconstructions techniques that have become indispensable for interpretation of a vertical structure such as the trachea. Chest X-ray is no longer the frontline imaging technique. MRI has not yet reached all its potential as compared to CT.     

Estimation de la dépense énergétique lors d'une régate en dériveur

Introduction. – Assess the energetic cost during small craft competition.Methods. – Height healthy sailors have been tested during three regattas. Heart rate, vertical jump, glycemia, cortisol and testosterone have been recorded.Results and discussion. – Regattas did not show significant difference for hormones. However, a significant 10% decrease of glycemia was presented. Heart rate increased during competition, but it was different according to the wind velocity and wind direction. The oxygen cost of sailing is relatively light. However, this cost could be increase with bad conditions of sailing. It seems that aerobic capacity is important regarding performance.     

La résistance cutanée comme indice objectif de la concentration au lancer de poids

Aims – Rules of track and fields events allow subjects to prepare themselves before throwing. As time allocated to preparation was two minutes, it has been reduced to one minute. The aim of this study was to test whether preparation duration decrease had an effect on subjects activation and on performance in shot put.Materiels and methods – Subjects were divided into two groups: beginners and experts. Each subject had to perform seven throws in i) throwing with preparation within the minute allowed ii) without preparation iii) mental representation. Skin resistance tonic level was continuously recorded during the experiment. This autonomic variable is well-known to be a reliable index in predicting activation variations.Results – No difference in performance between the preparation and no-preparation modalities is showed. All the subjects did not reach the same activation during the mental imagery. Activation was shown to be higher in novice than in expert population. However, differences in activation between throwing with and without preparation did not reach the significant threshold. These results suggested that decrease in preparation duration did not affect performance. Subjects were shown to increase their activation themselves rapidly. Performance seems to be mainly dependent upon execution quality rather than reaching an optimal activation level. Motor program of throwing is thought to be rapidly intialised by subjects whatever their practice level.Conclusion – Differences have been evidenced between real trials and mental imagery, both, in movement sequences duration and in activation. If the subjects are not training in the mental imagery, the imagery ability improve with the expertise level.     

Analyse cinématique tridimensionnelle du lancer de javelot : de la situation réelle au modèle biomécanique

Introduction. – In this preliminary study, we introduce a biomechanical model to analyse javelin throw movement in order to determine how the maximal velocity at release time is reached.Fact synthesis. – We calculated many parameters. Only javelin velocity at release time is correlated with the throwing distance. By using this method, we could note an increase of joint velocity peaks and segment kinetics energy in a proximodistal axis.Conclusion. – The results obtained seem to validate our modeling methods. However, this biomechanical analysis should be completed with recording ground reaction forces to provide complete model of the javelin throw’s final movement.     

Influence de la distance de course sur les paramètres cinématiques de nage chez les nageurs avec palmes de haut niveau

Introduction – Finswimming is a new sport activity. The optimization of the leg’s propulsive action is fundamental to improve the performance. The aim of this work is to quantify finswimmer’s movements per race distances, using a kinematic analysis.Fact synthesis – Five elite finswimmers were video recorded during underwater races. The connections between the average velocity of stroke, frequency and range of finswimmers undulation are observed as a fonction of race distance.Conclusion – Finswimmers are shown to adjust and to stabilize instantaneously their movements in terms of race distance.     

Dynamique de la locomotion en fauteuil roulant manuel : influences de la masse totale et de sa répartition antéropostérieure sur la résultante des forces de freinage

Purpose. – This study presents a new method for determining the resultant braking force during wheelchair displacement and investigates the respective effects of the level and the distribution of the system’s mass.Method and results. – A three-dimensional accelerometer was fixed directly under the seat of wheelchair and was used to measure the deceleration of the mass-and-wheelchair’s system. Three masses (50, 70 and 90 kg) were laid on a support in 3 positions corresponding to three distributions (10, 40 and 70%) of the system’s total mass upon the front casters. A series of 15 deceleration trials was performed for each of the 9 combinations. Statistical results showed that the system’s deceleration was mainly explained by the mass distribution upon the front casters (92%) and in the least by the system’s total mass (8%).Conclusion. – Considering the fore-and-aft movements of the subject’s centre of mass during wheelchair locomotion, the results of this study let us assume that the resultant braking force does not remain constant along the propulsion cycle. Moreover, the present method could be used to investigate the influence of wheelchair’s adjustments and floor’s characteristics on the resultant braking force.