Inter-limb coordination in swimming: Effect of speed and skill level

International audienc

Effect of Additional Respiratory Muscle Endurance Training in Young Well- Trained Swimmers

International audienceWhile some studies have demonstrated that respiratory muscle endurance training (RMET) improves performances during various exercise modalities, controversy continues about the transfer of RMET effects to swimming performance. The objective of this study was to analyze the added effects of respiratory muscle endurance training (RMET; normocapnic hyperpnea) on the respiratory muscle function and swimming performance of young well-trained swimmers. Two homogenous groups were recruited: ten swimmers performed RMET (RMET group) and ten swimmers performed no RMET (control group). During the 8-week RMET period, all swimmers followed the same training sessions 5-6 times/week. Respiratory muscle strength and endurance , performances on 50-and 200-m trials, effort perception , and dyspnea were assessed before and after the intervention program. The results showed that ventilatory function parameters , chest expansion, respiratory muscle strength and endurance, and performances were improved only in the RMET group. Moreover, perceived exertion and dyspnea were lower in the RMET group in both trials (i.e., 50-and 200-m). Consequently , the swim training associated with RMET was more effective than swim training alone in improving swimming performances. RMET can therefore be considered as a worthwhile ergogenic aid for young competitive swimmers

BIOMECHANICAL ANALYSIS OF STARTING PREFERENCE FOR EXPERT SWIMMERS

The purpose of this study was to compare kinetics, body angles and angular momenta during the swimming start for preferred and non-preferred technique of expert grab starters. Results showed that in preferred technique, starts were executed with less global angular momentum around the transverse axis. By searching further, less loss of angular momentum in the other dimensions was found for grab start as preferred technique, inducing a less efficiency in non-preferred technique (twisting effect in track start as non-preferred technique). Body angles showed that legs in non-preferred technique permit to increase quantity of body rotation during aerial phase. Finally, subject effect was found for arms movements (confirming that expert swimmers can organize themselves differently to achieve to an optimal performance

INTRACYCLIC SPEED FLUCTUATIONS OF THE CENTER OF MASS AND ITS RELATIONSHIP WITH THE INDEX OF COORDINATION - A PILOT STUDY

The purpose of this study was to analyse the relationship between the intracyclic speed fluctuations (dv) of the center of mass (CM), in the x,y,z axes, and the Index of Coordination (IdC), as well as to assess the general stroking parameters during the 200 m front crawl event. A good level male swimmer performed the 200 m front crawl at maximum intensity, being video taped by six cameras (2 above and 4 under the water). One complete stroke cycle was analysed in each 50 m of the 200 m test, using the APASystem (Ariel Dynamics Inc). IdC appeared to be well related to dv, both in the horizontal and vertical axes. It was also observed, during the 200 m effort, that the IdC, dv, stroke rate and stroke length changed during the exercise

Traitement des signalements relatifs à l’intégrité scientifique

La liste des questions auxquelles ce manuel a cherché à répondre est très longue (près de 200 questions, dont plus d’une centaine dans les 10 fiches pratiques, et une cinquantaine d’ordre juridique) et donnera, aux acteurs de l’intégrité scientifique ainsi qu’aux responsables des opérateurs de recherche, une idée de la complexité et de la difficulté de cette mission centrale des RIS : celle consistant à instruire les dossiers de manquement (potentiel) à l’intégrité scientifique

Multiple controls affect arsenite oxidase gene expression in Herminiimonas arsenicoxydans

<p>Abstract</p> <p>Background</p> <p>Both the speciation and toxicity of arsenic are affected by bacterial transformations, i.e. oxidation, reduction or methylation. These transformations have a major impact on environmental contamination and more particularly on arsenic contamination of drinking water. <it>Herminiimonas arsenicoxydans </it>has been isolated from an arsenic- contaminated environment and has developed various mechanisms for coping with arsenic, including the oxidation of As(III) to As(V) as a detoxification mechanism.</p> <p>Results</p> <p>In the present study, a differential transcriptome analysis was used to identify genes, including arsenite oxidase encoding genes, involved in the response of <it>H. arsenicoxydans </it>to As(III). To get insight into the molecular mechanisms of this enzyme activity, a Tn<it>5 </it>transposon mutagenesis was performed. Transposon insertions resulting in a lack of arsenite oxidase activity disrupted <it>aoxR </it>and <it>aoxS </it>genes, showing that the <it>aox </it>operon transcription is regulated by the AoxRS two-component system. Remarkably, transposon insertions were also identified in <it>rpoN </it>coding for the alternative N sigma factor (σ⁵⁴) of RNA polymerase and in <it>dnaJ </it>coding for the Hsp70 co-chaperone. Western blotting with anti-AoxB antibodies and quantitative RT-PCR experiments allowed us to demonstrate that the <it>rpoN </it>and <it>dnaJ </it>gene products are involved in the control of arsenite oxidase gene expression. Finally, the transcriptional start site of the <it>aoxAB </it>operon was determined using rapid amplification of cDNA ends (RACE) and a putative -12/-24 σ⁵⁴-dependent promoter motif was identified upstream of <it>aoxAB </it>coding sequences.</p> <p>Conclusion</p> <p>These results reveal the existence of novel molecular regulatory processes governing arsenite oxidase expression in <it>H. arsenicoxydans</it>. These data are summarized in a model that functionally integrates arsenite oxidation in the adaptive response to As(III) in this microorganism.</p

Individual-environment interactions in swimming: The smallest unit for analysing the emergence of coordination dynamics in performance?

Displacement in competitive swimming is highly dependent on fluid characteristics, since athletes use these properties to propel themselves. It is essential for sport scientists and practitioners to clearly identify the interactions that emerge between each individual swimmer and properties of an aquatic environment. Traditionally, the two protagonists in these interactions have been studied separately. Determining the impact of each swimmer’s movements on fluid flow, and vice versa, is a major challenge. Classic biomechanical research approaches have focused on swimmers’ actions, decomposing stroke characteristics for analysis, without exploring perturbations to fluid flows. Conversely, fluid mechanics research has sought to record fluid behaviours, isolated from the constraints of competitive swimming environments (e.g. analyses in two-dimensions, fluid flows passively studied on mannequins or robot effectors). With improvements in technology, however, recent investigations have focused on the emergent circular couplings between swimmers’ movements and fluid dynamics. Here, we provide insights into concepts and tools that can explain these on-going dynamical interactions in competitive swimming within the theoretical framework of ecological dynamics

Assessment of the influence of pole carriage on sprint kinematics: A case study of novice athletes

The purpose of this study was to determine the influence of pole carrying on the biomechanics of the run-up in the pole vault. Eight novice male pole vaulters participated and performed six 30-m sprints, three with and three without a pole. A tripod-mounted digital video camera was horizontally panned to follow the athletes from left to right and electronic timing cells recorded the sprint times. The experimental setup recorded the average velocities and the times of the stance and swing phases; it also determined the sagittal plane angles of the hip, knee and ankle joints during a cycle. The results indicated that the average velocities during the runs were significantly lower with pole than without (P < 0.05). The runs with pole were characterized by significantly less flexion of the hip and knee joints at the instant of maximal hip flexion during the swing phase. Consequently, an anterior imbalance was created by running with a pole whose length was much greater than the athletes' height. This tended to increase the braking phase and decrease the stride length, causing a 'slight precipitation' by the athletes' anticipation of the foot touchdown