Positionnement par satellites (GPS) et accélérométrie : nouvelles applications dans le domaine du sport

Grâce à des développements technologiques récents, tels que le système de positionnement par satellites GPS (Global Positioning System) en mode différentie on est maintenant capable de mesurer avec une grande précision non seulement le profil de vitesse de déplacement d'un sujet sur la terre mais aussi sa trajectoire en faisant totalement abstraction de la chronométrie classique. De plus, des capteurs accélérométriques miniaturisés permettent d'obtenir un complément d'information biomécanique utile (fréquence et longueur du pas, signature accélérométrique individuelle). Dans cet artide, un exemple d'application de ces deux techniques à des sports tels que le ski alpin (descente ou Super G) et le sprint est présenté. La combinaison de plusieurs mesures physiologiques, cinétiques et biomécaniques permettra de mieux comprendre les facteurs endogènes et exogènes qui jouent un rôle dans l'amélioration des performances de l'homme.

A mega-analysis of genome-wide association studies for major depressive disorder.

Prior genome-wide association studies (GWAS) of major depressive disorder (MDD) have met with limited success. We sought to increase statistical power to detect disease loci by conducting a GWAS mega-analysis for MDD. In the MDD discovery phase, we analyzed more than 1.2 million autosomal and X chromosome single-nucleotide polymorphisms (SNPs) in 18 759 independent and unrelated subjects of recent European ancestry (9240 MDD cases and 9519 controls). In the MDD replication phase, we evaluated 554 SNPs in independent samples (6783 MDD cases and 50 695 controls). We also conducted a cross-disorder meta-analysis using 819 autosomal SNPs with P<0.0001 for either MDD or the Psychiatric GWAS Consortium bipolar disorder (BIP) mega-analysis (9238 MDD cases/8039 controls and 6998 BIP cases/7775 controls). No SNPs achieved genome-wide significance in the MDD discovery phase, the MDD replication phase or in pre-planned secondary analyses (by sex, recurrent MDD, recurrent early-onset MDD, age of onset, pre-pubertal onset MDD or typical-like MDD from a latent class analyses of the MDD criteria). In the MDD-bipolar cross-disorder analysis, 15 SNPs exceeded genome-wide significance (P<5 × 10(-8)), and all were in a 248 kb interval of high LD on 3p21.1 (chr3:52 425 083-53 822 102, minimum P=5.9 × 10(-9) at rs2535629). Although this is the largest genome-wide analysis of MDD yet conducted, its high prevalence means that the sample is still underpowered to detect genetic effects typical for complex traits. Therefore, we were unable to identify robust and replicable findings. We discuss what this means for genetic research for MDD. The 3p21.1 MDD-BIP finding should be interpreted with caution as the most significant SNP did not replicate in MDD samples, and genotyping in independent samples will be needed to resolve its status.

The impact of past direct-personal traumatic events on 12-month outcome in first episode psychotic mania: trauma and early psychotic mania.

OBJECTIVE: Past traumatic events have been associated with poorer clinical outcomes in people with bipolar disorder. However, the impact of these events in the early stages of the illness remains unclear. The aim of this study was to investigate whether prior traumatic events were related to poorer outcomes 12 months following a first episode of psychotic mania. METHODS: Traumatic events were retrospectively evaluated from patient files in a sample of 65 participants who had experienced first episode psychotic mania. Participants were aged between 15 and 28 years and were treated at a specialised early psychosis service. Clinical outcomes were measured by a variety of symptomatic and functioning scales at the 12-month time-point. RESULTS: Direct-personal traumatic experiences prior to the onset of psychotic mania were reported by 48% of the sample. Participants with past direct-personal trauma had significantly higher symptoms of mania (p=0.02), depression (p=0.03) and psychopathology (p=0.01) 12 months following their first episode compared to participants without past direct-personal trauma, with medium to large effects observed. After adjusting for baseline scores, differences in global functioning (as measured by the Global Assessment of Functioning scale) were non-significant (p=0.05); however, participants with past direct-personal trauma had significantly poorer social and occupational functioning (p=0.04) at the 12-month assessment with medium effect. CONCLUSIONS: Past direct-personal trauma may predict poorer symptomatic and functional outcomes after first episode psychotic mania. Limitations include that the findings represent individuals treated at a specialist early intervention centre for youth and the retrospective assessment of traumatic events may have been underestimated.

International Olympic Committee consensus statement on thermoregulatory and altitude challenges for high-level athletes

Challenging environmental conditions, including heat and humidity, cold, and altitude, pose particular risks to the health of Olympic and other high-level athletes. As a further commitment to athlete safety, the International Olympic Committee (IOC) Medical Commission convened a panel of experts to review the scientific evidence base, reach consensus, and underscore practical safety guidelines and new research priorities regarding the unique environmental challenges Olympic and other international-level athletes face. For non-aquatic events, external thermal load is dependent on ambient temperature, humidity, wind speed and solar radiation, while clothing and protective gear can measurably increase thermal strain and prompt premature fatigue. In swimmers, body heat loss is the direct result of convection at a rate that is proportional to the effective water velocity around the swimmer and the temperature difference between the skin and the water. Other cold exposure and conditions, such as during Alpine skiing, biathlon and other sliding sports, facilitate body heat transfer to the environment, potentially leading to hypothermia and/or frostbite; although metabolic heat production during these activities usually increases well above the rate of body heat loss, and protective clothing and limited exposure time in certain events reduces these clinical risks as well. Most athletic events are held at altitudes that pose little to no health risks; and training exposures are typically brief and well-tolerated. While these and other environment-related threats to performance and safety can be lessened or averted by implementing a variety of individual and event preventative measures, more research and evidence-based guidelines and recommendations are needed. In the mean time, the IOC Medical Commission and International Sport Federations have implemented new guidelines and taken additional steps to mitigate risk even further.

A one-year monitoring of nicotine use in sport: frontier between potential performance enhancement and addiction issues.

Tobacco consumption is a global epidemic responsible for a vast burden of disease. With pharmacological properties sought-after by consumers and responsible for addiction issues, nicotine is the main reason of this phenomenon. Accordingly, smokeless tobacco products are of growing popularity in sport owing to potential performance enhancing properties and absence of adverse effects on the respiratory system. Nevertheless, nicotine does not appear on the 2011 World Anti-Doping Agency (WADA) Prohibited List or Monitoring Program by lack of a comprehensive large-scale prevalence survey. Thus, this work describes a one-year monitoring study on urine specimens from professional athletes of different disciplines covering 2010 and 2011. A method for the detection and quantification of nicotine, its major metabolites (cotinine, trans-3-hydroxycotinine, nicotine-N'-oxide and cotinine-N-oxide) and minor tobacco alkaloids (anabasine, anatabine and nornicotine) was developed, relying on ultra-high pressure liquid chromatography coupled to triple quadrupole mass spectrometry (UHPLC-TQ-MS/MS). A simple and fast dilute-and-shoot sample treatment was performed, followed by hydrophilic interaction chromatography-tandem mass spectrometry (HILIC-MS/MS) operated in positive electrospray ionization (ESI) mode with multiple reaction monitoring (MRM) data acquisition. After method validation, assessing the prevalence of nicotine consumption in sport involved analysis of 2185 urine samples, accounting for 43 different sports. Concentrations distribution of major nicotine metabolites, minor nicotine metabolites and tobacco alkaloids ranged from 10 (LLOQ) to 32,223, 6670 and 538 ng/mL, respectively. Compounds of interest were detected in trace levels in 23.0% of urine specimens, with concentration levels corresponding to an exposure within the last three days for 18.3% of samples. Likewise, hypothesizing conservative concentration limits for active nicotine consumption prior and/or during sport practice (50 ng/mL for nicotine, cotinine and trans-3-hydroxycotinine and 25 ng/mL for nicotine-N'-oxide, cotinine-N-oxide, anabasine, anatabine and nornicotine) revealed a prevalence of 15.3% amongst athletes. While this number may appear lower than the worldwide smoking prevalence of around 25%, focusing the study on selected sports highlighted more alarming findings. Indeed, active nicotine consumption in ice hockey, skiing, biathlon, bobsleigh, skating, football, basketball, volleyball, rugby, American football, wrestling and gymnastics was found to range between 19.0 and 55.6%. Therefore, considering the adverse effects of smoking on the respiratory tract and numerous health threats detrimental to sport practice at top level, likelihood of smokeless tobacco consumption for performance enhancement is greatly supported.

Evolution of anaesthesia care and related events between 1996 and 2010 in a developed country

Background: Anaesthesia Databank Switzerland (ADS) is a voluntary data registry introduced in 1996. The goal was to promote quality in anaesthesiology. Methods: Analysis of routinely recorded adverse events. Internal and external benchmark comparisons between anaesthesia departments. Results: In 2010, the database included 2'158'735 anaesthetic procedures. Forty-four anaesthesia departments were participating to the data collection in 2010. Over time, the number of patients in older age groups increased, the largest group being patients aged 50 to 64 years. Over time, the percentage of patients with ASA physical status score 1 decreased while the number of ASA 2 or 3 patients increased. The most frequent co-morbidities were hypertension (21%), smoking (16%), allergy (15%), and obesity (12%). Between 1996 and 2010, 146'459 adverse events were recorded, of which 34% were cardiovascular, 7% respiratory, 39% specific to anaesthesia and 17% nonspecific. The overall proportion of adverse events decreased over time, whatever their severity. Conclusion: The ADS routine data collection contributes to monitoring the trends of anaesthesia care in Switzerland.

Weekly sport practice and adolescent well-being.

OBJECTIVE: Sport practice is widely encouraged, both in guidelines and in clinical practice, because of its broad range of positive effects on health. However, very limited evidence directly supports this statement among adolescents and the sport duration that we should recommend remains unknown. We aimed to determine sport durations that were associated with poor well-being. METHODS: We conducted a survey including 1245 adolescents (16-20 years) from the general Swiss population. Participants were recruited from various settings (sport centres, peers of sport practicing adolescents, websites) and asked to complete a web-based questionnaire. Weekly sport practice was categorised into four groups: low (0-3.5 h), average (≈ recommended 7 h (3.6-10.5)), high (≈14 h (10.6-17.5)) and very high (>17.5 h). We assessed well-being using the WHO-5 Well-Being Index. RESULTS: Compared with adolescents in the average group, those in the very high group had a higher risk of poor well-being (OR 2.29 (95% CI 1.11 to 4.72)), as did those in the low group (OR 2.33 (1.58 to 3.44)). In contrast, those in the high group had a lower risk of poor well-being than those in the average group (OR 0.46 (0.23 to 0.93)). CONCLUSIONS: We found an inverted, U-shaped relationship between weekly sport practice duration and well-being among adolescents. The peak scores of well-being were around 14 h per week of sport practice, corresponding to twice the recommended 7 h. Practicing higher sport durations was an independent risk factor of poor well-being.

Trace-element and phosphorus contents in sediment associated with Cretaceous oceanic anoxic events

ABSTRACT : During my SNSF-funded Ph.D. thesis project, I studied the evolution of redox conditions and organic-carbon preservation in the western Tethyan realm during three major positive excursions in the Cretaceous δ13C record, corresponding to the Valanginian, Early Aptian and Late Cenomanian. These periods were characterized by important global environmental and climate change, which was associated with perturbations in the carbon cycle. For the period of the Valanginian δ13C excursion, total organic carbon (TOC) contents and the quality of preserved organic matter are typical of oxic pelagic settings in the western Tethys. This is confirmed by the absence of major excursions in the stratigraphic distribution of RSTE during the δ13C shift. Published TOC data from other parts of the Valanginian oceans indicate that dys- to anaerobic zones were restricted to marginal seas within the Atlantic and Southern Ocean, and to the Pacific. Phosphorus (P) and mineralogical contents suggest a stepwise climatic evolution during the Valanginian, with a humid and warm climate prior to the δ13C shift leading to an increase in continental runoff. During the δ13C shift, a decrease in detrital input and P contents suggests a change in the climate towards more and conditions. During the early Aptian oceanic anoxic event (OAE 1a), a general increase followed by a rapid decrease in P contents suggests enhanced nutrient input at the beginning of OAE 1a. The return to lower values during OAE 1 a, associated with an increase in RSTE contents, may have been related to the weakened capacity to retain P in the sedimentary reservoir due to bottom-water oxygen depletion. In basinal settings, the RSTE distribution indicates well-developed anoxic conditions during OAE la, whereas in the shallower-water environments, conditions were oxic to suboxic, rather than anoxic. Furthermore, in the deeper part of the Tethys, two distinct enrichments have been observed, indicating fluctuations in the intensity of water column anoxia during the δ73C excursion. We also studied the effect of the end-Cenomanian oceanic anoxic event (OAE 2) on an expanded section in the Chrummflueschlucht (E of Euthal, Ct Switzerland). The goal here was to identify paleoceanographic and paleoenvironmental conditions during OAE 2 in this part of the northern Tethyan margin. The results show that this section is one of the most complete sections for the Cenomanian-Turonian boundary interval known from the Helvetic realm, despite a small hiatus between sediments corresponding to peaks 1 and 2 in the δ13C record. The evolution of P contents points to an increase in the input of this nutrient at the onset of OAE 2. The trends in RSTE contents show, however, that this part of the Helvetic realm was not affected by a strong depletion in oxygen conditions during OAE 2, despite its hemipelagic position. A further goal of this project was to submit the samples to a total extraction method (a combined HF/HNO3/HCI acid digestion) and compare the results obtained by the partial HNO3 acid extraction in order to standardize the analytical prócedures in the extraction of RSTE. The obtained results for samples of OAE 1 a suggest that RSTE trends using the partial HNO3 digestion are very comparable to those obtained by the total digestion method and subsequently normalized with regards to AI contents. RÉSUMÉ : Durant ce projet de thèse, financé par le Swiss National Science Funding (SNSF), j'ai étudié l'évolution des conditions redox et de la préservation de carbone organique dans le domnaine ouesttéthysien pendant trois excursions majeures du δ13C au Crétacé correspondant au Valanginien, à l'Aptien inférieur et à la limite Cénomanien-Turonien. Ces périodes sont caractérisées par des changements climatiques et environnementaux globaux associés à des perturbations dans le cylce du carbone. Pour L'excursion positive en δ13C du Valanginien, les analyses du carbone organique total (COT) et les observations palynologiques du domaine téthysien ont présenté des indications d'environnement pélagique relativementbienoxygéné. L'absence d'enrichissements en éléments traces sensibles aux conditions redox (TE) pendant l'excursion positive en δ13C confirme ces interprétations. Les données publiées de COT dans d'autres partie du globe indiquent cependant l'existence de conditions dys- à anaérobiques dans certains bassins restreints de l'Atlantique, l'Océan Austral et du Pacifique. L'évolution du phosphore (P) et la composition minéralogique des sédiments semblent indiquer un climat relativement chaud et humide avant l'excursion en δ13C entraînant une augmentation de l'altération continentale. Pendant le shift isotopique, une diminution des apports détritiques et du P suggèrent une transition vers des conditions plus arides. À l'Aptien Inférieur, le début de l'événement anoxique (OAE 1a) est marqué par une augmentation générale du P dans les sédiments indiquant une augmentation du niveau trophique à la base de l'excursion isotopique. Durant l'événement anoxique, les sédiments sont relativement appauvris en P. Cette diminution rapide associée à des enrichissements en TE est probablement liée à une remobilisation plus importante du P lors de la mise en place de conditions anoxiques dans les eaux de fond. Dans les environnements de bassin, le comportement des TE (enrichissements bien marqués) attestent de conditions réductrices bien marquées alors que dans les environnements moins profonds, les conditions semblent plutôt oxiques à dysoxiques. De plus, deux niveaux d'enrichissement en TE ont été observés dans la partie plus profonde de la Téthys, indiquant des fluctuations assez rapides dans l'intensité de l'anoxie de la colonne d'eau. Nous avons ensuite étudié les effets de l'événement anoxique de la fin du Cenomanien (OAE 2) dans un basin marginal de la marge nord de la Téthys avec la coupe de Chrummflueschlucht (à l'est de Euthal, Ct Schwyz). Les résultats ont montré que cette coupe présente un des enregistrements sédimentaires des plus complets de l'OAE 2 dans le domaine helvétique malgré un hiatus entre le pic 1 et 2 de l'excursion en δ13C. L'évolution du P montre une augmentation au début de l'OAE 2. Cependant, la distribution des TE indique que cette région n'a pas été affectée par des conditions réductrices trop importantes. Un second aspect de ce travail a été l'étude des différentes méthodes sur l'analyse de la distribution des TE. Des échantillons de l'OAE 1a ont été soumis à deux types d'extractions, l'une dite «totale » (attaque combinée d'acides HF/HNO3/HCI) et l'autre dite partielle » (HNO3). Les résultats obtenus suggèrent que les courbes de tendances des TE acquises par extraction partielle sont semblables à celle obtenues par extraction totale et normalisées par l'AI.

Power laws and scaling of rain events and dry spells in the Catalonia region

We analyze the statistics of rain-event sizes, rain-event durations, and dry-spell durations in a network of 20 rain gauges scattered in an area situated close to the NW Mediterranean coast. Power-law distributions emerge clearly for the dryspell durations, with an exponent around 1.50 ± 0.05, although for event sizes and durations the power-law ranges are rather limited, in some cases. Deviations from power-law behavior are attributed to finite-size effects. A scaling analysis helps to elucidate the situation, providing support for the existence of scale invariance in these distributions. It is remarkable that rain data of not very high resolution yield findings in agreement with self-organized critical phenomena.

Artificial Snow Optimization in Winter Sport Destinations Using a Multi-agent Simulation

This paper presents the Juste-Neige system for predicting the snow height on the ski runs of a resort using a multi-agent simulation software. Its aim is to facilitate snow cover management in order to i) reduce the production cost of artificial snow and to improve the profit margin for the companies managing the ski resorts; and ii) to reduce the water and energy consumption, and thus to reduce the environmental impact, by producing only the snow needed for a good skiing experience. The software provides maps with the predicted snow heights for up to 13 days. On these maps, the areas most exposed to snow erosion are highlighted. The software proceeds in three steps: i) interpolation of snow height measurements with a neural network; ii) local meteorological forecasts for every ski resort; iii) simulation of the impact caused by skiers using a multi-agent system. The software has been evaluated in the Swiss ski resort of Verbier and provides useful predictions.

Health impact of sport and exercise in emerging adult men: a prospective study.

PURPOSE: Health benefits of sport and exercise are well documented in children, adolescents and adults, but little is known about emerging adulthood-a period of life characterized by significant demographic and developmental changes. The present study aimed to assess the health impact of changes in sport and exercise levels during that specific period of life. METHODS: The analysis used baseline and 15-month follow-up data (N = 4,846) from the cohort study on substance use risk factors. Associations between baseline exercise levels or changes in exercise levels and health indicators (i.e., health-related quality of life, depression, body mass index, alcohol dependence, nicotine dependence and cannabis use disorder) were measured using chi-squared tests and ANOVA. Direction of effects was tested using cross-lagged analysis. RESULTS: At baseline, all health indicator scores were observed to be better for regular exercisers than for other exercise levels. At follow-up, participants who had maintained regular exercise over time had better scores than those who had remained irregular exercisers or had discontinued, but their scores for health-related quality of life and depression were close to those of participants who had adopted regular exercise after the baseline questionnaire. Cross-lagged analysis indicated that regular exercise at baseline was a significant predictor of health-related quality of life and substance use dependence at follow-up, but was itself predicted only by health-related quality of life. CONCLUSIONS: From a health promotion perspective, this study emphasizes how important it is for emerging adult men to maintain, or adopt, regular sport and exercise.