Cutoff value for predicting success in triathlon mixed team relay

IntroductionThe Mixed-Team-Relay (MTR) triathlon is an original race format present on the international scene since 2009, which became an Olympic event at the Tokyo 2020 Games. The aim of this study was to define the probabilities of reaching a victory, a podium, or a finalist rank in a relay triathlon, according to the position of any of the four relayers (Women/Men/Women/Men) during each of the four segments (leg) of the race.MethodsAll MTR results from the World Series, Continental Championships, World Championships from 2009 to 2021 and Tokyo 2020 Olympics have been collected. We calculated the set of probability frequencies of reaching a given final state, according to any transient state during the race. All results are compared with a V' Cramer method.ResultsThe frequency of winning is similar at the end of Leg 1 for TOP1 (first position) and TOP2-3 (second and third positions). Then, a difference in the winning-associated frequencies is first observed after the Bike stage of Leg 2, where 47% of TOP1 athletes will win, vs 13% of the TOP2-3.DiscussionThis difference continually increases until the end of the race. Legs 2 and 3 are preponderant on the outcome of the race, the position obtained by each triathlete, especially in swimming and cycling, greatly influences the final performance of the team. Leg 1 allows to maintain contact with the head of the race, while Leg 4 sets in stone the position obtained by the rest of the team

New model to estimate daily global solar radiation over Nigeria

This study focussed on developing an appropriate model for estimating daily global solar radiation for any location in Nigeria. Data for the study were obtained from the Nigeria Meteorological Agency, covering 12 sites, spread across the six geopolitical zones, for a period between 1987 and 2010. Various statistical methods were employed to determine the performance and accuracy of the model. A multivariate model that expresses global solar irradiance in terms of location latitude, daily relative sunshine, maximum daily temperature, daily average relative humidity, and cosine of day number was developed. The inclusion of the maximum daily temperature and daily mean relative humidity makes the model much more sensitive to climatic and weather changes. Also, the seasonal fluctuations of the humid tropical region are also well captured in the model. The analysis showed a good agreement between the measured data and computed results. Thus the model can be used to predict the global solar irradiance over Nigeria with minimum error. Further to this, the global solar radiation intensity values produced by this approach can be used in the design and estimation of the performance of solar applications

Le développement de la force dans les sports à dominante aérobie comme facteur d’individualisation

Introduction du chapitre 7. De la force-vitesse à la force-endurancepar Claude ColomboAprès avoir évoqué les relations force-vitesse dans la contribution précédente, celle de Thibaut Ledanois aborde l’intérêt qu’il y a à développer la force dans un sport à dominante aérobie comme le triathlon. Dans une première partie il relate des travaux portant sur les aspects positifs de l’entraînement de force pour les sportifs d’endurance. Des éléments d’intérêt d’ordre physiologique, biochimique et bi..

Grandeurs, dimensions, et conversions d'unités Quantities, Dimensions and Units Conversions

Il n'est plus besoin de démontrer que le Système International d'Unités (SI) est un fait. Il est normalement enseigné dans les lycées et universités. Les scientifiques l'utilisent systématiquement dans leurs publications; les nouveaux livres et banques de données s'en servent couramment. Cependant, certaines industries (la pétrolière entre autres) continuent à se servir de systèmes techniques. On trouve dans des archives de vieilles données ou des spécifications d'usines qui ont été faites dans d'autres systèmes. Il n'est pas rare, dans la vie professionnelle, de rencontrer un problème où une unité doit être transformée. Cet article souhaite aider les personnes qui doivent résoudre ce genre d'écueil en leur présentant une vision globale des différents systèmes d'unités qui ont historiquement existé. Une définition des unités, soit traditionnelles, soit étranges, accompagne également l'article. L'aide la plus importante sera sans doute trouvée dans le programme inclus dans une disquette. Un logiciel complet, sous Windows, permettra à quiconque de résoudre, sans erreur, son problème de conversion d'unité. La technique de conversion, basée sur l'utilisation du calcul dimensionnel, et utilisée dans le programme, est également expliquée. <br> It is not longer necessary to prove that the International System of Units (SI) is a fact. It is normally used in schools and universities. Scientists systematically use SI in their publications. New books and databases are commonly built on it. Meanwhile, some industries (oil companies among others) keep on using technical systems. It is possible to find old data and plant designs that use other systems. It is not uncommon, in professional life, to find a problem in which units need to be transformed. This article aims to help people who have to solve this kind of difficulty, by giving an overview of the different unit systems. A description of traditional and unusual units is also included in this article. Undoubtedly, the best help will be found in the program included in a floppy disk. A software, in the Windows environment will enable whoever wants to solve, its units conversion problem accurately. The conversion technique, based on dimensional analysis, is used in the program and explained in this article

Sterilisation sous cœlioscopie

En matière de stérilisation, lorsque les conditions techniques sont satisfaisantes, la voie coelioscopique nous semble la solution idéale. Sur une série de cent cas, nous n'avons aucun échec; l'âge moyen étant de trente-cinq ans, avec quatre enfants en moyenne. Les indications somatiques représentent 54 % des cas, avec risque maternel général dans 42 % - dont 20 % d'indications cardio-vasculaires, 6 % d'indications respiratoires et neurologiques, 4 % d'indications rénales. Le risque maternel local représente 7 %, le risque foetal 5 %. Enfin, dans les indications psycho-sociales (46 %), les indications sociales comptent pour 22 %, avec neuf enfants en moyenne et quarante ans d'âge moyen

Return to Sport Among French Alpine Skiers After an Anterior Cruciate Ligament Rupture: Results From 1980 to 2013

International audienceBackground: There is little known about return to sport and performance after anterior cruciate ligament (ACL) tear in high-level alpine skiers. Purpose: To analyze the parameters that influence the return to sport and performance after an ACL tear in French alpine skiers from 1980 to 2013. Study Design: Descriptive epidemiology study. Methods: The study population included 239 male and 238 female skiers who competed on the national French alpine ski team for at least 1 season between 1980 and 2013 in the speed (downhill and super-G) and technical disciplines (giant slalom and slalom). Two groups were formed: group 1 (G1) included athletes who had sustained an ACL rupture, and group 2 (G2) included athletes who had never sustained an ACL rupture. Three performance indicators were selected: International Ski Federation (FIS) points calculation, FIS ranking, and podium finishes in the World Cup, World Championships, and Olympic Games. Results: The first-decile FIS points and international FIS ranking showed that G1 skiers obtained better performance than did G2 skiers. The mean ± SD career length of G1 skiers (men, 7.9 ± 4.7 years; women, 7.1 ± 4.1 years) was longer than that of G2 skiers (men, 4.5 ± 3.3 years; women, 4.2 ± 3.5 years). In addition, 12.8% (61 of 477) of the skiers achieved at least a podium finish during their careers: 23.0% (34 of 148) in G1 and 8.3% (27 of 329) in G2. The mean age at ACL rupture was 22.6 ± 4.1 years for men and 19.9 ± 3.5 years for women. In G1, 55 podiums were achieved before ACL rupture and 176 after in all competitions. Skiers who improved their performances after ACL rupture were significantly younger (men, 22.2 ± 3.0 years; women, 18.7 ± 2.2 years; P\.0001) at the time of injury than those showing a performance deterioration after ACL rupture (men, 25.3 ± 4.2 years; women, 22.4 ± 4.0 years). All skiers who had ACL tears continued their competitive careers after the injury. Conclusion: The overall results showed that it is possible to return to preinjury or even higher levels of performance after an ACL rupture and that age is the main element that guides postsurgical recovery

Spatial-temporal variables for swimming coaches: A comparison study between video and TritonWear sensor

International audienceThe main aim of this study was to evaluate the validity and the reliability of a swimming sensor to assess swimming performance and spatial-temporal variables. Six international male open-water swimmers completed a protocol which consisted of two training sets: a 6×100m individual medley and a continuous 800 m set in freestyle. Swimmers were equipped with a wearable sensor, the TritonWear to collect automatically spatial-temporal variables: speed, lap time, stroke count (SC), stroke length (SL), stroke rate (SR), and stroke index (SI). Video recordings were added as a “gold-standard” and used to assess the validity and the reliability of the TritonWear sensor. The results show that the sensor provides accurate results in comparison with video recording measurements. A very high accuracy was observed for lap time with a mean absolute percentage error (MAPE) under 5% for each stroke (2.2, 3.2, 3.4, 4.1% for butterfly, backstroke, breaststroke and freestyle respectively) but high error ranges indicate a dependence on swimming technique. Stroke count accuracy was higher for symmetric strokes than for alternate strokes (MAPE: 0, 2.4, 7.1 & 4.9% for butterfly, breaststroke, backstroke & freestyle respectively). The other variables (SL, SR & SI) derived from the SC and the lap time also show good accuracy in all strokes. The wearable sensor provides an accurate real time feedback of spatial-temporal variables in six international open-water swimmers during classical training sets (at low to moderate intensities), which could be a useful tool for coaches, allowing them to monitor training load with no effort