1,721,137 research outputs found
Differential effects of exercise on sex hormone-binding globulin and non-sex hormone-binding globulin-bound testosterone
No full textThe response of total testosterone (T), free testosterone (fT), sex hormone-binding globulin (SHBG) and non-SHBG-bound testosterone (NST) to the same exercise protocol was evaluated in two different experiments on long distance runners. The first experiment was performed in the morning at 0900 hours with nine athletes, while the second was carried out in the afternoon at 1500 hours with seven athletes. During each experiment, each athlete ran for 1 h at the previously determined speed corresponding to 2 mmol.l-1 blood lactate concentration. Three venous blood samples were collected in each experiment: before exercise, at the end of running and after 1 h of recovery. Total T and SHBG showed similar responses: in the first experiment they had decreased after exercise, while in the second they had increased at the end of running. A positive correlation between total T and SHBG concentrations was found at the end of exercise. In both experiments, NST and fT had increased after exercise and decreased to initial concentrations during recovery. The results would suggest the existence of a compensatory mechanism which maintains adequate concentrations of biologically active T when total T concentrations decrease
Estimation of swimmer’s power propulsion: comparison between power thrust and power drag
No full textIf the swimmer action is covered at constant average speed is possible to investigate the balance between thrust force (Ft) and resistant drag force (Fd) (Toussaint, 1992). The towing passive drag
in a hydrodynamic stable position has been showed a remarkable consistency method to measure the swimmer’s drag. Fully tethered swimming is a useful tool to asses the Ft and it has a high correlation with the swimming sprint performances (v). In relationship to 25m speed (v25), we compared the estimation of the swimming power propulsion obtained with the power thrust experiments (15s all-out of front crawl tethered) and the power drag method estimated from the passive towing measurement
Pacing profile in the main international open-water swimming competitions
No full textPurpose: Different aspects of pacing in endurance events have been investigated, however, there are very limited information on pacing strategies during open-water swimming. The aim was to describe and compare the pacing profile used by male and female open-water swimmers (OW-swimmers) during the 5-, 10- and 25 km races in the main international competitions. Methods: A total of 438 performances were analysed for 5 km, 579 for 10 km and 189 for 25 km, from 2012 to 2017. Swimmers were divided into four groups based on finishing time. G1 whose finishing times were within 0.5% of the winner’s time, G2 between 0.51% and 1% slower than winner’s time; G3 between 1.1% and 2% slower than winner’s time; G4 over 2% of winner’s time. Kolmogorov–Smirnov test was used to verify the normal distribution of data and repeated measures ANOVA was performed. Results: G1 adopted a negative pacing and significantly increased the speed in the last split compared with the other groups during the 5-, 10- and 25-km races in both males and females (p <.001). During the 5- and 10-km race, the last split speed of G1 was significantly faster compared to the other groups in both males and females (p <.05). Conclusions: OW-swimmers that used a conservative approach remaining in G1 until the finish of the race, increase the possibility to win a medal in the main international competitions
Preparatory versus main competitions: differences in performances, lactate responses, and pre-competitions plasma cortisol concentrations in elite male swimmers
No full textTwo groups of elite male swimmers were studied with a similar protocol during the winter training seasons of two consecutive years. In the first season (September 1997-January 1998), eight male swimmers (age 19-25 years) of the Italian National Team participated, after 12 weeks of increased training volume, in a preparatory national competition (PWC) and then, after a further 6 weeks of specific training, in the World Championships (WC, both competitions in a 50-m pool), which represented the main competition at the end of the 18 week-long winter season. In the second season (September 1998-December 1998), a group of ten high-level male swimmers (18-22 years) participated, after 8 weeks of increased training volume, in a preparatory national competition (PNC) and then, after a further 6 weeks of specific training, in the Italian Championships (IC, both competitions in a 25-m pool), the the main competition at the end of the 14 week-long winter season. A tapering period lasting 1-3 weeks was observed before the main competition in both seasons. All swimmers were competing in distances up to 400 m; two of them participated in the study in both seasons. The swimming velocities and post-competition blood lactate concentrations were higher in the main competitions than in the preparatory competitions in both seasons. Pre-competition cortisol (CORT) plasma concentrations were higher than the initial values at the beginning of the season, reaching maximal values at the preparatory competitions and then decreasing before the main competitions in both seasons. The percentage increase in individual swimming velocity from the preparatory to the main competition was positively correlated with the corresponding increase in post-competition blood lactate (r=0.63, p=0.046) in the 1997 season (WC) and negatively correlated with the corresponding decrease in pre-competition CORT concentration (r=-0.66, p=0.019) in the 1998 season (IC). Our results indicate that a decrease in pre-competition CORT could be a prerequisite for an improvement in swimming performance
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Game activity and blood lactate in men's elite water-polo players
No full textThe purpose of this study was to examine game demands during highly competitive men’s water-polo games after the introduction of the new Federation International Natation Association (FINA)
rules. Participants of this study were 77 outfield international
level men’s water-polo players (age 25.9 +/- 4.5 years, height
188 +/- 4.5 cm, body mass 93 +/- 10.9 kg). Game earlobe blood
lactate, speed, and distance covered (semiautomatic image
recognition system) were measured during 6 highly competitive
matches (FINA International Tournament). In the game, players
covered 1,613 +/- 150 m (n = 68). This corresponds to a mean
coverage rate of 54 6 5.8 mmin21 (n = 68). At speeds faster
than 1.4 m/s (high-intensity swimming), players covered 44%
of the total distance. A significant decrease in coverage rate
was detected during the final stage of the game. Mean blood lactate concentration was 7.7 +/- 1.0 mmol/l (range 2.2–14.3). Center Defenders (1,816 +/- 496 m) covered significantly more distance swimming compared to Field (1,676 +/- 348 m) and Center-Forward (1,317 +/- 281 m) players. Mean match blood lactate concentrations for Center Forwards, Center Defenders, and Field Players were 11.2 +/- 1.0 (3–14.3), 6.7 +/- 0.9 (1.4–8), and 5.3 +/- 0.9 mmol/l (2.2–11.9), respectively. This study confirmed the high-intensity nature of male elite level water polo showing remarkable roledependent game demands. As a result, strength and conditioning interventions should be individualized and mainly address intermittent high-intensity endurance and anaerobic fitness
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Time division digital programmable OTA for cellular neural networks
No full textThe design of a new Digital Programmable Transconductance Amplifier (TD-DPTA) for Cellular Neural Networks will be shown in the paper. The proposed approach is based on a time division strategy with the main goal of a reduction of the area by the minimization of the number of the analogue multipliers inside each cell. So, the new CNN cell will be composed of a single TD-DPTA only, which will be able to feed the whole neighbourhood by the proper weighted current contribution by using a time division approach. The paper presents the design of a new DPTA architecture as well as a multiplexer circuit tailored for this particular application
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