1,721,203 research outputs found
Recovery time profiling after short-, middle-and long-distance swimming performance
No full textPiras, A, Cortesi, M, Campa, F, Perazzolo, M, and Gatta, G. Recovery time profiling after short-, middle- and long-distance swimming performance. J Strength Cond Res 33(5): 1408-1415, 2019-We investigated cardiac autonomic responses and hemodynamic parameters on recovery time after short-, middle- and long-swimming performance. Ten male regional-level swimmers were tested to estimate time and frequency domains of arterial baroreflex sensitivity (BRS) and heart rate variability after 100, 200, and 400 m of front crawl. We found a BRS reduction for 90 minutes after a maximal 100- and 200-m front crawl event, meanwhile the reflex was restored back to the baseline value approximately 70 minutes after 400 m. The vagally mediated high-frequency power of R-R intervals was significantly reduced for 30 minutes after 400 m, and more than 90 minutes after 100 and 200 m, with a concomitant increase of sympathetic modulation. After 400 m, athletes have reduced their stroke volume for 50 minutes, which remained at the baseline level after 100 and 200 m. Heart rate was restored back after 90 minutes in all conditions, whereas total peripheral vascular resistance was significantly reduced for 50 minutes after 200 and 400 m, with a persistent reduction after 100 m. Time course of autonomic recovery after 3 different swimming performances is influenced by exercise intensity and duration, showing a rapid recovery after 400 m, an intermediate recovery after 200 m, and a significantly delayed recovery after a more strictly anaerobic performance like 100 m of front crawl. These results could encourage coaches to consider that athlete might be affected by the specific recovery time of the previous exercise performed, suggesting that the management of the exercise intensity, and appropriate monitoring of cardiac autonomic parameters might be helpful to know the physical condition of each athlete
Velocità e mezzofondo. Un approccio scientifico alle differenti tecniche
No full textI nuotatori in vasca tendono a specializzarsi in eventi veloci (50-100 m) o in eventi di distanza (400m +), in funzione delle loro caratteristiche fisiologiche, meccaniche e psicologiche, genetiche o allenate. Il tecnico deve essere in grado di organizzare un programma di allenamento in grado di valorizzare il nuotatore verso la prestazione che più si adatta all’ atleta, sviluppando gli aspetti tecnici appropriati alla durata della prova. Osservando i nuotatori in gare di differente distanza si colgono in modo immediato le diverse peculiarità tecniche della prova. Le differenti durate di gara richiedono andature specifiche, e il nuotatore tende ad adattare la tecnica alle esigenze del ritmo richiesto. Questo articolo ha lo scopo di analizzare le differenze della tecnica di nuotata tra il velocista ed il mezzofondista nello stile libero, aggiornando le conoscenze attraverso una revisione della letteratura scientifica di settore
Potential therapeutical effects of cannabidiol in children with pharmacoresistant epilepsy
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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
A comparison between elite swimmers and kayakers on upper body push and pull strength and power performance
Full text linkThe aim of the present study was to compare the load-power curve expressed at bench press (PR) and prone bench pull (PU) between elite swimmers and kayakers. Another aim was to calculate the strength and power PR/PU ratio in the same populations. Fifteen elite swimmers (SW: age = 23.8 ± 2.9 y; body mass = 82.8 ± 5.6 kg; body height = 184.1 ± 4.6 cm) and 13 elite kayakers (KA: age = 23.8 ± 2.9 y; body mass = 91.0 ± 3.5 kg; body height = 180.1 ± 5.4 cm) were assessed for PR 1RM and PU 1RM. They were then assessed for power produced at 40, 60 and 80% of 1RM in both PR and PU. The area under the load-power curve (AUC) and PR/PU ratios were calculated for both the SW and KA groups. The KA group showed significantly higher PR1RM (+18.2%; p = 0.002) and PU1RM (+25.7%; p < 0.001) compared to the SW group. Significant group differences were also detected for PUAUC (p < 0.001) and for the PR/PU power ratio (p < 0.001). No significant group differences were detected for PRAUC (p = 0.605) and for the PR/PU strength ratio (p = 0.065; 0.87 and 0.82 in SW and KA, respectively). The present findings indicate that elite KA were stronger and more powerful than elite SW in the upper body. Not consistently with other athletic populations, both KA and SW athletes were stronger and more powerful in upper body pull compared to push moves
Potenza propulsiva e potenza frenante. La ricerca di un equilibrio nello stile libero
No full textQuando un atleta nuota a velocità costante le forze propulsive (thrust force = Ft) sono uguali alle forze resistenti (drag force = Fd) ed è possibile scrivere che: Ft – Fd = 0 (Toussaint 1992)
The energy cost of swimming and its determinants
Full text linkThe energy expended to transport the body over a given distance (C, the energy cost) increases with speed both on land and in water. At any given speed, C is lower on land (e.g., running or cycling) than in water (e.g., swimming or kayaking) and this difference can be easily understood when one considers that energy should be expended (among the others) to overcome resistive forces since these, at any given speed, are far larger in water (hydrodynamic resistance, drag) than on land (aerodynamic resistance). Another reason for the differences in C between water and land locomotion is the lower capability to exert useful forces in water than on land (e.g., a lower propelling efficiency in the former case). These two parameters (drag and efficiency) not only can explain the differences in C between land and water locomotion but can also explain the differences in C within a given form of locomotion (swimming at the surface, which is the topic of this review): e.g., differences between strokes or between swimmers of different age, sex, and technical level. In this review, the determinants of C (drag and efficiency, as well as energy expenditure in its aerobic and anaerobic components) will, thus, be described and discussed. In aquatic locomotion it is difficult to obtain quantitative measures of drag and efficiency and only a comprehensive (biophysical) approach could allow to understand which estimates are “reasonable” and which are not. Examples of these calculations are also reported and discussed
L’ergometro di valutazione per il nuoto simulato. La tecnica del nuoto
No full textValutare il nuoto nelle sue componenti energetiche e biomeccaniche è particolarmente complesso; una strategia utilizzata per studiare attività sportive più accuratamente è quella di cercare di riprodurre l’attività stessa all’interno di un laboratorio. Per il nuoto, questo procedimento presenta notevoli vantaggi, perché le limitazioni imposte dall’ambiente acquatico sono tali e tante da richiedere l’uso di strumentazioni molto specifiche, ma una volta portato il nuotatore fuori dall’acqua è difficile simulare correttamente la tecnica che utilizza. Per questo scopo negli anni si è evoluto un tipo particolare di ergometro definito “Swim-Bench” (SB) e in questo breve articolo sono presentati i limiti e le potenzialità di questo strumento per lo studio del nuoto a secco
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