1,720,980 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
The effect of exercise on short-term memory subsystems
No full textDue to the arousal increment, physical exercise has been shown to improve cognitive abilities such as frontal and long-term memory processes. In the present work we aim at understanding whether different types of physical exercise -i.e. team-games, mainly relying on visuo-spatial abilities, and circuits, mainly relying on motor patterns- might specifically modulate different short-term-memory (STM) subsystems. We compared the performances on verbal, visuo-spatial, and motor STM spans in 3 groups of 10-11-years-old children: the control group was tested before and after an Italian class, the second group before and after 40-minutes on a circuit exercise and the third group before and after 40-minutes of team-game. Besides a general incremented performance, a double dissociation emerged: while the circuit improved the motor span, the team-game did the same for the visuo-spatial span However, no effect emerged in the control group. The finding might cast useful insight about how structuring specific training activities for children with learning deficits because it claims the specific positive effects of sport on different cognitive abilities
Sensory Input Modulates Microsaccades during Heading Perception
Full text linkMicrosaccades are small eye movements produced during attempted fixation. During locomotion, the eyes scan the environment; the gaze is not always directed to the focus of expansion of the optic flow field. We sought to investigate whether the microsaccadic activity was modulated by eye position during the view of radial optic flow stimuli, and if the presence or lack of a proprioceptive input signal may influence the microsaccade characteristics during self-motion perception. We recorded the oculomotor activity when subjects were either standing or sitting in front of a screen during the view of optic flow stimuli that simulated specific heading directions with different gaze positions. We recorded five trials of each stimulus. Results showed that microsaccade duration, peak velocity, and rate were significantly modulated by optic flow stimuli and trial sequence. We found that the microsaccade rate increased in each condition from trial 1 to trial 5. Microsaccade peak velocity and duration were significantly different across trials. The analysis of the microsaccade directions showed that the different combinations of optic flow and eye position evoked non-uniform directions of microsaccades in standing condition with mean vectors in the upper-left quadrant of the visual field, uncorrelated with optic flow directions and eye positions. In sitting conditions, all stimuli evoked uniform directions of microsaccades. Present results indicate that the proprioceptive signals when the subjects stand up creates a different input that could alter the eye-movement characteristics during heading perceptions
Il ruolo dell'esercizio fisico intenso sui sottosistemi di memoria a breve termine
No full textIntroduzione
Studi recenti hanno indagato il ruolo dell'esercizio fisico intenso sulle capacità cognitive di adulti e bambini. È stato dimostrato che l’elevato grado di attivazione che ne consegue ha un effetto positivo sia sulle funzioni frontali che sulla memoria a lungo termine. Nel presente studio abbiamo quindi cercato di capire se e come l’esercizio fisico abbia un effetto anche sulla memoria a breve termine (MBT) ed in particolare se due differenti tipologie di esercizio, il gioco di squadra ed il circuito, possano avere un ruolo specifico su sottosistemi di MBT diversi. Il gioco di squadra è stato scelto perché si riteneva si basasse principalmente sulle abilità visuo-spaziali mentre il circuito sulle abilità motorie.
Metodo
3 gruppi di bambini, tra i 10 e gli 11 anni, sono stati testati in compiti di span di MBT verbale, visuo-spaziale e motorio prima e dopo: a) una lezione di Italiano (gruppo di controllo); b) 40 minuti di circuito; c) 40 minuti di gioco di squadra,.
Risultati
I risultati non hanno mostrato alcun incremento nella prestazione dopo la lezione di italiano. Tuttavia, si è trovata una doppia dissociazione con lo span motorio che aumentava dopo il circuito (one-tailed t(20)=2,91,
Diazepam impairs place learning in native but not in maze-experienced rats in the Morris water maze.
No full textAnxiolytic benzodiazepines have been shown to impair place learning in the Morris water maze. However, a clear-cut demonstration of a direct and specific effect on mnemonic processes has not yet been offered. In the present study, the effects of diazepam on place navigation in the Morris water maze were studied in rats. Three conditions were examined: learning, reversal learning and learning after familiarisation of animals with the maze. In view of the anxiolytic and sedative properties of diazepam, appropriate doses of the drug, i.e. those that produced an anxiolytic effect but no major motor impairment, were initially selected in the water-lick conflict and rotarod tests, respectively. Doses of 2.5 and 5 mg/kg PO increased punished drinking in the water-lick conflict test without significantly decreasing rotarod performance. These doses were then used to assess the effects of diazepam on spatial behaviour. Diazepam, at both doses, impaired place learning in behaviourally naive rats. Such an effect appeared to be transient: diazepam-treated rats eventually reached control performance. Moreover, analysis of the probe trial at the end of training revealed adoption of a spatial strategy to locate the submerged platform. Neither reversal learning nor learning after familiarisation was affected. These results do not replicate previous findings in the Morris water maze and provide some evidence that the diazepam-induced place learning deficit may be primarily anxiolytic in nature
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
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
