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SLEEP BEHAVIOUR, ACTIVITY CIRCADIAN RHYTHM AND PSYCHOPHYSIOLOGICAL RESPONSES TO PHYSICAL ACTIVITY: THE CHRONOTYPE EFFECT.
Full text linkIn the past, several studies investigated the circadian rhythm of different physiological variables associated to sport, the time-of-day effects on physical performance and the reciprocal relationship between sleep and physical activity but there is a scarce literature on how the chronotype could influence all these aspects.
Therefore, the purposes of this Ph.D. thesis are: 1) to assess, with the use of actigraphy, the relationship between the three chronotypes and the circadian rhythm of activity levels and to determine whether sleep parameters respond differently with respect to the time (weekdays versus the weekend) in M-types, N-types and E-types; 2) to evaluate whether a linear regression formula using the MEQ score would predict the actigraphy-based acrophase in a young Italian population; 3) to investigate the effects of chronotype on psychophysiological responses (RPE, HR and walking time) to a submaximal self-paced walking task performed in two different times of day (08:30-09:00 vs 15:30-16:30).
The results showed that: 1) the acrophases of the activity levels were significantly different in M- (14:32h), N- (15:42h) and E-types (16:53h) (p<0.001) while MESOR and amplitude were similar among chronotypes; there was also a significant interaction between the chronotype and sleep parameters: Sleep Efficiency of the E-types was poorer than that of the M- and N-types during weekdays (77.9% ± 7.0 versus 84.1% ± 4.9 and 84.1% ± 5.2) (p=0.005) but was similar to that measured in the M- and N-types during the weekend. 2) There was a significant linear relationship between MEQ and the Acrophase thus, enabling us to use the equation of the regression line to obtain predictions. The predictive equation resulted as follows: 1238.7-5.487*MEQ. The precision of the estimates was excellent and the r2 was 0.70, indicating that 70% of the variance in the acrophase was explained by MEQ. 3) It was found a significant interaction between chronotype and time of day. The post hoc analysis showed a significant difference for RPE in the morning session, with E-types reporting higher RPE compared with the M-types (14.33 ± 2.45 vs 12.00 ± 1.66) (p<0.01).
This Ph.D. thesis highlights two key findings: 1) the chronotype influence the activity circadian rhythm and the sleep parameters suggesting that E-types accumulate a sleep deficit during weekdays, due to social and academic commitments and that they recover from this deficit during “free days” on the weekend; 2) the chronotype and the time of day when a physical task in undertaken can influence the RPE response
Star excursion balance test performance varies between elite and non-professional female volleyball players: a comparative study
No full textPossono i ritmi biologici e il cronotipo influenzare la risposta all’attività fisica?
No full textPer gli atleti d’élite, ma anche per quelli amatoriali, risulta sempre più necessario scegliere con accuratezza l’orario migliore per svolgere gli allenamenti per raggiungere la migliore performance e di conseguenza i migliori risultati; qual è quindi l’ora ideale per svolgere le sedute? La risposta è molto complicata poiché bisogna tenere in considerazione e avere un’ottima conoscenza dell’andamento dei ritmi biologici che regolano le variabili fisiologiche relative allo sport (frequenza cardiaca, consumo d’ossigeno, forza muscolare, tempo di reazione...) e dei diversi cronotipi. Le persone mostrano una diversa propensione a essere mattutini (“allodole”) o serotini (“gufi”). Il cronotipo influenza l’espressione dei ritmi fisiologici, modifica la risposta agli stimoli allenanti e influenza la performance fisica in diversi orari della giornata; un soggetto mattutino è favorito in competizioni che si svolgono di mattina ,mentre un soggetto serotino potrebbe essere svantaggiato. Quindi, è fondamentale determinare il cronotipo degli atleti
Influence of Chronotype on Responses To Physical Activity in the Morning vs. Evening
No full textIntroduction: General knowledge of “time of day” effects on exercise might not be enough, since everyone can have a different circadian propensity (chronotype) based on their position on a Morningness-Eveningness Scale (ranges from a morning-type = M-type to evening-type = E-type, or neither-type = N-type) (3). In this project we studied the response to the same physical activity performed in the morning and evening by different chronotypes. Methods: Each of 22 subjects (12 males and 10 females, age: 23.2 ± 3.6, BMI: 22.45 ± 2.7) filled out the Horne-Ostberg Morningness-Eveningness Questionnaire (MEQ) and the results have been compared to the Morningness-Eveningness Scale to determine their chronotype (3). They then performed, at their own voluntary speed, a
walking session, consisting of three repetitions uphill and downhill, first in the late afternoon at 16:30h and then the next morning at 8:30h. The performance time was recorded by an EKT-orienteering system. Each subject wore a HR monitor (PolarTeam 2) to record their HR during each entire walking session and reported their perceived exertion (Borg scale 6-20) upon completion (1). Results: MEQ= 14 N-types, 4 E-types and 4 M-types. Results from one M-type, one E-type and two N-types (as controls) are discussed in detail for the case-study. The M-type walked faster in the morning than in the late afternoon, but showed no difference in HR response. Conversely, the E-type walked faster in the evening than in the morning, with similar HR in both sessions. The N-types showed increased HR when performance time decreased. Conclusion: This case-study showed that response to physical activity can be influenced by chronotype, in agreement with other reports in the literature (2),(4). While a follow-up study with more subjects is necessary, the results suggest that when trying to increase the health and well-being in the population, it would be advisable to arrange physical activity classes both in the morning and in the evening, and have the public join the classes according to their chronotype to achieve the most benefit. References 1. Borg, G. A. (1982). Psychophysical bases of percieved exertion. Medicine and Science In Sports and Exercise, 14(5), 377-381 2. Brown, F. M., Neft, E. E., & LaJambe, C. M. (2008). Collegiate rowing crew performance varies by morningness-eveningness. J Strength Cond Res, 22(6), 1894-1900 3. Horne, J. A., & Ostberg, O. (1976). A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms. Int J Chronobiol, 4(2), 97-110 4. Sugawara, J., Hamada, Y., Nishijima, T., & Matsuda, M. (2001). Diurnal variations of post-exercise parasympathetic nervous reactivation in different chronotypes. Jpn Heart J, 42(2), 163-17
The chronotype can influence the perceived exertion during self-paced exercise performed at different times of day
No full textAim: Individual differences can influence circadian rhythms, resulting in a person’s preference for morning or evening activities. The aim of this study was to analyze the psychophysiological responses during morning (M) (0830 hours) and afternoon (A) (1530 hours) self-paced walking session in different chronotypes.
Method: Forty-six college students (24.81 ± 7.18 years) filled in the Morningness–Eveningness Questionnaire (MEQ) to determine their chronotype. In order to evaluate the psychophysiological responses during the walking sessions (1530 m long, uphill altitude gap 127.5 m and downhill altitude gap 85 m) at different times of day, the heart rate (HR) and the walking times were recorded; moreover, the subjects reported their rate of perceived exertion (RPE) using Borg’s scale at completion of the every walking session.
Results: The results showed that both M-types and E-types tended to walk slower during the M session, while presenting opposite trend in HR and RPE; M-types, as expected, had higher HR and lower RPE, while, E-types had lower HR and higher RPE during the morning session. Based on the multivariate analysis of covariance (MANCOVA) we found an effect for the individual chronotype (as an ordinal covariate) on HR mean, RPE and walking speed parameters (p = .05). A post hoc analysis showed a significant difference (p = .02; Cohen’s d = -1.21) between M-types vs. E-types for RPE in the morning, while no differences were found in the afternoon.
Conclusion: This study draws attention to the possibility that psychophysiological responses to physical activity can be influenced by individual chronotype. The subjects had lower perceived exertion in accordance with their chronotype. Knowledge of chronotypes could be important when prescribing physical exercise with the aim to increase the health and well-being in the population.
References
Adan A (1994) Chronotype and personality factors in the daily consumption of alcohol and psychostimulants. Addiction 89:455–462 Borg GA (1982) Psychophysical bases of perceived exertion. Med Sci Sports Exerc 14:377–38 Horne H, Ostberg O (1976) A self-assessment questionnaire to determine morningness–eveningness in human circadian rhythms. Int J Chronobiol 4:97–11
Il football americano : il modello fisiologico, le differenze tra ruoli ed il confronto tra Italia e USA
No full textIl football Americano è uno degli sport più popolari e competitivi negli U.S.A. ed in Canada e la partecipazione a questa attività richiede eccezionali abilità fisiche ed atletiche. Diversi autori negli ultimi 30 anni hanno cercato di descrivere le caratteristiche fisiche dei giocatori di football (Bosch TA et al., 2014; Dengel DR et al., 2013) ed è stato documentato che altezza, peso e composizione corporea sono estremamente diversi tra giocatori di football americano di una stessa squadra e questo è dovuto alla richiesta di differenti abilità atletiche specifiche dei diversi ruoli (Kraemer WJ et al., 2005). E’ importante anche sottolineare come, con il passare degli anni ed il conseguente aumento dei programmi di conditioning, i giocatori di football abbiamo incrementato in generale massa corporea, forza, velocità e potenza (Robbins DW et al., 2013; Secora CA et al., 2004). Negli USA è comune che gli strength and conditioning coaches programmino i loro allenamenti raggruppando i giocatori per ruolo in modo da lavorare specificatamente possibile sullo sviluppo delle caratteristiche atletiche richieste. Solitamente i giocatori vengono raggruppati in 3 diversi gruppi: 1) Skill players (SP) che includono i wide receivers, cornebacks, safeties e running backs; 2) Big Skill players (BSP) che comprendono i fullbacks, linebackers, tight ends, and defensive ends; 3) Lineman (LM) che includono i centers, offensive guards e i defensive/offensive tackles (Sierer SP et al., 2008). Negli USA inoltre c’è una forte selezione di giocatori di football americano ed esiste un evento in cui i giovani giocatori vengono sottoposti ad una serie di test fisici e psicologici in modo che gli scout ed i coaches possano valutare il reale potenziale di questi giocatori, questo sistema prende il nome di “NFL Scouting Combine”. Nelle ultime decadi anche in Europa il football americano ha iniziato ad espandersi ed in Italia il picco di questo sport è stato raggiunto negli anni ’80 quando il football ha fatto registrare il maggior numero di tesserati dopo il calcio. Tutt’ora esiste una Federazione Italiana (FIDAF) affiliata agli organi di football europei e l’Italian Football League (IFL) è il maggior campionato italiano per questo sport. Questo articolo vuole evidenziare le differenze antropometriche ed atletiche riscontrabili tra i diversi ruoli di giocatori di football in America e, soprattutto, confrontare tali caratteristiche con i giocatori italiani per mettere in evidenza il differente livello tra le leghe NFL ed IFL. Informare gli addetti ai lavori del football americano in Italia è il primo importante step per cercare di trovare soluzioni utili a migliorare le caratteristiche fisiche ad atletiche dei giocatori con lo scopo di ridurre gradualmente il gap attualmente esistente tra Italia ed America
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
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