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L'effetto sincronizzante dell'esercizio fisico : un percorso di ricerca
No full textThe synchronizing effects of the physical exercise: a research path. Three studies, concerning influences of the time of training on the circadian structure in humans, are presented. Goals of the researches are: to define how the time of training modifies the circadian structure; to evaluate if is possible face diseases related with biological rhythms disorders thanks to the training; to define guide lines for athletes, trainers and specialists. The works: STUDY 1) Influences of the time of training on the HR circadian rhythm; STUDY 2) reduction of the Jet Lag symptoms pre-adjusting the circadian structure by a training plan before an eastward trans-meridian flight; STUDY 3) synchronization state and effects of the training on the sleep and the circadian structure in lack of daylight conditions above the Artic Circle in north of Norway. The studies indicate it is possible to asses that the time of training influences the circadian structure, in particular an evening training induces a delay (3 hours in average) of the Acrophases of several Marker Rhythms (like HR and Activity Levels). This phenomenon can be used to induce a pre-adjustment of the circadian structure before an east-ward flight to prevent or reduce the symptoms of the Jet Lag syndrome, thanks to a reduction of the phase shift. It also seems that a regular morning training can reduce the psycho-physical symptoms that the people who live into the Circumpolar Circle commonly experience during the winter months, increasing the activity levels and improving the sleep quality
Influence of chronotype on responses to a standardized, self-paced walking task in the morning vs afternoon : a pilot study
No full textThe response to sub-maximal physical activity performed in the morning and late afternoon by individuals with different chronotypes was investigated. 22 participants filled out the Morningness-Eveningness Questionnaire and underwent a self-paced walking task that consisted of walking from the top to the bottom of a hill and back three times (1,836 meters, with a slope of 14.16%). The task was repeated twice: late afternoon (16:30) and early morning (08:30). Walking speed (time for completion in seconds), heart rate, and perceived exertion were measured during each task, with overall results given as a general descriptive analysis. Preliminary findings suggest that chronotype is likely to influence the responses to exercise, mostly with evening-types seeming at a disadvantage when performing a physical task in the morning. Individuals can be classified by circadian typology or chronotype, which is the propensity to be a morning-type, evening-type, or neither-type. The circadian typology, commonly referred to as being a morning person or an evening person or somewhere in between, is involved not only in the expression of physiological rhythms, but also in habits and lifestyles, such as sleeping patterns (Park, Matsumoto, Seo, & Shinkoda, 1999) that emerge especially during adolescence (Park, Matsumoto, Seo, Kang, & Nagashima, 2002) and remain throughout adult life (Koukkari & Sothern, 2006)
Methodological issues for studyng the rest-activity cycle and sleep disturbances : a chronobiological approach using actigraphy data
No full textShift work schedules, intensive physical exercise late in the day, psychological stress, or a busy lifestyle might induce disorders of the circadian structure, which can affect health on both the physiological and neurobehavioral levels. Rest-activity rhythm is strongly connected with an organism's circadian structure, and irregular sleep-wake patterns can lead to a disruption of entrainment, resulting in physiological and neurobehavioral dysfunction. Shift nurses are often subject to disturbances in the quality and duration of their sleep, raising the possibility of negative impacts on their health and their patients' safety. Researchers have used actigraphy in a number of studies to assess sleep patterns. Because of the close connection between sleep and circadian structure, it may be useful to extend the evaluation of actigraphy data to the analysis of the rest-activity rhythm with rhythmometric procedures to provide a better understanding of possible sleep disorders in relation to entrainment. Actigraphy is an easy and reliable way to study these rhythms and identify possible circadian-rhythm disorders. In this article, the authors discuss methodological issues concerning the evaluation of the rest-activity rhythm, with a focus on actigraphy
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
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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