Biological rhythms, chronodisruption and chrono-enhancement: The role of physical activity as synchronizer in correcting steroids circadian rhythm in metabolic dysfunctions and cancer

This is an Accepted Manuscript of an article published by Taylor & Francis in Chronobiology International on 28 June 2018, available online: http://www.tandfonline.com/10.1080/07420528.2018.1475395.Rhythms can be observed at all levels of the biologic integration in humans. The observation that a biological or physiological variable shows a circadian rhythm can be explained by several multifactorial systems including external (exogenous), internal (endogenous) and psychobiological (lifestyle) mechanisms. Our body clock can be synchronized with the environment by external factors, called “synchronizers”, i.e. the light–dark cycle, but it is also negatively influenced by some pathological conditions or factors, called “chronodisruptors,” i.e. aging or low physical activity (PA). The desynchronization of a 24-h rhythm in a chronic manner has been recently defined “chronodisruption” or “circadian disruption.” A very large number of hormonal variables, such as adrenal and gonadal stress steroids, are governed by circadian rhythmicity. Such hormones, in normal conditions, show a peak in the first part of the day, while their typical diurnal fluctuations are totally out of sync in subjects affected by cancer or metabolic diseases, such as obesity, diabetes and metabolic syndrome. In general, a flatter slope with altered peaks in cortisol and testosterone circadian rhythms has been observed in pathological individuals. PA, specifically chronic exercise, seems to play a key role as synchronizer for the whole circadian system in such pathologies even if specific data on steroids circadian pattern are still sparse and contradictory. Recently, it has been proposed that low-intensity chronic PA could be an effective intervention to decrease morning cortisol levels in pathological subjects. The standardization of all confounding factors is needed to reach more clear evidence-based results

Green exercise as a workplace intervention to reduce job stress: results from a pilot study

Stress and mental fatigue are major health threats to employees in office-based occupations. Physical activity is widely used as a stress-management intervention for employees. Moreover, experiences in contact with nature have been shown to provide stress-reduction and restoration from mental fatigue. OBJECTIVES:In a pilot study designed as a randomized controlled trial we investigated the impact of a green-exercise intervention on psychological and physiological indicators of stress in municipality employees. METHODS:Fourteen employees (7 females and 7 males, 49±8 yrs) volunteered in an exercise-based intervention in workplace either outdoors in a green/nature area or in an indoor exercise-setting. The intervention consisted of an information meeting and two exercise sessions, each including a biking bout and a circuit-strength sequence using elastic rubber bands (45-minutes, at about 55% of HR reserve, overall). Main outcomes were perceived environmental potential for restoration, affective state, blood pressure (BP) and cortisol awakening response (CAR AUCG and CAR AUCI) and cortisol levels in serum. Measurements were taken at baseline and in concomitance with the exercise sessions. Furthermore, affective state and self-reported physical activity levels were measured over a 10-weeks follow-up period. RESULTS:Compared with the indoor group, the nature group reported higher environmental potential for restoration (p <  0.001) and Positive Affect (p <  0.01), along with improved CAR AUCI (p = 0.04) and, marginally, diastolic BP (p = 0.05). The nature group also reported higher ratings of Positive Affect at follow-up (p = 0.02). Differences at post-exercise were not found for any of the other components of affective state, systolic BP, CAR AUCG and cortisol levels measured in serum. CONCLUSIONS:Green-exercise at the workplace could be a profitable way to manage stress and induce restoration among employees. Further studies on larger samples are needed in order to improve the generalizability of the results

Green exercise as a workplace intervention to reduce job stress: results from a pilot study

Stress and mental fatigue are major health threats to employees in office-based occupations. Physical activity is widely used as a stress-management intervention for employees. Moreover, experiences in contact with nature have been shown to provide stress-reduction and restoration from mental fatigue. OBJECTIVES:In a pilot study designed as a randomized controlled trial we investigated the impact of a green-exercise intervention on psychological and physiological indicators of stress in municipality employees. METHODS:Fourteen employees (7 females and 7 males, 49±8 yrs) volunteered in an exercise-based intervention in workplace either outdoors in a green/nature area or in an indoor exercise-setting. The intervention consisted of an information meeting and two exercise sessions, each including a biking bout and a circuit-strength sequence using elastic rubber bands (45-minutes, at about 55% of HR reserve, overall). Main outcomes were perceived environmental potential for restoration, affective state, blood pressure (BP) and cortisol awakening response (CAR AUCG and CAR AUCI) and cortisol levels in serum. Measurements were taken at baseline and in concomitance with the exercise sessions. Furthermore, affective state and self-reported physical activity levels were measured over a 10-weeks follow-up period. RESULTS:Compared with the indoor group, the nature group reported higher environmental potential for restoration (p <  0.001) and Positive Affect (p <  0.01), along with improved CAR AUCI (p = 0.04) and, marginally, diastolic BP (p = 0.05). The nature group also reported higher ratings of Positive Affect at follow-up (p = 0.02). Differences at post-exercise were not found for any of the other components of affective state, systolic BP, CAR AUCG and cortisol levels measured in serum. CONCLUSIONS:Green-exercise at the workplace could be a profitable way to manage stress and induce restoration among employees. Further studies on larger samples are needed in order to improve the generalizability of the results

TRAINING EFFCT DURING THE MIDNIGHTSUN PERIOD IN DIFFERENT CHRONOTYPES

Our research takes place at 70oN. Where the sun is above the horizon for 8 weeks during summer, midnight sun and below the horizon for 8 weeks during winter, polar night. Earlier we found that adults with different chronotypes responded differently to exercise performed in day-light or darkness1. During the polar night evening (E) and neither (N) -types respond to training better than morning (M) –types2. This study reports the effect of training during the midnight sun period in individuals with different chronotypes

Evening melatonin in January after changes in hours of habitual exercise during fall among youths living in the subarctic.

Secretion of the hormone melatonin shows a circadian rhythm and is inhibited by light. Light therapy with phase shifting of the melatonin rhythm has been used as treatment of sleeping problems and seasonal affective disorders (SAD). Exercise has also been shown to suppress the melatonin secretion. In order to investigate the effect of increased level of habitual physical activity upon melatonin secretion in areas with extreme short days and high level of midwinter insomnia, 18 high school students participated in this study. Their habitual physical activity throughout two consecutive falls were recorded. The following January, blood samples were taken for melatonin analyses from 1530h to 2300h. After the fall with highest habitual activity level, the plasma melatonin showed significantly decreased values at all sampling times compared to values after lowest level of activity. The relative increase in melatonin level at 2300h, however, tended to be of a greater magnitude after the fall with highest activity cornpared to the fall with Iowest activity (p=.094). A change in habitual level of activity should be thought of as a possible help for treating midwinter insomnia and SAD

Health challenges in long-distance dog sled racing: A systematic review of literature

Long-distance dog sled races, e.g. Iditarod (Alaska) and Finnmarksløpet (Northern Norway), are extremely demanding sporting events that might expose mushers, handlers and a large number of organisers and volunteers to risks for their health. The purpose of this systematic literature review (PROSPERO registration n. CRD42017069136) was to identify and summarise all available scientific literature relative to health issues connected to participating in these races. Using a literature search strategy in line with PRISMA guidelines, 117 scientific studies, sought through databases (Google Scholar and PubMed, between 2nd and 9th May 2017) and scrutiny of reference lists, were screened. Studies published in English treating any health issues assessed during or after a long-distance dog sled race were included, with no restriction in relation to their study design or the characteristics of participants studied. The quality of the studies was assessed using a standardised checklist. Ten studies met the criteria for being included in a qualitative analysis. The data synthesis showed that participants underwent strenuous psychophysical load, with insufficient sleep/rest and inadequate energy intake. Findings on hydrations are mixed. The risk of incurring in life-threatening injuries or infections was low, although injuries and infections of minor severity were common. No alterations of blood markers were observed from before to after the races. These findings will help planning prevention and treatment strategies in long-distance dog sled races. However, more research is needed in this field in the future

Barn og fysisk aktivitet i barnehagen: Hvordan kan aktivitetsnivået dokumenteres?

Vi målte det fysiske aktivitetsnivået til 42 barn i løpet av en vanlig dag i barnehagen ved hjelp av ulike instrumenter. Denne studien vil gi kunnskap om barns fysiske aktivitet i barnehagen, og om barnas aktivitetsnivå kan bli tilstrekkelig evaluert av lærerne eller om det er behov for tekniske målinger. Videre har vi sammenlignet de ulike instrumentene brukt i observasjonen. De ansatte i barnehagen ble bedt om å svare på et spørreskjema om barns fysiske aktivitetsnivå i løpet av dagen, og en student eller forsker observerte og registrerte ett barn hver. I løpet av samme dag, ble aktivitetsnivået overvåkt ved hjelp av actigraphy (AC; Actigraf GT3X) og kontinuerlig pulsmåling (HR, Team2 Polar ®) blant 14 barn (seks gutter og åtte jenter, 38- og 47-måneder gamle, henholdsvis). Forsker-observasjonene definerte de observerte barna som "moderat aktiv", og AC-data viste at alle barna hadde mer enn 60 minutter aktivitet med moderat eller høy intensitet. Våre sammenligninger viser at bruk av HR for å vurdere aktiviteten i barnehager er ikke anbefalt. I gjennomsnitt rapporterte spørreskjemaene lignende aktivitetsverdier for det samme barnet, selv om evalueringene varierte mellom ansatte. Når man sammenlignet et aktivt og et inaktivt barn, viste de ulike metodene lignende resultater. Vi konkluderer derfor at ansattes faglige blikk kan se barns fysiske aktivitetsnivå når de blir bedt om å vurdere de

Chronotype, Physical Activity, and Sport Performance: A Systematic Review

Background: Many variables related to sport have been shown to have circadian rhythms. Chronotype is the expression of circadian rhythmicity in an individual, and three categories of chronotype are defined: morning types (M-types), evening types (E-types), and neither types (N-types). M-types show earlier peaks of several psychophysiological variables during the day than E-types. The effect of chronotype on athletic performance has not been extensively investigated. Objective: The objective of the present review was to study the effect of chronotype on athletic performance and the psychophysiological responses to physical activity. Methods: The present review adheres to the PRISMA (Preferred Reporting Items for Systematic Reviews and MetaAnalyses) reporting guidelines. We searched PubMed, Scopus, and Web of Science for scientific papers using the keywords ‘‘chronotype’’, ‘‘circadian typology’’, ‘‘morningness’’, and ‘‘eveningness’’ in combination with each of the words ‘‘sport’’, ‘‘performance’’, and ‘‘athletic.’’ Relevant reference lists were inspected. We limited the search results to peerreviewed papers published in English from 1985 to 2015. Results: Ten papers met our inclusion criteria. Rating of perceived exertion and fatigue scores in relation to athletic performances are influenced by chronotype: M-types perceived less effort when performing a submaximal physical task in the morning than did N- and E-types. In addition, M-types generally showed better athletic performances, as measured by race times, in the morning than did N- and E-types. Other results concerning chronotype effect on physiological responses to physical activity were not always consistent: heterogeneous samples and different kinds of physical activity could partially explain these discrepancies. Conclusions: Sports trainers and coaches should take into account the influence of both the time of day and chronotype effect when scheduling training sessions into specific time periods