Daytime rest and short sleep, and what they do to performance and mood.
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276 to 300 of 645The emerging and evolving evidence supporting creatine as an ergogenic aid: history and applications.
Background: Creatine is one of the most extensively studied ergogenic aids, with over three decades of research supporting its role in exercise performance, recovery, and health.
Methods: This narrative review summarizes the historical development of creatine supplementation and evaluates evidence regarding its mechanisms, efficacy across active, athletic populations (e.g. strength, endurance, team-sport), and tactical (e.g. military, law enforcement) populations, and its safety profile.
Results: The evidence suggests that creatine enhances phosphocreatine resynthesis and cellular energy availability, resulting in consistent improvements in high-intensity exercise performance, training adaptations, lean body mass, strength, and power. Additional findings indicate that creatine may attenuate exercise-induced muscle damage and inflammation, support recovery, and improve functional outcomes…
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How Shift Work Affects Our Gut Microbiota: Impact on Gastrointestinal Diseases.
Background and Objectives: Shift work and night work are common among emergency physicians. It is necessary to provide continuous care to patients, especially with acute diseases, including throughout the night. Literature studies show that shift and night workers have an altered light exposure, timing of sleep and intake of food. The consequence of this desynchronization with the biological clock can lead these workers to be more exposed to developing some acute and chronic health conditions. In particular, the alteration of the sleep-wake cycle, fatigue, the shortened sleep duration and the misalignment of the body's hormone production is a codified risk factor of gut dysbiosis that can lead to acute and chronic diseases, also gastrointestinal ones. the aim of this narrative review is to collect and summarize evidence about the association between the disruption of the circadian rhythm…
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Excessive sleepiness in shift work disorder: a narrative review of the last 5 years.
Introduction: Shift work sleep disorder (SWSD), also known as shift work disorder (SWD), is a circadian rhythm sleep disorder characterized by insomnia and/or excessive sleepiness, associated with a recurring work schedule that overlaps the usual time designated for sleeping.
Purpose: This article aims to provide a narrative review of the pharmacological trials conducted on SWD in the last 5 years, to better address safety and health issues inherent to this disorder.
Methods: An electronic literature search was conducted using PubMed. All eligible randomized controlled trials (RCTs) and cross-over RCTs with employees undertaking shift work (including night shifts) were considered, yielding three articles.
Results: All three studies showed the efficacy of armodafinil in improving subjective and objective sleepiness, clinical conditions, and global functioning regardless of shift duration.…
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Jäger R, Mohr AE, Carpenter KC, Kerksick CM, Purpura M, Moussa A, Townsend JR, Lamprecht M, West NP, Black K, Gleeson M, Pyne DB, Wells SD, Arent SM, Smith-Ryan AE, Kreider RB, Campbell BI, Bannock L, Scheiman J, Wissent CJ, Pane M, Kalman DS, Pugh JN, Ter Haar JA, Antonio J (2019)reviewMEDLINE-indexed journal, not yet read by usJournal of the International Society of Sports Nutrition165 citations International Society of Sports Nutrition Position Stand: Probiotics.
Position statement: The International Society of Sports Nutrition (ISSN) provides an objective and critical review of the mechanisms and use of probiotic supplementation to optimize the health, performance, and recovery of athletes. Based on the current available literature, the conclusions of the ISSN are as follows: 1)Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host (FAO/WHO).2)Probiotic administration has been linked to a multitude of health benefits, with gut and immune health being the most researched applications.3)Despite the existence of shared, core mechanisms for probiotic function, health benefits of probiotics are strain- and dose-dependent.4)Athletes have varying gut microbiota compositions that appear to reflect the activity level of the host in comparison to sedentary people, with the differences linked pri…
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Working Time Society consensus statements: Evidence-based effects of shift work and non-standard working hours on workers, family and community.
Working time arrangements that require shift work or other non-standard working hours have significant potential to encroach on time that is highly valued for family, social and leisure activity. This can often result in workers experiencing poorer work-family or work-life balance. Based on an extensive literature search and expert knowledge, primary risk factors were identified including shift work; long, irregular and unpredictable working hours; and work on evenings and weekends (in combination and independent of shift work). On the other hand, flexibility, in the form of adequate worker control over work schedules, may be a protective factor. In addition, workers experiencing excessive work-life conflict are likely to reduce their working hours, reflecting a reciprocal relationship between working hours and work-life balance. Workers' families are also affected by shift work and non-…
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Levy E, Chu T (2019)reviewMEDLINE-indexed journal, not yet read by usCurrent sports medicine reports17 citations Intermittent Fasting and Its Effects on Athletic Performance: A Review.
Intermittent fasting (IFast) has been around for most of human history, and its proposed health benefits have been mentioned in ancient civilizations. However, recently, there has been a renewed public interest in IFast. Given the importance of nutrition in optimizing athletic performance, there is a concern about the effects of IFast on athletics. Most of the studies looking at performance and fasting are regarding athletes who observe Ramadan. Looking at high-intensity, endurance, and resistance exercises, studies have been varied but are uniform in showing that there is no benefit to athletic performance while fasting. More long-term studies need to be done to evaluate specific fasting protocols during sport.
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Sleep-wake control and the thalamus.
Sleep is an essential component of animal behavior, controlled by both circadian and homeostatic processes. Typical brain oscillations for sleep and wake states are distinctive and reflect recurrent activity amongst neural circuits spanning localized to global brain regions. Since the original discovery of hypothalamic centers controlling both sleep and wakefulness, current views now implicate networks of neuronal and non-neuronal cells distributed brain-wide. Yet the mechanisms of sleep-wake control remain unclear. In light of recent studies, here we review experimental evidence from lesional, correlational, pharmacological and genetics studies, which support a role for the thalamus in several aspects of sleep-wake states. How these thalamo-cortical network mechanisms contribute to other executive functions such as memory consolidation and cognition, remains an open question with direct…
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2016 update on eating disorders in athletes: A comprehensive narrative review with a focus on clinical assessment and management.
Eating disorders, such as anorexia nervosa and bulimia nervosa, can have devastating effects on both the health and performance of athletes. Compared to non-athletes, both female and male athletes are at higher risk of developing an eating disorder. This is especially true for athletes participating in sports where low body weight or leanness confers a competitive advantage. Screening for disordered eating behaviours, eating disorders and for related health consequences should be a standard component of preparticipation examinations, and team physicians should be knowledgeable of the updated diagnostic criteria for eating disorders in the Diagnostic and Statistical Manual-V. Athletes with eating disorders should undergo thorough evaluation and treatment by an experienced multidisciplinary team. Team physicians play a critical role in decision-making on clearance for participation and ret…
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Effects of Intermittent Fasting, Caloric Restriction, and Ramadan Intermittent Fasting on Cognitive Performance at Rest and During Exercise in Adults.
The aim of this review was to highlight the potent effects of intermittent fasting on the cognitive performance of athletes at rest and during exercise. Exercise interacts with dietary factors and has a positive effect on brain functioning. Furthermore, physical activity and exercise can favorably influence brain plasticity. Mounting evidence indicates that exercise, in combination with diet, affects the management of energy metabolism and synaptic plasticity by affecting molecular mechanisms through brain-derived neurotrophic factor, an essential neurotrophin that acts at the interface of metabolism and plasticity. The literature has also shown that certain aspects of physical performance and mental health, such as coping and decision-making strategies, can be negatively affected by daylight fasting. However, there are several types of intermittent fasting. These include caloric restric…
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Implications of gamma band activity in the pedunculopontine nucleus.
The fact that the pedunculopontine nucleus (PPN) is part of the reticular activating system places it in a unique position to modulate sensory input and fight-or-flight responses. Arousing stimuli simultaneously activate ascending projections of the PPN to the intralaminar thalamus to trigger cortical high-frequency activity and arousal, as well as descending projections to reticulospinal systems to alter posture and locomotion. As such, the PPN has become a target for deep brain stimulation for the treatment of Parkinson's disease, modulating gait, posture, and higher functions. This article describes the latest discoveries on PPN physiology and the role of the PPN in a number of disorders. It has now been determined that high-frequency activity during waking and REM sleep is controlled by two different intracellular pathways and two calcium channels in PPN cells. Moreover, there are th…
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Work Stress as a Risk Factor for Cardiovascular Disease.
The role of psychosocial work stress as a risk factor for chronic disease has been the subject of considerable debate. Many researchers argue in support of a causal connection while others remain skeptical and have argued that the effect on specific health conditions is either negligible or confounded. This review of evidence from over 600,000 men and women from 27 cohort studies in Europe, the USA and Japan suggests that work stressors, such as job strain and long working hours, are associated with a moderately elevated risk of incident coronary heart disease and stroke. The excess risk for exposed individuals is 10-40 % compared with those free of such stressors. Differences between men and women, younger versus older employees and workers from different socioeconomic backgrounds appear to be small, indicating that the association is robust. Meta-analyses of a wider range of health out…
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Training adaptation and heart rate variability in elite endurance athletes: opening the door to effective monitoring.
The measurement of heart rate variability (HRV) is often considered a convenient non-invasive assessment tool for monitoring individual adaptation to training. Decreases and increases in vagal-derived indices of HRV have been suggested to indicate negative and positive adaptations, respectively, to endurance training regimens. However, much of the research in this area has involved recreational and well-trained athletes, with the small number of studies conducted in elite athletes revealing equivocal outcomes. For example, in elite athletes, studies have revealed both increases and decreases in HRV to be associated with negative adaptation. Additionally, signs of positive adaptation, such as increases in cardiorespiratory fitness, have been observed with atypical concomitant decreases in HRV. As such, practical ways by which HRV can be used to monitor training status in elites are yet to…
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Neuroscience of exercise: from neurobiology mechanisms to mental health.
The neuroscience of exercise is a growing research area that is dedicated to furthering our understanding of the effects that exercise has on mental health and athletic performance. The present study examined three specific topics: (1) the relationship between exercise and mental disorders (e.g. major depressive disorder, dementia and Parkinson's disease), (2) the effects of exercise on the mood and mental health of athletes, and (3) the possible neurobiological mechanisms that mediate the effects of exercise. Positive responses to regular physical exercise, such as enhanced functional capacity, increased autonomy and improved self-esteem, are frequently described in the recent literature, and these responses are all good reasons for recommending regular exercise. In addition, physical exercise may improve both mood and adherence to an exercise program in healthy individuals and might mo…
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Oxytocin and the biopsychology of performance in team sports.
Little is known about the biopsychological underpinnings of expert performance in team sports. In this paper we show that there is a vast support for oxytocin as a neuropeptide involved in the encouragement of important processes linked to greater team performance in sport. We argue that oxytocin is related to biopsychological processes aimed at convergence of emotions and moods between people, and in doing so it is a critical neuropeptide involved in the shaping of important team processes in sport such as trust, generosity, altruism, cohesion, cooperation, and social motivation, and also envy and gloating. Future research should examine the role of oxytocin in these essential components of sport performance. In particular, the link between oxytocin, emotional contagion and the cultivation of experiences of positive emotions is a worthwhile line of investigation for sport participation …
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Zimmerman FH (2012)reviewMEDLINE-indexed journal, not yet read by usCardiology in review141 citations Cardiovascular disease and risk factors in law enforcement personnel: a comprehensive review.
Law enforcement is a high-stress occupation that is prone to increasing the prevalence and incidence of cardiovascular disease. Epidemiological studies suggest that police officers and related public safety personnel have an increased risk of cardiovascular morbidity and mortality. Currently employed police personnel have a high prevalence of traditional risk factors, including hypertension, hyperlipidemia, metabolic syndrome, cigarette smoking, and a sedentary lifestyle. Obesity may be more common in police officers compared with civilians, whereas diabetes is present less frequently. Law enforcement personnel are also exposed to occupation-specific risk factors that include sudden physical exertion, acute and chronic psychological stress, shift work, and noise. Workplace programs to promote the health and fitness of police officers are commonly lacking, but can be an effective means fo…
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Noradrenergic modulation of wakefulness/arousal.
The locus coeruleus-noradrenergic system supplies norepinephrine throughout the central nervous system. State-dependent neuronal discharge activity of locus coeruleus noradrenergic neurons has long-suggested a role of this system in the induction of an alert waking state. Work over the past two decades provides unambiguous evidence that the locus coeruleus, and likely other noradrenergic nuclei, exert potent wake-promoting actions via an activation of noradrenergic β- and α₁-receptors located within multiple subcortical structures, including the general regions of the medial septal area, the medial preoptic area and, most recently, the lateral hypothalamus. Conversely, global blockade of β- and α₁-receptors or suppression of norepinephrine release results in profound sedation. The wake-promoting action of central noradrenergic neurotransmission has clinical implications for treatment of …
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The use of chronobiotics in the resynchronization of the sleep/wake cycle. Therapeutical application in the early phases of Alzheimer's disease.
Treatment of circadian rhythm disorders, whether precipitated by intrinsic factors (e.g., sleep disorders, blindness, mental disorders, aging) or by extrinsic factors (e.g., shift work, jet-lag) has led to the development of a new type of agents called "chronobiotics". The term "chronobiotic" defines a substance displaying the therapeutic activity of shifting the phase or increasing the amplitude of the circadian rhythms. The prototype of this therapeutic group is melatonin, whose administration synchronizes the sleep-wake cycle in blind people and in individuals suffering from circadian rhythm sleep disorders, like delayed sleep phase syndrome, jet lag or shift-work. Daily melatonin production decreases with age, and in several pathologies, attaining its lowest values in Alzheimer's disease (AD) patients. About half of dementia patients have severe disruptions in their sleep-wakefulness…
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Thorpy M (2011)reviewMEDLINE-indexed journal, not yet read by usPostgraduate medicine15 citations Understanding and diagnosing shift work disorder.
A significant proportion of the workforce in industrialized countries (16%) are employed as shift workers. These workers may be susceptible to shift work disorder (SWD), a circadian rhythm sleep disorder, particularly those who work at night or on early-morning shifts. Shift work disorder remains an underdiagnosed and undertreated problem among this population. Patients with SWD have difficulty initiating sleep and waking up. Often, these patients have excessive sleepiness during their work shift. Shift work disorder has been associated with decreased productivity, impaired safety, diminished quality of life, and adverse effects on health. Several tools have been validated to assess excessive daytime sleepiness and are often used to assess excessive nighttime sleepiness, such as that experienced in patients with SWD, including the Epworth Sleepiness Scale and the Multiple Sleep Latency T…
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Hippocampal ripples and memory consolidation.
During slow wave sleep and quiet wakefulness, the hippocampus generates high frequency field oscillations (ripples) during which pyramidal neurons replay previous waking activity in a temporally compressed manner. As a result, reactivated firing patterns occur within shorter time windows propitious for synaptic plasticity within the hippocampal network and in downstream neocortical structures. This is consistent with the long-held view that ripples participate in strengthening and reorganizing memory traces, possibly by mediating information transfer to neocortical areas. Recent studies have confirmed that ripples and associated neuronal reactivations play a causal role in memory consolidation during sleep and rest. However, further research will be necessary to better understand the neurophysiological mechanisms of memory consolidation, in particular the selection of reactivated assembl…
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The effects of fasting on metabolism and performance.
An overnight fast of 8-10 h is normal for most people. Fasting is characterised by a coordinated set of metabolic changes designed to spare carbohydrate and increase reliance on fat as a substrate for energy supply. As well as sparing the limited endogenous carbohydrate, and increased rate of gluconeogenesis from amino acids, glycerol and ketone bodies help maintain the supply of carbohydrate. Many individuals undergo periodic fasts for health, religious or cultural reasons. Ramadan fasting, involving 1 month of abstention from food and fluid intake during daylight hours, is practised by a large part of the world population. This period involves a shift in the pattern of intake from daytime to the hours of darkness. There seems to be little effect on overall daily dietary intake and only small metabolic effects, but there may be implications for both physical and cognitive function. The …
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Effects of the dietary flavonoid quercetin upon performance and health.
There is increased interest among such diverse groups as the military, athletes, and the aged for novel plant-derived dietary supplements to enhance performance and maintain/improve health. Quercetin, a flavonoid found in fruits and vegetables, has unique biological properties that are likely to improve mental/physical performance and reduce infection risk during intense exercise. These properties include antiinflammatory, antioxidant, and psychostimulant activity, as well as the ability to stimulate mitochondrial biogenesis, and they form the basis for potential benefits to overall health and disease resistance. However, most information regarding quercetin is based upon in vitro and animal studies. Therefore, there is a pressing need for well-designed clinical trials to evaluate this novel dietary supplement further. This article will examine the recent scientific literature concerning…
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Physical performance limitations in the Childhood Cancer Survivor Study cohort.
Physical performance limitations are one of the potential long-term consequences following diagnosis and treatment for childhood cancer. The purpose of this review is to describe the risk factors for and the participation restrictions that result from physical performance limitations among childhood cancer survivors who participated in the Childhood Cancer Survivor Study (CCSS). Articles previously published from the CCSS cohort related to physical performance limitations were reviewed and the results summarized. Our review showed that physical performance limitations are prevalent among childhood cancer survivors and may increase as they age. Host-based risk factors for physical disability include an original diagnosis of bone tumor, brain tumor, or Hodgkin's disease; female sex; and an income less than $20,000 per year. Treatment-based risk factors include radiation and treatment with …
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Fries E, Dettenborn L, Kirschbaum C (2009)reviewMEDLINE-indexed journal, not yet read by usInternational journal of psychophysiology : official journal of the International Organization of Psychophysiology790 citations The cortisol awakening response (CAR): facts and future directions.
In humans, the secretion of cortisol from the adrenal glands follows a diurnal cycle with a profound increase after awakening. This increase after awakening, a phenomenon termed the cortisol awakening response (CAR), appears to be a distinct feature of the hypothalamus-pituitary-adrenal (HPA) axis, superimposing the circadian rhythmicity of cortisol secretion. Several studies point towards an important role of the hippocampus and, additionally, other brain structures (e. g. amygdala, prefrontal cortex, suprachiasmatic nucleus) in the regulation of the CAR. There is increasing knowledge that the CAR is influenced by a variety of factors such as gender, health status, and health behavior or stress perception. However, the exact function of the profound cortisol increase after awakening is still not clarified. We hypothesize that the anticipation of the upcoming day is of major relevance fo…
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Diagnosis of circadian rhythm sleep disorders.
Insomnia and excessive sleepiness are common in the investigation of sleep-disordered breathing. Circadian rhythm sleep disorders are perhaps the most often overlooked conditions in the differential diagnosis of these symptoms. Circadian rhythm sleep disorders manifest as misalignment between the sleep period and the physical/social 24-h environmental cycle. The two most prevalent circadian rhythm sleep disorders are delayed sleep phase (common in adolescents) and advanced sleep phase (common in the elderly), situations in which the sleep period is displaced to a later or earlier time, respectively. It is important to keep these two disorders in mind, since they can be confused with insomnia and excessive sleepiness. However, there are nine possible diagnoses, and all nine are of clinical interest. Since light is the principal cue used in synchronizing the biological clock, blind individ…
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Kumar R (2008)reviewMEDLINE-indexed journal, not yet read by usDrugs137 citations Approved and investigational uses of modafinil : an evidence-based review.
Modafinil is a wake-promoting agent that is pharmacologically different from other stimulants. It has been investigated in healthy volunteers, and in individuals with clinical disorders associated with excessive sleepiness, fatigue, impaired cognition and other symptoms. This review examines the use of modafinil in clinical practice based on the results of randomized, double-blind, placebo-controlled clinical trials available in the English language in the MEDLINE database. In sleep-deprived individuals, modafinil improves mood, fatigue, sleepiness and cognition to a similar extent as caffeine but has a longer duration of action. Evidence for improved cognition in non-sleep-deprived healthy volunteers is controversial. Modafinil improves excessive sleepiness and illness severity in all three disorders for which it has been approved by the US FDA, i.e. narcolepsy, shift-work sleep disorde…
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