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Sports Medicine (Auckland, N.Z.) Apr 2018Periodization theory has, over the past seven decades, emerged as the preeminent training planning paradigm. The philosophical underpinnings of periodization theory can...
Periodization theory has, over the past seven decades, emerged as the preeminent training planning paradigm. The philosophical underpinnings of periodization theory can be traced back to the integration of diverse shaping influences, whereby coaching beliefs and traditions were blended with historically available scientific insights and contextualized against pervading social planning models. Since then, many dimensions of elite preparation have evolved significantly, as driven by a combination of coaching innovations and science-led advances in training theory, techniques, and technologies. These advances have been incorporated into the fabric of the pre-existing periodization planning framework, yet the philosophical assumptions underpinning periodization remain largely unchallenged and unchanged. One particularly influential academic sphere of study, the science of stress, particularly the work of Hans Selye, is repeatedly cited by theorists as a central pillar upon which periodization theory is founded. A fundamental assumption emanating from the early stress research is that physical stress is primarily a biologically mediated phenomenon: a presumption translated to athletic performance contexts as evidence that mechanical training stress directly regulates the magnitude of subsequent 'fitness' adaptations. Interestingly, however, since periodization theory first emerged, the science of stress has evolved extensively from its historical roots. This raises a fundamental question: if the original scientific platform upon which periodization theory was founded has disintegrated, should we critically re-evaluate conventional perspectives through an updated conceptual lens? Realigning periodization philosophy with contemporary stress theory thus presents us with an opportunity to recalibrate training planning models with both contemporary scientific insight and progressive coaching practice.
Topics: Adaptation, Physiological; Athletic Performance; Exercise; Humans; Seasons; Stress, Physiological; Time Factors
PubMed: 29189930
DOI: 10.1007/s40279-017-0823-y -
Surgery Today Apr 2018The "chronology of cancer" is a concept that describes the nature of cancers through the measure of time. The field extends from carcinogenesis to development,... (Review)
Review
The "chronology of cancer" is a concept that describes the nature of cancers through the measure of time. The field extends from carcinogenesis to development, progression, and metastasis. Carcinogenesis is a multi-step process, which results from the accumulation of multiple genetic or epigenetic alterations. Various chronologies of gastrointestinal cancers have been reported for carcinogenesis caused by different risk factors. These chronologies are useful for developing cancer prevention strategies. The tumor growth rate is one of the most important factors in this field. Combining the factors of time and tumor growth enables us to estimate the time at which cancer or metastasis occurred, retrospectively, and to predict the survival of cancer patients, prospectively. It is noteworthy that these chronologies differ significantly among individual cases, even of cancers derived from the same organ. Thus, they are useful for individualization. We can apply the knowledge obtained in this field to the basic research and the diagnosis and treatment of cancers. The chronology of cancer is a classical but interesting field, which helps us consider and explore the essence of cancer. We review the topics related to the chronology of gastrointestinal cancer, ranging from carcinogenesis to metastasis.
Topics: Carcinogenesis; Cell Transformation, Neoplastic; Gastrointestinal Neoplasms; Humans; Neoplasm Metastasis; Time; Time Factors
PubMed: 28795270
DOI: 10.1007/s00595-017-1574-y -
Hormones and Behavior May 2022Changes to photoperiod (day length) occur in anticipation of seasonal environmental changes, altering physiology and behavior to maximize fitness. In order for... (Review)
Review
Changes to photoperiod (day length) occur in anticipation of seasonal environmental changes, altering physiology and behavior to maximize fitness. In order for photoperiod to be useful as a predictive factor of temperature or food availability, day and night must be distinct. The increasing prevalence of exposure to artificial light at night (ALAN) in both field and laboratory settings disrupts photoperiodic time measurement and may block development of appropriate seasonal adaptations. Here, we review the effects of ALAN as a disruptor of photoperiodic time measurement and season-specific adaptations, including reproduction, metabolism, immune function, and thermoregulation.
Topics: Circadian Rhythm; Light Pollution; Photoperiod; Reproduction; Seasons
PubMed: 35304351
DOI: 10.1016/j.yhbeh.2022.105150 -
Dento Maxillo Facial Radiology Oct 2020
Topics: Time Factors
PubMed: 32959694
DOI: 10.1259/dmfr.20209003 -
Frontiers in Neuroendocrinology Apr 2015Seasonal variations in immunity are common in nature, and changes in day length are sufficient to trigger enhancement and suppression of immune function in many... (Review)
Review
Seasonal variations in immunity are common in nature, and changes in day length are sufficient to trigger enhancement and suppression of immune function in many vertebrates. Drawing primarily on data from Siberian hamsters, this review describes formal and physiological aspects of the neuroendocrine regulation of seasonal changes in mammalian immunity. Photoperiod regulates immunity in a trait-specific manner, and seasonal changes in gonadal hormone secretion and thyroid hormone signaling all participate in seasonal immunomodulation. Photoperiod-driven changes in the hamster reproductive and immune systems are associated with changes in iodothyronine deiodinase-mediated thyroid hormone signaling, but photoperiod exerts opposite effects on select aspects of the epigenetic regulation of reproductive neuroendocrine and lymphoid tissues. Photoperiodic changes in immunocompetence may explain a proportion of the annual variance in disease incidence and severity in nature, and provide a useful framework to help understand brain-immune interactions.
Topics: Adaptation, Physiological; Animals; Hormones; Humans; Immune System; Photoperiod; Seasons
PubMed: 25456046
DOI: 10.1016/j.yfrne.2014.10.002 -
The Journal of Clinical Investigation Sep 2009When has an author been scooped? It sounds like a simple question, but in fact, as a recent editorial meeting unfolded, this issue became far more complex than I had...
When has an author been scooped? It sounds like a simple question, but in fact, as a recent editorial meeting unfolded, this issue became far more complex than I had thought.
Topics: Publishing; Research; Time Factors
PubMed: 19729840
DOI: 10.1172/JCI40681 -
Anais Da Academia Brasileira de Ciencias 2021The Intelligent Observatory (IO) refers to the vision of the South African Astronomical Observatory (SAAO) to meet the scientific needs of both the South African and...
The Intelligent Observatory (IO) refers to the vision of the South African Astronomical Observatory (SAAO) to meet the scientific needs of both the South African and international astronomical communities by providing a better and more efficient service. The idea behind the IO is to harmonise the astronomical operations of all the hosted and local astronomical facilities on the Sutherland Plateau. The vision requires both upgrades to some of the telescopes and a re-design of the current Sutherland operations model. The primary science driver, for the IO, is time-domain and transient science.
Topics: Astronomy; Time
PubMed: 34008768
DOI: 10.1590/0001-3756202120201026 -
Internal and Emergency Medicine Aug 2018Very recently, the European Parliament, called to decide on possible abolition of the Daylight Saving Time (DST), approved a resolution calling the scientific community... (Review)
Review
Very recently, the European Parliament, called to decide on possible abolition of the Daylight Saving Time (DST), approved a resolution calling the scientific community to conduct a more in-depth evaluation. The question is based on disruption of body's circadian rhythms. We review here the relationship between DST and cardiovascular health. The available evidence suggests the existence of an association between DST and a modest increase of occurrence of acute myocardial infarction, especially in the first week after the spring shift. Possible mechanisms include sleep deprivation, circadian misalignment and environmental conditions. The role of gender and individual preference in circadian rhythms (chronotype) will need further assessment.
Topics: Cardiovascular System; Circadian Rhythm; Humans; Risk Factors; Seasons; Time Factors
PubMed: 29971599
DOI: 10.1007/s11739-018-1900-4 -
ELife Aug 2022Complex systems are challenging to understand, especially when they defy manipulative experiments for practical or ethical reasons. Several fields have developed... (Review)
Review
Complex systems are challenging to understand, especially when they defy manipulative experiments for practical or ethical reasons. Several fields have developed parallel approaches to infer causal relations from observational time series. Yet, these methods are easy to misunderstand and often controversial. Here, we provide an accessible and critical review of three statistical causal discovery approaches (pairwise correlation, Granger causality, and state space reconstruction), using examples inspired by ecological processes. For each approach, we ask what it tests for, what causal statement it might imply, and when it could lead us astray. We devise new ways of visualizing key concepts, describe some novel pathologies of existing methods, and point out how so-called 'model-free' causality tests are not assumption-free. We hope that our synthesis will facilitate thoughtful application of methods, promote communication across different fields, and encourage explicit statements of assumptions. A video walkthrough is available (Video 1 or https://youtu.be/AIV0ttQrjK8).
Topics: Causality; Time Factors
PubMed: 35983746
DOI: 10.7554/eLife.72518 -
American Journal of Physiology. Heart... Jul 2022In March 2022, the US Senate passed the Sunshine Protection Act that would abolish the biannual change in clocks each fall and spring and permanently adopt daylight...
In March 2022, the US Senate passed the Sunshine Protection Act that would abolish the biannual change in clocks each fall and spring and permanently adopt daylight saving time that aligns with the "spring forward" time change each March. A number of scientific and medical societies have endorsed the abolishment of the biannual clock change, but oppose the permanent adoption of daylight saving time. Instead, leading organizations such as the American Academy of Sleep Medicine (AASM) and the Society for Research on Biological Rhythms (SRBR) position statements highlight peer-reviewed evidence in favor of a permanent shift to standard time. The present perspectives will summarize some of the key AASM and SRBR recommendations, with a particular focus on the potential cardiovascular implications of a legislative change that would result in a permanent switch to either standard time or daylight saving time. Collectively, although there is building scientific consensus that abolishing the biannual time change has several sleep and circadian health benefits, the preponderance of evidence is opposite to the current legislation and instead suggests a permanent switch to standard time may offer the maximum health and safety benefits. This scientific evidence should be considered as the United States House of Representatives considers the Sunshine Protection Act.
Topics: Cardiovascular System; Circadian Rhythm; Heart; Seasons; Sleep; Time Factors; United States
PubMed: 35622532
DOI: 10.1152/ajpheart.00218.2022