Medicine and sport science最新文献

High-throughput sequencing of multiple human exomes and genomes is rapidly identifying rare genetic variants that cause or contribute to disease. Microarray-based methodologies have also shed light onto the genes that contribute to common, non-disease human traits such as hair and eye colour. Sport scientists should keep in mind several things when interpreting the literature, and when designing their own genetic studies. First of all, most genetic association methods are more powerful for detecting disease phenotypes (such as susceptibility to injury) than they are for detecting healthy phenotypes (such as sport performance). This is because there are likely to be many more biological factors contributing to the latter, and the effect size of most of these biological factors is likely to be small. Second, implicating a particular gene in a human phenotype like athletic performance or injury susceptibility requires an unbiased population data set. Third, new types of non-coding biological variability continue to be uncovered in the human genome (e.g. epigenetic modifications, microRNAs, etc.). These other types of variability may contribute significantly to differences in athletic performance.

Genetic factors have been shown to associate with various exercise-related phenotypes, including exercise performance, adaptation to training and sports injuries. The genes implicated in the pathogenesis of musculoskeletal soft-tissue injuries all code for either structural components or regulatory components of the extracellular matrix. It has been hypothesized that these genetic associations with injuries are due to genetically regulated changes in mechanical properties of musculoskeletal soft tissue. Thus, the objective of this review is to highlight the research which has advanced our understanding of how genetic variation within these structural genes affects the properties of our connective tissue. The genetics of various exercise-related phenotypes, such as range of motion, endurance performance and exercise-associated muscle cramps, are reviewed. Lastly, a model is presented where genetic variations within a collagen-encoding gene result in a continuum of phenotype ranging from a normal tissue to a seriously deleterious or lethal disorder.

Humans vary in their ability to achieve success in sports, and this variability mostly depends on genetic factors. The main goal of this work was to review the current progress in the understanding of genetic determinism of athlete status and to describe some novel and important DNA polymorphisms that may underlie differences in the potential to be an elite athlete. In the past 19 years, at least 155 genetic markers (located within almost all chromosomes and mtDNA) were found to be linked to elite athlete status (93 endurance-related genetic markers and 62 power/strength-related genetic markers). Importantly, 41 markers were identified within the last 2 years by performing genome-wide association studies (GWASs) of African-American, Jamaican, Japanese, and Russian athletes, indicating that GWASs represent a promising and productive way to study sports-related phenotypes. Of note, 31 genetic markers have shown positive associations with athlete status in at least 2 studies and 12 of them in 3 or more studies. Conversely, the significance of 29 markers was not replicated in at least 1 study, raising the possibility that several findings might be false-positive. Future research, including multicentre GWASs and whole-genome sequencing in large cohorts of athletes with further validation and replication, will substantially contribute to the discovery of large numbers of the causal genetic variants (mutations and DNA polymorphisms) that would partly explain the heritability of athlete status and related phenotypes.

This paper addresses practical and ethical considerations regarding genetic tests to predict performance and/or risk of exercise-related injury or illness. Various people might wish to conduct sport-related genetic tests for a variety of reasons. For example, an individual might seek personal genetic information to help guide their own sport participation. A sports coach might wish to test young athletes to aid team selection or individualize training. A physician might want to predict the risk of injury or illness in athletes and advise regarding selection or preventative measures. An insurance company might seek to estimate the risk of career-threatening injury for athletes based partly on genetic information. Whilst this information is, in part, encoded in our DNA sequence, the available tests allow generally only a poor prediction of the aforementioned variables. In other words, the current genetic tests and analysis methods are not powerful enough to inform important decisions in sport to a substantial degree. It is particularly disappointing that more than half of the commercially available genetic tests related to exercise and sport do not appear to identify publicly the genetic variants they assess, making scrutiny by academic scholars and consumers (or their representatives) impossible. There are also challenging ethical issues to consider. For example, the imposition of genetic tests on individuals (especially young people) by third parties is potentially susceptible to abuse. Scientists and practitioners should understand the limitations of the tests currently available, the ethical concerns and the importance of counselling before and after testing so that they are only used in a responsible manner.

There is mounting evidence suggesting a genetic contribution to the susceptibility of sustaining a musculoskeletal soft-tissue injury. To date, more than 70 loci have been implicated in several injury profiles. The genes implicated through these loci encode a broad spectrum of matrix proteins including collagens and non-collagens. The large majority of these studies have followed a candidate gene case-control study design. A small proportion of these loci have been repeated in independent studies, of which some have included different musculoskeletal injuries. However, the large majority of these studies are underpowered to detect contributions of small effect sizes (odds ratio <2.0). It is therefore critical that large data sets are collected and that consortia are established to effectively pool resources to understand the biological significance of these genetic loci and risk susceptibility. We are in the era of omics and high-throughput technologies but it is only through collaborations that we will realize the clinical significance of the genomic revolution and its application to musculoskeletal soft-tissue injury susceptibility.

This overview provides a general discussion of the roles of nature and nurture in determining human athletic ability. On the nature (genetics) side, a review is provided with emphasis on the historical research and on several areas which are likely to be important for future research, including next-generation sequencing technologies. In addition, a number of well-designed training studies that could possibly reveal the biological mechanism ('cause') behind the association between gene variants and athletic ability are discussed. On the nurture (environment) side, we discuss common environmental variables including deliberate practice, family support, and the birthplace effect, which may be important in becoming an elite athlete. Developmental effects are difficult to disassociate with genetic effects, because the early life environment may have long-lasting effects in adulthood. With this in mind, the fetal programming hypothesis is also briefly reviewed, as fetal programming provides an excellent example of how the environment interacts with genetics. We conclude that the traditional argument of nature versus nurture is no longer relevant, as it has been clearly established that both are important factors in the road to becoming an elite athlete. With the availability of the next-generation genetics (sequencing) techniques, it is hoped that future studies will reveal the relevant genes influencing performance, as well as the interaction between those genes and environmental (nurture) factors.

In the present review, we focus on evaluating the state of the literature in the area of genetic aspects of exercise training adaptation, in particular focusing on findings published since 2009. Our focus is primarily on studies examining genetic polymorphisms and their association with variability in training responses for a number of exercise-related traits, including aerobic fitness, hemodynamic variables, metabolic traits, body composition and obesity, and muscular strength and size. Very few large-scale studies are available to provide the quality scientific evidence needed to conclusively identify specific genetic factors that contribute to exercise training adaptations. As such, despite years of effort by a number of groups, the search continues for specific genes and combinations of genetic factors that contribute to the interindividual variability observed in phenotype adaptations to exercise training interventions.

Gestational diabetes mellitus (GDM) is defined as 'carbohydrate intolerance resulting in hyperglycemia of variable severity with onset or first recognition during pregnancy'. GDM is associated with several detrimental health consequences during pregnancy and delivery for both mother and baby. The largest public health impact of GDM is through its role on future diabetes in the mother and obesity and diabetes in the offspring. Physical activity (PA) is likely an effective intervention for prevention and treatment of GDM, given its known effectiveness in prevention and treatment of type 2 diabetes. Based on observational studies, PA initiated before and/or during pregnancy has a positive influence on maternal glucose and insulin metabolism and reduces the risk of GDM. However, although PA interventions have been reported to be effective at improving glycemic control in women who already developed GDM, prenatal PA interventions aimed at preventing GDM have shown modest effectiveness in increasing PA levels and thus were not effective in improving glucose/insulin metabolism or reducing GDM incidence. There is therefore a strong need to develop effective strategies for increasing PA levels, especially in women at high risk for GDM who are often obese and inactive. The optimal intervention for preventing or managing GDM is still unknown, and further studies are needed to determine the type, intensity, frequency and duration for the most successful PA intervention. Furthermore, the effects of PA on neonatal outcomes are not clear, and it is highly recommended that future studies examine more specific neonatal outcomes such as body composition.

Over the past 5 years, the fastest growing new area of physical activity research centered around the concept that the large amount of time people spend sitting inactive may have significant physiological consequences hazardous to human health, including risk for type 2 diabetes and poor metabolism of lipids and glucose. Meta-analysis (10 studies) suggests there is a 112% greater relative risk associated with a large duration of sedentary behavior for type 2 diabetes. Meta-analysis also indicates significantly greater odds for metabolic syndrome. We also summarize results for 7 studies using objective measures of total sedentary time and focusing on cardiometabolic risks in persons at high risk for type 2 diabetes or already diagnosed with type 2 diabetes. The underlying hypothesis introduced in 2004 by the inactivity physiology paradigm has been that frequent and abundant contractile activity by certain types of skeletal muscle can have a potent influence on key physiological processes, even when the intensity is below that achieved through exercise. We explain some of the mechanisms for why the metabolism in slow-twitch oxidative skeletal muscle is key for understanding the healthy responses to low-intensity physical activity (LIPA). Findings from objective measures from inclinometry indicated that the quartile range for weekly sedentary time is ∼29 h/week. The total daily time that people sit, stand, and accumulate nonexercise steps is independent of traditionally recommended moderate-vigorous physical activity. The large amount of sedentary time associated with risk for disease can only be reduced significantly with safe and nonfatiguing LIPA, especially in the most at-risk proportion of the population. Importantly, experimental studies are starting to indicate that it will be especially insightful to understand the acute dose-response effects of LIPA in order to understand why reducing sedentary time can improve lipid and glucose metabolism for the prevention and treatment of chronic disorders related to type 2 diabetes.

This chapter reviews current knowledge of the various signaling pathways that cause the glucose transporter isoform 4 (GLUT4)-containing vesicles to translocate from intracellular compartments of skeletal muscle cells to the plasma membrane in response to exercise. Specifically, the signaling cascades that arise from increases in AMP (adenosine monophosphate), nitric oxide (NO) and calcium (Ca2+) are described. Evidence is provided that these signaling pathways converge with the insulin signaling cascade at: (a) aPKC (atypical protein kinase C), which signals via GTPases to remodel microtubules along which GLUT4-containing vesicles translocate, and (b) AS160 (a 160-kDa Akt substrate that has Rab-GTPase activity) to activate microtubule motor kinesin proteins that power vesicle translocation. Experimental evidence showing that joint activation of AS160 and aPKC pathways are necessary for GLUT4 mobilization to the cell surface is given along with evidence of overlap between Ca2+, NO and AMP-dependent protein kinase-signaling pathways. The chapter also describes the molecular mechanisms by which exercise increases GLUT4 expression to boost glucose disposal capacity of skeletal muscle.