Familial aggregation of exercise heart rate and blood pressure in response to 20 weeks of endurance training: the HERITAGE family study.
ABSTRACT Changes of heart rate (HR) and blood pressure (BP) relative to baseline levels in response to an extended period of endurance training are indices of cardiovascular adaptability. Familial influences were investigated for HR and BP at work rates of 50 W and 60 % of the maximal oxygen uptake (VO2max) in response to 20 weeks of endurance training. A total of 481 participants from 99 sedentary White nuclear families in the HERITAGE Family Study (HERITAGE) were analyzed using a familial correlation model. Each of these training response phenotypes was adjusted for the effects of age, BMI, cigarette smoking, baseline VO2max, and its baseline values in fathers, mothers, sons and daughters, respectively. We found that maximal heritabilities reached 34 % and 29 % for HR training responses at 50 W and 60 % of VO2 max, respectively. The heritability was 22 % for systolic BP (SBP) training response at 50 W, but negligible at 60 % of VO2max. No significant heritabilities were found for diastolic BP (DBP) training responses at either 50 W or 60 % of VO2max. Familial influences for exercise HR and BP training responses were also assessed in a total of 257 participants from 113 Black family units in HERITAGE. However, there was no significant familial resemblance, which may be attributable to the small sample size. In conclusion, HR and SBP training responses during submaximal exercise in Whites were influenced by a modest, but significant, familial component. These observations are therefore in contrast to substantial familial effects (heritability estimates of about 50 %) previously reported for these variables measured at baseline.
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Article: Epigenetics in Sports.[Show abstract] [Hide abstract]
ABSTRACT: The heritability of specific phenotypical traits relevant for physical performance has been extensively investigated and discussed by experts from various research fields. By deciphering the complete human DNA sequence, the human genome project has provided impressive insights into the genomic landscape. The hope that this information would reveal the origin of phenotypical traits relevant for physical performance or disease risks has proven overly optimistic, and it is still premature to refer to a 'post-genomic' era of biological science. Linking genomic regions with functions, phenotypical traits and variation in disease risk is now a major experimental bottleneck. The recent deluge of genome-wide association studies (GWAS) generates extensive lists of sequence variants and genes potentially linked to phenotypical traits, but functional insight is at best sparse. The focus of this review is on the complex mechanisms that modulate gene expression. A large fraction of these mechanisms is integrated into the field of epigenetics, mainly DNA methylation and histone modifications, which lead to persistent effects on the availability of DNA for transcription. With the exceptions of genomic imprinting and very rare cases of epigenetic inheritance, epigenetic modifications are not inherited transgenerationally. Along with their susceptibility to external influences, epigenetic patterns are highly specific to the individual and may represent pivotal control centers predisposing towards higher or lower physical performance capacities. In that context, we specifically review how epigenetics combined with classical genetics could broaden our knowledge of genotype-phenotype interactions. We discuss some of the shortcomings of GWAS and explain how epigenetic influences can mask the outcome of quantitative genetic studies. We consider epigenetic influences, such as genomic imprinting and epigenetic inheritance, as well as the life-long variability of epigenetic modification patterns and their potential impact on phenotype with special emphasis on traits related to physical performance. We suggest that epigenetic effects may also play a considerable role in the determination of athletic potential and these effects will need to be studied using more sophisticated quantitative genetic models. In the future, epigenetic status and its potential influence on athletic performance will have to be considered, explored and validated using well controlled model systems before we can begin to extrapolate new findings to complex and heterogeneous human populations. A combination of the fields of genomics, epigenomics and transcriptomics along with improved bioinformatics tools and precise phenotyping, as well as a precise classification of the test populations is required for future research to better understand the inter-relations of exercise physiology, performance traits and also susceptibility towards diseases. Only this combined input can provide the overall outlook necessary to decode the molecular foundation of physical performance.Sports Medicine 01/2013; · 5.32 Impact Factor
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ABSTRACT: A small number of excellent papers on exercise genomics issues have been published in 2012. A new PYGM knockout mouse model will provide opportunities to investigate the exercise intolerance and very low activity level of people with McArdle disease. New reports on variants in ACTN3 and ACE have increased the level of uncertainty regarding their true role in skeletal muscle metabolism and strength traits. The evidence continues to accumulate on the positive effects of regular physical activity on body mass index (BMI) or adiposity in individuals at risk of obesity as assessed by their FTO genotype or by the number of risk alleles they carry at multiple obesity-susceptibility loci. Serum levels of triglycerides and the risk of hypertriglyceridemia were shown to be influenced by the interactions between a single nucleotide polymorphism (SNP) in the NOS3 gene and physical activity level. Allelic variation at nine SNPs was shown to account for the heritable component of the changes in submaximal exercise heart rate induced by the HERITAGE Family Study exercise program. SNPs at the RBPMS, YWHAQ, and CREB1 loci were found to be particularly strong predictors of the changes in submaximal exercise heart rate. The 2012 review ends with comments on the importance of relying more on experimental data, the urgency of identifying panels of genomic predictors of the response to regular exercise and particularly of adverse responses, and the exciting opportunities offered by recent advances in our understanding of the global architecture of the human genome as reported by the ENCODE project.Medicine and science in sports and exercise 03/2013; · 4.48 Impact Factor
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ABSTRACT: The response to an exercise intervention is often described in general terms, with the assumption that the group average represents a typical response for most individuals. In reality, however, it is more common for individuals to show a wide range of responses to an intervention rather than a similar response. This phenomenon of 'high responders' and 'low responders' following a standardized training intervention may provide helpful insights into mechanisms of training adaptation and methods of training prescription. Therefore, the aim of this review was to discuss factors associated with inter-individual variation in response to standardized, endurance-type training. It is well-known that genetic influences make an important contribution to individual variation in certain training responses. The association between genotype and training response has often been supported using heritability estimates; however, recent studies have been able to link variation in some training responses to specific single nucleotide polymorphisms. It would appear that hereditary influences are often expressed through hereditary influences on the pre-training phenotype, with some parameters showing a hereditary influence in the pre-training phenotype but not in the subsequent training response. In most cases, the pre-training phenotype appears to predict only a small amount of variation in the subsequent training response of that phenotype. However, the relationship between pre-training autonomic activity and subsequent maximal oxygen uptake response appears to show relatively stronger predictive potential. Individual variation in response to standardized training that cannot be explained by genetic influences may be related to the characteristics of the training program or lifestyle factors. Although standardized programs usually involve training prescribed by relative intensity and duration, some methods of relative exercise intensity prescription may be more successful in creating an equivalent homeostatic stress between individuals than other methods. Individual variation in the homeostatic stress associated with each training session would result in individuals experiencing a different exercise 'stimulus' and contribute to individual variation in the adaptive responses incurred over the course of the training program. Furthermore, recovery between the sessions of a standardized training program may vary amongst individuals due to factors such as training status, sleep, psychological stress, and habitual physical activity. If there is an imbalance between overall stress and recovery, some individuals may develop fatigue and even maladaptation, contributing to variation in pre-post training responses. There is some evidence that training response can be modulated by the timing and composition of dietary intake, and hence nutritional factors could also potentially contribute to individual variation in training responses. Finally, a certain amount of individual variation in responses may also be attributed to measurement error, a factor that should be accounted for wherever possible in future studies. In conclusion, there are several factors that could contribute to individual variation in response to standardized training. However, more studies are required to help clarify and quantify the role of these factors. Future studies addressing such topics may aid in the early prediction of high or low training responses and provide further insight into the mechanisms of training adaptation.Sports medicine (Auckland, N.Z.). 05/2014;