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It is clear, based on a deep scientific literature base, that genetic and genomic factors play significant roles in determining a wide range of sport and exercise characteristics including exercise endurance capacity, strength, daily physical activity levels, and trainability of both endurance and strength. Although the research field of exercise systems genetics has rapidly expanded over the past two decades, many researchers publishing in this field are not extensively trained in molecular biology or genomics techniques, sometimes creating gaps in generating high-quality and cutting-edge research for publication. As current or former Associate Editors for Medicine and Science in Sports and Exercise that have handled the majority of exercise genetics articles for Medicine and Science in Sports and Exercise in the past 15 yr, we have observed a large number of scientific manuscripts submitted for publication review that have exhibited significant flaws preventing their publication; flaws that often directly stem from a lack of knowledge regarding the "state-of-the-art" methods and accepted literature base that is rapidly changing as the field evolves. The purpose of this commentary is to provide researchers—especially those coming from a nongenetics background attempting to publish in the exercise system genetics area—with recommendations regarding best-practice research standards and data analysis in the field of exercise systems genetics, to strengthen the overall literature in this important and evolving field of research. [ABSTRACT FROM AUTHOR]

Physical activity has long been touted as a means of reducing susceptibility to age-related disease and multiple studies have shown reduced mortality rates in individuals with a lifestyle including regular exercise. A variety of mechanisms for how physical activity reduces age-related diseases have been explored and multiple, redundant explanatory mechanisms are likely to emerge. Evidence has emerged that physical activity may impact directly on telomere biology, one of the primary theories of cellular aging. Telomeres are located at the ends of chromosomes and as cells divide, incomplete DNA replication results in telomere shortening; once shortening reaches a critical threshold, cell senescence results. Investigators hypothesize that part of the favorable influence of physical activity on mortality rates and age-related disease occurs through a direct impact on telomere biology, including delaying rates of telomere shortening. The present review examines key recent findings in this area and explores some of the unanswered questions and future directions for the field. [ABSTRACT FROM AUTHOR]

Muscle strength is important in functional activities of daily living and the prevention of common pathologies. We describe the two-staged fine mapping of a previously identified linkage peak for knee strength on chr12q12-14. First, 209 tagSNPs in/around 74 prioritized genes were genotyped in 500 Caucasian brothers from the Leuven Genes for Muscular Strength study (LGfMS). Combined linkage and family-based association analyses identified activin receptor 1B (ACVR1B) and inhibin β C (INHBC), part of the transforming growth factor β pathway regulating myostatin - a negative regulator of muscle mass - signaling, for follow-up. Second, 33 SNPs, selected in these genes based on their likelihood to functionally affect gene expression/function, were genotyped in an extended sample of 536 LGfMS siblings. Strong associations between ACVR1B genotypes and knee muscle strength (P-values up to 0.00002) were present. Of particular interest was the association with rs2854464, located in a putative miR-24-binding site, as miR-24 was implicated in the inhibition of skeletal muscle differentiation. Rs2854464 AA individuals were ∼2% stronger than G-allele carriers. The strength increasing effect of the A-allele was also observed in an independent replication sample (n=266) selected from the Baltimore Longitudinal Study of Aging and a Flemish Policy Research Centre Sport, Physical Activity and Health study. However, no genotype-related difference in ACVR1B mRNA expression in quadriceps muscle was observed. In conclusion, we applied a two-stage fine mapping approach, and are the first to identify and partially replicate genetic variants in the ACVR1B gene that account for genetic variation in human muscle strength. [ABSTRACT FROM AUTHOR]

Physical activity is associated with reduced risk of several age-related diseases as well as with increased longevity in both rodents and humans. Though these associations are well established, evidence of the molecular and cellular factors associated with reduced disease risk and increased longevity resulting from physical activity is sparse. A long-standing hypothesis of aging is the telomere hypothesis: as a cell divides, telomeres shorten resulting eventually in replicative senescence and an aged phenotype. Several reports have recently associated telomeres and telomere-related proteins to diseases associated with physical inactivity and aging including cardiovascular disease, insulin resistance, and hypertension. Interestingly several reports have also shown that longer telomeres are associated with higher physical activity levels, indicating a potential mechanistic link between physical activity, reduced agerelated disease risk, and longevity. The primary purpose of this review is to discuss the potential importance of physical activity in telomere biology in the context of inactivity- and age-related diseases. A secondary purpose is to explore potential mechanisms and important avenues for future research in the field of telomeres and diseases associated with physical inactivity and aging. [ABSTRACT FROM AUTHOR]

The article focuses on studies related to performance genomics and the correlation between physical activity and the genetic make-up of an individual. It states that certain studies reveal that genetic factors affect an individual's level of activeness. The genome-wide association study (GWAS) and its publication in 2009 was noted to compensate for the scarcity of data on the functions of DNA on the emergence of genetic variance that influence physical activity. It mentions that much of the studies published on the topic of genetic function in cardiorespiratory endurance are centered on genes acted upon by the nuclear genome. The functions of Apolipoprotein E in lipid metabolism are also cited. Moreover, it suggests that exercise scientists should arrive at high-quality research designs.

This review of the exercise genomics literature encompasses the highest-quality articles published in 2015 across seven broad topics: physical activity behavior, muscular strength and power, cardiorespiratory fitness and endurance performance, body weight and adiposity, insulin and glucose metabolism, lipid and lipoprotein metabolism, and hemodynamic traits. One study used a quantitative trait locus for wheel running in mice to identify single nucleotide polymorphisms (SNPs) in humans associated with physical activity levels. Two studies examined the association of candidate gene ACTN3 R577X genotype on muscular performance. Several studies examined gene--physical activity interactions on cardiometabolic traits. One study showed that physical inactivity exacerbated the body mass index (BMI)--increasing effect of an FTO SNP but only in individuals of European ancestry, whereas another showed that high-density lipoprotein cholesterol (HDL-C) SNPs from genome-wide association studies exerted a smaller effect in active individuals. Increased levels of moderate-to-vigorous--intensity physical activity were associated with higher Matsuda insulin sensitivity index in PPARG Ala12 carriers but not Pro12 homozygotes. One study combined genome-wide and transcriptome-wide profiling to identify genes and SNPs associated with the response of triglycerides (TG) to exercise training. The genome-wide association study results showed that four SNPs accounted for all of the heritability of ΔTG, whereas the baseline expression of 11 genes predicted 27% of ΔTG. A composite SNP score based on the top eight SNPs derived from the genomic and transcriptomic analyses was the strongest predictor of $TG, explaining 14% of the variance. The review concludes with a discussion of a conceptual framework defining some of the critical conditions for exercise genomics studies and highlights the importance of the recently launched National Institutes of Health Common Fund program titled "Molecular Transducers of Physical Activity in Humans." [ABSTRACT FROM AUTHOR]

The beneficial effects of physical activity on brain health (synaptogenesis, neurogenesis, enhanced synaptic plasticity, improved learning and memory) appear to be mediated through changes in region-specific expression of neurotrophins, transcription factors, and postsynaptic receptors, though investigations of sex differences in response to long-term voluntary wheel running are limited. Purpose To examine the effect of five months of voluntary wheel running on hippocampal mRNA and protein expression of factors critical for exercise-induced structural and functional plasticity in male and female adult mice. Methods At 8 weeks of age, male and female C57BL/6 mice were individually housed with (PA; n = 20; 10 male) or without (SED; n = 20; 10 male) access to a computer monitored voluntary running wheel. At 28 weeks, all mice were sacrificed and hippocampi removed. Total RNA was isolated from the hippocampus and expression of total Bdnf , Bdnf transcript IV, tPA , Pgc-1a , GluR1 , NR2A , and NR2B were assessed with quantitative RT-PCR and total and mature Bdnf protein were assessed with ELISA. Results We found significantly higher Bdnf IV mRNA expression in PA males (p = 0.03) and females (p = 0.03) compared to SED animals. Total Bdnf mRNA expression was significantly greater in PA males compared to SED males (p = 0.01), but there was no difference in females. Similarly, we observed significantly higher mature Bdnf protein in PA males compared to SED males (p = 0.04), but not in females. Conclusion These findings indicate that the impact of long-term voluntary wheel running on transcriptional and post-translational regulation of Bdnf may be sex-dependent, though the activity-dependent Bdnf IV transcript is sensitive to exercise independent of sex. [ABSTRACT FROM AUTHOR]

This is the annual review of the exercise genomics literature in which we report on the highest quality papers published in 2014. We identified a number of noteworthy papers across a number of fields. In 70-89 yr olds, only 19% of angiotensin-converting enzyme (ACE) II homozygotes exhibited significant improvement in gait speed in response to a yearlong physical activity program compared to 30% of ACE D-allele carriers. New studies continue to support the notion that the genetic susceptibility to obesity, as evidenced by a genomic risk score (GRS; based on multiple single nucleotide polymorphisms), is attenuated by 40%-50% in individuals who are physically active, compared to those who are sedentary. One study reported that the polygenic risk for hypertriglyceridemia was reduced by 30%-40% in individuals with high cardiorespiratory fitness. One report showed that there was a significant interaction of a type 2 diabetes GRS with physical activity, with active individuals having the lowest risk of developing diabetes. The protective effect of physical activity was most pronounced in the low GRS tertile (hazard ratio, 0.82). The interaction observed with the diabetes GRS seemed to be dependent on a genetic susceptibility to insulin resistance and not insulin secretion. A significant interaction between PPARα sequence variants and physical activity levels on cardiometabolic risk was observed, with higher activity levels associated with lower risk only in carriers of specific genotypes and haplotypes. The review concludes with a discussion of the importance of replication studies when very large population or intervention discovery studies are not feasible or are cost prohibitive. [ABSTRACT FROM AUTHOR]

Reviews of several articles on exercise genomics are presented which includes the reports "Exercise and Diet Affect Quantitative Trait Loci for Body Weight and Composition Traits in an Advanced Intercross Population of Mice, by L. J. Leamy, S. A. Kelly, K. Hua, and D. Pomp in a 2012 issue of the journal "Physiological Genomics," "Variation in the Uncoupling Protein 2 and 3 Genes and Human Performance," by S. S. Dhamrait, A. G. Williams, and S. H. Day et al. in a 2012 issue of the "Journal of Applied Physiology," and "Knock-in Mice for the R50X Mutation in the PYGM Gene Present With McArdle Disease," by G. Nogales-Gadea, T. Pinos, and A. Lucia et al. in a 2012 issue of the journal "Brain."