Advances in exercise, fitness, and performance genomics in 2012

Genetics and athletic performance: a systematic SWOT analysis of non-systematic reviews

Exercise genetics/genomics is a growing research discipline comprising several Strengths and Opportunities but also deals with Weaknesses and Threats. This "systematic SWOT overview of non-systematic reviews" (sSWOT) aimed to identify the Strengths, Weaknesses, Opportunities, and Threats linked to exercise genetics/genomics. A systematic search was conducted in the Medline and Embase databases for non-systematic reviews to provide a comprehensive overview of the current literature/research area. The extracted data was thematically analyzed, coded, and categorized into SWOT clusters. In the 45 included reviews five Strengths, nine Weaknesses, six Opportunities, and three Threats were identified. The cluster of Strengths included "advances in technology", "empirical evidence", "growing research discipline", the "establishment of consortia", and the "acceptance/accessibility of genetic testing". The Weaknesses were linked to a "low research quality", the "complexity of exercise-related traits", "low generalizability", "high costs", "genotype scores", "reporting bias", "invasive methods", "research progress", and "causality". The Opportunities comprised of "precision exercise", "omics", "multicenter studies", as well as "genetic testing" as "commercial"-, "screening"-, and "anti-doping" detection tool. The Threats were related to "ethical issues", "direct-to-consumer genetic testing companies", and "gene doping". This overview of the present state of the art research in sport genetics/genomics indicates a field with great potential, while also drawing attention to the necessity for additional advancement in methodological and ethical guidance to mitigate the recognized Weaknesses and Threats. The recognized Strengths and Opportunities substantiate the capability of genetics/genomics to make significant contributions to the performance and wellbeing of athletes.

Genetic profiles to identify talents in elite endurance athletes and professional football players

The genetic profile that is needed to identify talents has been studied extensively in recent years. The main objective of this investigation was to approach, for the first time, the study of genetic variants in several polygenic profiles and their role in elite endurance and professional football performance by comparing the allelic and genotypic frequencies to the non-athlete population. In this study, genotypic and allelic frequencies were determined in 452 subjects: 292 professional athletes (160 elite endurance athletes and 132 professional football players) and 160 non-athlete subjects. Genotyping of polymorphisms in liver metabolisers (CYP2D6, GSTM1, GSTP and GSTT), iron metabolism and energy efficiency (HFE, AMPD1 and PGC1a), cardiorespiratory fitness (ACE, NOS3, ADRA2A, ADRB2 and BDKRB2) and muscle injuries (ACE, ACTN3, AMPD1, CKM and MLCK) was performed by Polymerase Chain Reaction-Single Nucleotide Primer Extension (PCR-SNPE). The combination of the polymorphisms for the “optimal” polygenic profile was quantified using the genotype score (GS) and total genotype score (TGS). Statistical differences were found in the genetic distributions between professional athletes and the non-athlete population in liver metabolism, iron metabolism and energy efficiency, and muscle injuries (p<0.001). The binary logistic regression model showed a favourable OR (odds ratio) of being a professional athlete against a non-athlete in liver metabolism (OR: 1.96; 95% CI: 1.28–3.01; p = 0.002), iron metabolism and energy efficiency (OR: 2.21; 95% CI: 1.42–3.43; p < 0.001), and muscle injuries (OR: 2.70; 95% CI: 1.75–4.16; p < 0.001) in the polymorphisms studied. Genetic distribution in professional athletes as regards endurance (professional cyclists and elite runners) and professional football players shows genetic selection in these sports disciplines.

Prediction and Identification of Power Performance Using Polygenic Models of Three Single-Nucleotide Polymorphisms in Chinese Elite Athletes

Objective: The manuscript aims to explore the relationship between power performance and SNPs of Chinese elite athletes and to create polygenic models.

Methods: One hundred three Chinese elite athletes were divided into the power group (n = 60) and endurance group (n = 43) by their sports event. Best standing long jump (SLJ) and standing vertical jump (SVJ) were collected. Twenty SNPs were genotyped by SNaPshot. Genotype distribution and allele frequency were compared between groups. Additional genotype data of 125 Chinese elite athletes were used to verify the screened SNPs. Predictive and identifying models were established by multivariate logistic regression analysis.

Results: ACTN3 (rs1815739), ADRB3 (rs4994), CNTFR (rs2070802), and PPARGC1A (rs8192678) were significantly different in genotype distribution or allele frequency between groups (p < 0.05). The predictive model consisted of ACTN3 (rs1815739), ADRB3 (rs4994), and PPARGC1A (rs8192678), the area under curve (AUC) of which was 0.736. The identifying model consisted of body mass index (BMI), standing vertical jump (SVJ), ACTN3, ADRB3, and PPARGC1A, the area under curve (AUC) of which was 0.854. Based on the two models, nomograms were created to visualize the results.

Conclusion: Two models can be used for talent identification in Chinese athletes, among which the predictive model can be used in adolescent athletes to predict development potential of power performance and the identifying one can be used in elite athletes to evaluate power athletic status. These can be applied quickly and visually by using nomograms. When the score is more than the 130 or 148 cutoff, it suggests that the athlete has a good development potential or a high level for power performance.

FABP2 Ala54Thr Polymorphism and Post-Training Changes of Body Composition and Biochemical Parameters in Caucasian Women

The functional FABP2 Ala54Thr polymorphism (rs1799883) is strongly associated with lipid and carbohydrate metabolism, although the function of its potential modifying effect on training-induced changes in obesity-related parameters is still unknown. The aim of the present study was to investigate the influence of the Ala54Thr polymorphism on post-training changes of selected body mass and body composition measurements, as well as with biochemical parameters of energy metabolism. Accordingly, alleles and genotypes distribution in a group of 168 young, nonobese Caucasian women measured for chosen body composition parameters, lipid profile, and glucose levels before and after the completion of a 12-week aerobic training program were studied. Although the obtained results showed changes in body mass, BMI, FM, %FM, FFM, TBW, HDL-C, and glucose levels during the training program, none of the examined parameters changed significantly across the FABP2 genotypes. Instead, we found a main effect of genotype on BMI (p = 0.033), with carriers of the Thr54 allele having a higher BMI during the whole study period compared with the Ala54 carriers. We confirm that the FABP2 Ala54Thr polymorphism may help identify women at risk for overweight and obesity. However, we did not notice evidence of an interaction between physical activity and the Ala54Thr polymorphism on the examined parameters.

Association of whole mtDNA, an NADPH G11914A variant, and haplogroups with high physical performance in an elite military troop

Physical performance is a multifactorial and complex trait influenced by environmental and hereditary factors. Environmental factors alone have been insufficient to characterize all outstanding phenotypes. Recent advances in genomic technologies have enabled the investigation of whole nuclear and mitochondrial genome sequences, increasing our ability to understand interindividual variability in physical performance. Our objective was to evaluate the association of mitochondrial polymorphic loci with physical performance in Brazilian elite military personnel. Eighty-eight male military personnel who participated in the Command Actions Course of the Army were selected. Total DNA was obtained from blood samples and a complete mitochondrial genome (mtDNA) was sequenced using Illumina MiSeq platform. Twenty-nine subjects completed the training program (FINISHED, 'F'), and fifty-nine failed to complete (NOT_FINISHED, 'NF'). The mtDNA from NF was slightly more similar to genomes from African countries frequently related to endurance level. Twenty-two distinct mtDNA haplogroups were identified corroborating the intense genetic admixture of the Brazilian population, but their distribution was similar between the two groups (FST=0.0009). Of 745 polymorphisms detected in the mtDNA, the position G11914A within the NADPH gene component of the electron transport chain, was statistically different between F and NF groups (P=0.011; OR: 4.286; 95%CI: 1.198-16.719), with a higher frequency of the G allele in group F individuals). The high performance of military personnel may be mediated by performance-related genomic traits. Thus, mitochondrial genetic markers such as the ND4 gene may play an important role on physical performance variability.

Structure-activity relationship analysis of dammarane-type natural products as muscle-type creatine kinase activators

Muscle-type creatine kinase (CK-MM) is the target protein of ginsenosides in skeletal muscle. 20(S)-protopanaxadiol [20(S)-PPD] is an activator of CK-MM and exerts an anti-fatigue effect. In this study, twelve dammarane-type compounds were used for structure-activity relationship analysis in terms of enzyme activity, intermolecular interaction, and molecular docking. Enzyme activity analysis showed that 20(S)-PPD, 20(R)-PPD, 20(S)-protopanaxatriol [20(S)-PPT], 25-OH-PPD, 24-COOH-PPD, panaxadiol (PD), and ginsenoside Rh2 significantly increased CK-MM activity. Panaxatriol (PT), ocotillol, ginsenoside Rg1, and ginsenoside Rd had no significant influence on CK-MM activity, while jujubogenin inhibited its activity. Biolayer Interferometry (BLI) assay produced the same results as those on enzyme activity. The interaction intensity between dammarane-type compounds and CK-MM was linearly related to the compounds' maximum increment rate of enzyme activity. Molecular docking showed the following sequence of docking scores: Rd > Rg1 > Rh2 > 24-COOH-PPD > 20(S)-PPD > 20(S)-PPT > 25-OH-PPD > 20(R)-PPD > ocotillol > PT > PD > jujubogenin. We demonstrated that 20(S)-PPD was the best activator of CK-MM among the 12 dammarane-type compounds. The cyclization of the dammarane side chain, the hydroxyl group at position C6, and the glycosylation of C3, C6, and C20 reduced the ability to activate CK-MM. These findings can help in the development of enhanced CK-MM activators through structural modification.

AMPD1 C34T Polymorphism (rs17602729) Is Not Associated with Post-Exercise Changes of Body Weight, Body Composition, and Biochemical Parameters in Caucasian Females

Background: The C34T polymorphism (rs 17602729) in adenosine monophosphate deaminase 1 gene (AMPD1) is associated with muscular energy metabolism in exercise. However, the role of its potential modifying impact on exercise-induced changes in obesity related parameters is unknown. The aim of the study was to determine if the C34T polymorphism influences the effects of an exercise training. Methods: This study examines a group of one hundred and sixty-eight, young, non-obese Caucasian women in Poland who took part in a 12-week aerobic training program to determine the impact of allele and genotype distribution on training outcomes. Results: A two-way analysis of variance ANOVA was conducted assuming a dominant model by pooling rare homozygotes and heterozygotes (TT + CT, n = 79) and comparing against common homozygotes (CC, n = 89). Our results showed that the AMPD1 C34T polymorphism was not related with selected parameters in study group. After completing the 12-week training program, a wide array of parameters (body mass, body mass index, fat mass, free fat mass, total body water) were significantly changed in the study participants with the exception of AMPD1 genotypes, among whom no significant changes were observed. Conclusions: The results did not confirm that harboring the rs 17602729 T allele influences the effects of the training program.

A Medal in the Olympics Runs in the Family: A Cohort Study of Performance Heritability in the Games History

Introduction: Elite performance in sports is known to be influenced by heritable components, but the magnitude of such an influence has never been quantified.

Hypothesis/Objectives: We hypothesized that having a former world-class champion in the family increases the chances of an athlete to repeat the achievement of her or his kinship. We aimed to measure the heritability of a medal in the Olympic Games (OG) among Olympians and to estimate the percentage of the genetic contribution to such a heritance.

Study Design: Twin-family study of a retrospective cohort.

Methods: All the 125,051 worldwide athletes that have participated in the OG between 1896 and 2012 were included. The expected probability to win a medal in the OG was defined as the frequency of medallists among Olympians without any blood kinship in the OG. This expected probability was compared with the probability to win a medal for Olympians having a kinship (grandparent, aunt/uncle, parent, or siblings) with a former Olympian that was a (1) non-medallist or (2) medallist. The heritability of the genetically determined phenotype (h²) was assessed by probandwise concordance rates among dizygotic (DZ) and monozygotic (MZ) twins (n = 90).

Results: The expected probability to win a medal in the OG was 20.4%. No significant difference of medal probability was found in the subgroups of Olympians with a Non-medallist kinship, except among siblings for whom this probability was lower: 13.3% (95% CI 11.2–14.8). The medal probability was significantly greater among Olympians having a kinship with a former Olympic Medallist: 44.4% for niece/nephew (33.7–54.2); 43.4% for offspring (37.4–48.6); 64.8% for siblings (61.2–68.8); 75.5% for DZ twins (63.3–86.6); and 85.7% for MZ twins (63.6–96.9); with significantly greater concordance between MZ than DZ (p = 0.01) and h² estimated at 20.5%.

Conclusion: Having a kinship with a former Olympic medallist is associated with a greater probability for an Olympian to also become a medallist, the closer an athlete is genetically to such kinship the greater this probability. Once in the OG, the genetic contribution to win a medal is estimated to be 20.5%.

Advances in Exercise, Fitness, and Performance Genomics in 2015

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 △TG, whereas the baseline expression of 11 genes predicted 27% of △TG. A composite SNP score based on the top eight SNPs derived from the genomic and transcriptomic analyses was the strongest predictor of ΔTG, 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."

Effects of Light-Emitting Diode Therapy on Muscle Hypertrophy, Gene Expression, Performance, Damage, and Delayed-Onset Muscle Soreness: Case-control Study with a Pair of Identical Twins

OBJECTIVE

The aim of this study was to verify how a pair of monozygotic twins would respond to light-emitting diode therapy (LEDT) or placebo combined with a strength-training program during 12 weeks.

DESIGN

This case-control study enrolled a pair of male monozygotic twins, allocated randomly to LEDT or placebo therapies. Light-emitting diode therapy or placebo was applied from a flexible light-emitting diode array (λ = 850 nm, total energy = 75 J, t = 15 seconds) to both quadriceps femoris muscles of each twin immediately after each strength training session (3 times/wk for 12 weeks) consisting of leg press and leg extension exercises with load of 80% and 50% of the 1-repetition maximum test, respectively. Muscle biopsies, magnetic resonance imaging, maximal load, and fatigue resistance tests were conducted before and after the training program to assess gene expression, muscle hypertrophy and performance, respectively. Creatine kinase levels in blood and visual analog scale assessed muscle damage and delayed-onset muscle soreness, respectively, during the training program.

RESULTS

Compared with placebo, LEDT increased the maximal load in exercise and reduced fatigue, creatine kinase, and visual analog scale. Gene expression analyses showed decreases in markers of inflammation (interleukin 1β) and muscle atrophy (myostatin) with LEDT. Protein synthesis (mammalian target of rapamycin) and oxidative stress defense (SOD2 [mitochondrial superoxide dismutase]) were up-regulated with LEDT, together with increases in thigh muscle hypertrophy.

CONCLUSIONS

Light-emitting diode therapy can be useful to reduce muscle damage, pain, and atrophy, as well as to increase muscle mass, recovery, and athletic performance in rehabilitation programs and sports medicine.

Endurance Exercise Ability in the Horse: A Trait with Complex Polygenic Determinism

Endurance horses are able to run at more than 20 km/h for 160 km (in bouts of 30-40 km). This level of performance is based on intense aerobic metabolism, effective body heat dissipation and the ability to endure painful exercise. The known heritabilities of endurance performance and exercise-related physiological traits in Arabian horses suggest that adaptation to extreme endurance exercise is influenced by genetic factors. The objective of the present genome-wide association study (GWAS) was to identify single nucleotide polymorphisms (SNPs) related to endurance racing performance in 597 Arabian horses. The performance traits studied were the total race distance, average race speed and finishing status (qualified, eliminated or retired). We used three mixed models that included a fixed allele or genotype effect and a random, polygenic effect. Quantile-quantile plots were acceptable, and the regression coefficients for actual vs. expected log10p-values ranged from 0.865 to 1.055. The GWAS revealed five significant quantitative trait loci (QTL) corresponding to 6 SNPs on chromosomes 6, 1, 7, 16, and 29 (two SNPs) with corrected p-values from 1.7 × 10-6 to 1.8 × 10-5. Annotation of these 5 QTL revealed two genes: sortilin-related VPS10-domain-containing receptor 3 (SORCS3) on chromosome 1 is involved in protein trafficking, and solute carrier family 39 member 12 (SLC39A12) on chromosome 29 is active in zinc transport and cell homeostasis. These two coding genes could be involved in neuronal tissues (CNS). The other QTL on chromosomes 6, 7, and 16 may be involved in the regulation of the gene expression through non-coding RNAs, CpG islands and transcription factor binding sites. On chromosome 6, a new candidate equine long non-coding RNA (KCNQ1OT1 ortholog: opposite antisense transcript 1 of potassium voltage-gated channel subfamily Q member 1 gene) was predicted in silico and validated by RT-qPCR in primary cultures of equine myoblasts and fibroblasts. This lncRNA could be one element of the cardiac rhythm regulation. Our GWAS revealed that equine performance during endurance races is a complex polygenic trait, and is partially governed by at least 5 QTL: two coding genes involved in neuronal tissues and three other loci with many regulatory functions such as slowing down heart rate.

ACTN3 R577X Gene Variant Is Associated With Muscle-Related Phenotypes in Elite Chinese Sprint/Power Athletes

Yang, R, Shen, X, Wang, Y, Voisin, S, Cai, G, Fu, Y, Xu, W, Eynon, N, Bishop, DJ, and Yan, X. ACTN3 R577X gene variant is associated with muscle-related phenotypes in elite Chinese sprint/power athletes. J Strength Cond Res 31(4): 1107-1115, 2017-The ACTN3 R577X polymorphism (rs1815739) has been shown to influence athletic performance. The aim of this study was to investigate the prevalence of this polymorphism in elite Chinese track and field athletes, and to explore its effects on athletes' level of competition and lower-extremity power. We compared the ACTN3 R577X genotypes and allele frequencies in 59 elite sprint/power athletes, 44 elite endurance athletes, and 50 healthy controls from Chinese Han origin. We then subcategorized the athletes into international level and national level and investigated the effects of ACTN3 genotype on lower-extremity power. Genotype distribution of the sprint/power athletes was significantly different from endurance athletes (p = 0.001) and controls (p < 0.001). The frequency of the RR genotype was significantly higher in international-level than that in the national-level sprint/power athletes (p = 0.004), with no international-level sprint/power athletes with XX genotype. The best standing long jump and standing vertical jump results of sprint/power athletes were better in the RR than those in the RX + XX genotypes (p = 0.004 and p = 0.001, respectively). In conclusion, the ACTN3 R577X polymorphism influences the level of competition and lower-extremity power of elite Chinese sprint/power athletes. Including relevant phenotypes such as muscle performance in future studies is important to further understand the effects of gene variants on elite athletic performance.

Exploring the relationship between α-actinin-3 deficiency and obesity in mice and humans

Obesity is a worldwide health crisis, and the identification of genetic modifiers of weight gain is crucial in understanding this complex disorder. A common null polymorphism in the fast fiber-specific gene ACTN3 (R577X) is known to influence skeletal muscle function and metabolism. α-Actinin-3 deficiency occurs in an estimated 1.5 billion people worldwide, and results in reduced muscle strength and a shift towards a more efficient oxidative metabolism. The X-allele has undergone strong positive selection during recent human evolution, and in this study, we sought to determine whether ACTN3 genotype influences weight gain and obesity in mice and humans. An Actn3 KO mouse has been generated on two genetic backgrounds (129X1/SvJ and C57BL/6J) and fed a high-fat diet (HFD, 45% calories from fat). Anthropomorphic features (including body weight) were examined and show that Actn3 KO 129X1/SvJ mice gained less weight compared to WT. In addition, six independent human cohorts were genotyped for ACTN3 R577X (Rs1815739) and body mass index (BMI), waist-to-hip ratio-adjusted BMI (WHRadjBMI) and obesity-related traits were assessed. In humans, ACTN3 genotype alone does not contribute to alterations in BMI or obesity.

G Allele of the IGF2 ApaI Polymorphism Is Associated With Judo Status

Itaka, T, Agemizu, K, Aruga, S, and Machida, S. G allele of the IGF2 ApaI polymorphism is associated with judo status. J Strength Cond Res 30(7): 2043-2048, 2016-Previous studies have reported that the insulin-like growth factor 2 (IGF2) ApaI polymorphism is associated with body mass index, fat mass, and grip strength. Competitive judo requires high levels of strength and power. The purpose of this study was to investigate the association between the IGF2 ApaI and ACTN3 R577X polymorphisms and judo status. The subjects were 156 male judo athletes from a top-level university in Japan. They were divided into 3 groups based on their competitive history: international-level athletes, national-level athletes, and others. Genomic DNA was extracted from the saliva of each athlete, and the maximal isometric strength of the trunk muscles and handgrip strength were measured. Genotyping by polymerase chain reaction-restriction fragment length polymorphism was used to detect IGF2 (rs680) and α-actinin-3 (ACTN3) (rs1815739) gene polymorphisms. The genotype frequencies of the 2 gene polymorphisms were compared among the 3 groups of judo athletes and controls. International-level judo athletes showed a higher frequency of the GG + GA genotype of the IGF2 gene than that of the national-level athletes and others. There was an inverse linear correlation between the frequency of the IGF2 AA genotype and level of judo performance (p = 0.041). Back muscle strength relative to height and weight was higher in subjects with the GG + GA genotype than in those with the AA genotype. Conversely, the ACTN3 R577X polymorphism was not associated with judo status. Additionally, no differences were found in back muscle or handgrip strength among the ACTN3 genotypes. In conclusion, the results indicate that the IGF2 gene polymorphism may be associated with judo status.

Heritability estimates of muscle strength-related phenotypes: A systematic review and meta-analysis

The purpose of this study was to clarify the heritability estimates of human muscle strength-related phenotypes (H² -msp). A systematic literature search was conducted using PubMed (through August 22, 2016). Studies reporting the H² -msp for healthy subjects in a sedentary state were included. Random-effects models were used to calculate the weighted mean heritability estimates. Moreover, subgroup analyses were performed based on phenotypic categories (eg, grip strength, isotonic strength, jumping ability). Sensitivity analyses were also conducted to investigate potential sources of heterogeneity of H² -msp, which included age and sex. Twenty-four articles including 58 measurements were included in the meta-analysis. The weighted mean H² -msp for all 58 measurements was 0.52 (95% confidence intervals [CI]: 0.48-0.56), with high heterogeneity (I² =91.0%, P<.001). Subgroup analysis showed that the heritability of isometric grip strength, other isometric strength, isotonic strength, isokinetic strength, jumping ability, and other power measurements was 0.56 (95% CI: 0.46-0.67), 0.49 (0.47-0.52), 0.49 (0.32-0.67), 0.49 (0.37-0.61), 0.55 (0.45-0.65), and 0.51 (0.31-0.70), respectively. The H² -msp decreased with age (P<.05). In conclusion, our results indicate that the influence of genetic and environmental factors on muscle strength-related phenotypes is comparable. Moreover, the role of environmental factors increased with age. These findings may contribute toward an understanding of muscle strength-related phenotypes.

Direct-to-consumer genetic testing for predicting sports performance and talent identification: Consensus statement

The general consensus among sport and exercise genetics researchers is that genetic tests have no role to play in talent identification or the individualised prescription of training to maximise performance. Despite the lack of evidence, recent years have witnessed the rise of an emerging market of direct-to-consumer marketing (DTC) tests that claim to be able to identify children's athletic talents. Targeted consumers include mainly coaches and parents. There is concern among the scientific community that the current level of knowledge is being misrepresented for commercial purposes. There remains a lack of universally accepted guidelines and legislation for DTC testing in relation to all forms of genetic testing and not just for talent identification. There is concern over the lack of clarity of information over which specific genes or variants are being tested and the almost universal lack of appropriate genetic counselling for the interpretation of the genetic data to consumers. Furthermore independent studies have identified issues relating to quality control by DTC laboratories with different results being reported from samples from the same individual. Consequently, in the current state of knowledge, no child or young athlete should be exposed to DTC genetic testing to define or alter training or for talent identification aimed at selecting gifted children or adolescents. Large scale collaborative projects, may help to develop a stronger scientific foundation on these issues in the future.

Genetic variants influencing effectiveness of exercise training programmes in obesity - an overview of human studies

Frequent and regular physical activity has significant benefits for health, including improvement of body composition and help in weight control. Consequently, promoting training programmes, particularly in those who are genetically predisposed, is a significant step towards controlling the presently increasing epidemic of obesity. Although the physiological responses of the human body to exercise are quite well described, the genetic background of these reactions still remains mostly unknown. This review not only summarizes the current evidence, through a literature review and the results of our studies on the influence of gene variants on the characteristics and range of the body's adaptive response to training, but also explores research organization problems, future trends, and possibilities. We describe the most reliable candidate genetic markers that are involved in energy balance pathways and body composition changes in response to training programmes, such as FTO, MC4R, ACE, PPARG, LEP, LEPR, ADRB2, and ADRB3. This knowledge can have an enormous impact not only on individualization of exercise programmes to make them more efficient and safer, but also on improved recovery, traumatology, medical care, diet, supplementation and many other areas. Nevertheless, the current studies still represent only the first steps towards a better understanding of the genetic factors that influence obesity-related traits, as well as gene variant x physical activity interactions, so further research is necessary.

Advances in exercise, fitness, and performance genomics in 2014

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.

How can bioinformatics and toxicogenomics assist the next generation of research on physical exercise and athletic performance

The past 2-3 decades have seen an explosion in analytical areas related to "omic" technologies. These advancements have reached a point where their application can be and are being used as a part of exercise physiology and sport performance research. Such advancements have drastically enabled researchers to analyze extremely large groups of data that can provide amounts of information never before made available. Although these "omic" technologies offer exciting possibilities, the analytical costs and time required to complete the statistical approaches are substantial. The areas of exercise physiology and sport performance continue to witness an exponential growth of published studies using any combination of these techniques. Because more investigators within these traditionally applied science disciplines use these approaches, the need for efficient, thoughtful, and accurate extraction of information from electronic databases is paramount. As before, these disciplines can learn much from other disciplines who have already developed software and technologies to rapidly enhance the quality of results received when searching for key information. In addition, further development and interest in areas such as toxicogenomics could aid in the development and identification of more accurate testing programs for illicit drugs, performance enhancing drugs abused in sport, and better therapeutic outcomes from prescribed drug use. This review is intended to offer a discussion related to how bioinformatics approaches may assist the new generation of "omic" research in areas related to exercise physiology and toxicogenomics. Consequently, more focus will be placed on popular tools that are already available for analyzing such complex data and highlighting additional strategies and considerations that can further aid in developing new tools and data management approaches to assist future research in this field. It is our contention that introducing more scientists to how this type of work can complement existing experimental approaches within exercise physiology and sport performance will foster additional discussion and stimulate new research in these areas.

Angiogenesis-related ultrastructural changes to capillaries in human skeletal muscle in response to endurance exercise

The ultrastructure of capillaries in skeletal muscle was morphometrically assessed in vastus lateralis muscle (VL) biopsies taken before and after exercise from 22 participants of two training studies. In study 1 (8 wk of ergometer training), light microscopy revealed capillary-fiber (C/F) ratio (+27%) and capillary density (+16%) to be higher (P ≤ 0.05) in postexercise biopsies than in preexercise biopsies from all 10 participants. In study 2 (6 mo of moderate running), C/F ratio and capillary density were increased (+23% and +20%; respectively, P ≤ 0.05) in VL biopsies from 6 angiogenesis responders (AR) after training, whereas 6 nonangiogenesis responders (NR) showed nonsignificant changes in these structural indicators (-4%/-4%, respectively). Forty capillary profiles per participant were evaluated by point and intersection counting on cross sections after transmission electron microscopy. In study 1, volume density (Vv) and mean arithmetic thickness (T) of endothelial cells (ECs; +19%/+17%, respectively) and pericytes (PCs; +20%/+21%, respectively) were higher (P ≤ 0.05), whereas Vv and T of the pericapillary basement membrane (BM) were -23%/-22% lower (P ≤ 0.05), respectively, in posttraining biopsies. In study 2, exercise-related differences between AR and NR-groups were found for Vv and T of PCs (AR, +26%/+22%, respectively, both P ≤ 0.05; NR, +1%/-3%, respectively, both P > 0.05) and BM (AR, -14%/-13%, respectively, both P ≤ 0.05; NR, -9%/-11%, respectively, P = 0.07/0.10). Vv and T of ECs were higher (AR, +16%/+18%, respectively; NR, +6%/+6%, respectively; all P ≤ 0.05) in both groups. The PC coverage was higher (+13%, P ≤ 0.05) in VL biopsies of individuals in the AR group but nonsignificantly altered (+3%, P > 0.05) in those of the NR group after training. Our study suggests that intensified PC mobilization and BM thinning are related to exercise-induced angiogenesis in human skeletal muscle, whereas training per se induces EC-thickening.

Predictors of individual adaptation to high-volume or high-intensity endurance training in recreational endurance runners

The aim of this study was to investigate factors that can predict individual adaptation to high-volume or high-intensity endurance training. After the first 8-week preparation period, 37 recreational endurance runners were matched into the high-volume training group (HVT) and high-intensity training group (HIT). During the next 8-week training period, HVT increased their running training volume and HIT increased training intensity. Endurance performance characteristics, heart rate variability (HRV), and serum hormone concentrations were measured before and after the training periods. While HIT improved peak treadmill running speed (RSpeak ) 3.1 ± 2.8% (P < 0.001), no significant changes occurred in HVT (RSpeak : 0.5 ± 1.9%). However, large individual variation was found in the changes of RSpeak in both groups (HVT: -2.8 to 4.1%; HIT: 0-10.2%). A negative relationship was observed between baseline high-frequency power of HRV (HFPnight ) and the individual changes of RSpeak (r = -0.74, P = 0.006) in HVT and a positive relationship (r = 0.63, P = 0.039) in HIT. Individuals with lower HFP showed greater change of RSpeak in HVT, while individuals with higher HFP responded well in HIT. It is concluded that nocturnal HRV can be used to individualize endurance training in recreational runners.

The heritable path of human physical performance: from single polymorphisms to the "next generation"

Human physical performance is a complex multifactorial trait. Historically, environmental factors (e.g., diet, training) alone have been unable to explain the basis of all prominent phenotypes for physical performance. Therefore, there has been an interest in the study of the contribution of genetic factors to the development of these phenotypes. Support for a genetic component is found with studies that shown that monozygotic twins were more similar than were dizygotic twins for many physiological traits. The evolution of molecular techniques and the ability to scan the entire human genome enabled association of several genetic polymorphisms with performance. However, some biases related to the selection of cohorts and inadequate definition of the study variables have complicated the already difficult task of studying such a large and polymorphic genome, often resulting in inconsistent results about the influence of candidate genes. This review aims to provide a critical overview of heritable genetic aspects. Novel molecular technologies, such as next-generation sequencing, are discussed and how they can contribute to improving understanding of the molecular basis for athletic performance. It is important to ensure that the large amount of data that can be generated using these tools will be used effectively by ensuring well-designed studies.

ACE and UCP2 gene polymorphisms and their association with baseline and exercise-related changes in the functional performance of older adults

Maintaining high levels of physical function is an important aspect of successful ageing. While muscle mass and strength contribute to functional performance in older adults, little is known about the possible genetic basis for the heterogeneity of physical function in older adults and in how older adults respond to exercise. Two genes that have possible roles in determining levels of muscle mass, strength and function in young and older adults are angiotensin-converting enzyme (ACE) and mitochondrial uncoupling protein 2 (UCP2). This study examined whether polymorphisms in these two individual genes were associated with baseline functional performance levels and/or the training-related changes following exercise in previously untrained older adults. Five-eight Caucasian older adults (mean age 69.8 years) with no recent history of resistance training enrolled in a 12 week program of resistance, balance and cardiovascular exercises aimed at improving functional performance. Performance in 6 functional tasks was recorded at baseline and after 12 weeks. Genomic DNA was assayed for the ACE intron 16 insertion/deletion (I/D) and the UCP2 G-866A polymorphism. Baseline differences among genotype groups were tested using analysis of variance. Genotype differences in absolute and relative changes in physical function among the exercisers were tested using a general linear model, adjusting for age and gender. The genotype frequencies for each of the studied polymorphisms conformed to the Hardy-Weinberg equilibrium. The ACE I/D genotype was significantly associated with mean baseline measures of handgrip strength (II 30.9 ± 3.01 v. ID 31.7 ± 1.48 v. DD 29.3 ± 2.18 kg, p < 0.001), 8ft Up and Go time (II 6.45 ± 0.48 v. ID/DD 4.41 ± 0.19 s, p < 0.001) and 6 min walk distance (II 458 ± 28.7 v. ID/DD 546 ± 12.1m, p = 0.008). The UCP2 G-866A genotype was also associated with baseline 8ft Up and Go time (GG 5.45 ± 0.35 v. GA 4.47 ± 0.26 v. AA 3.89 ± 0.71 s, p = 0.045). After 12 weeks of training, a significant difference between UCP2 G-886A genotype groups for change in 8ft Up and Go time was detected (GG −0.68 ± 0.17 v. GA −0.10 ± 0.14 v. AA +0.05 ± 0.31 s, p = 0.023). While several interesting and possibly consistent associations with older adults’ baseline functional performance were found for the ACE and UCP2 polymorphisms, we found no strong evidence of genetic associations with exercise responses in this study. The relative equivalence of some of these training-response findings to the literature may have reflected the current study’s focus on physical function rather than just strength, the relatively high levels of baseline function for some genotype groups as well as the greater statistical power for detecting baseline differences than the training-related changes.

The association of fitness with reduced cardiometabolic risk among smokers

INTRODUCTION

Despite the health benefits associated with smoking cessation, continued smoking and relapse following cessation are common. Physical activity is associated with reduced risk of cardiovascular disease in general, though less is known about how cardiorespiratory fitness may influence cardiometabolic risk among smokers. Strategies are needed to protect against the health consequences of smoking among those unwilling or unable to quit smoking. The purpose of this study is to determine whether greater cardiorespiratory fitness is associated with reduced metabolic risk among smokers.

METHODS

The prospective influence of estimated cardiorespiratory fitness (i.e., maximal METs) on the development of metabolic syndrome and its components were examined among adult smokers (N=1,249) who completed at least two preventive medical visits at the Cooper Clinic (Dallas TX) between 1979 and 2011. Statistical analyses were completed in 2013 and 2014.

RESULTS

The rate and risk for metabolic syndrome, as well as abnormal fasting glucose and high-density lipoprotein cholesterol levels declined linearly with increases in cardiorespiratory fitness (all p<0.05). Smokers in the moderate and high fitness categories had significantly reduced risk of developing metabolic syndrome and elevated fasting glucose relative to smokers in the lowest fitness category. In addition, smokers in the high fitness category were less likely to develop abnormal high-density lipoprotein cholesterol levels.

CONCLUSIONS

Moderate to high cardiorespiratory fitness among smokers is associated with a reduced likelihood of developing certain cardiovascular disease risk factors and metabolic syndrome.

FTO gene: association to weight regain after lifestyle intervention in overweight children

OBJECTIVE

Polymorphisms in intron 1 of the 'fat mass and obesity-associated' (FTO) gene are associated with weight status. We hypothesized that the risk allele at a polymorphism in intron 1 of FTO is associated with weight regain after end of lifestyle intervention.

METHODS

We longitudinally analyzed the changes of weight status as BMI-SDS in 346 unrelated overweight children (mean age 10.6 ± 2.6 years, 45% male, mean BMI-SDS 2.39 ± 0.49) both at the end of a 1-year lifestyle intervention and 1 year after the end of this intervention. We genotyped the obesity risk SNP rs9939609 at FTO by ARMS-PCR.

RESULTS

The children reduced their BMI-SDS (-0.29 ± 0.33; p < 0.001) during intervention and increased their BMI-SDS between the end of intervention and 1 year later (+0.10 ± 0.41; p < 0.001). The obesity risk allele at FTO SNP rs9939609 was not associated with BMI-SDS reduction during the lifestyle intervention (p = 0.622), but with weight regain 1 year after end of the intervention in multiple linear regression analyses adjusted for age, sex, pubertal stage, and baseline BMI-SDS (Bonferroni corrected p = 0.002).

CONCLUSIONS

The obesity risk allele at a polymorphism in intron 1 of FTO was associated with weight regain 1 year after a 1-year lifestyle intervention.

A variant within the AQP1 3'-untranslated region is associated with running performance, but not weight changes, during an Ironman Triathlon

The objective of this study was to test the association of the rs1049305 (G > C) variant within the 3'-untranslated region of the aquaporin 1 gene, AQP1, with changes in body weight, post-race serum sodium concentration and performance in Ironman triathletes. Five hundred and four male Ironman triathletes were genotyped for the rs1049305 variant within the AQP1 gene. Change in pre- and post-race body weight was calculated for 470 triathletes and used as a proxy for changes in body fluid during the race, as well as to divide triathletes into biologically relevant weight-loss groups (0-3%, 3-5% and >5%). There were no rs1049305 genotype effects on post-race serum sodium concentrations (P = 0.647), pre-race weight (P = 0.610) nor relative weight change during the Ironman Triathlons (P = 0.705). In addition, there were no significant differences in genotype (P = 0.640) nor allele (P = 0.643) distributions between the weight loss groups. However, triathletes who carry a C-allele were found to complete the 42.2-km run stage faster (mean 286, s = 49 min) than triathletes with a GG genotype (mean 296, s = 47 min; P = 0.032). The AQP1 rs1049305 variant is associated with running performance, but not relative body weight change, during the 2000, 2001 and 2006 South African Ironman Triathlons.

Genetic variations underlying self-reported physical functioning: a review

PURPOSE

Genetic associations with self-reported physical functioning (SPF) are less well-studied than genetic associations with performance-measured physical functioning (PPF). We review the literature on the associations of genetic variations on SPF. We provide an overview of SPF assessment, genetic contributions to SPF including heritability, effects of genetic variations and mutations, and effects of interventions on the gene-SPF relationship. We also aim to provide directions for future research.

METHODS

A computerized literature search using PubMed, Web of Science, and PsychInfo was conducted to select relevant literature published up to November 2013. Inclusion criteria were the use of an SPF questionnaire, original articles in English on human subjects, published in peer-reviewed journals and reporting significant associations between SPF and the genome.

RESULTS

Nineteen articles were included. SPF was commonly assessed with the Short Form-36 questionnaire involving mainly convenience samples of either older persons or chronically ill. Heritability estimates were 10-30 %. Candidate genes associated with SPF could be ascribed to biological pathways associated with neurodegeneration, physiological systems regulation, or cell regulation. The APOE gene associated with neurodegeneration was most studied (n = 3). Three papers included both SPF and PPF assessments. No genome-wide association study on SPF has been conducted.

CONCLUSIONS

Associations between SPF and the genome have been investigated in selected populations in a limited number of publications. Future research should consider increasing sample variation and incorporate both SPF and PPF assessments. Also, longitudinal studies should be conducted in order to elicit stronger conclusions regarding the genetic associations with SPF.

Epigenetic adaptation to regular exercise in humans

Regular exercise has numerous health benefits, for example, it reduces the risk of cardiovascular disease and cancer. It has also been shown that the risk of type 2 diabetes can be halved in high-risk groups through nonpharmacological lifestyle interventions involving exercise and diet. Nevertheless, the number of people living a sedentary life is dramatically increasing worldwide. Researchers have searched for molecular mechanisms explaining the health benefits of regular exercise for decades and it is well established that exercise alters the gene expression pattern in multiple tissues. However, until recently it was unknown that regular exercise can modify the genome-wide DNA methylation pattern in humans. This review will focus on recent progress in the field of regular exercise and epigenetics.

Likely additive ergogenic effects of combined preexercise dietary nitrate and caffeine ingestion in trained cyclists

Aims. To evaluate the possible additive effects of beetroot juice plus caffeine on exercise performance. Methods. In a randomized, double-blinded study design, fourteen healthy well-trained men aged 22 ± 3 years performed four trials on different occasions following preexercise ingestion of placebo (PLA), PLA plus 5 mg/kg caffeine (PLA+C), beetroot juice providing 8 mmol of nitrate (BR), and beetroot juice plus caffeine (BR+C). Participants cycled at 60% maximal oxygen uptake (V˙O2max) for 30 min followed by a time to exhaustion (TTE) trial at 80% V˙O2max. Saliva was collected before supplement ingestion, before exercise, and after the TTE trial for salivary nitrate, nitrite, and cortisol analysis. Results. In beetroot trials, saliva nitrate and nitrite increased >10-fold before exercise compared with preingestion (P ≤ 0.002). TTE in BR+C was 46% higher than in PLA (P = 0.096) and 18% and 27% nonsignificant TTE improvements were observed on BR+C compared with BR and PLA+C alone, respectively. Lower ratings of perceived exertion during TTE were found during 80% V˙O2max on BR+C compared with PLA and PLA+C (P < 0.05 for both). Conclusions. Acute preexercise beetroot juice coingestion with caffeine likely has additive effects on exercise performance compared with either beetroot or caffeine alone.

Genomic haplotype within the Peroxisome Proliferator-Activated Receptor Delta (PPARD) gene is associated with elite athletic status

Peroxisome proliferator-activated receptor delta (PPARδ; encoded by the PPARD gene) plays a role in energy metabolism and mitochondrial function. We have investigated the distribution of PPARD rs2267668, rs2016520 and rs1053049 polymorphisms, individually and in haplotype, in a cohort of 660 elite athletes which was subdivided into four different groups based on the different metabolic demands of their respective sports and 704 healthy controls. PPARD rs2016529 and rs1053049 were individually associated with overall elite athletic performance (P = 0.00002; and P = 0.0002) and also with athletes grouped as strength endurance (P = 0.00008; and P = 0.0003). Furthermore, PPARD A/C/C haplotype (rs2267668/rs2016520/rs1053049) was significantly underrepresented in all athletes and each subgroup of athletes when compared with controls (P < 0.000001), suggesting that harboring this specific haplotype is unfavorable for becoming an elite athlete. These results help to identify which genetic profiles may contribute to elite athletic performance, specifically the role of variants within the PPARD gene, and may be useful in talent identification or optimizing the response to training.

Personalized lifestyle medicine: relevance for nutrition and lifestyle recommendations

Public health recommendations for lifestyle modification, including diet and physical activity, have been widely disseminated for the prevention and treatment of disease. These guidelines are intended for the overall population without significant consideration for the individual with respect to one's genes and environment. Personalized lifestyle medicine is a newly developed term that refers to an approach to medicine in which an individual's health metrics from point-of-care diagnostics are used to develop lifestyle medicine-oriented therapeutic strategies for improving individual health outcomes in managing chronic disease. Examples of the application of personalized lifestyle medicine to patient care include the identification of genetic variants through laboratory tests and/or functional biomarkers for the purpose of designing patient-specific prescriptions for diet, exercise, stress, and environment. Personalized lifestyle medicine can provide solutions to chronic health problems by harnessing innovative and evolving technologies based on recent discoveries in genomics, epigenetics, systems biology, life and behavioral sciences, and diagnostics and clinical medicine. A comprehensive, personalized approach to medicine is required to promote the safety of therapeutics and reduce the cost of chronic disease. Personalized lifestyle medicine may provide a novel means of addressing a patient's health by empowering them with information they need to regain control of their health.

Genomics of elite sporting performance: what little we know and necessary advances

Numerous reports of genetic associations with performance-related phenotypes have been published over the past three decades but there has been limited progress in discovering and characterising the genetic contribution to elite/world-class performance, mainly owing to few coordinated research efforts involving major funding initiatives/consortia and the use primarily of the candidate gene analysis approach. It is timely that exercise genomics research has moved into a new era utilising well-phenotyped, large cohorts and genome-wide technologies--approaches that have begun to elucidate the genetic basis of other complex traits/diseases. This review summarises the most recent and significant findings from sports genetics and explores future trends and possibilities.

Genomics of elite sporting performance: what little we know and necessary advances

Numerous reports of genetic associations with performance- and injury-related phenotypes have been published over the past three decades; these studies have employed primarily the candidate gene approach to identify genes that associate with elite performance or with variation in performance-and/or injury-related traits. Although generally with small effect sizes and heavily prone to type I statistic error, the number of candidate genetic variants that can potentially explain elite athletic status, injury predisposition, or indeed response to training will be much higher than that examined by numerous biotechnology companies. Priority should therefore be given to applying whole genome technology to sufficiently large study cohorts of world-class athletes with adequately measured phenotypes where it is possible to increase statistical power. Some of the elite athlete cohorts described in the literature might suffice, and collectively, these cohorts could be used for replication purposes. Genome-wide association studies are ongoing in some of these cohorts (i.e., Genathlete, Russian, Spanish, Japanese, United States, and Jamaican cohorts), and preliminary findings include the identification of one single nucleotide polymorphism (SNP; among more than a million SNPs analyzed) that associates with sprint performance in Japanese, American (i.e., African American), and Jamaican cohorts with a combined effect size of ~2.6 (P-value <5×10(-7)) and good concordance with endurance performance between select cohorts. Further replications of these signals in independent cohorts will be required, and any replicated SNPs will be taken forward for fine-mapping/targeted resequencing and functional studies to uncover the underlying biological mechanisms. Only after this lengthy and costly process will the true potential of genetic testing in sport be determined.