DNA methylation of exercise-responsive genes differs between trained and untrained men.

BACKGROUND: Physical activity is well known for its multiple health benefits and although the knowledge of the underlying molecular mechanisms is increasing, our understanding of the role of epigenetics in long-term training adaptation remains incomplete. In this intervention study, we included individuals with a history of > 15 years of regular endurance or resistance training compared to age-matched untrained controls performing endurance or resistance exercise. We examined skeletal muscle DNA methylation of genes involved in key adaptation processes, including myogenesis, gene regulation, angiogenesis and metabolism. RESULTS: A greater number of differentially methylated regions and differentially expressed genes were identified when comparing the endurance group with the control group than in the comparison between the strength group and the control group at baseline. Although the cellular composition of skeletal muscle samples was generally consistent across groups, variations were observed in the distribution of muscle fiber types. Slow-twitch fiber type genes MYH7 and MYL3 exhibited lower promoter methylation and elevated expression in endurance-trained athletes, while the same group showed higher methylation in transcription factors such as FOXO3, CREB5, and PGC-1α. The baseline DNA methylation state of those genes was associated with the transcriptional response to an acute bout of exercise. Acute exercise altered very few of the investigated CpG sites. CONCLUSIONS: Endurance- compared to resistance-trained athletes and untrained individuals demonstrated a different DNA methylation signature of selected skeletal muscle genes, which may influence transcriptional dynamics following a bout of acute exercise. Skeletal muscle fiber type distribution is associated with methylation of fiber type specific genes. Our results suggest that the baseline DNA methylation landscape in skeletal muscle influences the transcription of regulatory genes in response to an acute exercise bout.

Skeletal muscle BMAL1 is necessary for transcriptional adaptation of local and peripheral tissues in response to endurance exercise training.

OBJECTIVE: In this investigation, we addressed the contribution of the core circadian clock factor, BMAL1, in skeletal muscle to both acute transcriptional responses to exercise and transcriptional remodeling in response to exercise training. Additionally, we adopted a systems biology approach to investigate how loss of skeletal muscle BMAL1 altered peripheral tissue homeostasis as well as exercise training adaptations in iWAT, liver, heart, and lung of male mice. METHODS: Combining inducible skeletal muscle specific BMAL1 knockout mice, physiological testing and standardized exercise protocols, we performed a multi-omic analysis (transcriptomics, chromatin accessibility and metabolomics) to explore loss of muscle BMAL1 on muscle and peripheral tissue responses to exercise. RESULTS: Muscle-specific BMAL1 knockout mice demonstrated a blunted transcriptional response to acute exercise, characterized by the lack of upregulation of well-established exercise responsive transcription factors including Nr4a3 and Ppargc1a. Six weeks of exercise training in muscle-specific BMAL1 knockout mice induced significantly greater and divergent transcriptomic and metabolomic changes in muscle. Surprisingly, liver, lung, inguinal white adipose and heart showed divergent exercise training transcriptomes with less than 5% of 'exercise-training' responsive genes shared for each tissue between genotypes. CONCLUSIONS: Our investigation has uncovered the critical role that BMAL1 plays in skeletal muscle as a key regulator of gene expression programs for both acute exercise and training adaptations. In addition, our work has uncovered the significant impact that altered exercise response in muscle and its likely impact on the system plays in the peripheral tissue adaptations to exercise training. Our work also demonstrates that if the muscle adaptations diverge to a more maladaptive state this is linked to increased gene expression signatures of inflammation across many tissues. Understanding the molecular targets and pathways contributing to health vs. maladaptive exercise adaptations will be critical for the next stage of therapeutic design for exercise mimetics.

ACE gene polymorphisms (rs4340) II and DI are more responsive to the ergogenic effect of caffeine than DD on aerobic power, heart rate, and perceived exertion in a homogeneous Brazilian group of adolescent athletes.

The purpose of this study was to verify the association between angiotensin-converting enzyme (ACE) genotypes DD, DI, and II and caffeine (CAF) ingestion on endurance performance, heart rate, ratio of perceived exertion (RPE), and habitual caffeine intake (HCI) of adolescent athletes. Seventy-four male adolescent athletes (age: DD=16±1.7; DI=16±2.0; II=15±1.7 years) ingested CAF (6 mg/kg) or placebo (PLA) one hour before performing the Yo-Yo Intermittent Recovery level 1 (Yo-Yo IR1) test. No difference was found among groups for HCI. However, CAF increased the maximal distance covered and VO2max in DI and II genotype carriers compared to PLA (DD: Δ=31 m and 0.3 mL·kg-1·min-1; DI: Δ=286 m and 1.1 mL·kg-1·min-1; II: Δ=160 m and 1.4 mL·kg-1·min-1). Heart rate of DI and II genotype carriers increased with CAF compared to PLA, while RPE was higher in the II and lower in the DD genotypes. The correlations between HCI and maximal distance covered or VO2max were significant in the II genotype carriers with CAF. CAF increased endurance capacity, heart rate, and RPE in adolescent athletes with allele I, while endurance performance and aerobic power had a positive correlation to HCI in the II genotype group. These findings suggested that DD genotype were less responsive to CAF and that genetic variations should be taken into account when using CAF supplementation to enhance exercise performance.

Temporal dynamics of the multi-omic response to endurance exercise training.

Regular exercise promotes whole-body health and prevents disease, but the underlying molecular mechanisms are incompletely understood1-3. Here, the Molecular Transducers of Physical Activity Consortium4 profiled the temporal transcriptome, proteome, metabolome, lipidome, phosphoproteome, acetylproteome, ubiquitylproteome, epigenome and immunome in whole blood, plasma and 18 solid tissues in male and female Rattus norvegicus over eight weeks of endurance exercise training. The resulting data compendium encompasses 9,466 assays across 19 tissues, 25 molecular platforms and 4 training time points. Thousands of shared and tissue-specific molecular alterations were identified, with sex differences found in multiple tissues. Temporal multi-omic and multi-tissue analyses revealed expansive biological insights into the adaptive responses to endurance training, including widespread regulation of immune, metabolic, stress response and mitochondrial pathways. Many changes were relevant to human health, including non-alcoholic fatty liver disease, inflammatory bowel disease, cardiovascular health and tissue injury and recovery. The data and analyses presented in this study will serve as valuable resources for understanding and exploring the multi-tissue molecular effects of endurance training and are provided in a public repository ( https://motrpac-data.org/ ).

Meta-analysis of genomic variants in power and endurance sports to decode the impact of genomics on athletic performance and success.

Association between genomic variants and athletic performance has seen a high degree of controversy, as there is often conflicting data as far as the association of genomic variants with endurance, speed and strength is concerned. Here, findings from a thorough meta-analysis from 4228 articles exploring the association of genomic variants with athletic performance in power and endurance sports are summarized, aiming to confirm or overrule the association of genetic variants with athletic performance of all types. From the 4228 articles, only 107 were eligible for further analysis, including 37 different genes. From these, there were 21 articles for the ACE gene, 29 articles for the ACTN3 gene and 8 articles for both the ACE and ACTN3 genes, including 54,382 subjects in total, from which 11,501 were endurance and power athletes and 42,881 control subjects. These data show that there is no statistically significant association between genomic variants and athletic performance either for endurance or power sports, underlying the fact that it is highly risky and even unethical to make such genetic testing services for athletic performance available to the general public. Overall, a strict regulatory monitoring should be exercised by health and other legislative authorities to protect the public from such services from an emerging discipline that still lacks the necessary scientific evidence and subsequent regulatory approval.

Examining the relationship between genetic polymorphisms (BDKRB2, GNB3, HIF1A, MCT1, NOS3) and endurance athlete status.

PURPOSE: Genetic factors are important in terms of athletic performance. Recent studies to determine the relationship between the genes that lead to physiological responses have attracted attention. In this respect, this meta-analysis study was designed to examine the relationship between genetic polymorphism (BDKRB2 rs5810761, GNB3 rs5443, HIF1A rs11549565, MCT1 rs1049434, NOS3 rs2070744) and endurance athlete's status. METHODS: The search included studies published from 2009 to 2022. To determine the relevant studies, Pubmed, Web of Science databases were systematically scanned. Only case-control studies were included in the meta-analysis. To determine the relevant studies, Pubmed, Web of Science databases were systematically scanned, and a total of 31 studies met the criteria for inclusion in the meta-analysis. Relevant data from the included studies were collected and analyzed using a random effects or fixed effects model. The effect size was calculated as the odds ratio or a risk ratio the corresponding 95% confidence intervals. RESULTS: According to the results of the analysis, BDKRB2 rs5810761 + 9 allele, and NOS3 rs2070744 T allele were significantly more prevalent in endurance athletes (p < 0.05). Genotype distributions of BDKRB2 rs5810761, MCT1 rs1049434, and NOS3 rs2070744 showed significant differences in the dominant model (p < 0.05). However, no significant association was found between endurance athlete status and GNB3 rs5443 and HIF1A rs11549465 polymorphisms. CONCLUSION: These results show that some gene polymorphisms play an important role in endurance athlete status and suggest that having a specific genetic basis may also confer a physiological advantage for performance.

Reduced Ejection Fraction in Elite Endurance Athletes: Clinical and Genetic Overlap With Dilated Cardiomyopathy.

BACKGROUND: Exercise-induced cardiac remodeling can be profound, resulting in clinical overlap with dilated cardiomyopathy, yet the significance of reduced ejection fraction (EF) in athletes is unclear. The aim is to assess the prevalence, clinical consequences, and genetic predisposition of reduced EF in athletes. METHODS: Young endurance athletes were recruited from elite training programs and underwent comprehensive cardiac phenotyping and genetic testing. Those with reduced EF using cardiac magnetic resonance imaging (defined as left ventricular EF <50%, or right ventricular EF <45%, or both) were compared with athletes with normal EF. A validated polygenic risk score for indexed left ventricular end-systolic volume (LVESVi-PRS), previously associated with dilated cardiomyopathy, was assessed. Clinical events were recorded over a mean of 4.4 years. RESULTS: Of the 281 elite endurance athletes (22±8 years, 79.7% male) undergoing comprehensive assessment, 44 of 281 (15.7%) had reduced left ventricular EF (N=12; 4.3%), right ventricular EF (N=14; 5.0%), or both (N=18; 6.4%). Reduced EF was associated with a higher burden of ventricular premature beats (13.6% versus 3.8% with >100 ventricular premature beats/24 h; P=0.008) and lower left ventricular global longitudinal strain (-17%±2% versus -19%±2%; P<0.001). Athletes with reduced EF had a higher mean LVESVi-PRS (0.57±0.13 versus 0.51±0.14; P=0.009) with athletes in the top decile of LVESVi-PRS having an 11-fold increase in the likelihood of reduced EF compared with those in the bottom decile (P=0.034). Male sex and higher LVESVi-PRS were the only significant predictors of reduced EF in a multivariate analysis that included age and fitness. During follow-up, no athletes developed symptomatic heart failure or arrhythmias. Two athletes died, 1 from trauma and 1 from sudden cardiac death, the latter having a reduced right ventricular EF and a LVESVi-PRS >95%. CONCLUSIONS: Reduced EF occurs in approximately 1 in 6 elite endurance athletes and is related to genetic predisposition in addition to exercise training. Genetic and imaging markers may help identify endurance athletes in whom scrutiny about long-term clinical outcomes may be appropriate. REGISTRATION: URL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=374976&isReview=true; Unique identifier: ACTRN12618000716268.

The Distinguishing Factor in Soccer Players is Aerobic Performance, not the ACTN3 Gene / El Factor Distintivo en los Jugadores de Fútbol es el Rendimiento Aeróbico y no el gen ACTN3

SUMMARY: The purpose of this study was to reveal the differences between ACTN3 genotype (RR, RX, XX) and aerobic performance [Yo-Yo IRT1 (m), VO2 max (ml/kg/min)] in professional and regional amateur league soccer players and to reveal which of these parameters was a distinctive factor in these athletes.71 professional soccer players (age: 23.66 ± 4.11 years; body height: 1.79 ± 6.99 m; body weight: 76.02 ± 6.76 kg; body fat: 11.59±3.11 %) and 62 regional amateur soccer players (age: 23.63 ±3.77 years; body height: 1.81 ± 5.77 m; body weight: 76.36 ± 7.53 kg; body fat: 15.60±4.65 %) volunteered for the study. After DNA extraction from buccal epithelial cells via a commercial kit was performed for the genetic background of the athletes, Real-Time PCR was carried out for genotyping. Furthermore, Yo-Yo IRT1 test was performed to determine the aerobic performance of the soccer players. SPSS 23 (SPSS Inc., Chicago, IL, USA) package program was used for the statistical analysis of the data obtained in the tests. Shapiro-Wilk test for normality and Levene's test for homogeneity of variance were performed. Chi-Square, Independent Sample T Test and One Way ANOVA test were used in the analysis of the parameters. Statistical significance was set as p0.05); however, there was a statistical significance in favor of professional soccer players in terms of aerobic parameters (p<0.05). Consequently, it can be said that aerobic performance is the distinguishing factor, not the ACTN3 gene, in soccer players.

El objetivo de este estudio fue revelar las diferencias entre el genotipo ACTN3 (RR, RX, XX) y el rendimiento aeróbico [Yo-Yo IRT1 (m), VO2 max (ml/kg/min)] en jugadores de fútbol de ligas profesionales y amateurs regionales y determinar cuál de estos parámetros es un factor distintivo en estos deportistas. 71 futbolistas profesionales (edad: 23,66 ±4,11 años; altura corporal: 1,79 ± 6,99 m; peso corporal: 76,02 ± 6,76 kg; grasa corporal: 11,59±3,11 %) y 62 jugadores de fútbol amateur regionales (edad: 23,63 ± 3,77 años; altura corporal: 1,81 ± 5,77 m; peso corporal: 76,36 ± 7,53 kg; grasa corporal: 15,60 ± 4,65 %) se ofrecieron como voluntarios para el estudio. Después de realizar la extracción de ADN de las células epiteliales orales mediante un kit comercial para obtener los antecedentes genéticos de los atletas, se llevó a cabo una PCR en tiempo real para el genotipado. Además, se realizó la prueba Yo-Yo IRT1 para determinar el rendimiento aeróbico de los futbolistas. Para el análisis estadístico de los datos obtenidos en las pruebas se utilizó el programa SPSS 23 (SPSS Inc., Chicago, IL, EE. UU.). Se realizó la prueba de normalidad de Shapiro- Wilk y la prueba de homogeneidad de la varianza de Levene. En el análisis de los parámetros se utilizaron Chi-cuadrado, prueba T para muestra independiente y prueba ANOVA unidireccional. La significancia estadística se estableció en p0,05); sin embargo, hubo significación estadística a favor de los futbolistas profesionales en cuanto a los parámetros aeróbicos (p<0,05). En consecuencia, se puede decir que el rendimiento aeróbico es el factor distintivo, no el gen ACTN3, en los jugadores de fútbol.

Omics-driven investigation of the biology underlying intrinsic submaximal working capacity and its trainability.

Submaximal exercise capacity is an indicator of cardiorespiratory fitness with clinical and public health implications. Submaximal exercise capacity and its response to exercise programs are characterized by heritability levels of about 40%. Using physical working capacity (power output) at a heart rate of 150 beats/min (PWC150) as an indicator of submaximal exercise capacity in subjects of the HERITAGE Family Study, we have undertaken multi-omics and in silico explorations of the underlying biology of PWC150 and its response to 20 wk of endurance training. Our goal was to illuminate the biological processes and identify panels of genes associated with human variability in intrinsic PWC150 (iPWC150) and its trainability (dPWC150). Our bioinformatics approach was based on a combination of genome-wide association, skeletal muscle gene expression, and plasma proteomics and metabolomics experiments. Genes, proteins, and metabolites showing significant associations with iPWC150 or dPWC150 were further queried for the enrichment of biological pathways. We compared genotype-phenotype associations of emerging candidate genes with reported functional consequences of gene knockouts in mouse models. We investigated the associations between DNA variants and multiple muscle and cardiovascular phenotypes measured in HERITAGE subjects. Two panels of prioritized genes of biological relevance to iPWC150 (13 genes) and dPWC150 (6 genes) were identified, supporting the hypothesis that genes and pathways associated with iPWC150 are different from those underlying dPWC150. Finally, the functions of these genes and pathways suggested that human variation in submaximal exercise capacity is mainly driven by skeletal muscle morphology and metabolism and red blood cell oxygen-carrying capacity.NEW & NOTEWORTHY Multi-omics and in silico explorations of the genes and underlying biology of submaximal exercise capacity and its response to 20 wk of endurance training were undertaken. Prioritized genes were identified: 13 genes for variation in submaximal exercise capacity in the sedentary state and 5 genes for the response level to endurance training, with no overlap between them. Genes and pathways associated with submaximal exercise capacity in the sedentary state are different from those underlying trainability.

Responsiveness to endurance training can be partly explained by the number of favorable single nucleotide polymorphisms an individual possesses.

Cardiorespiratory fitness is a key component of health-related fitness. It is a necessary focus of improvement, especially for those that have poor fitness and are classed as untrained. However, much research has shown individuals respond differentially to identical training programs, suggesting the involvement of a genetic component in individual exercise responses. Previous research has focused predominantly on a relatively low number of candidate genes and their overall influence on exercise responsiveness. However, examination of gene-specific alleles may provide a greater level of understanding. Accordingly, this study aimed to investigate the associations between cardiorespiratory fitness and an individual's genotype following a field-based endurance program within a previously untrained population. Participants (age: 29 ± 7 years, height: 175 ± 9 cm, mass: 79 ± 21 kg, body mass index: 26 ± 7 kg/m2) were randomly assigned to either a training (n = 21) or control group (n = 24). The training group completed a periodized running program for 8-weeks (duration: 20-30-minutes per session, intensity: 6-7 Borg Category-Ratio-10 scale rating, frequency: 3 sessions per week). Both groups completed a Cooper 12-minute run test to estimate cardiorespiratory fitness at baseline, mid-study, and post-study. One thousand single nucleotide polymorphisms (SNPs) were assessed via saliva sample collections. Cooper run distance showed a significant improvement (0.23 ± 0.17 km [11.51 ± 9.09%], p < 0.001, ES = 0.48 [95%CI: 0.16-0.32]), following the 8-week program, whilst controls displayed no significant changes (0.03 ± 0.15 km [1.55 ± 6.98%], p = 0.346, ES = 0.08, [95%CI: -0.35-0.95]). A significant portion of the inter-individual variation in Cooper scores could be explained by the number of positive alleles a participant possessed (r = 0.92, R2 = 0.85, p < 0.001). These findings demonstrate the relative influence of key allele variants on an individual's responsiveness to endurance training.

The PPARGC1A Gly482Ser polymorphism is associated with elite long-distance running performance.

Success in long-distance running relies on multiple factors including oxygen utilisation and lactate metabolism, and genetic associations with athlete status suggest elite competitors are heritably predisposed to superior performance. The Gly allele of the PPARGC1A Gly482Ser rs8192678 polymorphism has been associated with endurance athlete status and favourable aerobic training adaptations. However, the association of this polymorphism with performance amongst long-distance runners remains unclear. Accordingly, this study investigated whether rs8192678 was associated with elite status and competitive performance of long-distance runners. Genomic DNA from 656 Caucasian participants including 288 long-distance runners (201 men, 87 women) and 368 non-athletes (285 men, 83 women) was analysed. Medians of the 10 best UK times (Top10) for 10 km, half-marathon and marathon races were calculated, with all included athletes having personal best (PB) performances within 20% of Top10 (this study's definition of "elite"). Genotype and allele frequencies were compared between athletes and non-athletes, and athlete PB compared between genotypes. There were no differences in genotype frequency between athletes and non-athletes, but athlete Ser allele carriers were 2.5% faster than Gly/Gly homozygotes (p = 0.030). This study demonstrates that performance differences between elite long-distance runners are associated with rs8192678 genotype, with the Ser allele appearing to enhance performance.

Genetic Profile in Genes Associated with Sports Injuries in Elite Endurance Athletes.

Injuries are a complex trait that can stem from the interaction of several genes. The aim of this research was to examine the relationship between muscle performance-related genes and overuse injury risk in elite endurance athletes, and to examine the feasibility of determining a total genotype score that significantly correlates with injury. A cohort of 100 elite endurance athletes (50 male and 50 female) was selected. AMPD1 (rs17602729), ACE (rs4646994), ACTN3 (rs1815739), CKM (rs8111989) and MLCK ([rs2849757] and [rs2700352]) polymorphisms were genotyped by using real-time polymerase chain reaction (real time-PCR). Injury characteristics during the athletic season were classified following the Consensus Statement for injuries evaluation. The mean total genotype score (TGS) in non-injured athletes (68.263±13.197 arbitrary units [a.u.]) was different from that of injured athletes (50.037±17.293 a.u., p<0.001). The distribution of allelic frequencies in the AMPD1 polymorphism was also different between non-injured and injured athletes (p<0.001). There was a TGS cut-off point (59.085 a.u.) to discriminate non-injured from injured athletes with an odds ratio of 7.400 (95% CI 2.548-21.495, p<0.001). TGS analysis appears to correlate with elite endurance athletes at higher risk for injury. Further study may help to develop this as one potential tool to help predict injury risk in this population.

Whole blood transcriptome characterization of young female triathlon athletes following an endurance exercise: a pilot study.

The vast majority of studies focusing on the effects of endurance exercise on hematological parameters and leukocyte gene expression were performed in adult men, so our aim was to investigate these changes in young females. Four young (age 15.3 ± 1.3 yr) elite female athletes completed an exercise session, in which they accomplished the cycling and running disciplines of a junior triathlon race. Blood samples were taken immediately before the exercise, right after the exercise, and then 1, 2, and 7 days later. Analysis of cell counts and routine biochemical parameters were complemented by RNA sequencing (RNA-seq) to whole blood samples. The applied exercise load did not trigger remarkable changes in either cardiovascular or biochemical parameters; however, it caused a significant increase in the percentage of neutrophils and a significant reduction in the ratio of lymphocytes immediately after exercise. Furthermore, endurance exercise induced a characteristic gene expression pattern change in the blood transcriptome. Gene set enrichment analysis (GSEA) using the Reactome database revealed that the expression of genes involved in immune processes and neutrophil granulocyte activation was upregulated, whereas the expression of genes important in translation and rRNA metabolism was downregulated. Comparison of a set of immune cell gene signatures (ImSig) and our transcriptomic data identified 15 overlapping genes related to T-cell functions and involved in podosome formation and adhesion to the vessel wall. Our results suggest that RNA-seq to whole blood together with ImSig analysis are useful tools for the investigation of systemic responses to endurance exercise.

Genetic polymorphisms of muscular fitness in young healthy men.

The effects of genetic polymorphisms on muscle structure and function remain elusive. The present study tested for possible associations of 16 polymorphisms (across ten candidate genes) with fittness and skeletal muscle phenotypes in 17- to 37-year-old healthy Caucasian male endurance (n = 86), power/strength (n = 75) and team athletes (n = 60), and non-athletes (n = 218). Skeletal muscle function was measured with eight performance tests covering multiple aspects of muscular fitness. Along with body mass and height, the upper arm and limb girths, and maximal oxygen uptake were measured. Genotyping was conducted on DNA extracted from blood. Of the 16 polymorphisms studied, nine (spanning seven candidate genes and four gene families/signalling pathways) were independently associated with at least one skeletal muscle fitness measure (size or function, or both) measure and explained up to 4.1% of its variation. Five of the studied polymorphisms (activin- and adreno-receptors, as well as myosine light chain kinase 1) in a group of one to three combined with body height, age and/or group explained up to 20.4% of the variation of muscle function. ACVR1B (rs2854464) contributed 2.0-3.6% to explain up to 14.6% of limb proximal girths. The G allele (genotypes AG and GG) of the ACVR1B (rs2854464) polymorphism was significantly overrepresented among team (60.4%) and power (62.0%) athletes compared to controls (52.3%) and endurance athletes (39.2%), and G allele was also most consistently/frequently associated with muscle size and power. Overall, the investigated polymorphisms determined up to 4.1% of the variability of muscular fitness in healthy young humans.

Constitutive activation of estrogen receptor α signaling in muscle prolongs exercise endurance in mice.

Estrogen is a female hormone that plays a role in various tissues, although the mechanism in skeletal muscle has not been fully clarified. We previously showed that systemic administration of estrogen for 10 weeks ameliorated decreased exercise endurance in ovariectomized mice. To assess whether a long-term and muscle-specific activation of estrogen signaling modulates muscle function, we constructed an expression plasmid for a constitutively active estrogen receptor α (caERα) under the control of muscle creatine kinase (Mck) gene promoter/enhancer. In C2C12 mouse myoblastic cells, transfection of the Mck-caERα plasmid elevated the estrogen response element-driven transcription in a ligand-independent manner. Using this construct, we generated Mck-caERα transgenic mice, in which caERα is predominantly expressed in muscle. Treadmill running test revealed that female Mck-caERα mice exhibit a prolonged running time and distance compared with the wild-type mice. Moreover, microarray expression analysis revealed that the genes related to lipid metabolism, insulin signaling, and growth factor signaling were particularly upregulated in the quadriceps femoris muscle of Mck-caERα mice. These results suggest that estrogen signaling potentiates exercise endurance in skeletal muscle through modulating the expression of metabolism-associated genes.

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.

Genetic differentiation in East African ethnicities and its relationship with endurance running success.

Since the 1960s, East African athletes, mainly from Kenya and Ethiopia, have dominated long-distance running events in both the male and female categories. Further demographic studies have shown that two ethnic groups are overrepresented among elite endurance runners in each of these countries: the Kalenjin, from Kenya, and the Oromo, from Ethiopia, raising the possibility that this dominance results from genetic or/and cultural factors. However, looking at the life history of these athletes or at loci previously associated with endurance athletic performance, no compelling explanation has emerged. Here, we used a population approach to identify peaks of genetic differentiation for these two ethnicities and compared the list of genes close to these regions with a list, manually curated by us, of genes that have been associated with traits possibly relevant to endurance running in GWAS studies, and found a significant enrichment in both populations (Kalenjin, P = 0.048, and Oromo, P = 1.6x10-5). Those traits are mainly related to anthropometry, circulatory and respiratory systems, energy metabolism, and calcium homeostasis. Our results reinforce the notion that endurance running is a systemic activity with a complex genetic architecture, and indicate new candidate genes for future studies. Finally, we argue that a deterministic relationship between genetics and sports must be avoided, as it is both scientifically incorrect and prone to reinforcing population (racial) stereotyping.

HIF-1α and NFIA-AS2 Polymorphisms as Potential Determinants of Total Hemoglobin Mass in Endurance Athletes.

ABSTRACT: Malczewska-Lenczowska, J, Orysiak, J, Majorczyk, E, Sitkowski, D, Starczewski, M, and Zmijewski, P. HIF-1α and NFIA-AS2 polymorphisms as potential determinants of total hemoglobin mass in endurance athletes. J Strength Cond Res 36(6): 1596-1604, 2022-The aims of this study were to examine (1) the genotype distribution of rs11549465:C>T of the HIF-1α gene and rs1572312:C>A of the NFIA-AS2 gene; (2) the association between the genes and hematological status in endurance-oriented athletes; and (3) the association between the NFIA-AS2 gene and aerobic capacity in cyclists. Two hundred thirty-eight well-trained athletes (female n = 90, male n = 148) participated in the study. Total hemoglobin mass (tHbmass), blood morphology, intravascular volumes, i.e., erythrocyte volume (EV), blood volume (BV) and plasma volume (PV), and aerobic capacity indices, e.g., peak oxygen uptake (V̇o2peak), and power at anaerobic threshold (PAT) were determined. In both studied genes, the CC genotype was predominant. In the HIF-1α gene, there were no differences in genotype and allele distribution among athletes from different disciplines and between sexes. The distribution of genotypes and alleles of the NFIA-AS2 gene differed significantly in male athletes; the frequency of A allele carriers (CA + AA) was significantly higher in cyclists than in rowers and middle- and long-distance runners. The athletes with CC genotype of NF1A-AS2 had significantly higher relative values of: tHbmass (total female athletes, cyclists), PV, BV (cyclists), and EV (total male athletes, cyclists) and PAT (cyclists) than A allele carriers (CA + AA genotypes). In conclusion, our study indicates that NFIA-AS2 rs1572312:C>A polymorphism was associated with hematological status in endurance athletes, as well as aerobic capacity indices in male cyclists. It suggests that this polymorphism may be a determinant of quantity of hemoglobin and intrtavascular volumes, which in turn can have an impact on aerobic performance.

Mitochondrial mutations alter endurance exercise response and determinants in mice.

Primary mitochondrial diseases (PMDs) are a heterogeneous group of metabolic disorders that can be caused by hundreds of mutations in both mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) genes. Current therapeutic approaches are limited, although one approach has been exercise training. Endurance exercise is known to improve mitochondrial function in heathy subjects and reduce risk for secondary metabolic disorders such as diabetes or neurodegenerative disorders. However, in PMDs the benefit of endurance exercise is unclear, and exercise might be beneficial for some mitochondrial disorders but contraindicated in others. Here we investigate the effect of an endurance exercise regimen in mouse models for PMDs harboring distinct mitochondrial mutations. We show that while an mtDNA ND6 mutation in complex I demonstrated improvement in response to exercise, mice with a CO1 mutation affecting complex IV showed significantly fewer positive effects, and mice with an ND5 complex I mutation did not respond to exercise at all. For mice deficient in the nDNA adenine nucleotide translocase 1 (Ant1), endurance exercise actually worsened the dilated cardiomyopathy. Correlating the gene expression profile of skeletal muscle and heart with the physiologic exercise response identified oxidative phosphorylation, amino acid metabolism, matrisome (extracellular matrix [ECM]) structure, and cell cycle regulation as key pathways in the exercise response. This emphasizes the crucial role of mitochondria in determining the exercise capacity and exercise response. Consequently, the benefit of endurance exercise in PMDs strongly depends on the underlying mutation, although our results suggest a general beneficial effect.

Genes controlling skeletal muscle glucose uptake and their regulation by endurance and resistance exercise.

Exercise improves the insulin sensitivity of glucose uptake in skeletal muscle. Due to that, exercise has become a cornerstone treatment for type 2 diabetes mellitus (T2DM). The mechanisms by which exercise improves skeletal muscle insulin sensitivity are, however, incompletely understood. We conducted a systematic review to identify all genes whose gain or loss of function alters skeletal muscle glucose uptake. We subsequently cross-referenced these genes with recently generated data sets on exercise-induced gene expression and signaling. Our search revealed 176 muscle glucose-uptake genes, meaning that their genetic manipulation altered glucose uptake in skeletal muscle. Notably, exercise regulates the expression or phosphorylation of more than 50% of the glucose-uptake genes or their protein products. This included many genes that previously have not been associated with exercise-induced insulin sensitivity. Interestingly, endurance and resistance exercise triggered some common but mostly unique changes in expression and phosphorylation of glucose-uptake genes or their protein products. Collectively, our work provides a resource of potentially new molecular effectors that play a role in the incompletely understood regulation of muscle insulin sensitivity by exercise.