Analysis of sports-relevant polymorphisms in a large Brazilian cohort of top-level athletes

Association between ACE (I/D) polymorphism and physical performance in Brazilian handballers

This study investigated the association between the ACE (I/D) polymorphism and strength phenotypes in Brazilian male handball players, considering their playing position. A total of 105 male junior handball players and 92 controls were evaluated. The ACE I/D polymorphism was genotyped by conventional PCR followed by electrophoresis in agarose gel. All participants were anthropometrically evaluated and performed the standing long jump (SLJ) and medicine ball throw (MBT) tests. Athletes presented superior performance in the SLJ and MBT tests compared to the control group in all playing positions (p<0.01). No significant differences were observed in genotype or allele frequencies when comparing athletes and controls or among playing positions. However, a significant difference was observed when comparing all athletes to controls using the over-dominant model (II+DD vs. ID; p=0.035). Additionally, ID athletes had better performance in the MBT than DD players (p=0.04), athletes with II+ID and II+DD genotypes exhibited superior performance in the SLJ test (p<0.04), and ID athletes demonstrated increased height compared to II+DD counterparts (p=0.01). In conclusion, our data showed a potential association between ACE (I/D) polymorphism and overall athletic predisposition in handball players, with no association with playing position.

Role of the PPARGC1A Gene and Its rs8192678 Polymorphism on Sport Performance, Aerobic Capacity, Muscle Adaptation and Metabolic Diseases: A Narrative Review

BACKGROUND/OBJECTIVES

The PPARGC1A gene, encoding the PGC-1α protein, is a critical regulator of energy metabolism, influencing mitochondrial biogenesis, fatty acid oxidation, and carbohydrate metabolism. This narrative review aims to evaluate the role of the PPARGC1A gene, with a specific focus on the c.1444G

METHODS

A comprehensive literature search was conducted using databases such as PubMed, Scopus, Science Direct, and Web of Science, following PRISMA guidelines. Studies investigating the rs8192678 polymorphism in athletes, its relationship with physical performance, and its broader metabolic effects were included. Data were synthesized qualitatively, and heterogeneity among findings was assessed. The rs8192678 polymorphism influences sports performance differently.

RESULTS

the G allele is associated with enhanced mitochondrial efficiency, higher aerobic capacity, and a greater proportion of fatigue-resistant type I muscle fibers, benefiting endurance sports like cycling and triathlon. Conversely, the A allele correlates with reduced mitochondrial biogenesis and oxidative capacity, potentially impairing endurance but showing possible utility in strength-based sports. Furthermore, the A allele is linked to increased risks of metabolic conditions, including type 2 diabetes and obesity. Discrepancies in results highlight the influence of genetic, environmental, and training interactions.

CONCLUSIONS

the PPARGC1A rs8192678 polymorphism plays a significant role in athletic performance and metabolic regulation. While the G allele confers advantages in endurance sports, the A allele presents mixed implications for strength and metabolic health. These findings support the potential for genetic profiling in personalized training and health interventions but emphasize the need for further research to clarify genotype-environment interactions.

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Key Words

• PGC-1α protein
• PPARGC1A gene
• metabolic diseases
• muscle adaptation
• sport performance

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MESH Headings

• Humans
• Adaptation, Physiological/genetics
• Athletic Performance/physiology
• Energy Metabolism/genetics
• Metabolic Diseases/genetics
• Metabolic Diseases/metabolism
• Muscle, Skeletal/physiology
• Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/genetics
• Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/metabolism
• Polymorphism, Single Nucleotide

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Affiliation(s)

David Varillas-Delgado Exercise and Sport Science, Faculty of Health Sciences, Universidad Francisco de Vitoria, 28223 Pozuelo, Spain; SPORTNOMICS S.L., 28922 Madrid, Spain

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Increased prevalence of the null allele of the p.Arg577Ter variant in the ACTN3 gene in Brazilian long-distance athletes: A retrospective study

INTRODUCTION

The phenotypic consequences of the p.Arg577Ter variant in the α-actinin-3 (ACTN3) gene are suggestive of a trade-off between performance traits for speed and endurance sports. Although there is a consistent association of the c.1729C allele (aka R allele) with strength/power traits, there is still a debate on whether the null allele (c.1729T allele; aka X allele) influences endurance performance. The present study aimed to test the association of the ACTN3 p.Arg577Ter variant with long-distance endurance athlete status, using previously published data with the Brazilian population.

METHODS

Genotypic data from 203 long-distance athletes and 1724 controls were analysed in a case-control approach.

RESULTS

The frequency of the X allele was significantly higher in long-distance athletes than in the control group (51.5% vs. 41.4%; p = 0.000095). The R/X and X/X genotypes were overrepresented in the athlete group. Individuals with the R/X genotype instead of the R/R genotype had a 1.6 increase in the odds of being a long-distance athlete (p = 0.012), whereas individuals with the X/X genotype instead of the R/R genotype had a 2.2 increase in the odds of being a long-distance athlete (p = 0.00017).

CONCLUSION

The X allele, mainly the X/X genotype, was associated with long-distance athlete status in Brazilians.

Influence of genetic polymorphism on sports talent performance versus non-athletes: a systematic review and meta-analysis

BACKGROUND

Talented athletes exhibit remarkable skills and performance in their respective sports, setting them apart from their peers. It has been observed that genetic polymorphisms can influence variations in sports performance, leading to numerous studies aimed at validating genetic markers for identifying sports talents. This study aims to evaluate the potential contribution of genetic factors associated with athletic performance predisposition in identifying sports talents.

METHODS

A systematic review was conducted following the PRISMA framework, utilizing the PICO methodology to develop the research question. The search was limited to case-control studies published between 2003 and June 2024, and databases such as Medline, LILACS, WPRIM, IBECS, CUMED, VETINDEX, Web of Science, Science Direct, Scopus and Scielo were utilized. The STREGA tool was employed to assess the quality of the selected studies.

RESULTS

A total of 1,132 articles were initially identified, of which 119 studies were included in the review. Within these studies, 50 genes and 94 polymorphisms were identified, showing associations with sports talent characteristics such as endurance, strength, power, and speed. The most frequently mentioned genes were ACTN3 (27.0%) and ACE (11.3%).

CONCLUSION

The ACE I/D and ACTN3 R577X polymorphisms are frequently discussed in the literature. Although athletic performance may be influenced by different genetic polymorphisms, limitations exist in associating them with athletic performance across certain genotypes and phenotypes. Future research is suggested to investigate the influence of polymorphisms in elite athletes from diverse backgrounds and sports disciplines.

Relative Age Effect and ACTN3 R577X and ACE I/D Polymorphisms in Brazilian Football Players: An Association Genetic Study

The Relative Age Effect (RAE) suggests older athletes within an annual cohort have advantages over their younger peers. We hypothesized that younger athletes could overcome these disadvantages through favorable α-actinin-3 (ACTN3) and angiotensin converting enzyme (ACE) polymorphisms. This study aimed to: 1) examine RAE prevalence among Brazilian football players; 2) investigate the distribution of the ACTN3 and ACE polymorphisms; and 3) explore the association between polymorphisms and RAE across competitive levels and positions. The sample included 627 male players from first-division Brazilian teams in four age categories: U15 (n = 172), U17 (n = 166), U20 (n = 161), and Professionals (n = 128). A control group was established using data from the general Brazilian population documented in previous studies Results showed RAE presence across all competitive levels and positions. Players with the ACTN3 R allele, especially the RR genotype, had the strongest associations with football players, particularly among defenders. On the other hand, the distribution of ACE polymorphism was not significantly different between controls and players, except in the U17 category, where the I/I genotype was more common. Relatively older players had higher total genotype scores than younger counterparts in the overall sample and defender subgroups. In conclusion, RAE is prevalent among Brazilian football players, with older athletes benefiting from favorable ACTN3 and ACE polymorphisms, contrary to our initial hypothesis.

A critical examination of sport discipline typology: identifying inherent limitations and deficiencies in contemporary classification systems

Exercise scientists (especially in the field of biomolecular research) frequently classify athletic cohorts into categories such as endurance, strength, or mixed, and create a practical framework for studying diverse athletic populations between seemingly similar groups. It is crucial to recognize the limitations and complexities of these classifications, as they may oversimplify the multidimensional characteristics of each sport. If so, the validity of studies dealing with such approaches may become compromised and the comparability across different studies challenging or impossible. This perspective critically examines and highlights the issues associated with current sports typologies, critiques existing sports classification systems, and emphasizes the imperative for a universally accepted classification model to enhance the quality of biomolecular research of sports in the future.

Association between ACTN3 (R577X), ACE (I/D), BDKRB2 (-9/+9), and AGT (M268T) polymorphisms and performance phenotypes in Brazilian swimmers

BACKGROUND

The influence of genetic polymorphisms on athletic performance has been widely explored. This study investigated the interactions between the polymorphisms ACTN3 (R577X), ACE (I/D), BDKRB2 (-9/+9), and AGT (M/T) and their association with endurance and strength phenotypes in Brazilian swimmers.

METHODS

123 athletes (aged 20-30 years) and 718 controls participated in the study. The athletes were divided into elite and sub-elite (N = 19 and 104, respectively) and strength and endurance experts (N = 98 and 25, respectively). Hardy-Weinberg equilibrium was observed in all groups.

RESULTS

Considering the ACE polymorphism, it was observed a higher frequency of the DD genotype than expected in the strength experts of the elite group, whereas the strength experts sub-elite athletes had a higher frequency of the ID genotype (χ2 = 8.17; p = 0.01). Subjects with XX genotypes of ACTN3 are more likely to belong to the athlete group when compared to the control group (OR = 1.79, p = 0.04). The DD homozygotes of the ACE are more likely to belong to the elite group with strength phenotypes than the group of sub-elite (OR = 7.96, p = 0.01) and elite strength experts compared to elite endurance (OR = 18.0, p = 0.03). However, no significant differences were observed in the allelic distribution of the polymorphisms evaluated when comparing Elite, sub-elite athletes and controls.

CONCLUSION

ACE and ACTN3 allele frequencies should be considered with regard to performance influencing factors in Brazilian swimmers.

Genomic predictors of physical activity and athletic performance

Physical activity and athletic performance are complex phenotypes influenced by environmental and genetic factors. Recent advances in lifestyle and behavioral genomics led to the discovery of dozens of DNA polymorphisms (variants) associated with physical activity and allowed to use them as genetic instruments in Mendelian randomization studies for identifying the causal links between physical activity and health outcomes. On the other hand, exercise and sports genomics studies are focused on the search for genetic variants associated with athlete status, sports injuries and individual responses to training and supplement use. In this review, the findings of studies investigating genetic markers and their associations with physical activity and athlete status are reported. As of the end of September 2023, a total of 149 variants have been associated with various physical activity traits (of which 42 variants are genome-wide significant) and 253 variants have been linked to athlete status (115 endurance-related, 96 power-related, and 42 strength-related).

Genetic Polymorphisms and Their Impact on Body Composition and Performance of Brazilians in a 105 Km Mountain Ultramarathon

Although the studied polymorphisms affect muscular proteins, aerobic adaptations, and recovery, their influence on the anthropometric variables and performance in ultramarathon runners is still poorly understood. This study aimed to determine the influence of ACTN3 R577X, ACE I/D, and CK MM A/G NcoI polymorphisms on the changes in the anthropometric variables and running time of 105 km mountain runners, in which 22 male Brazilian elite athletes (35.9 ± 6.5 years) were evaluated. Genotyping of the R577X (RR, RX, and XX), ACE I/D (DD, ID, and II), and CK MM A/G Ncol (AA, AG, and GG) polymorphisms was performed using the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) technique with DNA extracted from saliva. Body composition was determined via bioimpedance. Pre- and post-race weight differences were observed on athletes with the AA genotype (77.1 ± 5.9 kg; 74.6 ± 5.6 kg) compared with those with the AG genotype (74.5 ± 8.0 kg; 68 ± 5.1 kg) (p = 0.02; p = 0.02). The RR genotype showed a correlation between BMI and running time (R = 0.97; p = 0.004). The genotype II showed a correlation with % fat and fat mass concerning running time (R = 0.91; p = 0.003; R = 0.99; p < 0.0001). The AA genotype was associated with post-race weight and lean mass loss, while the RR genotype correlated with BMI, and the genotype II correlated with % body fat and fat mass in relation to times in the 105 km mountain ultramarathon.

Genes and Athletic Performance: The 2023 Update

Phenotypes of athletic performance and exercise capacity are complex traits influenced by both genetic and environmental factors. This update on the panel of genetic markers (DNA polymorphisms) associated with athlete status summarises recent advances in sports genomics research, including findings from candidate gene and genome-wide association (GWAS) studies, meta-analyses, and findings involving larger-scale initiatives such as the UK Biobank. As of the end of May 2023, a total of 251 DNA polymorphisms have been associated with athlete status, of which 128 genetic markers were positively associated with athlete status in at least two studies (41 endurance-related, 45 power-related, and 42 strength-related). The most promising genetic markers include the AMPD1 rs17602729 C, CDKN1A rs236448 A, HFE rs1799945 G, MYBPC3 rs1052373 G, NFIA-AS2 rs1572312 C, PPARA rs4253778 G, and PPARGC1A rs8192678 G alleles for endurance; ACTN3 rs1815739 C, AMPD1 rs17602729 C, CDKN1A rs236448 C, CPNE5 rs3213537 G, GALNTL6 rs558129 T, IGF2 rs680 G, IGSF3 rs699785 A, NOS3 rs2070744 T, and TRHR rs7832552 T alleles for power; and ACTN3 rs1815739 C, AR ≥21 CAG repeats, LRPPRC rs10186876 A, MMS22L rs9320823 T, PHACTR1 rs6905419 C, and PPARG rs1801282 G alleles for strength. It should be appreciated, however, that elite performance still cannot be predicted well using only genetic testing.

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.

Genome-wide assessment reveals a significant association between ACSS3 and physical activity

Recent genetic studies have identified physical activity (PA)-susceptible loci in European ancestry subjects; however, due to considerable genetic differences, these findings are not likely extendable to East Asian populations. Therefore, the present study aimed to identify significantly associated PA-susceptible loci using genome-wide association studies (GWASs) with East Asian (EAS) subjects and to generalize the findings to European (EUR) ancestries. The mRNA levels of genes located near the genome-wide significantly associated single-nucleotide polymorphisms (SNP) were compared under PA and control conditions. Rs74937256, located in ACSS3 (chromosome 12), which primarily functions in skeletal muscle tissues, was identified as a genome-wide significant variant (P = 6.06 × 10^-9 ) in EAS. Additionally, the rs2525840, also in ACSS3 satisfied the Bonferroni corrected significance (P = 3.77 × 10^-5 ) in EUR. We found that rs74937256 is an expressed trait locus of ACSS3 (P = 10^-4 ), and ACSS3 mRNA expression significantly differs after PA, based on PrediXcan (P = 7 × 10^-8 ) and the gene expression omnibus database (P = 0.043).

Genotype Distribution of the ACTN3 p.R577X Polymorphism in Elite Badminton Players: A Preliminary Study

α-Actinin-3 is a protein with a structural role at the sarcomeric Z-line in skeletal muscle. As it is only present in fast-type muscle fibers, α-actinin-3 is considered a key mechanical component to produce high-intensity muscle contractions and to withstand external tension applied to the skeletal muscle. α-Actinin-3 is encoded by the gene ACTN3, which has a single-nucleotide polymorphism (p.R577X; rs1815739) that affects the expression of α-actinin-3 due to the presence of a stop codon. Individuals homozygous for the 577R allele (i.e., RR genotype) and RX heterozygotes express functional α-actinin-3, while those homozygous for the 577X (i.e., XX genotype) express a non-functional protein. There is ample evidence to support the associations between the ACTN3 genotype and athletic performance, with higher frequencies of the 577R allele in elite and professional sprint and power athletes than in control populations. This suggests a beneficial influence of possessing functional α-actinin-3 to become an elite athlete in power-based disciplines. However, no previous investigation has determined the frequency of the ACTN3 genotypes in elite badminton players, despite this sport being characterized by high-intensity actions of intermittent nature such as changes of direction, accelerations, jumps and smashes. The purpose of this study was to analyze ACTN3 R577X genotype frequencies in professional badminton players to establish whether this polymorphism is associated with elite athlete status. A total of 53 European Caucasian professional badminton players competing in the 2018 European Badminton Championships volunteered to participate in the study. Thirty-one were men (26.2 ± 4.4 years) and twenty-two were women (23.4 ± 4.5 years). Chi-squared tests were used to analyze the differences in the distribution of ACTN3 genotypes (RR, RX and XX) between categories and sexes. The ACTN3 RR genotype was the most frequent in the sample of professional badminton players (RR = 49.1%, RX = 22.6% and XX = 28.3%). None of the badminton players ranked in the world's top ten possessed the XX genotype (RX = 60%, RR = 40%). The distribution of the ACTN3 genotypes was similar between male and female professional badminton players (men: RR = 45.2%, RX = 25.8% and XX = 29.0%; women: RR = 54.5%, RX = 18.2% and XX = 27.3%; χ² = 0.58; p = 0.750). The distribution of the ACTN3 genotypes in badminton players was different from the 1000 genome database for the European population (χ² = 15.5; p < 0.001), with an overrepresentation of the RR genotype (p < 0.05) and an underrepresentation of the RX genotype (p < 0.01). In conclusion, the expression of functional α-actinin-3, associated with RR and RX genotypes in the ACTN3 gene may confer an advantage for reaching the status of elite athlete in badminton, and especially the world's top-ten ranking. Large-scale studies with different ethnic backgrounds are needed to confirm the association of the R allele of ACTN3 with badminton performance.

Interaction Between ACTN3 (R577X), ACE (I/D), and BDKRB2 (-9/+9) Polymorphisms and Endurance Phenotypes in Brazilian Long-Distance Swimmers

ABSTRACT

Neto, SLdA, Herrera, JJB, Rosa, TS, de Almeida, SS, Silva, GCB, Ferreira, CES, dos Santos, MAP, Silvino, VO, de Melo, GF. Interaction between ACTN3 (R577X), ACE (I/D), and BDKRB2 (-9/+9) polymorphisms and endurance phenotypes in Brazilian long-distance swimmers. J Strength Cond Res 36(6): 1591-1595, 2022-This study investigated the interactions between the polymorphisms ACTN3 (R577X), ACE (I/D), and BDKRB2 (-9/+9) and their association with endurance phenotypes in Brazilian long-distance swimmers. Twenty-six volunteers (aged 18-30 years) were divided into 2 groups as follows: 19 subelite athletes formed the pool swimming experts (PSE: 400-1500 m) group and 7 elite athletes the open water swimming experts (OWSE: 5-25 km) group. ACTN3 (R577X), ACE (I/D), and BDKRB2 (-9/+9) polymorphisms were genotyped through polymerase chain reaction. A nonathletes control (CON) group derived from studies with the Brazilian population was created. Hardy-Weinberg equilibrium (X2) was observed in all groups. The total genotype score (TGS) associated with endurance phenotypes was used in this study. A significance level was established at p ≤ 0.05. PSE and CON groups had very similar genotyping distribution. The OWSE group had a greater frequency for the genotypes XX (57.1%), ID (57.1%), and the alleles X (71.4%) and I (57.2%) than CON and PSE groups (XX = 21.1 and 21.1%; ID = 47.1 and 52.6% [p > 0.05]; X = 44.0 and 42.1%; I = 45.3 and 42.1%, respectively). Considering BDKRB2, OWSE and PSE groups had a greater frequency of +9/+9 than the CON group (42.9% and 31.6 vs. 27.5%, respectively). Although the expected genotypic distribution was not verified among athletes, the TGS revealed small supremacy of 3-5 typical alleles in the OWSE group (54.8 ± 26.7%) compared with the PSE group (41.2 ± 17.8%) (p = 0.072; confidence interval = 95%; effect size = 0.95). The OWSE group seem to have benefited from the best genotype profile verified for ACTN3 and ACE. However, the results of this work should be approached with caution because of the small number of athletes and polymorphisms assessed.

The Relationship between ACE, ACTN3 and MCT1 Genetic Polymorphisms and Athletic Performance in Elite Rugby Union Players: A Preliminary Study

Athletic performance is influenced by many factors such as the environment, diet, training and endurance or speed in physical effort and by genetic predisposition. Just a few studies have analyzed the impact of genotypes on physical performance in rugby. The aim of this study was to verify the modulation of genetic influence on rugby-specific physical performance. Twenty-seven elite rugby union players were involved in the study during the in-season phase. Molecular genotyping was performed for: angiotensin-converting enzyme (ACE rs4646994), alfa-actinin-3 (ACTN3 rs1815739) and monocarboxylate transporter 1 (MCT1 rs1049434) and their variants. Lean mass index (from skinfolds), lower-limb explosive power (countermovement jump), agility (505), speed (20 m), maximal aerobic power (Yo-yo intermittent recovery test level 1) and repeated sprint ability (12 × 20 m) were evaluated. In our rugby union players ACE and ACTN3 variants did not show any influence on athletic performance. MCT1 analysis showed that TT-variant players had the highest peak vertical power (p = 0.037) while the ones with the AA genotype were the fastest in both agility and sprint tests (p = 0.006 and p = 0.012, respectively). Considering the T-dominant model, the AA genotype remains the fastest in both tests (agility: p = 0.013, speed: p = 0.017). Only the MCT1 rs1049434 A allele seems to be advantageous for elite rugby union players, particularly when power and speed are required.

Advances in sports genomics

Sports genomics is the scientific discipline that focuses on the organization and function of the genome in elite athletes, and aims to develop molecular methods for talent identification, personalized exercise training, nutritional need and prevention of exercise-related diseases. It postulates that both genetic and environmental factors play a key role in athletic performance and related phenotypes. This update on the panel of genetic markers (DNA polymorphisms) associated with athlete status and soft-tissue injuries covers advances in research reported in recent years, including one whole genome sequencing (WGS) and four genome-wide association (GWAS) studies, as well as findings from collaborative projects and meta-analyses. At end of 2020, the total number of DNA polymorphisms associated with athlete status was 220, of which 97 markers have been found significant in at least two studies (35 endurance-related, 24 power-related, and 38 strength-related). Furthermore, 29 genetic markers have been linked to soft-tissue injuries in at least two studies. The most promising genetic markers include HFE rs1799945, MYBPC3 rs1052373, NFIA-AS2 rs1572312, PPARA rs4253778, and PPARGC1A rs8192678 for endurance; ACTN3 rs1815739, AMPD1 rs17602729, CPNE5 rs3213537, CKM rs8111989, and NOS3 rs2070744 for power; LRPPRC rs10186876, MMS22L rs9320823, PHACTR1 rs6905419, and PPARG rs1801282 for strength; and COL1A1 rs1800012, COL5A1 rs12722, COL12A1 rs970547, MMP1 rs1799750, MMP3 rs679620, and TIMP2 rs4789932 for soft-tissue injuries. It should be appreciated, however, that hundreds and even thousands of DNA polymorphisms are needed for the prediction of athletic performance and injury risk.

When one says yes and the other says no; does calcineurin participate in physiologic cardiac hypertrophy?

Developing engaging activities that build skills for understanding and appreciating research is important for undergraduate and postgraduate science students. Comparing and contrasting opposing research studies does this, and more: it also appropriately for these cohorts challenges higher level cognitive processing. Here, we present and discuss one such scenario, that of calcineurin in the heart and its response to exercise training. This scenario is further accentuated by the existence of only two studies. The background is that regular aerobic endurance exercise training stimulates the heart to physiologically adapt to chronically increase its ability to produce a greater cardiac output to meet the increased demand for oxygenated blood in working muscles, and this happens by two main mechanisms: 1) increased cardiac contractile function and 2) physiologic hypertrophy. The major underlying mechanisms have been delineated over the last decades, but one aspect has not been resolved: the potential role of calcineurin in modulating physiologic hypertrophy. This is partly because the existing research has provided opposing and contrasting findings, one line showing that exercise training does activate cardiac calcineurin in conjunction with myocardial hypertrophy, but another line showing that exercise training does not activate cardiac calcineurin even if myocardial hypertrophy is blatantly occurring. Here, we review and present the current evidence in the field and discuss reasons for this controversy. We present real-life examples from physiology research and discuss how this may enhance student engagement and participation, widen the scope of learning, and thereby also further facilitate higher level cognitive processing.

Population Genetic Polymorphism of Skeletal Muscle Strength Related Genes in Five Ethnic Minorities in North China

Musculoskeletal performance is a complex trait influenced by environmental and genetic factors, and it has different manifestations in different populations. Heilongjiang province, located in northern China, is a multi-ethnic region with human cultures dating back to the Paleolithic Age. The Daur, Hezhen, Ewenki, Mongolian and Manchu ethnic groups in Heilongjiang province may have strong physical fitness to a certain extent. Based on the genetic characteristics of significant correlation between some important genes and skeletal muscle function, this study selected 23 SNPs of skeletal muscle strength-related genes and analyzed the distribution of these loci and genetic diversity in the five ethnic groups. Use Haploview (version 4.1) software to calculate the chi-square and the Hardy-Weinberg equilibrium to assess the difference between the two ethnic groups. Use R (version 4.0.2) software to perform principal component analysis of different ethnic groups. Use MEGA (version 7.0) software to construct the phylogenetic tree of different ethnic groups. Use POPGENE (version 1.32) software to calculate the heterozygosity and the F_ST values of 23 SNPs. Use Arlequin (version 3.5.2.2) software to analyze molecular variance (AMOVA) among 31 populations. The results showed that there was haplotype diversity of VDR, angiotensin-converting enzyme, ACTN3, EPO and IGF1 genes in the five ethnic groups, and there were genetic differences in the distribution of these genes in the five ethnic groups. Among them, the average gene heterozygosity (AVE_HET) of the 23 SNPs in the five populations was 0.398. The F_ST values of the 23 SNPs among the five ethnic groups varied from 0.0011 to 0.0137. According to the principal component analysis, the genetic distance of Daur, Mongolian and Ewenki is relatively close. According to the phylogenetic tree, the five ethnic groups are clustered together with the Asian population. These data will enrich existing genetic information of ethnic minorities.

The MCT1 gene Glu490Asp polymorphism (rs1049434) is associated with endurance athlete status, lower blood lactate accumulation and higher maximum oxygen uptake

The purpose of this study was to explore the association of the MCT1 gene Glu490Asp polymorphism (rs1049434) with athletic status and performance of endurance athletes. A total of 1,208 Brazilians (318 endurance athletes and 890 non-athletes) and 867 Europeans (315 endurance athletes and 552 non-athletes) were evaluated in a case-control approach. Brazilian participants were classified based on self-declared ethnicity to test whether the polymorphism was different between Caucasians and Afro-descendants. Moreover, 66 Hungarian athletes underwent an incremental test until exhaustion to assess blood lactate levels, while 46 Russian athletes had their maximum oxygen uptake ( V ⋅ O 2 max ) compared between genotypes. In the Brazilian cohort, the major T-allele was more frequent in Caucasian top-level competitors compared to their counterparts of lower competitive level (P = 0.039), and in Afro-descendant athletes compared to non-athletes (P = 0.015). Similarly, the T-allele was more frequent in European athletes (P = 0.029). Meta-analysis of the Brazilian and European cohorts confirmed that the T-allele is over-represented in endurance athletes (OR: 1.48, P = 0.03), especially when Afro-descendant athletes were included in the meta-analysis (OR: 1.58, P = 0.005). Furthermore, carriers of the T/T genotype accumulated less blood lactate in response to intense effort (P < 0.01) and exhibited higher V ⋅ O 2 max (P = 0.04)_. In conclusion, the Glu490Asp polymorphism was associated with endurance athletic status and performance. Our findings suggest that, although ethnic differences may exist, the presence of the major T-allele (i.e., the Glu-490 allele) favours endurance performance more than the mutant A-allele (i.e., the 490-Asp allele).

Molecular Portrait of an Athlete

Sequencing of the human genome and further developments in "omics" technologies have opened up new possibilities in the study of molecular mechanisms underlying athletic performance. It is expected that molecular markers associated with the development and manifestation of physical qualities (speed, strength, endurance, agility, and flexibility) can be successfully used in the selection systems in sports. This includes the choice of sports specialization, optimization of the training process, and assessment of the current functional state of an athlete (such as overtraining). This review summarizes and analyzes the genomic, proteomic, and metabolomic studies conducted in the field of sports medicine.

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.

Association study of performance-related polymorphisms in Brazilian combat-sport athletes highlights variants in the GABPB1 gene

Combat sports are an intermittent sport, with mixed anaerobic and aerobic energy production. Here, we investigated whether the polymorphisms that have been previously suggested as genetic markers for endurance or power phenotypes were associated with combat-sport athletic status. A total of 23 previously reported performance-related polymorphisms were examined in a cohort of 1,129 Brazilian individuals (164 combat-sport athletes and 965 controls), using a case-control association study. We found that the GA-binding protein transcription factor subunit beta 1 (GABPβ1) gene (also known as nuclear respiratory factor 2; NRF2) was associated with athletic status, with the minor G (rs7181866) and T (rs8031031) alleles overrepresented in athletes (P ≤ 0.003), especially among world-class athletes (P ≤ 0.0002). These findings indicate that single-nucleotide polymorphisms (SNPs) within the GABPβ1 gene increase the likelihood of an individual being a combat-sport athlete, possibly because of a better mitochondrial response to intermittent exercises.

Association between MCT1 T1470A polymorphism and climbing status in Polish and Japanese climbers

Sport climbing will become an official event at the 2020 Tokyo Olympics; it is a popular wilderness sport among athletes and amateurs. Our previous study suggested that the T1470A polymorphism (rs1049434) of the monocarboxylate transporter 1 (MCT1) gene is associated with athletic performance and physiological phenotypes. The purpose of this study was to investigate the frequency of MCT1 T1470A polymorphism in Polish and Japanese climbers using a case-control study. Our sample consisted of 226 climbers (Japanese: n = 100, 64 male and 36 female; Polish: n = 126, 97 male and 29 female) and 1028 non-athletic controls (Japanese, n = 407; Polish = 621) who were genotyped for the MCT1 T1470A polymorphism (rs1049434) using the TaqMan SNP genotyping assay or restriction enzyme. The frequency of the TT genotype and T allele was significantly higher in climbers than in controls among the Polish subjects (genotype: p = 0.030, allele: p = 0.010); however, there were no significant differences in the genotype and allelic frequencies between the Japanese climbers and controls (genotype: p = 0.968; allele: p = 0.803). Our results suggested that the frequency of the T allele (TT+TA genotype) in the MCT1 T1470A polymorphism is over-represented in Polish climbers but not in Japanese climbers. In addition, the frequency of the T allele and TT genotype in Polish lead climbers is higher than that in controls.

Genotype scores in energy and iron-metabolising genes are higher in elite endurance athletes than in nonathlete controls

Information about the association of energy and iron-metabolising genes with endurance performance is scarce. The objective of this investigation was to compare the frequencies of polymorphic variations of genes involved in energy generation and iron metabolism in elite endurance athletes versus nonathlete controls. Genotype frequencies in 123 male elite endurance athletes (75 professional road cyclists and 48 elite endurance runners) and 122 male nonathlete participants were compared by assessing 4 genetic polymorphisms: AMPD1 c.34C/T (rs17602729), PPARGC1A c.1444G/A (rs8192678) HFE_H63D c.187C/G (rs1799945) and HFE_C282Y c.845G/A (rs1800562). A weighted genotype score (w-TGS; from 0 to 100 arbitrary units (a.u.)) was calculated by assigning a corresponding weight to each polymorphism. In the nonathlete population, the mean w-TGS value was lower (39.962 ± 14.654 a.u.) than in the group of elite endurance athletes (53.344 ± 17.053 a.u). The binary logistic regression analysis showed that participants with a w-TGS > 38.975 a.u had an odds ratio of 1.481 (95% confidence interval: 1.244-1.762; p < 0.001) for achieving elite athlete status. The genotypic distribution of polymorphic variations involved in energy generation and iron metabolism was different in elite endurance athletes vs. controls. Thus, an optimal genetic profile in these genes might contribute to physical endurance in athlete status. Novelty Genetic profile in energy generation and iron-metabolising genes in elite endurance athletes is different than that of nonathletes. There is an implication of an "optimal" genetic profile in the selected genes favouring endurance sporting performance.

Meta-analyses of the association between the PPARGC1A Gly482Ser polymorphism and athletic performance

Peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) encoded by the PPARGC1A gene is a vital regulator of glucose and fatty acid oxidation, mitochondrial biogenesis, and skeletal muscle fibre conversion. Several studies have investigated the association between PPARGC1A Gly482Ser polymorphism and athletic performance in humans. However, the results were contradictory. In the present study, two meta-analyses were performed to assess the association between the Gly482Ser polymorphism and endurance or power athletic performance to resolve this inconsistency. Ten articles were identified, including a total of 3,708 athletes and 6,228 controls. Higher frequencies of the Gly/Gly genotype (OR, 1.26; 95% CI, 1.11-1.42) and the Gly allele (OR, 1.29; 95% CI, 1.09-1.52) were observed in Caucasian endurance athletes. Furthermore, higher incidences of the Gly/Gly genotype (OR, 1.30; 95% CI, 1.16-1.46) and the Gly allele (OR, 1.22; 95% CI, 1.12-1.33) were observed in power athletes compared to controls. This finding demonstrates that the Gly/Gly genotype and the Gly allele of the PPARGC1A Gly482Ser polymorphism may facilitate athletic performance regardless of the type of sport, as well as providing solid evidence to support the possible influence of genetic factors on human athletic performance.

Total genotype score and athletic status: An exploratory cross-sectional study of a Brazilian athlete cohort

The purpose of the present study was to explore the ability of the total genotype score (TGS) for evaluation of the polygenic profile of elite athletes. Data from a Brazilian athlete cohort were used in this study, which included 368 athletes and 818 nonathletes. The TGS targeted to power athletes was computed using from two to 10 associated polymorphisms. In all models, the power group showed a higher TGS mean compared to the nonathlete group. In particular, scores using more associated polymorphisms showed stronger differences (P < 0.0001). Moreover, the more polymorphisms included in the score, the greater its discriminatory power. The frequency distribution of individuals according to the TGS computed using 10 associated polymorphisms showed that both the power group and the replication group were overrepresented in scores ≥60.0 (P < 0.0075). Individuals with a score ≥60.0 had an increased odds ratio (OR) of being an elite athlete compared to the nonathlete group (OR > 2.03; P < 0.006), although there were athletes with TGS values ranging from 15.0 to 90.0. By setting 60.0 as the cutoff point, the sensitivity and specificity of the TGS was approximately 30% and 82.5%, respectively. In conclusion, the TGS computed using 10 associated polymorphisms proved to be effective in discriminating the target athlete group, but with limited accuracy as evidenced by its sensitivity rate.

Single-Nucleotide-Polymorphism-Panel Population-Genetics Approach Based on the 1000 Genomes Database and Elite Soccer Players

Purpose: Soccer is one of the most popular sports worldwide, a physical activity of great physiological demand and complexity. Currently, numerous trials involving physiological responses such as hypertrophy, energy expenditure, vasodilation, cardiac output, VO₂max, and recovery have supported the possibility of genomic predictors' affecting performance. In a complementary way to association studies with single nucleotide polymorphisms (SNPs), the objective was to evaluate if the use of population genetics data from human-genomics databases can provide information for a better understanding of the relationship between heritability and sport performance. Methods: The study included 25 healthy male professional soccer players (25.5 [4.3] y, 177.4 [6.4] cm, 76.4 [6.4] kg, body fat 10.5% [4.3%]) from the Brazilian first-division soccer club. Anthropometric measurements and field and isokinetic tests were performed to evaluate performance and physiologic parameters of subjects. Moreover, 10 genetic polymorphisms previously related to performance were genotyped. The genotypes of the same polymorphisms were obtained for 2504 individuals from the populations deposited in the 1000 Genomes database. A principal-component analysis and matrix genetic-distances approach (Fst) were evaluated. Results: As expected, the admixture Brazilian population has numerous genetic similarities with the European and American populations from genomic databases. Although the African component is absolutely recognized in genomes from the Brazilian population, using the specific performance-related SNPs, surprisingly the African population was one of the most genetically distant of the players (P < .00001). Conclusions: The early results suggest a selective pressure on genes of elite soccer players, possibly related simultaneously to physical-performance, environmental, cognitive, and sociocultural aspects.

ACTN3 R577X Genotype and Exercise Phenotypes in Recreational Marathon Runners

Background: Homozygosity for the X-allele in the ACTN3 R577X (rs1815739) polymorphism results in the complete absence of α-actinin-3 in sarcomeres of fast-type muscle fibers. In elite athletes, the ACTN3 XX genotype has been related to inferior performance in speed and power-oriented sports; however, its influence on exercise phenotypes in recreational athletes has received less attention. We sought to determine the influence of ACTN3 genotypes on common exercise phenotypes in recreational marathon runners. Methods: A total of 136 marathoners (116 men and 20 women) were subjected to laboratory testing that included measurements of body composition, isometric muscle force, muscle flexibility, ankle dorsiflexion, and the energy cost of running. ACTN3 genotyping was performed using TaqMan probes. Results: 37 runners (27.2%) had the RR genotype, 67 (49.3%) were RX and 32 (23.5%) were XX. There was a difference in body fat percentage between RR and XX genotype groups (15.7 ± 5.8 vs. 18.8 ± 5.5%; effect size, ES, = 0.5 ± 0.4, p = 0.024), whereas the distance obtained in the sit-and-reach-test was likely lower in the RX than in the XX group (15.3 ± 7.8 vs. 18.4 ± 9.9 cm; ES = 0.4 ± 0.4, p = 0.046). Maximal dorsiflexion during the weight-bearing lunge test was different in the RR and XX groups (54.8 ± 5.8 vs. 57.7 ± 5.1 degree; ES = 0.5 ± 0.5, p = 0.044). Maximal isometric force was higher in the RR than in the XX group (16.7 ± 4.7 vs. 14.7 ± 4.0 N/kg; ES = −0.5 ± 0.3, p = 0.038). There was no difference in the energy cost of running between genotypes (~4.8 J/kg/min for all three groups, ES ~0.2 ± 0.4). Conclusions: The ACTN3 genotype might influence several exercise phenotypes in recreational marathoners. Deficiency in α-actinin-3 might be accompanied by higher body fatness, lower muscle strength and higher muscle flexibility and range of motion. Although there is not yet a scientific rationale for the use of commercial genetic tests to predict sports performance, recreational marathon runners who have performed such types of testing and have the ACTN3 XX genotype might perhaps benefit from personalized strength training to improve their performance more than their counterparts with other ACTN3 genotypes.

Association study of SLC6A2 gene Thr99Ile variant (rs1805065) with athletic status in the Brazilian population

Genetic variants in monoamine neurotransmitter genes have been recurrently associated with panic disorder, addiction and mood disorders. Recent evidence also indicates that norepinephrine neurotransmission can influence a series of psychophysical and psychobiological parameters related to athletic performance, and the presence of variants in the SLC6A2 (solute carrier family 6 member 2) gene, which encodes the norepinephrine transporter, can be detrimental to an adequate noradrenergic signaling. Accordingly, the objective of the present study was to explore the SLC6A2 Thr99Ile variant (rs1805065) in a cohort composed of highly-trained individuals and non-trained individuals. A total of 1556 Brazilians: 926 non-athletes and 630 athletes (322 endurance athletes and 308 power athletes) were compared in this case-control association study. The Thr99Ile variant showed only two genotypes (C/C or C/T), and a low minor allele frequency of ≈1%. However, none of the power athletes had the mutant T-allele (i.e., the C/T genotype), which may be related to decreased norepinephrine transporter activity. The genotype distribution and allele frequency observed in power athletes were significantly different when compared to non-athletes or endurance athletes. Therefore, the presence of the T-allele may decrease the chance of belonging to the group of athletes involved in explosive physical tasks. These results still need to be replicated in independent cohorts. However, it appears reasonable to assume that there is an association between the SLC6A2 gene variant and power athletic status.

More than a 'speed gene': ACTN3 R577X genotype, trainability, muscle damage, and the risk for injuries

A common null polymorphism (rs1815739; R577X) in the gene that codes for α-actinin-3 (ACTN3) has been related to different aspects of exercise performance. Individuals who are homozygous for the X allele are unable to express the α-actinin-3 protein in the muscle as opposed to those with the RX or RR genotype. α-actinin-3 deficiency in the muscle does not result in any disease. However, the different ACTN3 genotypes can modify the functioning of skeletal muscle during exercise through structural, metabolic or signaling changes, as shown in both humans and in the mouse model. Specifically, the ACTN3 RR genotype might favor the ability to generate powerful and forceful muscle contractions. Leading to an overall advantage of the RR genotype for enhanced performance in some speed and power-oriented sports. In addition, RR genotype might also favor the ability to withstand exercise-induced muscle damage, while the beneficial influence of the XX genotype on aerobic exercise performance needs to be validated in human studies. More information is required to unveil the association of ACTN3 genotype with trainability and injury risk during acute or chronic exercise.

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%.