Three DNA Polymorphisms Previously Identified as Markers for Handgrip Strength Are Associated With Strength in Weightlifters and Muscle Fiber Hypertrophy

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.

Identification and Characterization of Genomic Predictors of Sarcopenia and Sarcopenic Obesity Using UK Biobank Data

The substantial decline in skeletal muscle mass, strength, and gait speed is a sign of severe sarcopenia, which may partly depend on genetic risk factors. So far, hundreds of genome-wide significant single nucleotide polymorphisms (SNPs) associated with handgrip strength, lean mass and walking pace have been identified in the UK Biobank cohort; however, their pleiotropic effects on all three phenotypes have not been investigated. By combining summary statistics of genome-wide association studies (GWAS) of handgrip strength, lean mass and walking pace, we have identified 78 independent SNPs (from 73 loci) associated with all three traits with consistent effect directions. Of the 78 SNPs, 55 polymorphisms were also associated with body fat percentage and 25 polymorphisms with type 2 diabetes (T2D), indicating that sarcopenia, obesity and T2D share many common risk alleles. Follow-up bioinformatic analysis revealed that sarcopenia risk alleles were associated with tiredness, falls in the last year, neuroticism, alcohol intake frequency, smoking, time spent watching television, higher salt, white bread, and processed meat intake; whereas protective alleles were positively associated with bone mineral density, serum testosterone, IGF1, and 25-hydroxyvitamin D levels, height, intelligence, cognitive performance, educational attainment, income, physical activity, ground coffee drinking and healthier diet (muesli, cereal, wholemeal or wholegrain bread, potassium, magnesium, cheese, oily fish, protein, water, fruit, and vegetable intake). Furthermore, the literature data suggest that single-bout resistance exercise may induce significant changes in the expression of 26 of the 73 implicated genes in m. vastus lateralis, which may partly explain beneficial effects of strength training in the prevention and treatment of sarcopenia. In conclusion, we have identified and characterized 78 SNPs associated with sarcopenia and 55 SNPs with sarcopenic obesity in European-ancestry individuals from the UK Biobank.

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.

Association of Genetically Predicted BCAA Levels with Muscle Fiber Size in Athletes Consuming Protein

Branched-chain amino acid (BCAA) levels are associated with skeletal muscle cross-sectional area (CSA). Serum BCAA levels are enhanced by whey protein supplementation (WPS), and evidence in clinical populations suggests an association of single nucleotide polymorphisms (SNPs) with BCAA metabolite levels. It is not known whether the same SNPs are associated with the ability to catabolise BCAAs from exogenous sources, such as WPS. The present study investigated whether possessing a higher number of alleles associated with increased BCAA metabolites correlates with muscle fiber CSA of m. vastus lateralis in physically active participants, and whether any relationship is enhanced by WPS. Endurance-trained participants (n = 75) were grouped by self-reported habitual WPS consumption and genotyped for five SNPs (PPM1K rs1440580, APOA5 rs2072560, CBLN1 rs1420601, DDX19B rs12325419, and TRMT61A rs58101275). Body mass, BMI, and fat percentage were significantly lower and muscle mass higher in the WPS group compared to Non-WPS. The number of BCAA-increasing alleles was correlated with fiber CSA in the WPS group (r = 0.75, p < 0.0001) and was stronger for fast-twitch fibers (p = 0.001) than slow-twitch fibers (p = 0.048). Similar results remained when corrected for multiple covariates (age, physical activity, and meat and dairy intake). No correlation was found in the Non-WPS group. This study presents novel evidence of a positive relationship between BCAA-increasing alleles and muscle fiber CSA in athletes habitually consuming WPS. We suggest that a high number of BCAA-increasing alleles improves the efficiency of WPS by stimulation of muscle protein synthesis, and contributes to greater fiber CSA.

Genomic predictors of testosterone levels are associated with muscle fiber size and strength

PURPOSE

Circulating testosterone levels are a heritable trait with anabolic properties in various tissues, including skeletal muscle. So far, hundreds of single nucleotide polymorphisms (SNPs) associated with testosterone levels have been identified in nonathletic populations. The aim of the present study was to test the association of 822 testosterone-increasing SNPs with muscle-related traits (muscle fiber size, fat-free mass and handgrip strength) and to validate the identified SNPs in independent cohorts of strength and power athletes.

METHODS

One hundred and forty-eight physically active individuals (47 females, 101 males) were assessed for cross-sectional area (CSA) of fast-twitch muscle fibers. Significant SNPs were further assessed for fat-free mass and handgrip strength in > 354,000 participants from the UK Biobank cohort. The validation cohorts included Russian elite athletes.

RESULTS

From an initial panel of 822 SNPs, we identified five testosterone-increasing alleles (DOCK3 rs77031559 G, ESR1 rs190930099 G, GLIS3 rs34706136 TG, GRAMD1B rs850294 T, TRAIP rs62260729 C) nominally associated (P < 0.05) with CSA of fast-twitch muscle fibers, fat-free mass and handgrip strength. Based on these five SNPs, the number of testosterone-increasing alleles was positively associated with testosterone levels in male athletes (P = 0.048) and greater strength performance in weightlifters (P = 0.017). Moreover, the proportion of participants with ≥ 2 testosterone-increasing alleles was higher in power athletes compared to controls (68.9 vs. 55.6%; P = 0.012).

CONCLUSION

Testosterone-related SNPs are associated with muscle fiber size, fat-free mass and strength, which combined can partially contribute to a greater predisposition to strength/power sports.

Perspectives in Sports Genomics

Human athletic performance is a complex phenotype influenced by environmental and genetic factors, with most exercise-related traits being polygenic in nature. The aim of this article is to outline some of the challenge faced by sports genetics as this relatively new field moves forward. This review summarizes recent advances in sports science and discusses the impact of the genome, epigenome and other omics (such as proteomics and metabolomics) on athletic performance. The article also highlights the current status of gene doping and examines the possibility of applying genetic knowledge to predict athletes’ injury risk and to prevent the rare but alarming occurrence of sudden deaths during sporting events. Future research in large cohorts of athletes has the potential to detect new genetic variants and to confirm the previously identified DNA variants believed to explain the natural predisposition of some individuals to certain athletic abilities and health benefits. It is hoped that this article will be useful to sports scientists who seek a greater understanding of how genetics influences exercise science and how genomic and other multi-omics approaches might support performance analysis, coaching, personalizing nutrition, rehabilitation and sports medicine, as well as the potential to develop new rationale for future scientific investigation.

Genes and Weightlifting Performance

A recent case-control study identified 28 DNA polymorphisms associated with strength athlete status. However, studies of genotype-phenotype design are required to support those findings. The aim of the present study was to investigate both individually and in combination the association of 28 genetic markers with weightlifting performance in Russian athletes and to replicate the most significant findings in an independent cohort of Japanese athletes. Genomic DNA was collected from 53 elite Russian (31 men and 22 women, 23.3 ± 4.1 years) and 100 sub-elite Japanese (53 men and 47 women, 21.4 ± 4.2 years) weightlifters, and then genotyped using PCR or micro-array analysis. Out of 28 DNA polymorphisms, LRPPRC rs10186876 A, MMS22L rs9320823 T, MTHFR rs1801131 C, and PHACTR1 rs6905419 C alleles positively correlated (p < 0.05) with weightlifting performance (i.e., total lifts in snatch and clean and jerk in official competitions adjusted for sex and body mass) in Russian athletes. Next, using a polygenic approach, we found that carriers of a high (6-8) number of strength-related alleles had better competition results than carriers of a low (0-5) number of strength-related alleles (264.2 (14.7) vs. 239.1 (21.9) points; p = 0.009). These findings were replicated in the study of Japanese athletes. More specifically, Japanese carriers of a high number of strength-related alleles were stronger than carriers of a low number of strength-related alleles (212.9 (22.6) vs. 199.1 (17.2) points; p = 0.0016). In conclusion, we identified four common gene polymorphisms individually or in combination associated with weightlifting performance in athletes from East European and East Asian geographic ancestries.

CKM Gene rs8111989 Polymorphism and Power Athlete Status

Multiple genetic variants are known to influence athletic performance. These include polymorphisms of the muscle-specific creatine kinase (CKM) gene, which have been associated with endurance and/or power phenotypes. However, independent replication is required to support those findings. The aim of the present study was to determine whether the CKM (rs8111989, c.*800A>G) polymorphism is associated with power athlete status in professional Russian and Lithuanian competitors. Genomic DNA was collected from 693 national and international standard athletes from Russia (n = 458) and Lithuania (n = 235), and 500 healthy non-athlete subjects from Russia (n = 291) and Lithuania (n = 209). Genotyping for the CKM rs8111989 (A/G) polymorphism was performed using PCR or micro-array analysis. Genotype and allele frequencies were compared between all athletes and non-athletes, and between non-athletes and athletes, segregated according to population and sporting discipline (from anaerobic-type events). No statistically significant differences in genotype or allele frequencies were observed between non-athletes and power athletes (strength-, sprint- and speed/strength-oriented) athletes. The present study reports the non-association of the CKM rs8111989 with elite status in athletes from sports in which anaerobic energy pathways determine success.

Genomic profile in association with sport-type, sex, ethnicity, psychological traits and sport injuries of elite athletes: review and future perspectives

In the last few years, some inherited determinants have been associated with elite athletic performance, but its polygenic trait character has limited the correct definition of elite athlete's genomic profile. This qualitative descriptive study aims to summarise the current understanding about genetic and epigenetic factors in elite athletes, as well as their genomic profile in association with sport-type, sex, ethnicity, psychological traits and sport injuries. A narrative review of the literature across a broad cross-section of the elite athletes' genomic profile was undertaken. Elite performance relies on rare gene variants within a great interface between molecular, cellular and behavioural sport-related phenotypes and the environment, which is still poorly understood. ACTN3 rs1815739 and ACE I/D polymorphisms appear to be associated to specific sprint phenotypes and influence the athletic status, i.e., the rs1815739 variant is more influential to 200-m performance and the ACE ID polymorphism is more involved in the longer, 400-m sprint performance. Generally, athletes show endurance-based sports characteristics or power-based sports characteristics, but some studies have reported some genes associations to both sports-based characteristics. Furthermore, genetic studies with larger cohorts of single-sport athletes might be preferable than studies combining athletes of different sports, given the existence of distinct athlete profiles and sport demands. Athletic performance may be influenced by the serotonergic pathway and the potential injury risk (namely stress fracture) might be associated to a genetic predisposition associated to the mechanical loading from the intense physical exercise. The study of gene variants associated to sex and ethnicity-related to athletic performance needs further investigation. The combination of genome-wide association studies addressing the genetic architecture of athletes and the subsequent replication and validation studies might for additional genetic data is mandatory.

The GALNTL6 Gene rs558129 Polymorphism Is Associated With Power Performance

Díaz, J, Álvarez Herms, J, Castañeda, A, Larruskain, J, Ramírez de la Piscina, X, Borisov, OV, Semenova, EA, Kostryukova, ES, Kulemin, NA, Andryushchenko, ON, Larin, AK, Andryushchenko, LB, Generozov, EV, Ahmetov, II, and Odriozola, A. The GALNTL6 gene rs558129 polymorphism is associated with power performance. J Strength Cond Res 34(11): 3031-3036, 2020-The largest genome-wide association study to date in sports genomics showed that endurance athletes were 1.23 times more likely to possess the C allele of the single nucleotide polymorphism rs558129 of N-acetylgalactosaminyltransferase-like 6 gene (GALNTL6), compared with controls. Nevertheless, no further study has investigated GALNTL6 gene in relation to physical performance. Considering that previous research has shown that the same polymorphism can be associated with both endurance and power phenotypes (ACTN3, ACE, and PPARA), we investigated the association between GALNTL6 rs558129 polymorphism and power performance. According to this objective we conducted 2 global studies regarding 2 different communities of athletes in Spain and Russia. The first study involved 85 Caucasian physically active men from the north of Spain to perform a Wingate anaerobic test (WAnT). In the second study we compared allelic frequencies between 173 Russian power athletes (49 strength and 124 speed-strength athletes), 169 endurance athletes, and 201 controls. We found that physically active men with the T allele of GALNTL6 rs558129 had 5.03-6.97% higher power values compared with those with the CC genotype (p < 0.05). Consistent with these findings, we have shown that the T allele was over-represented in power athletes (37.0%) compared with endurance athletes (29.3%; OR = 1.4, p = 0.032) and controls (28.6%; OR = 1.5, p = 0.015). Furthermore, the highest frequency of the T allele was observed in strength athletes (43.9%; odds ratio [OR] = 1.9, p = 0.0067 compared with endurance athletes; OR = 2.0, p = 0.0036 compared with controls). In conclusion, our data suggest that the GALNTL6 rs558129 T allele can be favorable for anaerobic performance and strength athletes. In addition, we propose a new possible functional role of GALNTL6 rs558129, gut microbiome regarding short-chain fatty acid regulation and their anti-inflammatory and resynthesis functions. Nevertheless, further studies are required to understand the mechanisms involved.

Ciliary Neurotrophic Factor Receptor rs41274853 Polymorphism Is Associated With Weightlifting Performance in Japanese Weightlifters

Homma, H, Kobatake, N, Sekimoto, Y, Saito, M, Mochizuki, Y, Okamoto, T, Nakazato, K, Nishiyama, T, and Kikuchi, N. Ciliary neurotrophic factor receptor rs41274853 polymorphism is associated with weightlifting performance in Japanese weightlifters. J Strength Cond Res 34(11): 3037-3041, 2020-At least 69 genetic markers are associated with power athlete status. In the present study, we investigated the genotype frequency of the ciliary neurotrophic factor receptor (CNTFR) rs41274853 polymorphism and the association between specific CNTFR genotype and weightlifting performance in Japanese weightlifters. One hundred sixty-five Japanese weightlifters (103 men and 62 women) and 338 controls (122 men and 216 women) participated in the present case-control study. Saliva samples were collected using the Oragene DNA self-collection kit and genotyping for the CNTFR (rs41274853) polymorphism was performed using the TaqMan assay. A questionnaire, noting each subject's best record in an official weightlifting competition, was used to obtain the weightlifting performance. The frequencies of the CNTFR genotypes CC, CT, and TT were 56, 32, 12% in the weightlifters, and 53, 40, and 7% in the controls, respectively. There was no significant difference in CNTFR genotype frequencies between the weightlifters and controls. However, the frequency of the CT + TT genotype was significantly higher in international-level weightlifters than in the national-level weightlifters. The relative value per body weight of snatch, clean, and jerk, and total record were significantly higher in the athletes with CT + TT genotype than in the athletes with CC genotype (p < 0.05). Our results suggest that the CNTFR rs41274853 CT + TT genotype is associated with weightlifting performance in Japanese weightlifters. The CNTFR rs41274853 polymorphism may enable coaches to develop tailor-made training programs for individual athletes. In addition, strength and conditioning coaches could benefit from genetic information when assessing potential athletic talents and creating strength training programs for their athletes.