A gene for speed? The evolution and function of alpha-actinin-3

Influence of ACTN3 R577X Polymorphism on Blood Creatine Kinase Levels Relative to Number of Sprints in Brazilian Professional Soccer Players

This study sought to assess how post-game creatine kinase (CK) levels correlate with the number of sprints and the impact of the ACTN3 polymorphism on this response. This research constituted a descriptive/observational, retrospective cross-sectional study. DNA was extracted from blood samples for ACTN3 polymorphism genotyping. CK was measured 48 h after official matches, and the number of sprints (>19 km/h) was tracked using Global Positioning System (GPS) technology. The main cohort included 23 professional soccer players from the top tier of the Brazilian Championship. We analyzed 115 GPS + CK data sets. The replication cohort comprised 18 professional soccer players from the First Division of the Championship, had the same methodology applied, and featured a total of 90 GPS (sprints > 25.2 km/h) + CK data sets. For the main cohort, a significant positive correlation was seen between the number of sprints and the CK levels (p = 0.009). Athletes with the ACTN3 RR genotype had higher CK levels as more sprints were performed during the match (p = 0.017). However, the relationship was not found for X allele carriers (p > 0.05). For the replication cohort, there was a near-significant correlation between CK levels and the number of sprints (p = 0.05), and RR individuals showed a significant association (p = 0.01), whereas X allele carriers did not (p = 0.06). A greater number of sprints during matches is linked to higher CK levels, primarily among players with the ACTN3 RR genotype, which is potentially due to an increased presence of type II muscle fibers. These findings were replicated for both cohorts of elite Brazilian soccer players, emphasizing the importance of genetic factors in injury prevention.

Genome-wide identification of quantitative trait loci and candidate genes for seven carcass traits in a four-way intercross porcine population

BACKGROUND

Carcass traits are essential economic traits in the commercial pig industry. However, the genetic mechanism of carcass traits is still unclear. In this study, we performed a genome-wide association study (GWAS) based on the specific-locus amplified fragment sequencing (SLAF-seq) to study seven carcass traits on 223 four-way intercross pigs, including dressing percentage (DP), number of ribs (RIB), skin thinkness (ST), carcass straight length (CSL), carcass diagonal length (CDL), loin eye width (LEW), and loin eye thickness (LET).

RESULTS

A total of 227,921 high-quality single nucleotide polymorphisms (SNPs) were detected to perform GWAS. A total of 30 SNPs were identified for seven carcass traits using the mixed linear model (MLM) (p < 1.0 × 10- 5), of which 9 SNPs were located in previously reported quantitative trait loci (QTL) regions. The phenotypic variation explained (PVE) by the significant SNPs was from 2.43 to 16.32%. Furthermore, 11 candidate genes (LYPLAL1, EPC1, MATN2, ZFAT, ZBTB10, ZNF704, INHBA, SMYD3, PAK1, SPTBN2, and ACTN3) were found for carcass traits in pigs.

CONCLUSIONS

The GWAS results will improve our understanding of the genetic basis of carcass traits. We hypothesized that the candidate genes associated with these discovered SNPs would offer a biological basis for enhancing the carcass quality of pigs in swine breeding.

The relationships between ACTN3 rs1815739 and PPARA-α rs4253778 gene polymorphisms and athletic performance characteristics in professional soccer players

BACKGROUND

Current research on athletic performance focuses on genetic variants that contribute significantly to individuals' performance. ACTN3 rs1815739 and PPARA-α rs4253778 gene polymorphisms are variants frequently associated with athletic performance among different populations. However, there is limited research examining the pre-and post-test results of some variants of athletic performance in soccer players. Therefore, the presented research is to examine the relationships between the ACTN3 rs1815739 and PPARA-α rs4253778 gene polymorphisms and athletic performance improvement rates in adaptations to six weeks of training in elite soccer players using some athletic performance tests.

METHODOLOGY

Twenty-two soccer players between the ages of 18 and 35 voluntarily participated in the study. All participants were actively engaged in a rigorous six-day-a-week training program during the pre-season preparation period. Preceding and following the training program, a battery of diverse athletic performance tests was administered to the participants. Moreover, Genomic DNA was extracted from oral epithelial cells using the Invitrogen DNA isolation kit (Invitrogen, USA), following the manufacturer's protocol. Genotyping was conducted using real-time PCR. To assess the pre- and post-test performance differences of soccer players, the Wilcoxon Signed Rank test was employed.

RESULTS

Upon analyzing the results of the soccer players based on the ACTN3 genotype variable, it was observed that there were no statistically significant differences in the SJ (Squat Jump), 30m sprint, CMJ (Counter Movement Jump), and DJ (Drop Jump) performance tests (p > 0.05). However, a statistically significant difference was identified in the YOYO IRT 2 (Yo-Yo Intermittent Recovery Test Level 2) and 1RM (One Repetition Maximum) test outcomes (YOYO IRT 2: CC, CT, and TT, p = 0.028, 0.028, 0.008, 0.000, respectively; 1RM: CC, CT, and TT, p = 0.010, 0.34, 0.001, respectively). Regarding the PPARA-α genotype variable, the statistical analysis revealed no significant differences in the SJ, 30m sprint, CMJ, and DJ performance tests (p > 0.05). Nevertheless, a statistically significant difference was observed in the YOYO IRT 2 and 1RM test results (YOYO IRT 2: CC, CG p = 0.001, 0.020; 1RM: CC, p = 0.000) CONCLUSIONS: The current study demonstrated significant enhancements in only YOYO INT 2 and 1RM test outcomes across nearly all gene variants following the six-day-a-week training program. Other performance tests, such as the 30m sprint, SJ, CMJ, and DJ tests did not exhibit statistically significant differences. These findings contribute novel insights into the molecular processes involving PPARA-α rs4253778 and ACTN3 rs1815739 that underpin enhancements in endurance (YOYO INT 2) and maximal strength (1RM) aspects of athletic performance. However, to comprehensively elucidate the mechanisms responsible for the association between these polymorphisms and athletic performance, further investigations are warranted. It is thought that the use of field and genetic analyses together to support each other will be an important detail for athletes to reach high performance.

Slow or fast: Implications of myofibre type and associated differences for manifestation of neuromuscular disorders

Many neuromuscular disorders can have a differential impact on a specific myofibre type, forming the central premise of this review. The many different skeletal muscles in mammals contain a spectrum of slow- to fast-twitch myofibres with varying levels of protein isoforms that determine their distinctive contractile, metabolic, and other properties. The variations in functional properties across the range of classic 'slow' to 'fast' myofibres are outlined, combined with exemplars of the predominantly slow-twitch soleus and fast-twitch extensor digitorum longus muscles, species comparisons, and techniques used to study these properties. Other intrinsic and extrinsic differences are discussed in the context of slow and fast myofibres. These include inherent susceptibility to damage, myonecrosis, and regeneration, plus extrinsic nerves, extracellular matrix, and vasculature, examined in the context of growth, ageing, metabolic syndrome, and sexual dimorphism. These many differences emphasise the importance of carefully considering the influence of myofibre-type composition on manifestation of various neuromuscular disorders across the lifespan for both sexes. Equally, understanding the different responses of slow and fast myofibres due to intrinsic and extrinsic factors can provide deep insight into the precise molecular mechanisms that initiate and exacerbate various neuromuscular disorders. This focus on the influence of different myofibre types is of fundamental importance to enhance translation for clinical management and therapies for many skeletal muscle disorders.

Association of ACTN3 R577X Polymorphism with Elite Basketball Player Status and Training Responses

The α-actinin-3 (ACTN3) gene rs1815739 (C/T, R577X) polymorphism is a variant frequently associated with athletic performance among different populations. However, there is limited research on the impact of this variant on athlete status and physical performance in basketball players. Therefore, the aim of this study was twofold: (1) to determine the association of ACTN3 rs1815739 polymorphism with changes in physical performance in response to six weeks of training in elite basketball players using 30 m sprint and Yo-Yo Intermittent Recovery Test Level 2 (IR 2) tests, and (2) to compare ACTN3 genotype and allelic frequencies between elite basketball players and controls. The study included a total of 363 individuals, comprising 101 elite basketball players and 262 sedentary individuals. Genomic DNA was isolated from oral epithelial cells or leukocytes, and genotyping was performed by real-time PCR using KASP genotyping method or by microarray analysis. We found that the frequency of the ACTN3 rs1815739 XX genotype was significantly lower in basketball players compared to controls (10.9 vs. 21.4%, p = 0.023), suggesting that RR/RX genotypes were more favorable for playing basketball. Statistically significant (p = 0.045) changes were observed in Yo-Yo IRT 2 performance measurement tests in basketball players with the RR genotype only. In conclusion, our findings suggest that the carriage of the ACTN3 rs1815739 R allele may confer an advantage in basketball.

Lunar gravity prevents skeletal muscle atrophy but not myofiber type shift in mice

Skeletal muscle is sensitive to gravitational alterations. We recently developed a multiple artificial-gravity research system (MARS), which can generate gravity ranging from microgravity to Earth gravity (1 g) in space. Using the MARS, we studied the effects of three different gravitational levels (microgravity, lunar gravity [1/6 g], and 1 g) on the skeletal muscle mass and myofiber constitution in mice. All mice survived and returned to Earth, and skeletal muscle was collected two days after landing. We observed that microgravity-induced soleus muscle atrophy was prevented by lunar gravity. However, lunar gravity failed to prevent the slow-to-fast myofiber transition in the soleus muscle in space. These results suggest that lunar gravity is enough to maintain proteostasis, but a greater gravitational force is required to prevent the myofiber type transition. Our study proposes that different gravitational thresholds may be required for skeletal muscle adaptation.

Association between ACE and ACTN3 genes polymorphisms and athletic performance in elite and sub-elite Chinese youth male football players

Background

Previous studies have shown controversial relationships between ACE I/D and ACTN3 R577x polymorphisms and athletic performance. Therefore, the aim of this study was to assess athletic performance indicators of Chinese youth male football players with different ACE and ACTN3 gene profiles.

Methods and Materials

This study recruited 73 elite (26 13-year-olds, 28 14-year-olds, and 19 15-year-olds) and 69 sub-elite (37 13-year-olds, 19 14-year-olds, and 13 15-year-olds) and 107 controls (63 13-year-olds, and 44 14-year olds aged 13-15 years, all participants were of Chinese Han origin. We measured height, body mass, thigh circumference, speed, explosive power, repeat sprints ability, and aerobic endurance in elite and sub-elite players. We used single nucleotide polymorphism technology to detect controls elite and sub-elite players' ACE and ACTN3 genotypes, Chi-squared (χ ²) tests were employed to test for Hardy-Weinberg equilibrium. χ ² tests were also used to observe the association between the genotype distribution and allele frequencies between controls and elite and sub-elite players. The differences in parameters between the groups were analyzed using one-way analysis of variance and a Bonferroni's post-hoc test, with statistical significance set at p ≤ 0.05.

Results

(1) The genotype distribution of the ACE I/D and ACTN3 R577x polymorphisms in controls, elite and sub-elite football players were consistent with Hardy-Weinberg equilibrium, except for the ACE genotype distribution of sub-elite players. (2) The RR and DD genotypes were significantly different between elite and sub-elite players (p = 0.024 and p = 0.02, respectively). (3) Elite players were more likely to have the RR genotype and less likely to have the DD genotype compared with sub-elite players. (4) Both elite and sub-elite RR players' Yo-yo intermittent recovery level 1 (YYIR1) running distance was significantly longer than that of RX players (p = 0.05 and p = 0.025, respectively). However, there was no significantly different in YYIR1 running distance between elite and sub-elite RR players. (5) Elite XX players' VO₂ max was significantly higher than that of RX and sub-elite players.

Conclusion

These results indicate that ACE I/D and ACTN3 R577x polymorphisms are not associated with muscle power in Chinese elite and sub-elite players. The XX genotype of ACTN3 is associated with the aerobic endurance of elite players.

Influence of Alpha-Actinin-3 R577X Polymorphism on Muscle Damage and the Inflammatory Response after an Acute Strength Training Session

The objective of this study was to verify the influence of the ACTN3 R577X polymorphism on muscle damage and the inflammatory response after an acute strength training (ST) session. Twenty-seven healthy male individuals (age: 25 ± 4.3 years) participated in the study, including 18 RR/RX and 9 XX individuals. The participants were divided into two groups (RR/RX and XX groups) and subjected to an acute ST session, which consisted of a series of leg press, leg extension machine, and seated leg curl machine. The volunteers were instructed to perform the greatest volume of work until concentric muscle failure. Each volunteer's performance was analyzed as the load and total volume of training, and the blood concentrations of C-C motif chemokine ligand 2 (CCL2), interleukin-8 (IL-8), creatine kinase (CK), lactate dehydrogenase (LDH), myoglobin, testosterone, and cortisol were measured before the ST session and 30 min and 24 h postsession. The ACTN3 R577X polymorphism effect was observed, with increased concentrations of CCL2 (p < 0.01), IL-8 (p < 0.01), and LDH (p < 0.001) in XX individuals. There was an increase in the concentration of CK in the RR/RX group compared to XX at 24 h after training (p > 0.01). The testosterone/cortisol ratio increased more markedly in the XX group (p < 0.001). Regarding performance, the RR/RX group presented higher load and total volume values in the training exercises when compared to the XX group (p < 0.05). However, the XX group presented higher values of delayed onset muscle soreness (DOMS) than the RR/RX group (p < 0.05). The influence of ACTN3 R577X polymorphism on muscle damage and the inflammatory response was observed after an acute ST session, indicating that the RR/RX genotype shows more muscle damage and a catabolic profile due to a better performance in this activity, while the XX genotype shows more DOMS.

A Pilot Study on the Prediction of Non-Contact Muscle Injuries Based on ACTN3 R577X and ACE I/D Polymorphisms in Professional Soccer Athletes

Muscle injuries are among the main reasons for medical leavings of soccer athletes, being a major concern within professional teams and their prevention associated with sport success. Several factors are associated with a greater predisposition to injury, and genetic background is increasingly being investigated. The aim of this study was to analyze whether ACTN3 R577X and ACE I/D polymorphisms are predictors of the incidence and severity of muscle injury in professional soccer athletes from Brazil, individually and in association. Eighty-three professional athletes from the first and second divisions of the Brazilian Championship were evaluated regarding the polymorphisms through blood samples. Nighty-nine muscle injuries were identified during the seasons of 2018, 2019 and 2020 and categorized according to severity. ACTN3 XX individuals had a higher frequency of severe injuries compared to the RX and RR genotypes (p = 0.001), and in the dominant model (compared to RX+RR), with p < 0.001. The trend p-value test showed an increased number of injuries/season following the order XX > RX > RR (p = 0.045). Those with the ACE II genotype had almost 2 fold the number of injuries per season compared to those with the ID+DD genotypes (p = 0.03). Logistic regression showed that the polymorphisms are predictors of the development of severe injury (ACTN3 R577X model with p = 0.004, R2: 0.259; ACE I/D model with p = 0.045, R2: 0.163), where ACTN3 XX individuals were more likely to suffer from severe injury (OR: 5.141, 95% CI: 1.472-17.961, p = 0.010). The combination of the ACTN3 577X allele and the ACE II genotype showed an increased number of injuries per season, enhanced by 100% (1.682 injuries/season versus 0.868 injuries/season, p = 0.016). Our findings suggest that both polymorphisms ACTN3 R577X and ACE I/D (and their interaction) are associated with the susceptibility and severity of non-contact muscle injury in soccer players.

Effects of high-intensity and moderate-intensity exercise training on cardiopulmonary function in patients with coronary artery disease: A meta-analysis

Purpose

The study aims to evaluate the effects of high-intensity and moderate-intensity exercise training on cardiopulmonary function and exercise endurance in patients with coronary artery diseases (CAD).

Methods

We performed a systematic search of the English and Chinese databases from their inception to March 2022. Randomized controlled trials (RCTs) were included to compare high-intensity and moderate-intensity exercise training on cardiopulmonary function in patients with CAD. The primary outcomes included peak oxygen uptake (peak VO₂) and anaerobic threshold (AT). The secondary outcomes included left ventricular ejection fraction (LVEF), exercises duration (ED), respiratory exchange ratio (RER), resting heart rate (RHR), peak heart rate (PHR) and oxygen pulse (O₂ pulse). The continuous variables were expressed as mean differences (MD) along with their corresponding standard deviations (SD), and the I² test was applied in the assessment of heterogeneity.

Results

After systematically literature search, 19 studies were finally selected for our meta-analysis (n = 1,036), with 511 patients in the experimental group (high-intensity exercise) and 525 patients in the control group (moderate-intensity exercise). The results showed that high-intensity exercise significantly increased patients' Peak VO₂ [MD = 2.67, 95% CI (2.24, 3.09), P < 0.00001], LVEF [MD = 3.60, 95% CI (2.17, 5.03), P < 0.00001], ED [MD = 37.51, 95% CI (34.02, 41.00), P < 0.00001], PHR [MD = 6.86, 95% CI (4.49, 9.24), P < 0.00001], and O₂ pulse [MD = 0.97, 95% CI (0.34, 1.60), P = 0.003] compared with moderate-intensity exercise. However, there were no significant differences in AT [MD = 0.49, 95% CI (−0.12, 1.10), P = 0.11], RER [MD = 0.00, 95% CI (−0.01, 0.02), P = 0.56], and RHR [MD = 1.10, 95% CI (−0.43, 2.63), P = 0.16].

Conclusion

Our results show that high-intensity exercise training has more significant positive effects compared with moderate-intensity exercise training in improving peak VO₂, LVEF, ED, PHR and O₂ pulse in patients with CAD, while no significant differences were observed in AT, RER and RHR. To sum up, high-intensity exercise training is better than moderate-intensity exercise training in improving cardiopulmonary function and exercise endurance in patients with CAD.

Systematic review registration

PROSPERO (CRD42022328475), https://www.crd.york.ac.uk/PROSPERO/.

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.

The ACTN3 R577X polymorphism is associated with metabolic alterations in a sex-dependent manner in subjects from western Mexico

BACKGROUND

The ACTN3 gene is primarily expressed in fast skeletal muscle fibres. A common nonsense polymorphism in this gene is ACTN3 R577X (rs1815739), which causes an absolute deficiency of α-actinin-3 protein and alterations in muscle metabolism. Considering metabolic alterations are influenced by nutrition and genetic factors, as well as lifestyle factors, we hypothesise a possible association of the ACTN3 R577X polymorphism with metabolic alterations.

METHODS

In this cross-sectional study, 397 adults met the inclusion criteria. Body composition was measured by electrical bioimpedance. Dietary data were analysed using Nutritionist Pro™ software. Biochemical variables were determined by dry chemistry. Genomic DNA was extracted from peripheral leukocytes and genotyping of the ACTN3 R577X polymorphism was determined by allelic discrimination using TaqMan probes. The statistical analyses were performed using SPSS statistical software. p < 0.05 was considered statistically significant.

RESULTS

The ACTN3 577XX genotype was associated with high glucose, triglyceride and very low density lipoprotein-cholesterol levels and a higher frequency of hypertriglyceridaemia and insulin resistance in women. In males, the genetic variant showed a trend towards significance for insulin resistance.

CONCLUSIONS

The ACTN3 R577X polymorphism was associated with metabolic alterations in women and a tendency was observed in men variant carriers. Thus, this common genetic variant could be implicated in the development of chronic metabolic diseases.

Associations of alpha-actinin-3 genotype with thigh muscle volume and physical performance in older adults with sarcopenia or pre-sarcopenia

BACKGROUND

This cross-sectional study aimed to investigate the relationship of the ACTN3 genotype with thigh muscle volume and physical performance in older adults with sarcopenia or pre-sarcopenia.

METHODS

Data from 64 older Japanese adults (mean age 74.4 ± 6.9 years, women 71.9%) with sarcopenia or pre-sarcopenia were analyzed. Sarcopenia and pre-sarcopenia were defined using the Asian Working Group for Sarcopenia. We collected oral mucosa samples to determine the ACTN3 genotype. Thigh muscle volumes were measured using magnetic resonance imaging. Physical performance was assessed using the usual and maximum gait speed, timed up and go test, and five-repetition sit-to-stand test. Muscle strength was assessed using grip strength.

RESULT

The ACTN3 genotype proportions were 20.3% for RR, 51.6% for RX, and 28.1% for XX. Participants with the RR genotype showed greater thigh muscle volume/ht² compared to those with the RX and XX ACTN3 genotypes (p < 0.05). The multiple linear regression analysis revealed that RX (p < 0.01) and XX (p < 0.01) ACTN3 genotypes, compared to RR, were associated with lower thigh muscle volume/ht² and with age, sex (reference; men), weight and maximum walking speed. There was no significant difference between physical performance and muscle strength between the ACTN3 genotypes.

CONCLUSION

The ACTN3 genotype of the X allele was associated with decreased thigh muscle volume compared to the ACTN3 genotype of RR in older adults with sarcopenia or pre-sarcopenia.

Nuclear factor E2-related factor 2 (NRF2) deficiency accelerates fast fibre type transition in soleus muscle during space flight

Microgravity induces skeletal muscle atrophy, particularly in the soleus muscle, which is predominantly composed of slow-twitch myofibre (type I) and is sensitive to disuse. Muscle atrophy is commonly known to be associated with increased production of reactive oxygen species. However, the role of NRF2, a master regulator of antioxidative response, in skeletal muscle plasticity during microgravity-induced atrophy, is not known. To investigate the role of NRF2 in skeletal muscle within a microgravity environment, wild-type and Nrf2-knockout (KO) mice were housed in the International Space Station for 31 days. Gene expression and histological analyses demonstrated that, under microgravity conditions, the transition of type I (oxidative) muscle fibres to type IIa (glycolytic) was accelerated in Nrf2-KO mice without affecting skeletal muscle mass. Therefore, our results suggest that NRF2 affects myofibre type transition during space flight.

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.

Influence of the ACTN3 Genotype and the Exercise Intensity on the Respiratory Exchange Ratio and Excess Oxygen Consumption After Exercise

ABSTRACT

de L. Corrêa, H, Ribeiro, HS, Maya, ÁTD, Neves, RP, de Moraes, MR, Lima, RM, Nóbrega, OT, and Ferreira, AP. Influence of the ACTN3 genotype and the exercise intensity on the respiratory exchange ratio and excess oxygen consumption after exercise. J Strength Cond Res 35(5): 1380-1388, 2021-This study aimed to assess the respiratory exchange ratio (RER) and excess postexercise oxygen consumption (EPOC) after high-intensity interval training and continuous moderate-intensity aerobic training in accordance with the ACTN3 genotype. A cross-sectional study with 30 physically active individuals who participated in 3 experimental sessions, as follows: a high-intensity interval aerobic exercise, for 3 minutes at 115% anaerobic threshold, with 90 seconds of passive recovery; a continuous moderate-intensity aerobic exercise at 85% anaerobic threshold; and a control session. Respiratory exchange ratio and V̇o2 were obtained through an indirect, calorimetry-based gas analysis method, using a breath-by-breath approach, assessed at baseline, during the trials, and at 1, 2, 3, and 4 hours after exercise. We found that lower postexercise RER values were observed only in subjects with the X allele, in both the high- and the moderate-intensity training protocols. Homozygous RR subjects showed no differences in postexercise RER compared with the scores at the control day. After both sessions of exercise, EPOC levels were higher compared with scores at the control day for 2 hours among X allele carriers, and only in the first hour among RR homozygous. Thus, the RER and EPOC presented different responses after moderate and intense exercise according to the ACTN3 genotype. Moreover, individuals with the X allele of the ACTN3 gene show a higher oxidation of fats in the postexercise period.

Responses to Maximal Strength Training in Different Age and Gender Groups

Purpose

The present study aimed to investigate the potential impact of age, gender, baseline strength, and selected candidate polymorphisms on maximal strength training (MST) adaptations.

Methods

A total of 49 subjects (22 men and 27 women) aged 20–76 years, divided into five age groups, completed an 8 weeks MST intervention. Each MST session consisted of 4 sets with 4 repetitions at ∼85–90% of one-repetition maximum (1RM) intensity in leg-press, three times per week. 1RM was tested pre and post the intervention and blood samples were drawn to genotype candidate polymorphisms ACE I/D (rs1799752), ACTN3 R577X (rs1815739), and PPARGC1A Gly482Ser (rs8192678).

Results

All age groups increased leg-press 1RM (p < 0.01), with a mean improvement of 24.2 ± 14.0%. There were no differences in improvements between the five age groups or between male and female participants, and there were no non-responders. Baseline strength status did not correlate with 1RM improvements. PPARGC1A rs8192678 T allele carriers had a 15% higher age- and gender corrected baseline 1RM than the CC genotype (p < 0.05). C allele carriers improved 1RM (%) by 34.2% more than homozygotes for the T allele (p < 0.05).

Conclusion

To the best of our knowledge, this is the first study to report improvement in leg-press maximal strength regardless of gender, baseline strength status in all age groups. The present study is also first to demonstrate an association between the PPARGC1A rs8192678 and maximal strength and its trainability in a moderately trained cohort. MST may be beneficial for good health and performance of all healthy individuals.

Maintenance of type 2 glycolytic myofibers with age by Mib1-Actn3 axis

Age-associated muscle atrophy is a debilitating condition associated with loss of muscle mass and function with age that contributes to limitation of mobility and locomotion. However, the underlying mechanisms of how intrinsic muscle changes with age are largely unknown. Here we report that, with age, Mind bomb-1 (Mib1) plays important role in skeletal muscle maintenance via proteasomal degradation-dependent regulation of α-actinin 3 (Actn3). The disruption of Mib1 in myofibers (Mib1^ΔMF) results in alteration of type 2 glycolytic myofibers, muscle atrophy, impaired muscle function, and Actn3 accumulation. After chronic exercise, Mib1^ΔMF mice show muscle atrophy even at young age. However, when Actn3 level is downregulated, chronic exercise-induced muscle atrophy is ameliorated. Importantly, the Mib1 and Actn3 levels show clinical relevance in human skeletal muscles accompanied by decrease in skeletal muscle function with age. Together, these findings reveal the significance of the Mib1-Actn3 axis in skeletal muscle maintenance with age and suggest the therapeutic potential for the treatment or amelioration of age-related muscle atrophy.

Masticatory Functional Load Increases the mRNA Expression Levels of ACTN2 and ACTN3 and the Protein Expression of α-Actinin-2 in Rat Masseter Muscle

Objectives

α-actinins play structural and regulatory roles in cytoskeletal organization. They form a lattice structure that secures actin in thin filaments, which generate and transmit muscle contractile forces. The morphological and biochemical characteristics of rat masseter muscles are known to change reactions to masticatory functional loads, but their effect on α-actinins remains unknown. This study aimed to determine the response of α-actinins to masticatory functional loads.

Materials and Methods

Twenty-four male Wistar rats aged 3 weeks were divided randomly into 3 groups of liquid diet (LD), soft diet, and hard diet (HD). The rats were then sacrificed at the end of 8 weeks. The middle part of superficial masseter muscles was examined to investigate the masticatory effect of functional load on the mRNA expression levels of ACTN2 and ACTN3 and the protein expression levels of α-actinin-2 and α-actinin-3.

Results

The mRNA expression levels of ACTN2 and ACTN3 and the protein expression levels of α-actinin-2 of the HD group were significantly higher than those of the LD group, which served as the control group.

Conclusion

Masticatory functional load organizes the mRNA expression levels of ACTN2 and ACTN3 and the protein expression levels of α-actinin-2 in rat masseter muscles through stimuli during muscle physiological adaptation.

Body flexibility and incident hypertension: The Niigata wellness study

A high level of physical fitness, especially cardiorespiratory fitness, is associated with lower incidence of hypertension. However, the relationship between flexibility, which is a component of physical fitness, and the incidence of hypertension is unknown. The purpose of this study was to investigate the relationship between flexibility and the incidence of hypertension in a cohort study. A total of 22,972 (14,805 men and 8167 women; median age 49 years) normotensive participants were included in this study. Between April 2001 and March 2002, flexibility (standing forward bending) was measured using a standing trunk flexion meter. The participants were divided into quartiles of flexibility by sex and age group. Hypertension was defined as systolic blood pressure ≥ 140 mm Hg, diastolic blood pressure ≥ 90 mm Hg, or a self-reported history of previously diagnosed hypertension or current medication for hypertension at a health examination between April 2002 and March 2008. Hazard ratios and 95% confidence intervals (95% CI) for the incidence of hypertension were estimated using Cox proportional hazards models after adjusting for age, sex, body mass index, exercise habits, smoking status, and drinking status. During 102,948 person years of follow-up (median 5.6 years), 4235 participants developed hypertension. Compared with the lowest flexibility (quartile 1), hazard ratios and 95% CI were 0.96 (0.88 - 1.04) for quartile 2, 0.94 (0.86 - 1.03) for quartile 3, and 0.83 (0.76 - 0.91) for quartile 4. A high level of flexibility was associated with lower incidence of hypertension, independent of other confounding factors.

Effect of ACTN3 Genotype on Sports Performance, Exercise-Induced Muscle Damage, and Injury Epidemiology

Genetic factors play a significant role in athletic performance and its related phenotypes such as power, strength and aerobic capacity. In this regard, the lack of a muscle protein due to a genetic polymorphism has been found to affect sport performance in a wide variety of ways. α-actinin-3 is a protein located within the skeletal muscle with a key role in the production of sarcomeric force. A common stop-codon polymorphism (rs1815739; R577X) in the gene that codes for α-actinin-3 (ACTN3) produces individuals with the XX genotype that lack expression of a functional α-actinin-3. In contrast, individuals with the R-allele (i.e., RX vs. RR genotypes) in this polymorphism can express α-actinin-3. Interestingly, around ~18% of the world population have the XX genotype and much has been debated about why a polymorphism that produces a lack of a muscle protein has endured natural selection. Several investigations have found that α-actinin-3 deficiency due to XX homozygosity in the ACTN3 R577X polymorphism can negatively affect sports performance through several structural, metabolic, or signaling changes. In addition, new evidence suggests that α-actinin-3 deficiency may also impact sports performance through indirect factors such a higher risk for injury or lower resistance to muscle-damaging exercise. The purpose of this discussion is to provide a clear explanation of the effect of α-actinin-3 deficiency due to the ACTN3 XX genotype on sport. Key focus has been provided about the effect of α-actinin-3 deficiency on morphologic changes in skeletal muscle, on the low frequency of XX athletes in some athletic disciplines, and on injury epidemiology.

ACTN3's R577X Single Nucleotide Polymorphism Allele Distribution Differs Significantly in Professional Football Players according to Their Field Position

INTRODUCTION

Football is characterised by intermittent high-intensity efforts varying according to the field position of a player. We aimed to ascertain whether polymorphisms in the ACTN3 gene are associated with different playing positions in elite professional football players.

SUBJECTS AND METHODS

Genotyping of the ACTN3 gene was conducted in 43 elite professional football players of a single team. Playing position was recorded based on the player's most frequent position.

RESULTS

The genotype distribution was not significant between positions (p = 0.057), while the allele distribution differed significantly (p = 0.035). Goalkeepers (p = 0.04, p = 0.03), central defenders (p = 0.03, p = 0.01), and central midfielders (p = 0.01, p = 0.00) had a significantly different allele distribution compared with wide midfielders and forward players.

CONCLUSIONS

Genetic biomarkers may be important when analysing performance capability in elite professional football. Identifying the genetic characteristics of a player to adapt his playing position may lead to orientation of positions based on physical capabilities and tissue quality in young football players, and also to performance enhancement in those who are already playing in professional teams.

High-throughput proteomics fiber typing (ProFiT) for comprehensive characterization of single skeletal muscle fibers

BACKGROUND

Skeletal muscles are composed of a heterogeneous collection of fiber types with different physiological adaption in response to a stimulus and disease-related conditions. Each fiber has a specific molecular expression of myosin heavy chain molecules (MyHC). So far, MyHCs are currently the best marker proteins for characterization of individual fiber types, and several proteome profiling studies have helped to dissect the molecular signature of whole muscles and individual fibers.

METHODS

Herein, we describe a mass spectrometric workflow to measure skeletal muscle fiber type-specific proteomes. To bypass the limited quantities of protein in single fibers, we developed a Proteomics high-throughput fiber typing (ProFiT) approach enabling profiling of MyHC in single fibers. Aliquots of protein extracts from separated muscle fibers were subjected to capillary LC-MS gradients to profile MyHC isoforms in a 96-well format. Muscle fibers with the same MyHC protein expression were pooled and subjected to proteomic, pulsed-SILAC, and phosphoproteomic analysis.

RESULTS

Our fiber type-specific quantitative proteome analysis confirmed the distribution of fiber types in the soleus muscle, substantiates metabolic adaptions in oxidative and glycolytic fibers, and highlighted significant differences between the proteomes of type IIb fibers from different muscle groups, including a differential expression of desmin and actinin-3. A detailed map of the Lys-6 incorporation rates in muscle fibers showed an increased turnover of slow fibers compared to fast fibers. In addition, labeling of mitochondrial respiratory chain complexes revealed a broad range of Lys-6 incorporation rates, depending on the localization of the subunits within distinct complexes.

CONCLUSION

Overall, the ProFiT approach provides a versatile tool to rapidly characterize muscle fibers and obtain fiber-specific proteomes for different muscle groups.

Alpha-Actinin-3 R577X Polymorphism Influences Muscle Damage and Hormonal Responses After a Soccer Game

Coelho, DB, Pimenta, EM, Rosse, IC, Veneroso, C, Pussieldi, GDA, Becker, LK, De Oliveira, EC, Carvalho, MRS, and Silami-Garcia, E. Alpha-actinin-3 R577X polymorphism influences muscle damage and hormonal responses after a soccer game. J Strength Cond Res 33(10): 2655-2664, 2019-The purpose of this study was to evaluate indicators of muscle damage and hormonal responses after soccer matches and its relation to alpha-actinin-3 (ACTN3) gene expression (XX vs. RR/RX), considering that the R allele produces alpha-actinin-3 and provides greater muscle strength and power. Thirty players (10 XX and 20 RR/RX) younger than 16 years were evaluated in this study. Blood samples were collected immediately before, after, 2, and 4 hours after the games to assess muscle damage (creatine kinase [CK] and alpha-actin) and hormonal responses (interleukin-6 [IL-6], cortisol, and testosterone). Postgame CK was higher as compared to the pregame values in both groups and it was also higher in the RR/RX (p < 0.05) than in the XX. The concentrations of alpha-actin and IL-6 were similar for both groups and did not change over time. Testosterone was increased after the game only in the RR/RX group (p < 0.05). Cortisol concentrations in group RR/RX were higher immediately after the game than before the game, and 2 and 4 hours after the game the concentration decreased (p < 0.05). The RR and RX individuals presented higher markers of muscle microtrauma and hormonal stress, probably because they performed more speed and power actions during the game, which is a self-regulated activity. From the different responses presented by RR/RX and XX genotypes, we conclude that the genotypic profile should be taken into account when planning training workloads and recovery of athletes.

ACTN3 single nucleotide polymorphism is associated with non-contact musculoskeletal soft-tissue injury incidence in elite professional football players

PURPOSE

Muscle injuries are common in professional football, even though prevention protocols are being implemented. Genetics constitutes a novel field for studying intrinsic injury risks and performance. Since previous studies involving single nucleotide polymorphisms (SNPs) have shown that SNPs influence muscle injury rate, injury severity and recovery time, the aim was to study the association the SNP of ACTN3 has with those parameters in professional football players.

METHODS

The medical staff team recorded non-contact musculoskeletal soft-tissue injuries in 43 professional football players in 7 different seasons (2007-2012 and 2015-2016). Injury rate, injury severity and injury recovery times were established. Players were genotyped by extracting DNA from a blood sample and using a polymerase chain reaction.

RESULTS

Injury rate was associated with the SNP of ACTN3 (p = 0.003). The 577R allele was more frequent in subjects than in a normal population by showing presence in 93% of the subjects and suggesting that it could influence football performance. No statistically significant differences in injury severity and recovery time were associated with the SNP of ACTN3.

CONCLUSIONS

Genetics is gaining in importance when assessing injury risk and performance in professional football. ACTN3 can be regarded as a biomarker of injury susceptibility in this discipline. Identifying those players with the highest injury susceptibility through genetics could lead football teams to individualise workloads and prevention protocols.

LEVEL OF EVIDENCE

III.

Can Genetic Testing Identify Talent for Sport?

Elite athlete status is a partially heritable trait, as are many of the underpinning physiological, anthropometrical, and psychological traits that contribute to elite performance. In recent years, our understanding of the specific genetic variants that contribute to these traits has grown, such that there is considerable interest in attempting to utilise genetic information as a tool to predict future elite athlete status. In this review, we explore the extent of the genetic influence on the making of a sporting champion and we describe issues which, at present, hamper the utility of genetic testing in identifying future elite performers. We build on this by exploring what further knowledge is required to enhance this process, including a reflection on the potential learnings from the use of genetics as a disease prediction tool. Finally, we discuss ways in which genetic information may hold utility within elite sport in the future, including guiding nutritional and training recommendations, and assisting in the prevention of injury. Whilst genetic testing has the potential to assist in the identification of future talented performers, genetic tests should be combined with other tools to obtain an accurate identification of those athletes predisposed to succeed in sport. The use of total genotype scores, composed of a high number of performance-enhancing polymorphisms, will likely be one of the best strategies in the utilisation of genetic information to identify talent in sport.

A "human knockout" model to investigate the influence of the α-actinin-3 protein on exercise-induced mitochondrial adaptations

Research in α-actinin-3 knockout mice suggests a novel role for α-actinin-3 as a mediator of cell signalling. We took advantage of naturally-occurring human “knockouts” (lacking α-actinin-3 protein) to investigate the consequences of α-actinin-3 deficiency on exercise-induced changes in mitochondrial-related genes and proteins, as well as endurance training adaptations. At baseline, we observed a compensatory increase of α-actinin-2 protein in ACTN3 XX (α-actinin-3 deficient; n = 18) vs ACTN3 RR (expressing α-actinin-3; n = 19) participants but no differences between genotypes for markers of aerobic fitness or mitochondrial content and function. There was a main effect of genotype, without an interaction, for RCAN1-4 protein content (a marker of calcineurin activity). However, there was no effect of genotype on exercise-induced expression of genes associated with mitochondrial biogenesis, nor post-training physiological changes. In contrast to results in mice, loss of α-actinin-3 is not associated with higher baseline endurance-related phenotypes, or greater adaptations to endurance exercise training in humans.

In the search of a 'fitness gene': an analysis of ACTN gene polymorphisms in serving soldiers

Background

Genetic polymorphisms in the exon 15 and exon 16 of the ACTN3 gene are believed to be associated with athletic performance. Paratroopers are some of the fittest soldiers in the Indian Armed Forces. This study was taken up to assess if there was a significant difference in the genetic profile between paratroopers and non-paratroopers.

Method

Polymerase chain reaction (PCR) followed by restriction length fragment polymorphism (RFLP) was used to analyse the genetic polymorphisms in the exon 15 and 16 of the ACTN3 gene.

Results

There was a significant difference between paratroopers and non-paratroopers in the polymorphic loci at codon 15 and 16.

Conclusions

The study suggests that there is a significant difference in the genotype between paratroopers and non-paratroopers. It is likely that the differences in muscle fibres as a result of these genotypic changes confer a 'survival advantage'; people with a homozygous genotype are more likely to pass the harsh probation and qualify for the Parachute Regiment.

The Role of Genetic Profile in Functional Performance Adaptations to Exercise Training or Physical Activity: A Systematic Review of the Literature

Background: Variations in genotype may contribute to heterogeneity in functional adaptations to exercise. Methods: A systematic search of eight databases was conducted, and 9,696 citations were screened. Results: Eight citations from seven studies measuring 10 single-nucleotide polymorphisms and nine different functional performance test outcomes were included in the review. There was one observational study of physical activity and six experimental studies of aerobic or resistance training. The ACE (D) allele, ACTN3 (RR) genotype, UCP2 (GG) genotype, IL-6-174 (GG) genotype, TNF-α-308 (GG) genotype, and IL-10-1082 (GG) genotype all predicted significantly superior adaptations in at least one functional outcome in older men and women after prescribed exercise or in those with higher levels of physical activity. Conclusion: There is a small amount of evidence that older adults may have better functional outcomes after exercise/physical activity if they have specific alleles related to musculoskeletal function or inflammation. However, more robust trials are needed.

High Expression Levels of ACTN1 and ACTN3 Indicate Unfavorable Prognosis in Acute Myeloid Leukemia

Background: Actinins are major cytoskeletal proteins that mediate sarcomere function, and they also have important non-muscle functions such as regulating cytokinesis, cell adhesion and migration. There are four isoforms of actinins in mammals (ACTN1-4). Recently, the relationship between actinins and cancer has been discovered in many types of malignancy, yet their prognostic significance in acute myeloid leukemia (AML) remains unclear. Methods: We collected data of 155 de novo AML patients from The Cancer Genome Atlas (TCGA) database; 85 patients received chemotherapy only and 70 patients underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT). We divided each treatment groups into sub-groups based on the median expression levels of ACTN1-4. Results: Survival analysis showed that in the chemotherapy-only group, high ACTN1 and ACTN3 expression were associated with shorter event-free survival (EFS) and overall survival (OS) (p<0.01). Multivariate analysis suggested that high expression of ACTN1 and ACTN3 (p<0.05) were independent poor prognostic factors. In the allo-HSCT group, ACTN1-4 expression had no impact on survival. Conclusions: Our study suggested that high expression levels of ACTN1 and ACTN3 adversely affected the survival of AML patients, but their harmful impact could be overcome by allo-HSCT.

Association Between Hematological Parameters and Iron Metabolism Response After Marathon Race and ACTN3 Genotype

α-Actinin-3 (ACTN3 R577X, rs.1815739) polymorphism is a genetic variation that shows the most consistent influence on metabolic pathway and muscle phenotype. XX genotype is associated with higher metabolic efficiency of skeletal muscle; however, the role of ACTN3 polymorphism in oxygen transport and utilization system has not yet been investigated. Therefore, the aim of this study was to determine the influence of ACTN3 polymorphisms on hematological and iron metabolism response induced by marathon race. Eighty-one Brazilian amateur male endurance runners participated in the study. Blood samples and urine were collected before; immediately after; and 1, 3, and 15 days after the marathon race. Urine, hematological parameters, iron metabolism, and ACTN3 genotyping analyses were performed. The marathon race induced a decrease in erythrocytes, Hb, and Ht, and an increase in hematuria, creatinine, myoglobin, red cell distribution width, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin, direct and indirect bilirubin and erythropoietin. Moreover, an elevation immediately or 1 day after the marathon race follows a reduction 3 or 15 days after the marathon race were observed on transferrin saturation and iron and transferrin levels. Hematological parameters and iron metabolism changes induced by marathon race were not observed in XX genotypes. Hematuria and decreased erythrocytes, Hb, Ht, and iron and transferrin levels were observed only in RR and/or RX genotypes but not in XX genotypes. The percentage of runners with hematuria, leukocyturia, iron deficiency, creatinine, myoglobin, and bilirubin imbalance was higher in RR compared to XX genotypes. ACTN3 polymorphism is associated with iron metabolism and hematological responses after endurance exercise. Despite these results being based on a small sample, they highlight a protective role of the XX genotype on hematological and renal changes induced by long-distance exercise. Therefore, these findings should be further replicated.

Genetic and epigenetic sex-specific adaptations to endurance exercise

In recent years, the interest in personalised interventions such as medicine, nutrition, and exercise is rapidly rising to maximize health outcomes and ensure the most appropriate treatments. Exercising regularly is recommended for both healthy and diseased populations to improve health. However, there are sex-specific adaptations to exercise that often are not taken into consideration. While endurance exercise training alters the human skeletal muscle epigenome and subsequent gene expression, it is still unknown whether it does so differently in men and women, potentially leading to sex-specific physiological adaptations. Elucidating sex differences in genetics, epigenetics, gene regulation and expression in response to exercise will have great health implications, as it may enable gene targets in future clinical interventions and may better individualised interventions. This review will cover this topic and highlight the recent findings of sex-specific genetic, epigenetic, and gene expression studies, address the gaps in the field, and offer recommendations for future research.

The Development of a Personalised Training Framework: Implementation of Emerging Technologies for Performance

Over the last decade, there has been considerable interest in the individualisation of athlete training, including the use of genetic information, alongside more advanced data capture and analysis techniques. Here, we explore the evidence for, and practical use of, a number of these emerging technologies, including the measurement and quantification of epigenetic changes, microbiome analysis and the use of cell-free DNA, along with data mining and machine learning. In doing so, we develop a theoretical model for the use of these technologies in an elite sport setting, allowing the coach to better answer six key questions: (1) To what training will my athlete best respond? (2) How well is my athlete adapting to training? (3) When should I change the training stimulus (i.e., has the athlete reached their adaptive ceiling for this training modality)? (4) How long will it take for a certain adaptation to occur? (5) How well is my athlete tolerating the current training load? (6) What load can my athlete handle today? Special consideration is given to whether such an individualised training framework will outperform current methods as well as the challenges in implementing this approach.

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.

Identification of putative second genetic hits in schizophrenia carriers of high-risk copy number variants and resequencing in additional samples

Copy number variants (CNVs) conferring risk of schizophrenia present incomplete penetrance, suggesting the existence of second genetic hits. Identification of second hits may help to find genes with rare variants of susceptibility to schizophrenia. The aim of this work was to search for second hits of moderate/high risk in schizophrenia carriers of risk CNVs and resequencing of the relevant genes in additional samples. To this end, ten patients with risk CNVs at cytobands 15q11.2, 15q11.2-13.1, 16p11.2, or 16p13.11, were subjected to whole-exome sequencing. Rare single nucleotide variants, defined as those absent from main public databases, were classified according to bioinformatic prediction of pathogenicity by CADD scores. The average number of rare predicted pathogenic variants per sample was 13.6 (SD 2.01). Two genes, BFAR and SYNJ1, presented rare predicted pathogenic variants in more than one sample. Follow-up resequencing of these genes in 432 additional cases and 432 controls identified a significant excess of rare predicted pathogenic variants in case samples at SYNJ1. Taking into account its function in clathrin-mediated synaptic vesicle endocytosis at presynaptic terminals, our results suggest an impairment of this process in schizophrenia.

An innovative way to highlight the power of each polymorphism on elite athletes phenotype expression

The purpose of this study was to determine the probability of soccer players having the best genetic background that could increase performance, evaluating the polymorphism that are considered Performance Enhancing Polymorphism (PEPs) distributed on five genes: PPARα, PPARGC1A, NRF2, ACE e CKMM. Particularly, we investigated how each polymorphism works directly or through another polymorphism to distinguish elite athletes from non-athletic population. Sixty professional soccer players (age 22.5 ± 2.2) and sixty healthy volunteers (age 21.2± 2.3) were enrolled. Samples of venous blood was used to prepare genomic DNA. The polymorphic sites were scanned using PCR-RFLP protocols with different enzyme. We used a multivariate logistic regression analysis to demonstrate an association between the five PEPs and elite phenotype. We found statistical significance in NRF2 (AG/GG genotype) polymorphism/soccer players association (p < 0.05) as well as a stronger association in ACE polymorphism (p =0.02). Particularly, we noticed that the ACE ID genotype and even more the II genotype are associated with soccer player phenotype. Although the other PEPs had no statistical significance, we proved that some of these may work indirectly, amplifying the effect of another polymorphism; for example, seems that PPARα could acts on NRF2 (GG) enhancing the effect of the latter, notwithstanding it had not shown a statistical significance.

In conclusion, to establish if a polymorphism can influence the performance, it is necessary to understand how they act and interact, directly and indirectly, on each other.

ACTN3: More than Just a Gene for Speed

Over the last couple of decades, research has focused on attempting to understand the genetic influence on sports performance. This has led to the identification of a number of candidate genes which may help differentiate between elite and non-elite athletes. One of the most promising genes in that regard is ACTN3, which has commonly been referred to as “a gene for speed”. Recent research has examined the influence of this gene on other performance phenotypes, including exercise adaptation, exercise recovery, and sporting injury risk. In this review, we identified 19 studies exploring these phenotypes. Whilst there was large variation in the results of these studies, as well as extremely heterogeneous cohorts, there is overall a tentative consensus that ACTN3 genotype can impact the phenotypes of interest. In particular, the R allele of a common polymorphism (R577X) is associated with enhanced improvements in strength, protection from eccentric training-induced muscle damage, and sports injury. This illustrates that ACTN3 is more than just a gene for speed, with potentially wide-ranging influence on muscle function, knowledge of which may aid in the future personalization of exercise training programmes.

Nine genetic polymorphisms associated with power athlete status - A Meta-Analysis

OBJECTIVES

In this study the association between genetic polymorphisms and power athlete status with possible interference by race and sex was investigated to identify genetic variants favourable for becoming a power athlete.

DESIGN

This meta-analysis included both, case-control and Cohort studies.

METHODS

Databases of PubMed and Web of Science were searched for studies reporting on genetic polymorphisms associated with the status of being a power athlete. Thirty-five articles published between 2008 and 2016 were identified as eligible including a total number of 5834 power athletes and 14,018 controls. A series of meta-analyses were conducted for each of the identified genetic polymorphisms associated with power athlete status. Odds ratios (ORs) based on the allele and genotype frequency with corresponding 95% confidence intervals (95%CI) were calculated per genetic variant. Heterogeneity of the studies was addressed by Chi-square based Q-statistics at 5% significance level and a fixed or random effects model was used in absence or presence of heterogeneity respectively. Stratified analyses were conducted by race and sex to explore potential sources of heterogeneity.

RESULTS

Significant associations were found for the genetic polymorphisms in the ACE (rs4363, rs1799752), ACTN3 (rs1815739), AGT (rs699), IL6-174 (rs1800795), MnSOD (rs1799725), NOS3 (rs1799983, rs2070744) and SOD2 (rs4880) genes.

CONCLUSIONS

Nine genetic polymorphisms have been identified in the meta-analyses to have a significant association with the status of being a power athlete. Nevertheless, more research on the investigated genes needs to be done to draw comprehensive conclusions.

The influence of genetic polymorphisms on performance and cardiac and hemodynamic parameters among Brazilian soccer players

This study investigated whether ACTN3 R577X, AMPD1 C34T, I/D ACE, and M235T AGT polymorphisms can affect performance tests such as jumping, sprinting, and endurance in 220 young male athletes from professional minor league soccer team from São Paulo Futebol Clube, Brazil. I/D ACE and M235T AGT polymorphisms were also analyzed according to cardiac and hemodynamic parameters. Athletes were grouped or not by age. DNA from saliva and Taqman assays were used for genotyping 220 athletes and the results were associated with performance tests. Ventricle mass, ventricle end-diastolic diameter, end-diastolic volume, and ejection fraction were assessed by echocardiogram. Arterial pressure, heart rate, and oximetry were assessed by a cardioscope. The main results of this study were that athletes who carried RR/RX (ACTN3) and DD (ACE) genotypes presented better performance during jump and sprint tests. On the other hand, athletes with ID/II genotype presented better results during endurance test, while AGT genotypes did not seem to favor the athletes during the evaluated physical tests. CC genotype (AMPD1) only favored the athletes during 10-m sprint test. Although there are environmental interactions influencing performance, the present results suggest that RR/RX ACTN3 and ACE DD genotypes may benefit athletes in activities that require strength and speed, while II ACE genotype may benefit athletes in endurance activities. This information could help coaches to plan the training session to improve the athletes’ performance.

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

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

Persistent fibrosis, hypertrophy and sarcomere disorganisation after endoscopy-guided heart resection in adult Xenopus

Models of cardiac repair are needed to understand mechanisms underlying failure to regenerate in human cardiac tissue. Such studies are currently dominated by the use of zebrafish and mice. Remarkably, it is between these two evolutionary separated species that the adult cardiac regenerative capacity is thought to be lost, but causes of this difference remain largely unknown. Amphibians, evolutionary positioned between these two models, are of particular interest to help fill this lack of knowledge. We thus developed an endoscopy-based resection method to explore the consequences of cardiac injury in adult Xenopus laevis. This method allowed in situ live heart observation, standardised tissue amputation size and reproducibility. During the first week following amputation, gene expression of cell proliferation markers remained unchanged, whereas those relating to sarcomere organisation decreased and markers of inflammation, fibrosis and hypertrophy increased. One-month post-amputation, fibrosis and hypertrophy were evident at the injury site, persisting through 11 months. Moreover, cardiomyocyte sarcomere organisation deteriorated early following amputation, and was not completely recovered as far as 11 months later. We conclude that the adult Xenopus heart is unable to regenerate, displaying cellular and molecular marks of scarring. Our work suggests that, contrary to urodeles and teleosts, with the exception of medaka, adult anurans share a cardiac injury outcome similar to adult mammals. This observation is at odds with current hypotheses that link loss of cardiac regenerative capacity with acquisition of homeothermy.

Individual and Combined Influence of ACE and ACTN3 Genes on Muscle Phenotypes in Polish Athletes

Orysiak, J, Mazur-Różycka, J, Busko, K, Gajewski, J, Szczepanska, B, and Malczewska-Lenczowska, J. Individual and combined influence of ACE and ACTN3 genes on muscle phenotypes in polish athletes. J Strength Cond Res 32(10): 2776-2782, 2018-The aim of this study was to examine the association between angiotensin-converting enzyme (ACE) and α-actinin-3 (ACTN3) genes, independently or in combination, and muscle strength and power in male and female athletes. The study involved 398 young male (n = 266) and female (n = 132) athletes representing various sport disciplines (ice hockey, canoeing, swimming, and volleyball). All were Caucasians. The following measurements were taken: height of jump and mechanical power in countermovement jump (CMJ) and spike jump (SPJ), and muscle strength of 10 muscle groups (flexors and extensors of the elbow, shoulder, hip, knee, and trunk). The insertion-deletion (I/D) polymorphism of ACE and the R577X polymorphism of ACTN3 were typed using polymerase chain reaction (PCR) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), respectively. The genotype distribution of the ACE and ACTN3 genes did not differ significantly between groups of athletes for either sex. There was no association between ACE and ACTN3 genotypes (alone or in combination) and sum of muscle strength, height of jump or mechanical power in both jump tests (CMJ and SPJ) for male and female athletes. These findings do not support an influential role of the ACE and ACTN3 genes in determining power/strength performance of elite athletes.

Genetic characterization of physical activity behaviours in university students enrolled in kinesiology degree programs

Studies of physical activity behaviours have increasingly shown the importance of heritable factors such as genetic variation. Nonsynonymous polymorphisms of alpha-actinin 3 (ACTN3) and the β-adrenergic receptors 1 and 3 (ADRB1 and ADRB3) have been previously associated with exercise capacity and cardiometabolic health. We thus hypothesized that these polymorphisms are also related to physical activity behaviours in young adults. To test this hypothesis we examined relationships between ACTN3 (R577X), ARDB1 (Arg389Gly), ADRB3 (Trp64Arg), and physical activity behaviours in university students. We stratified for student enrollment in kinesiology degree programs compared with nonmajors as we previously found this to be a predictor of physical activity. We did not identify novel associations between physical activity and ACTN3. However, the minor alleles of ADRB1 and ADRB3 were significantly underrepresented in kinesiology students compared with nonmajors. Furthermore, carriers of the ADRB1 minor allele reported reduced participation in moderate physical activity and increased afternoon fatigue compared with ancestral allele homozygotes. Together, these findings suggest that the heritability of physical activity behaviours in young adults may be linked to nonsynonymous polymorphisms within β-adrenergic receptors.

Genetic variation and exercise-induced muscle damage: implications for athletic performance, injury and ageing

Prolonged unaccustomed exercise involving muscle lengthening (eccentric) actions can result in ultrastructural muscle disruption, impaired excitation-contraction coupling, inflammation and muscle protein degradation. This process is associated with delayed onset muscle soreness and is referred to as exercise-induced muscle damage. Although a certain amount of muscle damage may be necessary for adaptation to occur, excessive damage or inadequate recovery from exercise-induced muscle damage can increase injury risk, particularly in older individuals, who experience more damage and require longer to recover from muscle damaging exercise than younger adults. Furthermore, it is apparent that inter-individual variation exists in the response to exercise-induced muscle damage, and there is evidence that genetic variability may play a key role. Although this area of research is in its infancy, certain gene variations, or polymorphisms have been associated with exercise-induced muscle damage (i.e. individuals with certain genotypes experience greater muscle damage, and require longer recovery, following strenuous exercise). These polymorphisms include ACTN3 (R577X, rs1815739), TNF (-308 G>A, rs1800629), IL6 (-174 G>C, rs1800795), and IGF2 (ApaI, 17200 G>A, rs680). Knowing how someone is likely to respond to a particular type of exercise could help coaches/practitioners individualise the exercise training of their athletes/patients, thus maximising recovery and adaptation, while reducing overload-associated injury risk. The purpose of this review is to provide a critical analysis of the literature concerning gene polymorphisms associated with exercise-induced muscle damage, both in young and older individuals, and to highlight the potential mechanisms underpinning these associations, thus providing a better understanding of exercise-induced muscle damage.