ACTN3 Genotype Research Articles

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.

ACTN3 R577X Genotype and Exercise Phenotypes in Recreational Marathon Runners.

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

Effect of ACTN3 Polymorphism on Self-reported Running Times.

Kreutzer, A, Martinez, CA, Kreutzer, M, Stone, JD, Mitchell, JB, and Oliver, JM. Effect of ACTN3 polymorphism on self-reported running times. J Strength Cond Res 33(1): 80-88, 2019-This investigation examined the effect of ACTN3 genotype on self-reported distance running personal records (PRs). Of 94 (n = 94) recreationally active men and women, 82 (f = 42, m = 40; age: 22.6 ± 4.5 years; body mass index [BMI]: 23.5 ± 3.4 kg·m) reported 1-mile running PRs, whereas 57 (f = 33, m = 24; age: 23.4 ± 5.3 years; BMI: 22.9 ± 9.3 kg·m) reported 5K running PRs. Subjects were grouped by the presence (ACTN3) or absence (ACTN3) of α-actinin-3, as well as by individual genotype (RR, RX, and XX). Among female participants, ACTN3 reported 64.5 seconds faster (p = 0.048) 1-mile PRs compared with their ACTN3 counterparts. No differences were observed when comparing 5K PRs between genotypes. Two one-sided test equivalence testing revealed that none of the effects observed when comparing ACTN3 and ACTN3 were equivalent to zero. Our study confirms a reportedly greater prevalence of XX benefits for endurance performance in females when compared with males but fails to strongly link ACTN3 genotype to endurance performance. Practitioners should continue to be cautious when using genetic information for talent identification and sport selection.

Associação dos genótipos da ACTN3 aos indicadores de desempenho em atletas juvenis da natação brasileira especialistas em curtas distâncias

Foi objetivo da pesquisa identificar a frequência genotípica da ACTN3 e associa-la ao índice técnico (IT) e ao status de elite em 98 atletas juvenis de natação (16,80 ± 0,63 anos) especialistas em curtas distâncias (≤ 200m). Um grupo controle (GC) com 101 escolares não-atletas (16,52 ± 0,94 anos) foi incluído nas comparações. Os grupos foram analisados sem divisão por sexo. Os atletas foram divididos pelas experiências competitivas em elite (internacionais, n = 15) e sub-elite (nacionais, n = 83). Não verificou-se diferenças significativas (X2) na frequência genotípica entre atletas sub-elite e GC. Os atletas de elite apresentaram supremacia do genótipo RX (60,0%), baixa frequência do genótipo RR (13,3%), supremacia do alelo X (54,2%) e da adição RX+XX (86,7%). O ajuste das frequências genotípicas pelo quartil superior (QS) do IT revelou que os atletas com genótipos RR+RX apresentaram maior pontuação média (820,6 ± 40,0) quando comparados aos atletas XX (806,7 ± 34,8). Atletas de elite do grupo QS (RR+RX) apresentaram valores médios do IT ainda mais expressivos (853,9 ± 31,3). Os genótipos da ACTN3 demonstraram boa associação aos fenótipos da força/potência apenas entre os atletas identificados nos mais altos níveis de desempenho. 

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

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.

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.

PO-008 Influences of ACE I/D and ACTN3 R577X polymorphisms in elite female soccer athletes

Objective The performance phenotype is regulated by polygenes .There were few reports about the cumulative effect of the I/D polymorphism in the angiotensin I-converting enzyme (ACE) gene and ACTN3 in athletes.This study was to investigate the association of ACEI/D and ACTN3 R577X polymorphisms with the performance of Chinese elite female soccer athletes for the first time. 
 Methods The genotype distributions of ACE I/D and ACTN3 R577X in the athlete group (N=92) and the control group of Chinese females (N=200) were evaluated via PCR and compared.
 Results Regarding the distribution of ACE polymorphisms, the genotype frequency was indifferent between the athletes (II 40.2%, ID 46.7%, DD 13.1%) and the controls (II 42%, ID 48%, DD 10%) based on the chi-square test. No difference in the I/D allele frequency was observed between the athlete group (I allele: 59.25%; D allele: 40.75%) and the control group (I allele: 60.8%; D allele: 39.2%). Regarding the distribution of ACTN3 polymorphisms, the genotype frequency was significantly different between the athletes (XX 0%, XR 53.3%, RR 46.7%) and the controls (XX 16%, XR 44%, RR 40%). The allele frequency was observed no different between the athlete and the control group (X allele:34.8%/41.7%; R allele: 65.2%/58.3%, respectively). The ACE and ACTN3 genotype combinations (II/ID/DD+RR/XR) significantly differed between the athletes and the controls by χ2 test (p<0.05).
 Conclusions These results suggested that the Chinese elite female soccer athletes were more likely to harbor the I allele and the R allele and that the combination of ACE II/ID and ACTN3 RR/XR was a synergetic determinant of the athletic performance of females in soccer.

Is training‐induced increase in muscle mass influenced by ACTN3 genotype?

INTRODUCTIONAlpha‐actinin‐3 is a skeletal muscle specific protein. A polymorphism in the ACTN3 gene (R577X) results in lack of alpha‐actinin‐3 protein in skeletal muscle of individuals with XX‐genotype. In sprint/power oriented elite athletes the prevalence of the X‐allele is much lower than in control populations, implying that lack of alpha‐actinin‐3 is detrimental for these athletes. The mechanistic link, however, is not fully established. Actn3 knock‐out mice are shown to have lower muscle mass. We have previously reported that humans with XX‐genotype have lower activation of mTOR‐signaling pathway in response to acute sprint exercise. This may indicate that the XX‐genotype is associated with an attenuated skeletal muscle hypertrophy in response to exercise. The aim of the present study was to examine the impact of ACTN3 genotype on hypertrophy signaling in skeletal muscle and on training‐induced increase in muscle mass.METHODS69 male and female subjects participating in five different longitudinal training studies with different training conditions were investigated. 20 subjects performed 5 weeks of supervised progressive knee‐extensor resistance training (study 1), 16 subjects performed 8 weeks of the same resistance training but with intervention by oral intake of acetylic acid (study 2) and 19 subjects performed 10 weeks of combined leg‐press and knee‐extensor resistance training with one leg (study 3a) followed by a detraining period and a new 5 weeks of the same resistance training but with both legs (pre‐trained leg (study 3b) and previously untrained leg (study 3c)). The volume of m. quadriceps, before and after the training periods, was assessed by MRI (study 1 and 2) or ultrasonography (study 3a, 3b and 3c). Muscle samples obtained in connection with an acute exercise bout in each study were analyzed for phosphorylation of p70S6k by western blot. DNA was extracted from muscle samples and genotyping for the R577X polymorphism was performed by allelic discrimination.RESULTSThe mean relative increase in muscle volume with training was (mean ±SD) 9.7 ±6 % and there was no significant difference between the studies. Therefore the impact of ACTN3 genotype on the training‐induced increase in muscle mass was analyzed in pooled data from all five studies. The relative increase in muscle volume in the different ACTN3 genotypes was (mean ±SD) 10.5 ±6 % in RR, 9.4 ±5 % in RX and 8.4 ±6 % in XX. The acute‐exercise induced increase in relative phosphorylation of p70S6k was (mean ±SD) 25 ±36 % in RR, 14 ±25 % in RX and 10 ±7% in XX. The observed differences between ACTN3‐genotypes were found to be not statistically significant.CONCLUSIONDespite the fact, that the relative increase in muscle volume and phosphorylation of p70S6k was numerically lower in the XX‐genotype as compared to RR and RX, there were no statistically significant differences between the genotypes. Our hypothesis, that ACTN3 genotype is a genetic modifier important for regulation of muscle mass, could thus not be confirmed by a present investigation. A type 2 error cannot be excluded, however, due to, the in general, low relative increase in muscle volume by this type of intervention.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

ACTN3 genotype and physical function and frailty in an elderly Chinese population: the Rugao Longevity and Ageing Study.

To examine the associations of the actinin alpha 3 gene (ACTN3) R577X polymorphism with physical performance and frailty in an older Chinese population. Data from 1,463 individuals (57.8% female) aged 70-87 years from the Rugao Longevity and Ageing Study were used. The associations between R577X and timed 5-m walk, grip strength, timed Up and Go test, and frailty index (FI) based on deficits of 23 laboratory tests (FI-Lab) were examined. Analysis of variance and linear regression models were used to evaluate the genetic effects of ACTN3 R577X on physical performance and FI-Lab. The XX and RX genotypes of the ACTN3 R557X polymorphism accounted for 17.1 and 46.9%, respectively. Multivariate regression analysis revealed that in men aged 70-79 years, the ACTN3 577X allele was significantly associated with physical performance (5-m walk time, regression coefficient (β) = 0.258, P = 0.006; grip strength, β = -1.062, P = 0.012; Up and Go test time β = 0.368, P = 0.019). In women aged 70-79 years, a significant association between the ACTN3 577X allele and the FI-Lab score was observed, with a regression coefficient of β = 0.019 (P = 0.003). These findings suggest an age- and gender-specific X-additive model of R577X for 5-m walk time, grip strength, Up and Go Test time, and FI-Lab score. The ACTN3 577X allele is associated with an age- and sex-specific decrease in physical performance and an increase in frailty in an older population.

ACTN3, Morbidity, and Healthy Aging.

As human longevity increases, recent research has focused on the maintenance of optimal health during old age. One such area of focus is that of muscle function in the elderly, with a loss of muscle mass increasing the risk of negative outcomes such as sarcopenia and a decrease in bone mineral density. In this mini-review, we focus on the impact of a single nucleotide polymorphism in ACTN3, shown to impact muscle phenotype in elite athletes, on loss of muscle function, maintenance of bone mineral density, and metabolic disorder risk in an elderly population. From the surveyed research, this polymorphism has a clear and demonstrable impact on muscle phenotype and bone mineral density in this population, and acts as a potential modulator for metabolic disorders. As such, knowledge of an individual’s ACTN3 genotype may better inform the management of risk factors in the elderly, as well as driving innovations in exercise program design. Subsequently, such insights may contribute to the prolonged maintenance of health and function long into old age.

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.

Influence of ACTN3 R/X gene polymorphisms on racing strategy in rowing athletes

This study compared the polymorphisms RR, XX and RX of the ACTN3 gene among rowers with different race strategies across competitive levels and weight categories. We evaluated 137 rowers divided into: male non-elite openweight (n = 23), male elite openweight (n = 33), male non-elite lightweight (n = 31), male elite lightweight (n = 13), female non-elite openweight (n = 9), female elite openweight (n = 9) and female non-elite lightweight (n = 15), female elite lightweight (n = 4). The main results indicated that rowers who adopted starting/early (within the initial 500 m) or finishing/late (within the final 500 m) strategies exhibited similar ACTN3 genotype frequencies, while fewer athletes who adopted moderate (within the middle 1000 m) pacing strategies were categorised with the ACTN3 XX (8%) genotype as compared to the RR (50%) and RX (42%) genotypes (p = 0.002). Elite openweight male rowers with the ACTN3 RR more frequently preferred moderate pacing strategies (p = 0.006), while non-elite lightweight male athletes with ACTN3 RR more frequently preferred starting/early pacing strategies (p ≤ 0.001). Therefore, rowing athletes with specific ACTN3 genotypes may adopt unique race pacing strategies, while no differences were shown by competitive level or weight category.

The Effect Of ACTN3 Genotype On Self-reported One-mile Running Time In Young, Recreationally Active Women

Alpha-actinins form a crosslink between actin filaments and adjacent sarcomeres, and play a role in signaling and energy metabolism. Alpha-actinin-3, is encoded by the ACTN3 gene and only presents in Type II muscle fibers. Homozygosity for the 577X allele (XX) results in complete deficiency of α-actinin-3 and a compensatory upregulation of α-actinin-2, whereas heterozygosity (RX) and homozygosity for the 577R allele (RR) provide for the production of α-actinin-3. Research has reported a greater proportion of elite female distance runners are homozygous for the 577X allele compared to controls. However, no study to date has examined that apparent relationship in recreational women runners. PURPOSE: To examine the effect of ACTN3 genotype on self-reported one-mile running personal records (PR) in young, recreationally active women. METHODS: Thirty nine participants, grouped by the presence (RR+RX: n=27, age: 21.7 ± 3.8 years, BMI: 22.9 ± 3.3 kg/m2) or absence (XX: n=12, age: 21.2 ± 3.2 years, BMI: 21.5 ± 1.8 kg/m2) of the 577R allele, reported one-mile running PR. Genotype effects were examined using independent-sample t-tests and magnitude-based inference (MBI). RESULTS: A trend (p=0.065) toward faster one-mile times was observed in XX genotypes (415.7 ± 78.9 s) when compared to the RR+RX group (480.3 ± 104.8 s). MBI revealed a mechanistically beneficial effect of XX genotype (mean difference; ± 90% CI; -65 s, ± 57 s). Similar observations were made among a subset of thirteen faster runners, who reported a one-mile PR of less than seven minutes (RR+RX: n=7, age: 21.9 ± 5.0 years, BMI: 20.9 ± 3.4 kg/m2; XX: n=6, age: 19.5 ± 0.5 years; BMI: 21.8 ± 1.5 kg/m2). Though not statistically significant (p=0.378), those in the XX group (355.8 ± 46.5 s) reported 5.4% faster times than those in the RR+RX group (376.3 ± 33.6 s). MBI revealed a mechanistically beneficial effect of XX genotype (-20 s; ± 40 s). CONCLUSION: These findings suggest a potential benefit of XX genotype on middle-distance endurance performance. This is in agreement with prior investigations that have linked XX genotype to endurance capabilities in elite female athletes.

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

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

Exploring the relationship between \u03b1-actinin-3 deficiency and obesity in mice and humans

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

The influence of α-actinin-3 deficiency on bone remodelling markers in young men

There is a large individual variation in the bone remodelling markers (BRMs) osteocalcin (OC), procollagen 1 N-terminal propeptide (P1NP) and β-isomerized C-terminal telopeptide (β-CTx), as well as undercarboxylated osteocalcin (ucOC), at rest and in response to exercise. α-actinin-3 (ACTN3), a sarcomeric protein, is expressed in skeletal muscle and osteoblasts and may influence BRM levels and the cross-talk between muscle and bone. We tested the levels of serum BRMs in α-actinin-3 deficient humans (ACTN3 XX) at baseline, and following a single bout of exercise. Forty-three healthy Caucasian individuals were divided into three groups (ACTN3 XX, n=13; ACTN3 RX, n=16; ACTN3 RR, n=14). Participants completed a single session of High Intensity Interval Exercise (HIIE) on a cycle ergometer (8×2-min intervals at 85% of maximal power). Blood samples were taken before, immediately after, and three hours post exercise to identify the peak changes in serum BRMs. There was a stepwise increase in resting serum BRMs across the ACTN3 genotypes (XX>RX>RR) with significantly higher levels of tOC ~26%, P1NP ~34%, and β-CTX (~33%) in those with ACTN3 XX compared to ACTN3 RR. Following exercise BRMs and ucOC were higher in all three ACTN3 genotypes, with no significant differences between groups.Serum levels of tOC, P1NP and β-CTX are higher in men with ACTN3 XX genotype (α-actinin-3 deficiency) compared to RR and RX. It appears that the response of BRMs and ucOC to exercise is not explained by the ACTN3 genotype.

ACTN3 genotype influences exercise-induced muscle damage during a marathon competition

Exercise-induced muscle damage has been identified as one of the main causes of the progressive decrease in running and muscular performance in marathoners. The aim of this investigation was to determine the influence of the ACTN3 genotype on exercise-induced muscle damage produced during a marathon. Seventy-one experienced runners competed in a marathon race. Before and after the race, a sample of venous blood was obtained and maximal voluntary leg muscle power was measured during a countermovement jump. In the blood samples, the ACTN3 genotype (R577X) and the changes in serum creatine kinase and myoglobin concentrations were measured. Data from RX heterozygotes and XX mutant homozygotes were grouped as X allele carriers and compared to RR homozygotes. At the end of the race, X allele carriers presented higher serum myoglobin (774 ± 852 vs 487 ± 367 UL-1; P = 0.02) and creatine kinase concentrations (508 ± 346 vs 359 ± 170ngmL-1; P = 0.04) than RR homozygotes. Pre-to-post-race maximal voluntary leg muscle power reduction was more pronounced in X allele carriers than RR homozygotes (-34.4 ± 16.1 vs -27.3 ± 15.4%; P = 0.05). X allele carriers self-reported higher levels of lower limb muscle pain (7 ± 2 vs 6 ± 2cm; P = 0.02) than RR homozygotes at the end of the race. In comparison to RR homozygotes, X allele carriers for the R577X polymorphism of the ACTN3 gene presented higher values for typical markers of exercise-induced muscle damage during a competitive marathon. Thus, the absence of a functional α-actinin-3 produced by the X allele might induce higher levels of muscle breakdown during prolonged running events.

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.

ACE and ACTN3 Genotypes with Physical Fitness and Performance in Collegiate Elite Alpine Ski Racer

ACE and ACTN3 Genotypes with Physical Fitness and Performance in Collegiate Elite Alpine Ski Racer

ACTN3 X-allele carriers had greater levels of muscle damage during a half-ironman.

Alpha-actinin-3, encoded by the ACTN3 gene, is an actin-binding protein with an important role in myofibril contraction and muscle force output. In humans, there is a relatively common deficiency of the α-actinin-3 due to homozygosity in a polymorphism of the ACTN3 gene (R577X, rs1815739), that has been related to decreased resistance to strain during voluntary muscle contractions. The purpose of this study was to investigate the influence of the ACTN3 genotype on the level of exercise-induced muscle damage attained by 23 experienced triathletes during an official half-ironman competition. Before and after the race, a sample of venous blood was obtained and jump height was measured during a countermovement jump. The changes in serum creatine kinase (CK-MM isoform) were measured in the blood samples and muscle pain was measured with a visual analogue scale (0-10cm). Data from RX heterozygotes and XX mutant homozygotes were grouped as X-allele carriers (n=13) and compared to RR homozygotes (n=10). Race time was very similar between groups (313±31 vs. 313±25min; P=0.45); however, pre-to-post-competition reduction in jump height was greater in X-allele carriers than RR homozygotes (-18.4±11.4 vs. -8.2±6.9%; P=0.04). At the end of the race, X-allele carriers presented higher serum CK-MM concentrations (682±144 vs. 472±269U/L; P=0.03), and there was also a tendency for higher self-reported values of lower limb muscle pain (7.7±1.1 vs. 6.3±2.3cm; P=0.06). X-allele triathletes in the ACTN3 R577X polymorphism presented greater signs of exercise-induced muscle damage during a half-ironman race than RR homozygotes.