ACTN3 genotype in Spanish elite swimmers: no "heterozygous advantage".

The aim of the present case-control study was to examine the association of the ACTN3 R577X genotype with elite swimming status. We compared a group of Spanish (Caucasian) elite swimmers (n = 88) with other cohorts of the same ethnic origin, i.e., nonathletic controls (n = 343) and other types of athletes who are in both end-points of the sports performance continuum, i.e., world-class power (n = 119) and endurance male athletes (n = 154). Swimmers had a lower odds ratio (OR) of having the RX genotype [1.815, 95% confidence intervals (CI): 0.899-3.664] compared with nonathletic controls, yet the association did not reach statistical significance (P = 0.096). Endurance athletes had greater OR of having the XX genotype (OR: 2.88, 95% CI: 1.162-7.135, P = 0.022), or the RX+XX genotype (OR: 1.903, 95% CI: 1.015-3.567, P = 0.045) compared with swimmers. No other association was found. In summary, we did not observe an association between the ACTN3 R577X polymorphism and elite swimmer's status, suggesting that any influence of this polymorphism is not of sufficient magnitude as to significantly influence elite swimming performance, at least in Spanish athletes.

The C allele in NOS3 -786 T/C polymorphism is associated with elite soccer player's status.

The NOS3-786 T/C polymorphism (rs2070744) is a candidate to explain individual variations in sports related phenotypes. We determined the genotype and allele frequency of NOS3-786 T/C in a group of 60 male professional elite soccer players. Their results were compared with those of 100 world-class endurance athletes, 53 elite power athletes, and 100 sedentary, healthy men (controls) of the same Caucasian (Spanish) origin. There were significant differences in genotype frequencies between soccer players, controls, endurance and power elite athletes (all P ≤ 0.02). These results were confirmed when we analysed allelic frequencies (all P<0.01). The likelihood of having the C allele was higher in soccer players compared with (i) controls [odds ratio (OR), 2.165, 95% confidence interval (CI): 1.362-3.441], (ii) endurance athletes (OR: 1.879, 95%CI: 1.184-2.984), and (iii) power athletes (OR: 4.032, 95%CI: 2.307-7.047). In conclusion, the -786C allele is associated with the status of being an elite soccer player, compared with non-athletic controls and also with elite endurance and power athletes. More research is needed in other groups of elite soccer players in order to replicate the results of the present study.

ACTN3 R577X polymorphism does not influence explosive leg muscle power in elite volleyball players.

We examined the association of R577X polymorphism (rs1815739) in the α-actinin-3 (ACTN3) gene with "explosive" leg muscle power performance in a group of male and female elite volleyball players (n=66, 31 men, 35 women) and in a group of non-athletic male and female young adults (n=334, 243 men, 91 women). We assessed power performance by means of the vertical squat and counter-movement jump tests. We also determined whether the genotypic frequencies of the ACTN3 R577X genotypes differed between groups. We did not observe any effect of the ACTN3 R577X polymorphism on study phenotypes in both groups, regardless of gender (all P>0.05). Genotype frequencies were similar between volleyball and control groups (P=0.095). Moreover, we did not find an association between the ACTN3 R577X polymorphism and the likelihood of being an elite volleyball player using the dominant (RR vs RX+XX) and the recessive model (RR+RX vs XX). In summary, these findings suggest that the ACTN3 R577X polymorphism does not influence explosive leg muscle power in elite volleyball players.

ACE and ACTN3 genes and muscle phenotypes in nonagenarians.

We studied the association of ACE and ACTN3 polymorphisms with skeletal muscle phenotypes (i. e. upper and lower body muscular strength and functional tests) in Spanish nonagenarian subjects [n=41, 33 women, 8 men, age: 90-97 years]. Mean values of the study phenotypes were not significantly different (all P>0.05) between ACE and ACTN3 genotypes. The analyses of the combined effects between genotypes ( ACE DD & ACTN3 RR/RX vs. ACE II/ID & ACTN3 XX) did not yield any significant difference. Our data suggest that, in the elderly, the influence of genetic factors on muscle phenotype traits is not reducible to a few single polymorphisms, including ACE and ACTN3 variants.

Is there an association between ACTN3 R577X polymorphism and muscle power phenotypes in young, non-athletic adults?

We investigated the association between ACTN3 R577X polymorphism and jumping (vertical squat and counter-movement jump tests) and sprint ability (30 m dash) in non-athletic, healthy young adults [N=284 (217 male), mean (SD) age: 21 (2) years]. We analyzed the differences in the study phenotypes among ACTN3 R577X genotypes by one-way analysis of covariance before and after adjusting for sex, age, weight and height (confounders). We also compared the genotype and allele frequencies between those with the best and worst results in the aforementioned tests (≥90th vs <90th of the sex-specific percentile, respectively). We used logistic regression to calculate the odds ratio (OR) for having the best performance. We did not observe a significant association between ACTN3 R577X genotypes and the study phenotypes before and after adjusting for potential confounders, nor after analyzing males and females separately. We did not observe significant differences in genotype frequencies between those with the best or the worst performance. The OR for an individual with the RR genotype to be in the top 10 percentile was <1.00 for jump tests and <1.015 for sprint tests (all P>0.05). In summary, α-actinin-3 deficiency does not negatively influence the ability to generate explosive leg muscle power in a young non-athletic population.