Relationships between the Expression of the ACTN3 Gene and Explosive Power of Soccer Players

A Systematic Review and Meta-analysis of the Association Between ACTN3 R577X Genotypes and Performance in Endurance Versus Power Athletes and Non-athletes

BACKGROUND

Previous studies reported differences in genotype frequency of the ACTN3 R577X polymorphisms (rs1815739; RR, RX and XX) in athletes and non-athletic populations. This systematic review with meta-analysis assessed ACTN3 R577X genotype frequencies in power versus endurance athletes and non-athletes.

METHODS

Five electronic databases (PubMed, Web of Science, Scopus, Science Direct, SPORTDiscus) were searched for research articles published until December 31st, 2022. Studies were included if they reported the frequency of the ACTN3 R577X genotypes in power athletes (e.g., weightlifters) and if they included a comparison with endurance athletes (e.g., long-distance runners) or non-athletic controls. A meta-analysis was then performed using either fixed or random-effects models. Pooled odds ratios (OR) were determined. Heterogeneity was detected using I2 and Cochran's Q tests. Publication bias and sensitivity analysis tests were computed.

RESULTS

After screening 476 initial registrations, 25 studies were included in the final analysis (13 different countries; 14,541 participants). In power athletes, the RX genotype was predominant over the two other genotypes: RR versus RX (OR 0.70; 95% CI 0.57-0.85, p = 0.0005), RR versus XX (OR 4.26; 95% CI 3.19-5.69, p < 0.00001), RX versus XX (OR 6.58; 95% CI 5.66-7.67, p < 0.00001). The R allele was higher than the X allele (OR 2.87; 95% CI 2.35-3.50, p < 0.00001) in power athletes. Additionally, the frequency of the RR genotype was higher in power athletes than in non-athletes (OR 1.48; 95% CI 1.25-1.75, p < 0.00001). The RX genotype was similar in both groups (OR 0.84; 95% CI 0.71-1.00, p = 0.06). The XX genotype was lower in power athletes than in controls (OR 0.73; 95% CI 0.64-0.84, p < 0.00001). Furthermore, the R allele frequency was higher in power athletes than in controls (OR 1.28; 95% CI 1.19-1.38, p < 0.00001). Conversely, a higher frequency of X allele was observed in the control group compared to power athletes (OR 0.78; 95% CI 0.73-0.84, p < 0.00001). On the other hand, the frequency of the RR genotype was higher in power athletes than in endurance athletes (OR 1.27; 95% CI 1.09-1.49, p = 0.003). The frequency of the RX genotype was similar in both groups (OR 1.07; 95% CI 0.93-1.24, p = 0.36). In contrast, the frequency of the XX genotype was lower in power athletes than in endurance athletes (OR 0.63; 95% CI 0.52-0.76, p < 0.00001). In addition, the R allele was higher in power athletes than in endurance athletes (OR 1.32; 95% CI 1.11-1.57, p = 0.002). However, the X allele was higher in endurance athletes compared to power athletes (OR 0.76; 95% CI 0.64-0.90, p = 0.002). Finally, the genotypic and allelic frequency of ACTN3 genes were similar in male and female power athletes.

CONCLUSIONS

The pattern of the frequencies of the ACTN3 R577X genotypes in power athletes was RX > RR > XX. However, the RR genotype and R allele were overrepresented in power athletes compared to non-athletes and endurance athletes. These data suggest that the RR genotype and R allele, which is associated with a normal expression of α-actinin-3 in fast-twitch muscle fibers, may offer some benefit in improving performance development in muscle strength and power.

Prevalence of Polymorphism and Post-Training Expression of ACTN3 (R/X) and ACE (I/D) Genes in CrossFit Athletes

BACKGROUND

CrossFit is known as a functional fitness training high-intensity exercise to improve physical performance. The most studied polymorphisms are the ACTN3 R577X gene, known for speed, power, and strength, and ACE I/D, related to endurance and strength. The present investigation analyzed the effects of training on ACTN3 and ACE gene expression in CrossFit athletes for 12 weeks.

METHODS

the studies included 18 athletes from the Rx category, where ACTN3 (RR, RX, XX) and ACE (II, ID, DD) characterization of genotypes and tests of maximum strength (NSCA), power (T-Force), and aerobic endurance (Course Navette) were performed. The technique used was the reverse transcription-quantitative PCR real-time polymerase chain reaction (RT-qPCR) for the relative expression analysis.

RESULTS

the relative quantification (RQ) values for the ACTN3 gene increased their levels 2.3 times (p = 0.035), and for ACE, they increased 3.0 times (p = 0.049).

CONCLUSIONS

there is an overexpression of the ACTN3 and ACE genes due to the effect of training for 12 weeks. Additionally, the correlation of the expression of the ACTN3 (p = 0.040) and ACE (p = 0.030) genes with power was verified.

Genetic characteristics of competitive swimmers: a review

A successful swimming performance is a multi-factorial accomplishment, resulting from a complex interaction of physical, biomechanical, physiological and psychological factors, all of which are strongly affected by the special medium of water as well as by genetic factors. The nature of competitive swimming is unique, as most of the competitive events last less than four minutes. Yet training regimens have an endurance nature (many hours and many kilometres of swimming every day), which makes it impossible to classify swimming by definitions of aerobic-type or anaerobic-type events, as in track and field sports. Therefore, genetic variants associated with swimming performance are not necessarily related to metabolic pathways, but rather to blood lactate transport (MCT1), muscle functioning (IGF1 axis), muscle damage (IL6) and others. The current paper reviews the main findings on the leading 12 genetic polymorphisms (located in the ACE, ACTN3, AMPD1, BDKRB2, IGF1, IL6, MCT1, MSTN, NOS3, PPARA, PPARGC1A, and VEGFR2 genes) related to swimming performance, while taking into consideration the unique environment of this sport.

Accelerometers Provide Early Genetic Selection Criteria for Jumping Horses

The aim of this study was to evaluate the genetic component of the locomotor jumping ability, via a wearable accelerometer sensor, and to estimate the genetic correlation with performance in competition, to introduce such criteria in selection schema. A sample of 1,056 young 3-year-old horses were equipped with a 3-dimensional accelerometer during a free jumping test, in regular breeding shows from 2015 to 2017. Seven variables were extracted from the dorso-ventral acceleration curve for the last three jumps over a double bar obstacle of 1.15 m for the front pole and 1.20 m for the back pole with a 1.20 m spread. Variables were the peaks of forelimbs, hindlimbs, and landing acceleration, the duration between peaks at take-off, the peak of forelimb acceleration and start of jump, jump duration and duration between the beginning of the impact of forelimbs and the peak at landing. During breeding shows, judges scored balance, strength, style, and reactivity for free jumping and jumping tests under saddle. Jumping competition results were recorded by logarithm of the sum of points earned in each competition. All horses in official competitions were included, i.e., 160,257 horses born in 1997 with a total of 649,491 annual performances. An animal mixed model with complete pedigree over four generations (353,236 horses) were used with fixed effects of jumping test location and date, morning/afternoon, gender, month of birth, rank of jump for accelerometric data, effect of year of competition, combined with age and gender for competition results. As a result, jump duration was the most heritable and repeatable for jump variables: h ² = 0.16 (0.06), r = 0.52 (0.02), while accelerations were moderately heritable (h ² = 0.05-0.09, r = 0.39-0.51). Judgement scores were heritable: 0.21 (0.07)-0.33 (0.09) and were highly correlated. Scores during free jumping were genetically correlated to jump duration: 0.71 (0.15)-0.88 (0.16). Both jump duration and judgement scores were genetically correlated to competition performance: 0.59 (0.13) for jump duration, from 0.60 (0.11) to 0.77 (0.12) for scores. Jump duration and judgement scores can be used as early selection criteria. The advantage of the accelerometric measurement is its objectivity and the ease of recording.